Merge github.com:grpc/grpc into split-me-baby-one-more-time

64 files changed, 2396 insertions, 8049 deletions

diff --git a/src/core/lib/census/README.md b/src/core/lib/census/README.md
deleted file mode 100644
index fb615a2194..0000000000
--- a/src/core/lib/census/README.md
+++ /dev/null
@@ -1,76 +0,0 @@
-<!---
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--->
-
-# Census - a resource measurement and tracing system
-
-This directory contains code for Census, which will ultimately provide the
-following features for any gRPC-using system:
-* A [dapper](http://research.google.com/pubs/pub36356.html)-like tracing
-  system, enabling tracing across a distributed infrastructure.
-* RPC statistics and measurements for key metrics, such as latency, bytes
-  transferred, number of errors etc.
-* Resource measurement framework which can be used for measuring custom
-  metrics. Through the use of [tags](#Tags), these can be broken down across
-  the entire distributed stack.
-* Easy integration of the above with
-  [Google Cloud Trace](https://cloud.google.com/tools/cloud-trace) and
-  [Google Cloud Monitoring](https://cloud.google.com/monitoring/).
-
-## Concepts
-
-### Context
-
-### Operations
-
-### Tags
-
-### Metrics
-
-## API
-
-### Internal/RPC API
-
-### External/Client API
-
-### RPC API
-
-## Files in this directory
-
-Note that files and functions in this directory can be split into two
-categories:
-* Files that define core census library functions. Functions etc. in these
-  files are named census\_\*, and constitute the core census library
-  functionality. At some time in the future, these will become a standalone
-  library.
-* Files that define functions etc. that provide a convenient interface between
-  grpc and the core census functionality. These files are all named
-  grpc\_\*.{c,h}, and define function names beginning with grpc\_census\_\*.
-
diff --git a/src/core/lib/census/aggregation.h b/src/core/lib/census/aggregation.h
deleted file mode 100644
index 088ad808ef..0000000000
--- a/src/core/lib/census/aggregation.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <stddef.h>
-
-#ifndef GRPC_CORE_LIB_CENSUS_AGGREGATION_H
-#define GRPC_CORE_LIB_CENSUS_AGGREGATION_H
-
-/** Structure used to describe an aggregation type. */
-struct census_aggregation_ops {
-  /* Create a new aggregation. The pointer returned can be used in future calls
-     to clone(), free(), record(), data() and reset(). */
-  void *(*create)(const void *create_arg);
-  /* Make a copy of an aggregation created by create() */
-  void *(*clone)(const void *aggregation);
-  /* Destroy an aggregation created by create() */
-  void (*free)(void *aggregation);
-  /* Record a new value against aggregation. */
-  void (*record)(void *aggregation, double value);
-  /* Return current aggregation data. The caller must cast this object into
-     the correct type for the aggregation result. The object returned can be
-     freed by using free_data(). */
-  void *(*data)(const void *aggregation);
-  /* free data returned by data() */
-  void (*free_data)(void *data);
-  /* Reset an aggregation to default (zero) values. */
-  void (*reset)(void *aggregation);
-  /* Merge 'from' aggregation into 'to'. Both aggregations must be compatible */
-  void (*merge)(void *to, const void *from);
-  /* Fill buffer with printable string version of aggregation contents. For
-     debugging only. Returns the number of bytes added to buffer (a value == n
-     implies the buffer was of insufficient size). */
-  size_t (*print)(const void *aggregation, char *buffer, size_t n);
-};
-
-#endif /* GRPC_CORE_LIB_CENSUS_AGGREGATION_H */
diff --git a/src/core/lib/census/context.c b/src/core/lib/census/context.c
deleted file mode 100644
index 0dfc4ecbf1..0000000000
--- a/src/core/lib/census/context.c
+++ /dev/null
@@ -1,509 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/port_platform.h>
-#include <grpc/support/useful.h>
-#include <stdbool.h>
-#include <string.h>
-#include "src/core/lib/support/string.h"
-
-// Functions in this file support the public context API, including
-// encoding/decoding as part of context propagation across RPC's. The overall
-// requirements (in approximate priority order) for the
-// context representation:
-// 1. Efficient conversion to/from wire format
-// 2. Minimal bytes used on-wire
-// 3. Efficient context creation
-// 4. Efficient lookup of tag value for a key
-// 5. Efficient iteration over tags
-// 6. Minimal memory footprint
-//
-// Notes on tradeoffs/decisions:
-// * tag includes 1 byte length of key, as well as nil-terminating byte. These
-//   are to aid in efficient parsing and the ability to directly return key
-//   strings. This is more important than saving a single byte/tag on the wire.
-// * The wire encoding uses only single byte values. This eliminates the need
-//   to handle endian-ness conversions. It also means there is a hard upper
-//   limit of 255 for both CENSUS_MAX_TAG_KV_LEN and CENSUS_MAX_PROPAGATED_TAGS.
-// * Keep all tag information (keys/values/flags) in a single memory buffer,
-//   that can be directly copied to the wire.
-
-// min and max valid chars in tag keys and values. All printable ASCII is OK.
-#define MIN_VALID_TAG_CHAR 32   // ' '
-#define MAX_VALID_TAG_CHAR 126  // '~'
-
-// Structure representing a set of tags. Essentially a count of number of tags
-// present, and pointer to a chunk of memory that contains the per-tag details.
-struct tag_set {
-  int ntags;        // number of tags.
-  int ntags_alloc;  // ntags + number of deleted tags (total number of tags
-  // in all of kvm). This will always be == ntags, except during the process
-  // of building a new tag set.
-  size_t kvm_size;  // number of bytes allocated for key/value storage.
-  size_t kvm_used;  // number of bytes of used key/value memory
-  char *kvm;        // key/value memory. Consists of repeated entries of:
-  //   Offset  Size  Description
-  //     0      1    Key length, including trailing 0. (K)
-  //     1      1    Value length, including trailing 0 (V)
-  //     2      1    Flags
-  //     3      K    Key bytes
-  //     3 + K  V    Value bytes
-  //
-  // We refer to the first 3 entries as the 'tag header'. If extra values are
-  // introduced in the header, you will need to modify the TAG_HEADER_SIZE
-  // constant, the raw_tag structure (and everything that uses it) and the
-  // encode/decode functions appropriately.
-};
-
-// Number of bytes in tag header.
-#define TAG_HEADER_SIZE 3  // key length (1) + value length (1) + flags (1)
-// Offsets to tag header entries.
-#define KEY_LEN_OFFSET 0
-#define VALUE_LEN_OFFSET 1
-#define FLAG_OFFSET 2
-
-// raw_tag represents the raw-storage form of a tag in the kvm of a tag_set.
-struct raw_tag {
-  uint8_t key_len;
-  uint8_t value_len;
-  uint8_t flags;
-  char *key;
-  char *value;
-};
-
-// Use a reserved flag bit for indication of deleted tag.
-#define CENSUS_TAG_DELETED CENSUS_TAG_RESERVED
-#define CENSUS_TAG_IS_DELETED(flags) (flags & CENSUS_TAG_DELETED)
-
-// Primary representation of a context. Composed of 2 underlying tag_set
-// structs, one each for propagated and local (non-propagated) tags. This is
-// to efficiently support tag encoding/decoding.
-// TODO(aveitch): need to add tracing id's/structure.
-struct census_context {
-  struct tag_set tags[2];
-  census_context_status status;
-};
-
-// Indices into the tags member of census_context
-#define PROPAGATED_TAGS 0
-#define LOCAL_TAGS 1
-
-// Validate (check all characters are in range and size is less than limit) a
-// key or value string. Returns 0 if the string is invalid, or the length
-// (including terminator) if valid.
-static size_t validate_tag(const char *kv) {
-  size_t len = 1;
-  char ch;
-  while ((ch = *kv++) != 0) {
-    if (ch < MIN_VALID_TAG_CHAR || ch > MAX_VALID_TAG_CHAR) {
-      return 0;
-    }
-    len++;
-  }
-  if (len > CENSUS_MAX_TAG_KV_LEN) {
-    return 0;
-  }
-  return len;
-}
-
-// Extract a raw tag given a pointer (raw) to the tag header. Allow for some
-// extra bytes in the tag header (see encode/decode functions for usage: this
-// allows for future expansion of the tag header).
-static char *decode_tag(struct raw_tag *tag, char *header, int offset) {
-  tag->key_len = (uint8_t)(*header++);
-  tag->value_len = (uint8_t)(*header++);
-  tag->flags = (uint8_t)(*header++);
-  header += offset;
-  tag->key = header;
-  header += tag->key_len;
-  tag->value = header;
-  return header + tag->value_len;
-}
-
-// Make a copy (in 'to') of an existing tag_set.
-static void tag_set_copy(struct tag_set *to, const struct tag_set *from) {
-  memcpy(to, from, sizeof(struct tag_set));
-  to->kvm = gpr_malloc(to->kvm_size);
-  memcpy(to->kvm, from->kvm, from->kvm_used);
-}
-
-// Delete a tag from a tag_set, if it exists (returns true if it did).
-static bool tag_set_delete_tag(struct tag_set *tags, const char *key,
-                               size_t key_len) {
-  char *kvp = tags->kvm;
-  for (int i = 0; i < tags->ntags_alloc; i++) {
-    uint8_t *flags = (uint8_t *)(kvp + FLAG_OFFSET);
-    struct raw_tag tag;
-    kvp = decode_tag(&tag, kvp, 0);
-    if (CENSUS_TAG_IS_DELETED(tag.flags)) continue;
-    if ((key_len == tag.key_len) && (memcmp(key, tag.key, key_len) == 0)) {
-      *flags |= CENSUS_TAG_DELETED;
-      tags->ntags--;
-      return true;
-    }
-  }
-  return false;
-}
-
-// Delete a tag from a context, return true if it existed.
-static bool context_delete_tag(census_context *context, const census_tag *tag,
-                               size_t key_len) {
-  return (
-      tag_set_delete_tag(&context->tags[LOCAL_TAGS], tag->key, key_len) ||
-      tag_set_delete_tag(&context->tags[PROPAGATED_TAGS], tag->key, key_len));
-}
-
-// Add a tag to a tag_set. Return true on success, false if the tag could
-// not be added because of constraints on tag set size. This function should
-// not be called if the tag may already exist (in a non-deleted state) in
-// the tag_set, as that would result in two tags with the same key.
-static bool tag_set_add_tag(struct tag_set *tags, const census_tag *tag,
-                            size_t key_len, size_t value_len) {
-  if (tags->ntags == CENSUS_MAX_PROPAGATED_TAGS) {
-    return false;
-  }
-  const size_t tag_size = key_len + value_len + TAG_HEADER_SIZE;
-  if (tags->kvm_used + tag_size > tags->kvm_size) {
-    // allocate new memory if needed
-    tags->kvm_size += 2 * CENSUS_MAX_TAG_KV_LEN + TAG_HEADER_SIZE;
-    char *new_kvm = gpr_malloc(tags->kvm_size);
-    memcpy(new_kvm, tags->kvm, tags->kvm_used);
-    gpr_free(tags->kvm);
-    tags->kvm = new_kvm;
-  }
-  char *kvp = tags->kvm + tags->kvm_used;
-  *kvp++ = (char)key_len;
-  *kvp++ = (char)value_len;
-  // ensure reserved flags are not used.
-  *kvp++ = (char)(tag->flags & (CENSUS_TAG_PROPAGATE | CENSUS_TAG_STATS));
-  memcpy(kvp, tag->key, key_len);
-  kvp += key_len;
-  memcpy(kvp, tag->value, value_len);
-  tags->kvm_used += tag_size;
-  tags->ntags++;
-  tags->ntags_alloc++;
-  return true;
-}
-
-// Add/modify/delete a tag to/in a context. Caller must validate that tag key
-// etc. are valid.
-static void context_modify_tag(census_context *context, const census_tag *tag,
-                               size_t key_len, size_t value_len) {
-  // First delete the tag if it is already present.
-  bool deleted = context_delete_tag(context, tag, key_len);
-  bool added = false;
-  if (CENSUS_TAG_IS_PROPAGATED(tag->flags)) {
-    added = tag_set_add_tag(&context->tags[PROPAGATED_TAGS], tag, key_len,
-                            value_len);
-  } else {
-    added =
-        tag_set_add_tag(&context->tags[LOCAL_TAGS], tag, key_len, value_len);
-  }
-
-  if (deleted) {
-    context->status.n_modified_tags++;
-  } else {
-    if (added) {
-      context->status.n_added_tags++;
-    } else {
-      context->status.n_ignored_tags++;
-    }
-  }
-}
-
-// Remove memory used for deleted tags from a tag set. Basic algorithm:
-// 1) Walk through tag set to find first deleted tag. Record where it is.
-// 2) Find the next not-deleted tag. Copy all of kvm from there to the end
-//    "over" the deleted tags
-// 3) repeat #1 and #2 until we have seen all tags
-// 4) if we are still looking for a not-deleted tag, then all the end portion
-//    of the kvm is deleted. Just reduce the used amount of memory by the
-//    appropriate amount.
-static void tag_set_flatten(struct tag_set *tags) {
-  if (tags->ntags == tags->ntags_alloc) return;
-  bool found_deleted = false;  // found a deleted tag.
-  char *kvp = tags->kvm;
-  char *dbase = NULL;  // record location of deleted tag
-  for (int i = 0; i < tags->ntags_alloc; i++) {
-    struct raw_tag tag;
-    char *next_kvp = decode_tag(&tag, kvp, 0);
-    if (found_deleted) {
-      if (!CENSUS_TAG_IS_DELETED(tag.flags)) {
-        ptrdiff_t reduce = kvp - dbase;  // #bytes in deleted tags
-        GPR_ASSERT(reduce > 0);
-        ptrdiff_t copy_size = tags->kvm + tags->kvm_used - kvp;
-        GPR_ASSERT(copy_size > 0);
-        memmove(dbase, kvp, (size_t)copy_size);
-        tags->kvm_used -= (size_t)reduce;
-        next_kvp -= reduce;
-        found_deleted = false;
-      }
-    } else {
-      if (CENSUS_TAG_IS_DELETED(tag.flags)) {
-        dbase = kvp;
-        found_deleted = true;
-      }
-    }
-    kvp = next_kvp;
-  }
-  if (found_deleted) {
-    GPR_ASSERT(dbase > tags->kvm);
-    tags->kvm_used = (size_t)(dbase - tags->kvm);
-  }
-  tags->ntags_alloc = tags->ntags;
-}
-
-census_context *census_context_create(const census_context *base,
-                                      const census_tag *tags, int ntags,
-                                      census_context_status const **status) {
-  census_context *context = gpr_malloc(sizeof(census_context));
-  // If we are given a base, copy it into our new tag set. Otherwise set it
-  // to zero/NULL everything.
-  if (base == NULL) {
-    memset(context, 0, sizeof(census_context));
-  } else {
-    tag_set_copy(&context->tags[PROPAGATED_TAGS], &base->tags[PROPAGATED_TAGS]);
-    tag_set_copy(&context->tags[LOCAL_TAGS], &base->tags[LOCAL_TAGS]);
-    memset(&context->status, 0, sizeof(context->status));
-  }
-  // Walk over the additional tags and, for those that aren't invalid, modify
-  // the context to add/replace/delete as required.
-  for (int i = 0; i < ntags; i++) {
-    const census_tag *tag = &tags[i];
-    size_t key_len = validate_tag(tag->key);
-    // ignore the tag if it is invalid or too short.
-    if (key_len <= 1) {
-      context->status.n_invalid_tags++;
-    } else {
-      if (tag->value != NULL) {
-        size_t value_len = validate_tag(tag->value);
-        if (value_len != 0) {
-          context_modify_tag(context, tag, key_len, value_len);
-        } else {
-          context->status.n_invalid_tags++;
-        }
-      } else {
-        if (context_delete_tag(context, tag, key_len)) {
-          context->status.n_deleted_tags++;
-        }
-      }
-    }
-  }
-  // Remove any deleted tags, update status if needed, and return.
-  tag_set_flatten(&context->tags[PROPAGATED_TAGS]);
-  tag_set_flatten(&context->tags[LOCAL_TAGS]);
-  context->status.n_propagated_tags = context->tags[PROPAGATED_TAGS].ntags;
-  context->status.n_local_tags = context->tags[LOCAL_TAGS].ntags;
-  if (status) {
-    *status = &context->status;
-  }
-  return context;
-}
-
-const census_context_status *census_context_get_status(
-    const census_context *context) {
-  return &context->status;
-}
-
-void census_context_destroy(census_context *context) {
-  gpr_free(context->tags[PROPAGATED_TAGS].kvm);
-  gpr_free(context->tags[LOCAL_TAGS].kvm);
-  gpr_free(context);
-}
-
-void census_context_initialize_iterator(const census_context *context,
-                                        census_context_iterator *iterator) {
-  iterator->context = context;
-  iterator->index = 0;
-  if (context->tags[PROPAGATED_TAGS].ntags != 0) {
-    iterator->base = PROPAGATED_TAGS;
-    iterator->kvm = context->tags[PROPAGATED_TAGS].kvm;
-  } else if (context->tags[LOCAL_TAGS].ntags != 0) {
-    iterator->base = LOCAL_TAGS;
-    iterator->kvm = context->tags[LOCAL_TAGS].kvm;
-  } else {
-    iterator->base = -1;
-  }
-}
-
-int census_context_next_tag(census_context_iterator *iterator,
-                            census_tag *tag) {
-  if (iterator->base < 0) {
-    return 0;
-  }
-  struct raw_tag raw;
-  iterator->kvm = decode_tag(&raw, iterator->kvm, 0);
-  tag->key = raw.key;
-  tag->value = raw.value;
-  tag->flags = raw.flags;
-  if (++iterator->index == iterator->context->tags[iterator->base].ntags) {
-    do {
-      if (iterator->base == LOCAL_TAGS) {
-        iterator->base = -1;
-        return 1;
-      }
-    } while (iterator->context->tags[++iterator->base].ntags == 0);
-    iterator->index = 0;
-    iterator->kvm = iterator->context->tags[iterator->base].kvm;
-  }
-  return 1;
-}
-
-// Find a tag in a tag_set by key. Return true if found, false otherwise.
-static bool tag_set_get_tag(const struct tag_set *tags, const char *key,
-                            size_t key_len, census_tag *tag) {
-  char *kvp = tags->kvm;
-  for (int i = 0; i < tags->ntags; i++) {
-    struct raw_tag raw;
-    kvp = decode_tag(&raw, kvp, 0);
-    if (key_len == raw.key_len && memcmp(raw.key, key, key_len) == 0) {
-      tag->key = raw.key;
-      tag->value = raw.value;
-      tag->flags = raw.flags;
-      return true;
-    }
-  }
-  return false;
-}
-
-int census_context_get_tag(const census_context *context, const char *key,
-                           census_tag *tag) {
-  size_t key_len = strlen(key) + 1;
-  if (key_len == 1) {
-    return 0;
-  }
-  if (tag_set_get_tag(&context->tags[PROPAGATED_TAGS], key, key_len, tag) ||
-      tag_set_get_tag(&context->tags[LOCAL_TAGS], key, key_len, tag)) {
-    return 1;
-  }
-  return 0;
-}
-
-// Context encoding and decoding functions.
-//
-// Wire format for tag_set's on the wire:
-//
-// First, a tag set header:
-//
-// offset   bytes  description
-//   0        1    version number
-//   1        1    number of bytes in this header. This allows for future
-//                 expansion.
-//   2        1    number of bytes in each tag header.
-//   3        1    ntags value from tag set.
-//
-//   This is followed by the key/value memory from struct tag_set.
-
-#define ENCODED_VERSION 0      // Version number
-#define ENCODED_HEADER_SIZE 4  // size of tag set header
-
-// Encode a tag set. Returns 0 if buffer is too small.
-static size_t tag_set_encode(const struct tag_set *tags, char *buffer,
-                             size_t buf_size) {
-  if (buf_size < ENCODED_HEADER_SIZE + tags->kvm_used) {
-    return 0;
-  }
-  buf_size -= ENCODED_HEADER_SIZE;
-  *buffer++ = (char)ENCODED_VERSION;
-  *buffer++ = (char)ENCODED_HEADER_SIZE;
-  *buffer++ = (char)TAG_HEADER_SIZE;
-  *buffer++ = (char)tags->ntags;
-  if (tags->ntags == 0) {
-    return ENCODED_HEADER_SIZE;
-  }
-  memcpy(buffer, tags->kvm, tags->kvm_used);
-  return ENCODED_HEADER_SIZE + tags->kvm_used;
-}
-
-size_t census_context_encode(const census_context *context, char *buffer,
-                             size_t buf_size) {
-  return tag_set_encode(&context->tags[PROPAGATED_TAGS], buffer, buf_size);
-}
-
-// Decode a tag set.
-static void tag_set_decode(struct tag_set *tags, const char *buffer,
-                           size_t size) {
-  uint8_t version = (uint8_t)(*buffer++);
-  uint8_t header_size = (uint8_t)(*buffer++);
-  uint8_t tag_header_size = (uint8_t)(*buffer++);
-  tags->ntags = tags->ntags_alloc = (int)(*buffer++);
-  if (tags->ntags == 0) {
-    tags->ntags_alloc = 0;
-    tags->kvm_size = 0;
-    tags->kvm_used = 0;
-    tags->kvm = NULL;
-    return;
-  }
-  if (header_size != ENCODED_HEADER_SIZE) {
-    GPR_ASSERT(version != ENCODED_VERSION);
-    GPR_ASSERT(ENCODED_HEADER_SIZE < header_size);
-    buffer += (header_size - ENCODED_HEADER_SIZE);
-  }
-  tags->kvm_used = size - header_size;
-  tags->kvm_size = tags->kvm_used + CENSUS_MAX_TAG_KV_LEN;
-  tags->kvm = gpr_malloc(tags->kvm_size);
-  if (tag_header_size != TAG_HEADER_SIZE) {
-    // something new in the tag information. I don't understand it, so
-    // don't copy it over.
-    GPR_ASSERT(version != ENCODED_VERSION);
-    GPR_ASSERT(tag_header_size > TAG_HEADER_SIZE);
-    char *kvp = tags->kvm;
-    for (int i = 0; i < tags->ntags; i++) {
-      memcpy(kvp, buffer, TAG_HEADER_SIZE);
-      kvp += header_size;
-      struct raw_tag raw;
-      buffer =
-          decode_tag(&raw, (char *)buffer, tag_header_size - TAG_HEADER_SIZE);
-      memcpy(kvp, raw.key, (size_t)raw.key_len + raw.value_len);
-      kvp += raw.key_len + raw.value_len;
-    }
-  } else {
-    memcpy(tags->kvm, buffer, tags->kvm_used);
-  }
-}
-
-census_context *census_context_decode(const char *buffer, size_t size) {
-  census_context *context = gpr_malloc(sizeof(census_context));
-  memset(&context->tags[LOCAL_TAGS], 0, sizeof(struct tag_set));
-  if (buffer == NULL) {
-    memset(&context->tags[PROPAGATED_TAGS], 0, sizeof(struct tag_set));
-  } else {
-    tag_set_decode(&context->tags[PROPAGATED_TAGS], buffer, size);
-  }
-  memset(&context->status, 0, sizeof(context->status));
-  context->status.n_propagated_tags = context->tags[PROPAGATED_TAGS].ntags;
-  return context;
-}
diff --git a/src/core/lib/census/grpc_context.c b/src/core/lib/census/grpc_context.c
deleted file mode 100644
index 98285ab2d5..0000000000
--- a/src/core/lib/census/grpc_context.c
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-#include <grpc/grpc.h>
-#include "src/core/lib/surface/api_trace.h"
-#include "src/core/lib/surface/call.h"
-
-void grpc_census_call_set_context(grpc_call *call, census_context *context) {
-  GRPC_API_TRACE("grpc_census_call_set_context(call=%p, census_context=%p)", 2,
-                 (call, context));
-  if (census_enabled() == CENSUS_FEATURE_NONE) {
-    return;
-  }
-  if (context != NULL) {
-    grpc_call_context_set(call, GRPC_CONTEXT_TRACING, context, NULL);
-  }
-}
-
-census_context *grpc_census_call_get_context(grpc_call *call) {
-  GRPC_API_TRACE("grpc_census_call_get_context(call=%p)", 1, (call));
-  return (census_context *)grpc_call_context_get(call, GRPC_CONTEXT_TRACING);
-}
diff --git a/src/core/lib/census/grpc_filter.c b/src/core/lib/census/grpc_filter.c
deleted file mode 100644
index 1b09be2fe3..0000000000
--- a/src/core/lib/census/grpc_filter.c
+++ /dev/null
@@ -1,198 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/census/grpc_filter.h"
-
-#include <stdio.h>
-#include <string.h>
-
-#include <grpc/census.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/slice.h>
-#include <grpc/support/time.h>
-
-#include "src/core/lib/channel/channel_stack.h"
-#include "src/core/lib/statistics/census_interface.h"
-#include "src/core/lib/statistics/census_rpc_stats.h"
-#include "src/core/lib/transport/static_metadata.h"
-
-typedef struct call_data {
-  census_op_id op_id;
-  census_context *ctxt;
-  gpr_timespec start_ts;
-  int error;
-
-  /* recv callback */
-  grpc_metadata_batch *recv_initial_metadata;
-  grpc_closure *on_done_recv;
-  grpc_closure finish_recv;
-} call_data;
-
-typedef struct channel_data { uint8_t unused; } channel_data;
-
-static void extract_and_annotate_method_tag(grpc_metadata_batch *md,
-                                            call_data *calld,
-                                            channel_data *chand) {
-  grpc_linked_mdelem *m;
-  for (m = md->list.head; m != NULL; m = m->next) {
-    if (m->md->key == GRPC_MDSTR_PATH) {
-      gpr_log(GPR_DEBUG, "%s",
-              (const char *)GPR_SLICE_START_PTR(m->md->value->slice));
-      /* Add method tag here */
-    }
-  }
-}
-
-static void client_mutate_op(grpc_call_element *elem,
-                             grpc_transport_stream_op *op) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  if (op->send_initial_metadata) {
-    extract_and_annotate_method_tag(op->send_initial_metadata, calld, chand);
-  }
-}
-
-static void client_start_transport_op(grpc_exec_ctx *exec_ctx,
-                                      grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
-  client_mutate_op(elem, op);
-  grpc_call_next_op(exec_ctx, elem, op);
-}
-
-static void server_on_done_recv(grpc_exec_ctx *exec_ctx, void *ptr,
-                                bool success) {
-  grpc_call_element *elem = ptr;
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  if (success) {
-    extract_and_annotate_method_tag(calld->recv_initial_metadata, calld, chand);
-  }
-  calld->on_done_recv->cb(exec_ctx, calld->on_done_recv->cb_arg, success);
-}
-
-static void server_mutate_op(grpc_call_element *elem,
-                             grpc_transport_stream_op *op) {
-  call_data *calld = elem->call_data;
-  if (op->recv_initial_metadata) {
-    /* substitute our callback for the op callback */
-    calld->recv_initial_metadata = op->recv_initial_metadata;
-    calld->on_done_recv = op->recv_initial_metadata_ready;
-    op->recv_initial_metadata_ready = &calld->finish_recv;
-  }
-}
-
-static void server_start_transport_op(grpc_exec_ctx *exec_ctx,
-                                      grpc_call_element *elem,
-                                      grpc_transport_stream_op *op) {
-  /* TODO(ctiller): this code fails. I don't know why. I expect it's
-                    incomplete, and someone should look at it soon.
-
-  call_data *calld = elem->call_data;
-  GPR_ASSERT((calld->op_id.upper != 0) || (calld->op_id.lower != 0)); */
-  server_mutate_op(elem, op);
-  grpc_call_next_op(exec_ctx, elem, op);
-}
-
-static void client_init_call_elem(grpc_exec_ctx *exec_ctx,
-                                  grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
-  call_data *d = elem->call_data;
-  GPR_ASSERT(d != NULL);
-  memset(d, 0, sizeof(*d));
-  d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
-}
-
-static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
-                                     grpc_call_element *elem, void *ignored) {
-  call_data *d = elem->call_data;
-  GPR_ASSERT(d != NULL);
-  /* TODO(hongyu): record rpc client stats and census_rpc_end_op here */
-}
-
-static void server_init_call_elem(grpc_exec_ctx *exec_ctx,
-                                  grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
-  call_data *d = elem->call_data;
-  GPR_ASSERT(d != NULL);
-  memset(d, 0, sizeof(*d));
-  d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
-  /* TODO(hongyu): call census_tracing_start_op here. */
-  grpc_closure_init(&d->finish_recv, server_on_done_recv, elem);
-}
-
-static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,
-                                     grpc_call_element *elem, void *ignored) {
-  call_data *d = elem->call_data;
-  GPR_ASSERT(d != NULL);
-  /* TODO(hongyu): record rpc server stats and census_tracing_end_op here */
-}
-
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
-  channel_data *chand = elem->channel_data;
-  GPR_ASSERT(chand != NULL);
-}
-
-static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
-                                 grpc_channel_element *elem) {
-  channel_data *chand = elem->channel_data;
-  GPR_ASSERT(chand != NULL);
-}
-
-const grpc_channel_filter grpc_client_census_filter = {
-    client_start_transport_op,
-    grpc_channel_next_op,
-    sizeof(call_data),
-    client_init_call_elem,
-    grpc_call_stack_ignore_set_pollset,
-    client_destroy_call_elem,
-    sizeof(channel_data),
-    init_channel_elem,
-    destroy_channel_elem,
-    grpc_call_next_get_peer,
-    "census-client"};
-
-const grpc_channel_filter grpc_server_census_filter = {
-    server_start_transport_op,
-    grpc_channel_next_op,
-    sizeof(call_data),
-    server_init_call_elem,
-    grpc_call_stack_ignore_set_pollset,
-    server_destroy_call_elem,
-    sizeof(channel_data),
-    init_channel_elem,
-    destroy_channel_elem,
-    grpc_call_next_get_peer,
-    "census-server"};
diff --git a/src/core/lib/census/grpc_filter.h b/src/core/lib/census/grpc_filter.h
deleted file mode 100644
index e747fe6590..0000000000
--- a/src/core/lib/census/grpc_filter.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CENSUS_GRPC_FILTER_H
-#define GRPC_CORE_LIB_CENSUS_GRPC_FILTER_H
-
-#include "src/core/lib/channel/channel_stack.h"
-
-/* Census filters: provides tracing and stats collection functionalities. It
-   needs to reside right below the surface filter in the channel stack. */
-extern const grpc_channel_filter grpc_client_census_filter;
-extern const grpc_channel_filter grpc_server_census_filter;
-
-#endif /* GRPC_CORE_LIB_CENSUS_GRPC_FILTER_H */
diff --git a/src/core/lib/census/grpc_plugin.c b/src/core/lib/census/grpc_plugin.c
deleted file mode 100644
index 7f6df11f00..0000000000
--- a/src/core/lib/census/grpc_plugin.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/census/grpc_plugin.h"
-
-#include <limits.h>
-
-#include <grpc/census.h>
-
-#include "src/core/lib/census/grpc_filter.h"
-#include "src/core/lib/channel/channel_stack_builder.h"
-#include "src/core/lib/surface/channel_init.h"
-
-static bool maybe_add_census_filter(grpc_channel_stack_builder *builder,
-                                    void *arg_must_be_null) {
-  const grpc_channel_args *args =
-      grpc_channel_stack_builder_get_channel_arguments(builder);
-  if (grpc_channel_args_is_census_enabled(args)) {
-    return grpc_channel_stack_builder_prepend_filter(
-        builder, &grpc_client_census_filter, NULL, NULL);
-  }
-  return true;
-}
-
-void census_grpc_plugin_init(void) {
-  /* Only initialize census if no one else has and some features are
-   * available. */
-  if (census_enabled() == CENSUS_FEATURE_NONE &&
-      census_supported() != CENSUS_FEATURE_NONE) {
-    if (census_initialize(census_supported())) { /* enable all features. */
-      gpr_log(GPR_ERROR, "Could not initialize census.");
-    }
-  }
-  grpc_channel_init_register_stage(GRPC_CLIENT_CHANNEL, INT_MAX,
-                                   maybe_add_census_filter, NULL);
-  grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL, INT_MAX,
-                                   maybe_add_census_filter, NULL);
-}
-
-void census_grpc_plugin_destroy(void) { census_shutdown(); }
diff --git a/src/core/lib/census/initialize.c b/src/core/lib/census/initialize.c
deleted file mode 100644
index 896276e44a..0000000000
--- a/src/core/lib/census/initialize.c
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-
-static int features_enabled = CENSUS_FEATURE_NONE;
-
-int census_initialize(int features) {
-  if (features_enabled != CENSUS_FEATURE_NONE) {
-    // Must have been a previous call to census_initialize; return error
-    return 1;
-  }
-  features_enabled = features;
-  return 0;
-}
-
-void census_shutdown(void) { features_enabled = CENSUS_FEATURE_NONE; }
-
-int census_supported(void) {
-  /* TODO(aveitch): improve this as we implement features... */
-  return CENSUS_FEATURE_NONE;
-}
-
-int census_enabled(void) { return features_enabled; }
diff --git a/src/core/lib/census/mlog.c b/src/core/lib/census/mlog.c
deleted file mode 100644
index ce060a2d85..0000000000
--- a/src/core/lib/census/mlog.c
+++ /dev/null
@@ -1,600 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-// Implements an efficient in-memory log, optimized for multiple writers and
-// a single reader. Available log space is divided up in blocks of
-// CENSUS_LOG_2_MAX_RECORD_SIZE bytes. A block can be in one of the following
-// three data structures:
-// - Free blocks (free_block_list)
-// - Blocks with unread data (dirty_block_list)
-// - Blocks currently attached to cores (core_local_blocks[])
-//
-// census_log_start_write() moves a block from core_local_blocks[] to the end of
-// dirty_block_list when block:
-// - is out-of-space OR
-// - has an incomplete record (an incomplete record occurs when a thread calls
-//   census_log_start_write() and is context-switched before calling
-//   census_log_end_write()
-// So, blocks in dirty_block_list are ordered, from oldest to newest, by the
-// time when block is detached from the core.
-//
-// census_log_read_next() first iterates over dirty_block_list and then
-// core_local_blocks[]. It moves completely read blocks from dirty_block_list
-// to free_block_list. Blocks in core_local_blocks[] are not freed, even when
-// completely read.
-//
-// If the log is configured to discard old records and free_block_list is empty,
-// census_log_start_write() iterates over dirty_block_list to allocate a
-// new block. It moves the oldest available block (no pending read/write) to
-// core_local_blocks[].
-//
-// core_local_block_struct is used to implement a map from core id to the block
-// associated with that core. This mapping is advisory. It is possible that the
-// block returned by this mapping is no longer associated with that core. This
-// mapping is updated, lazily, by census_log_start_write().
-//
-// Locking in block struct:
-//
-// Exclusive g_log.lock must be held before calling any functions operating on
-// block structs except census_log_start_write() and census_log_end_write().
-//
-// Writes to a block are serialized via writer_lock. census_log_start_write()
-// acquires this lock and census_log_end_write() releases it. On failure to
-// acquire the lock, writer allocates a new block for the current core and
-// updates core_local_block accordingly.
-//
-// Simultaneous read and write access is allowed. Readers can safely read up to
-// committed bytes (bytes_committed).
-//
-// reader_lock protects the block, currently being read, from getting recycled.
-// start_read() acquires reader_lock and end_read() releases the lock.
-//
-// Read/write access to a block is disabled via try_disable_access(). It returns
-// with both writer_lock and reader_lock held. These locks are subsequently
-// released by enable_access() to enable access to the block.
-//
-// A note on naming: Most function/struct names are prepended by cl_
-// (shorthand for census_log). Further, functions that manipulate structures
-// include the name of the structure, which will be passed as the first
-// argument. E.g. cl_block_initialize() will initialize a cl_block.
-
-#include "src/core/lib/census/mlog.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/atm.h>
-#include <grpc/support/cpu.h>
-#include <grpc/support/log.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/useful.h>
-#include <stdbool.h>
-#include <string.h>
-
-// End of platform specific code
-
-typedef struct census_log_block_list_struct {
-  struct census_log_block_list_struct* next;
-  struct census_log_block_list_struct* prev;
-  struct census_log_block* block;
-} cl_block_list_struct;
-
-typedef struct census_log_block {
-  // Pointer to underlying buffer.
-  char* buffer;
-  gpr_atm writer_lock;
-  gpr_atm reader_lock;
-  // Keeps completely written bytes. Declared atomic because accessed
-  // simultaneously by reader and writer.
-  gpr_atm bytes_committed;
-  // Bytes already read.
-  size_t bytes_read;
-  // Links for list.
-  cl_block_list_struct link;
-// We want this structure to be cacheline aligned. We assume the following
-// sizes for the various parts on 32/64bit systems:
-// type                 32b size    64b size
-// char*                   4           8
-// 3x gpr_atm             12          24
-// size_t                  4           8
-// cl_block_list_struct   12          24
-// TOTAL                  32          64
-//
-// Depending on the size of our cacheline and the architecture, we
-// selectively add char buffering to this structure. The size is checked
-// via assert in census_log_initialize().
-#if defined(GPR_ARCH_64)
-#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 64)
-#else
-#if defined(GPR_ARCH_32)
-#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 32)
-#else
-#error "Unknown architecture"
-#endif
-#endif
-#if CL_BLOCK_PAD_SIZE > 0
-  char padding[CL_BLOCK_PAD_SIZE];
-#endif
-} cl_block;
-
-// A list of cl_blocks, doubly-linked through cl_block::link.
-typedef struct census_log_block_list {
-  int32_t count;            // Number of items in list.
-  cl_block_list_struct ht;  // head/tail of linked list.
-} cl_block_list;
-
-// Cacheline aligned block pointers to avoid false sharing. Block pointer must
-// be initialized via set_block(), before calling other functions
-typedef struct census_log_core_local_block {
-  gpr_atm block;
-// Ensure cachline alignment: we assume sizeof(gpr_atm) == 4 or 8
-#if defined(GPR_ARCH_64)
-#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 8)
-#else
-#if defined(GPR_ARCH_32)
-#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 4)
-#else
-#error "Unknown architecture"
-#endif
-#endif
-#if CL_CORE_LOCAL_BLOCK_PAD_SIZE > 0
-  char padding[CL_CORE_LOCAL_BLOCK_PAD_SIZE];
-#endif
-} cl_core_local_block;
-
-struct census_log {
-  int discard_old_records;
-  // Number of cores (aka hardware-contexts)
-  unsigned num_cores;
-  // number of CENSUS_LOG_2_MAX_RECORD_SIZE blocks in log
-  uint32_t num_blocks;
-  cl_block* blocks;                        // Block metadata.
-  cl_core_local_block* core_local_blocks;  // Keeps core to block mappings.
-  gpr_mu lock;
-  int initialized;  // has log been initialized?
-  // Keeps the state of the reader iterator. A value of 0 indicates that
-  // iterator has reached the end. census_log_init_reader() resets the value
-  // to num_core to restart iteration.
-  uint32_t read_iterator_state;
-  // Points to the block being read. If non-NULL, the block is locked for
-  // reading(block_being_read_->reader_lock is held).
-  cl_block* block_being_read;
-  char* buffer;
-  cl_block_list free_block_list;
-  cl_block_list dirty_block_list;
-  gpr_atm out_of_space_count;
-};
-
-// Single internal log.
-static struct census_log g_log;
-
-// Functions that operate on an atomic memory location used as a lock.
-
-// Returns non-zero if lock is acquired.
-static int cl_try_lock(gpr_atm* lock) { return gpr_atm_acq_cas(lock, 0, 1); }
-
-static void cl_unlock(gpr_atm* lock) { gpr_atm_rel_store(lock, 0); }
-
-// Functions that operate on cl_core_local_block's.
-
-static void cl_core_local_block_set_block(cl_core_local_block* clb,
-                                          cl_block* block) {
-  gpr_atm_rel_store(&clb->block, (gpr_atm)block);
-}
-
-static cl_block* cl_core_local_block_get_block(cl_core_local_block* clb) {
-  return (cl_block*)gpr_atm_acq_load(&clb->block);
-}
-
-// Functions that operate on cl_block_list_struct's.
-
-static void cl_block_list_struct_initialize(cl_block_list_struct* bls,
-                                            cl_block* block) {
-  bls->next = bls->prev = bls;
-  bls->block = block;
-}
-
-// Functions that operate on cl_block_list's.
-
-static void cl_block_list_initialize(cl_block_list* list) {
-  list->count = 0;
-  cl_block_list_struct_initialize(&list->ht, NULL);
-}
-
-// Returns head of *this, or NULL if empty.
-static cl_block* cl_block_list_head(cl_block_list* list) {
-  return list->ht.next->block;
-}
-
-// Insert element *e after *pos.
-static void cl_block_list_insert(cl_block_list* list, cl_block_list_struct* pos,
-                                 cl_block_list_struct* e) {
-  list->count++;
-  e->next = pos->next;
-  e->prev = pos;
-  e->next->prev = e;
-  e->prev->next = e;
-}
-
-// Insert block at the head of the list
-static void cl_block_list_insert_at_head(cl_block_list* list, cl_block* block) {
-  cl_block_list_insert(list, &list->ht, &block->link);
-}
-
-// Insert block at the tail of the list.
-static void cl_block_list_insert_at_tail(cl_block_list* list, cl_block* block) {
-  cl_block_list_insert(list, list->ht.prev, &block->link);
-}
-
-// Removes block *b. Requires *b be in the list.
-static void cl_block_list_remove(cl_block_list* list, cl_block* b) {
-  list->count--;
-  b->link.next->prev = b->link.prev;
-  b->link.prev->next = b->link.next;
-}
-
-// Functions that operate on cl_block's
-
-static void cl_block_initialize(cl_block* block, char* buffer) {
-  block->buffer = buffer;
-  gpr_atm_rel_store(&block->writer_lock, 0);
-  gpr_atm_rel_store(&block->reader_lock, 0);
-  gpr_atm_rel_store(&block->bytes_committed, 0);
-  block->bytes_read = 0;
-  cl_block_list_struct_initialize(&block->link, block);
-}
-
-// Guards against exposing partially written buffer to the reader.
-static void cl_block_set_bytes_committed(cl_block* block,
-                                         size_t bytes_committed) {
-  gpr_atm_rel_store(&block->bytes_committed, (gpr_atm)bytes_committed);
-}
-
-static size_t cl_block_get_bytes_committed(cl_block* block) {
-  return (size_t)gpr_atm_acq_load(&block->bytes_committed);
-}
-
-// Tries to disable future read/write access to this block. Succeeds if:
-// - no in-progress write AND
-// - no in-progress read AND
-// - 'discard_data' set to true OR no unread data
-// On success, clears the block state and returns with writer_lock_ and
-// reader_lock_ held. These locks are released by a subsequent
-// cl_block_access_enable() call.
-static bool cl_block_try_disable_access(cl_block* block, int discard_data) {
-  if (!cl_try_lock(&block->writer_lock)) {
-    return false;
-  }
-  if (!cl_try_lock(&block->reader_lock)) {
-    cl_unlock(&block->writer_lock);
-    return false;
-  }
-  if (!discard_data &&
-      (block->bytes_read != cl_block_get_bytes_committed(block))) {
-    cl_unlock(&block->reader_lock);
-    cl_unlock(&block->writer_lock);
-    return false;
-  }
-  cl_block_set_bytes_committed(block, 0);
-  block->bytes_read = 0;
-  return true;
-}
-
-static void cl_block_enable_access(cl_block* block) {
-  cl_unlock(&block->reader_lock);
-  cl_unlock(&block->writer_lock);
-}
-
-// Returns with writer_lock held.
-static void* cl_block_start_write(cl_block* block, size_t size) {
-  if (!cl_try_lock(&block->writer_lock)) {
-    return NULL;
-  }
-  size_t bytes_committed = cl_block_get_bytes_committed(block);
-  if (bytes_committed + size > CENSUS_LOG_MAX_RECORD_SIZE) {
-    cl_unlock(&block->writer_lock);
-    return NULL;
-  }
-  return block->buffer + bytes_committed;
-}
-
-// Releases writer_lock and increments committed bytes by 'bytes_written'.
-// 'bytes_written' must be <= 'size' specified in the corresponding
-// StartWrite() call. This function is thread-safe.
-static void cl_block_end_write(cl_block* block, size_t bytes_written) {
-  cl_block_set_bytes_committed(
-      block, cl_block_get_bytes_committed(block) + bytes_written);
-  cl_unlock(&block->writer_lock);
-}
-
-// Returns a pointer to the first unread byte in buffer. The number of bytes
-// available are returned in 'bytes_available'. Acquires reader lock that is
-// released by a subsequent cl_block_end_read() call. Returns NULL if:
-// - read in progress
-// - no data available
-static void* cl_block_start_read(cl_block* block, size_t* bytes_available) {
-  if (!cl_try_lock(&block->reader_lock)) {
-    return NULL;
-  }
-  // bytes_committed may change from under us. Use bytes_available to update
-  // bytes_read below.
-  size_t bytes_committed = cl_block_get_bytes_committed(block);
-  GPR_ASSERT(bytes_committed >= block->bytes_read);
-  *bytes_available = bytes_committed - block->bytes_read;
-  if (*bytes_available == 0) {
-    cl_unlock(&block->reader_lock);
-    return NULL;
-  }
-  void* record = block->buffer + block->bytes_read;
-  block->bytes_read += *bytes_available;
-  return record;
-}
-
-static void cl_block_end_read(cl_block* block) {
-  cl_unlock(&block->reader_lock);
-}
-
-// Internal functions operating on g_log
-
-// Allocates a new free block (or recycles an available dirty block if log is
-// configured to discard old records). Returns NULL if out-of-space.
-static cl_block* cl_allocate_block(void) {
-  cl_block* block = cl_block_list_head(&g_log.free_block_list);
-  if (block != NULL) {
-    cl_block_list_remove(&g_log.free_block_list, block);
-    return block;
-  }
-  if (!g_log.discard_old_records) {
-    // No free block and log is configured to keep old records.
-    return NULL;
-  }
-  // Recycle dirty block. Start from the oldest.
-  for (block = cl_block_list_head(&g_log.dirty_block_list); block != NULL;
-       block = block->link.next->block) {
-    if (cl_block_try_disable_access(block, 1 /* discard data */)) {
-      cl_block_list_remove(&g_log.dirty_block_list, block);
-      return block;
-    }
-  }
-  return NULL;
-}
-
-// Allocates a new block and updates core id => block mapping. 'old_block'
-// points to the block that the caller thinks is attached to
-// 'core_id'. 'old_block' may be NULL. Returns true if:
-// - allocated a new block OR
-// - 'core_id' => 'old_block' mapping changed (another thread allocated a
-//   block before lock was acquired).
-static bool cl_allocate_core_local_block(uint32_t core_id,
-                                         cl_block* old_block) {
-  // Now that we have the lock, check if core-local mapping has changed.
-  cl_core_local_block* core_local_block = &g_log.core_local_blocks[core_id];
-  cl_block* block = cl_core_local_block_get_block(core_local_block);
-  if ((block != NULL) && (block != old_block)) {
-    return true;
-  }
-  if (block != NULL) {
-    cl_core_local_block_set_block(core_local_block, NULL);
-    cl_block_list_insert_at_tail(&g_log.dirty_block_list, block);
-  }
-  block = cl_allocate_block();
-  if (block == NULL) {
-    return false;
-  }
-  cl_core_local_block_set_block(core_local_block, block);
-  cl_block_enable_access(block);
-  return true;
-}
-
-static cl_block* cl_get_block(void* record) {
-  uintptr_t p = (uintptr_t)((char*)record - g_log.buffer);
-  uintptr_t index = p >> CENSUS_LOG_2_MAX_RECORD_SIZE;
-  return &g_log.blocks[index];
-}
-
-// Gets the next block to read and tries to free 'prev' block (if not NULL).
-// Returns NULL if reached the end.
-static cl_block* cl_next_block_to_read(cl_block* prev) {
-  cl_block* block = NULL;
-  if (g_log.read_iterator_state == g_log.num_cores) {
-    // We are traversing dirty list; find the next dirty block.
-    if (prev != NULL) {
-      // Try to free the previous block if there is no unread data. This
-      // block
-      // may have unread data if previously incomplete record completed
-      // between
-      // read_next() calls.
-      block = prev->link.next->block;
-      if (cl_block_try_disable_access(prev, 0 /* do not discard data */)) {
-        cl_block_list_remove(&g_log.dirty_block_list, prev);
-        cl_block_list_insert_at_head(&g_log.free_block_list, prev);
-      }
-    } else {
-      block = cl_block_list_head(&g_log.dirty_block_list);
-    }
-    if (block != NULL) {
-      return block;
-    }
-    // We are done with the dirty list; moving on to core-local blocks.
-  }
-  while (g_log.read_iterator_state > 0) {
-    g_log.read_iterator_state--;
-    block = cl_core_local_block_get_block(
-        &g_log.core_local_blocks[g_log.read_iterator_state]);
-    if (block != NULL) {
-      return block;
-    }
-  }
-  return NULL;
-}
-
-#define CL_LOG_2_MB 20  // 2^20 = 1MB
-
-// External functions: primary stats_log interface
-void census_log_initialize(size_t size_in_mb, int discard_old_records) {
-  // Check cacheline alignment.
-  GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0);
-  GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0);
-  GPR_ASSERT(!g_log.initialized);
-  g_log.discard_old_records = discard_old_records;
-  g_log.num_cores = gpr_cpu_num_cores();
-  // Ensure that we will not get any overflow in calaculating num_blocks
-  GPR_ASSERT(CL_LOG_2_MB >= CENSUS_LOG_2_MAX_RECORD_SIZE);
-  GPR_ASSERT(size_in_mb < 1000);
-  // Ensure at least 2x as many blocks as there are cores.
-  g_log.num_blocks =
-      (uint32_t)GPR_MAX(2 * g_log.num_cores, (size_in_mb << CL_LOG_2_MB) >>
-                                                 CENSUS_LOG_2_MAX_RECORD_SIZE);
-  gpr_mu_init(&g_log.lock);
-  g_log.read_iterator_state = 0;
-  g_log.block_being_read = NULL;
-  g_log.core_local_blocks = (cl_core_local_block*)gpr_malloc_aligned(
-      g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG);
-  memset(g_log.core_local_blocks, 0,
-         g_log.num_cores * sizeof(cl_core_local_block));
-  g_log.blocks = (cl_block*)gpr_malloc_aligned(
-      g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG);
-  memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block));
-  g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
-  memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
-  cl_block_list_initialize(&g_log.free_block_list);
-  cl_block_list_initialize(&g_log.dirty_block_list);
-  for (uint32_t i = 0; i < g_log.num_blocks; ++i) {
-    cl_block* block = g_log.blocks + i;
-    cl_block_initialize(block, g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * i));
-    cl_block_try_disable_access(block, 1 /* discard data */);
-    cl_block_list_insert_at_tail(&g_log.free_block_list, block);
-  }
-  gpr_atm_rel_store(&g_log.out_of_space_count, 0);
-  g_log.initialized = 1;
-}
-
-void census_log_shutdown(void) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_destroy(&g_log.lock);
-  gpr_free_aligned(g_log.core_local_blocks);
-  g_log.core_local_blocks = NULL;
-  gpr_free_aligned(g_log.blocks);
-  g_log.blocks = NULL;
-  gpr_free(g_log.buffer);
-  g_log.buffer = NULL;
-  g_log.initialized = 0;
-}
-
-void* census_log_start_write(size_t size) {
-  // Used to bound number of times block allocation is attempted.
-  GPR_ASSERT(size > 0);
-  GPR_ASSERT(g_log.initialized);
-  if (size > CENSUS_LOG_MAX_RECORD_SIZE) {
-    return NULL;
-  }
-  uint32_t attempts_remaining = g_log.num_blocks;
-  uint32_t core_id = gpr_cpu_current_cpu();
-  do {
-    void* record = NULL;
-    cl_block* block =
-        cl_core_local_block_get_block(&g_log.core_local_blocks[core_id]);
-    if (block && (record = cl_block_start_write(block, size))) {
-      return record;
-    }
-    // Need to allocate a new block. We are here if:
-    // - No block associated with the core OR
-    // - Write in-progress on the block OR
-    // - block is out of space
-    gpr_mu_lock(&g_log.lock);
-    bool allocated = cl_allocate_core_local_block(core_id, block);
-    gpr_mu_unlock(&g_log.lock);
-    if (!allocated) {
-      gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
-      return NULL;
-    }
-  } while (attempts_remaining--);
-  // Give up.
-  gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
-  return NULL;
-}
-
-void census_log_end_write(void* record, size_t bytes_written) {
-  GPR_ASSERT(g_log.initialized);
-  cl_block_end_write(cl_get_block(record), bytes_written);
-}
-
-void census_log_init_reader(void) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_lock(&g_log.lock);
-  // If a block is locked for reading unlock it.
-  if (g_log.block_being_read != NULL) {
-    cl_block_end_read(g_log.block_being_read);
-    g_log.block_being_read = NULL;
-  }
-  g_log.read_iterator_state = g_log.num_cores;
-  gpr_mu_unlock(&g_log.lock);
-}
-
-const void* census_log_read_next(size_t* bytes_available) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_lock(&g_log.lock);
-  if (g_log.block_being_read != NULL) {
-    cl_block_end_read(g_log.block_being_read);
-  }
-  do {
-    g_log.block_being_read = cl_next_block_to_read(g_log.block_being_read);
-    if (g_log.block_being_read != NULL) {
-      void* record =
-          cl_block_start_read(g_log.block_being_read, bytes_available);
-      if (record != NULL) {
-        gpr_mu_unlock(&g_log.lock);
-        return record;
-      }
-    }
-  } while (g_log.block_being_read != NULL);
-  gpr_mu_unlock(&g_log.lock);
-  return NULL;
-}
-
-size_t census_log_remaining_space(void) {
-  GPR_ASSERT(g_log.initialized);
-  size_t space = 0;
-  gpr_mu_lock(&g_log.lock);
-  if (g_log.discard_old_records) {
-    // Remaining space is not meaningful; just return the entire log space.
-    space = g_log.num_blocks << CENSUS_LOG_2_MAX_RECORD_SIZE;
-  } else {
-    GPR_ASSERT(g_log.free_block_list.count >= 0);
-    space = (size_t)g_log.free_block_list.count * CENSUS_LOG_MAX_RECORD_SIZE;
-  }
-  gpr_mu_unlock(&g_log.lock);
-  return space;
-}
-
-int64_t census_log_out_of_space_count(void) {
-  GPR_ASSERT(g_log.initialized);
-  return gpr_atm_acq_load(&g_log.out_of_space_count);
-}
diff --git a/src/core/lib/census/mlog.h b/src/core/lib/census/mlog.h
deleted file mode 100644
index dea43de725..0000000000
--- a/src/core/lib/census/mlog.h
+++ /dev/null
@@ -1,95 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-/* A very fast in-memory log, optimized for multiple writers. */
-
-#ifndef GRPC_CORE_LIB_CENSUS_MLOG_H
-#define GRPC_CORE_LIB_CENSUS_MLOG_H
-
-#include <grpc/support/port_platform.h>
-#include <stddef.h>
-
-/* Maximum record size, in bytes. */
-#define CENSUS_LOG_2_MAX_RECORD_SIZE 14 /* 2^14 = 16KB */
-#define CENSUS_LOG_MAX_RECORD_SIZE (1 << CENSUS_LOG_2_MAX_RECORD_SIZE)
-
-/* Initialize the statistics logging subsystem with the given log size. A log
-   size of 0 will result in the smallest possible log for the platform
-   (approximately CENSUS_LOG_MAX_RECORD_SIZE * gpr_cpu_num_cores()). If
-   discard_old_records is non-zero, then new records will displace older ones
-   when the log is full. This function must be called before any other
-   census_log functions.
-*/
-void census_log_initialize(size_t size_in_mb, int discard_old_records);
-
-/* Shutdown the logging subsystem. Caller must ensure that:
-   - no in progress or future call to any census_log functions
-   - no incomplete records
-*/
-void census_log_shutdown(void);
-
-/* Allocates and returns a 'size' bytes record and marks it in use. A
-   subsequent census_log_end_write() marks the record complete. The
-   'bytes_written' census_log_end_write() argument must be <=
-   'size'. Returns NULL if out-of-space AND:
-       - log is configured to keep old records OR
-       - all blocks are pinned by incomplete records.
-*/
-void* census_log_start_write(size_t size);
-
-void census_log_end_write(void* record, size_t bytes_written);
-
-void census_log_init_reader(void);
-
-/* census_log_read_next() iterates over blocks with data and for each block
-   returns a pointer to the first unread byte. The number of bytes that can be
-   read are returned in 'bytes_available'. Reader is expected to read all
-   available data. Reading the data consumes it i.e. it cannot be read again.
-   census_log_read_next() returns NULL if the end is reached i.e last block
-   is read. census_log_init_reader() starts the iteration or aborts the
-   current iteration.
-*/
-const void* census_log_read_next(size_t* bytes_available);
-
-/* Returns estimated remaining space across all blocks, in bytes. If log is
-   configured to discard old records, returns total log space. Otherwise,
-   returns space available in empty blocks (partially filled blocks are
-   treated as full).
-*/
-size_t census_log_remaining_space(void);
-
-/* Returns the number of times gprc_stats_log_start_write() failed due to
-   out-of-space. */
-int64_t census_log_out_of_space_count(void);
-
-#endif /* GRPC_CORE_LIB_CENSUS_MLOG_H */
diff --git a/src/core/lib/census/operation.c b/src/core/lib/census/operation.c
deleted file mode 100644
index 5c58704372..0000000000
--- a/src/core/lib/census/operation.c
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-
-/* TODO(aveitch): These are all placeholder implementations. */
-
-census_timestamp census_start_rpc_op_timestamp(void) {
-  census_timestamp ct;
-  /* TODO(aveitch): assumes gpr_timespec implementation of census_timestamp. */
-  ct.ts = gpr_now(GPR_CLOCK_MONOTONIC);
-  return ct;
-}
-
-census_context *census_start_client_rpc_op(
-    const census_context *context, int64_t rpc_name_id,
-    const census_rpc_name_info *rpc_name_info, const char *peer, int trace_mask,
-    const census_timestamp *start_time) {
-  return NULL;
-}
-
-census_context *census_start_server_rpc_op(
-    const char *buffer, int64_t rpc_name_id,
-    const census_rpc_name_info *rpc_name_info, const char *peer, int trace_mask,
-    census_timestamp *start_time) {
-  return NULL;
-}
-
-census_context *census_start_op(census_context *context, const char *family,
-                                const char *name, int trace_mask) {
-  return NULL;
-}
-
-void census_end_op(census_context *context, int status) {}
diff --git a/src/core/lib/census/placeholders.c b/src/core/lib/census/placeholders.c
deleted file mode 100644
index fe23d13971..0000000000
--- a/src/core/lib/census/placeholders.c
+++ /dev/null
@@ -1,109 +0,0 @@
-/*
- *
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-
-#include <grpc/support/log.h>
-
-/* Placeholders for the pending APIs */
-
-int census_get_trace_record(census_trace_record *trace_record) {
-  (void)trace_record;
-  abort();
-}
-
-void census_record_values(census_context *context, census_value *values,
-                          size_t nvalues) {
-  (void)context;
-  (void)values;
-  (void)nvalues;
-  abort();
-}
-
-void census_set_rpc_client_peer(census_context *context, const char *peer) {
-  (void)context;
-  (void)peer;
-  abort();
-}
-
-void census_trace_scan_end() { abort(); }
-
-int census_trace_scan_start(int consume) {
-  (void)consume;
-  abort();
-}
-
-const census_aggregation *census_view_aggregrations(const census_view *view) {
-  (void)view;
-  abort();
-}
-
-census_view *census_view_create(uint32_t metric_id, const census_context *tags,
-                                const census_aggregation *aggregations,
-                                size_t naggregations) {
-  (void)metric_id;
-  (void)tags;
-  (void)aggregations;
-  (void)naggregations;
-  abort();
-}
-
-const census_context *census_view_tags(const census_view *view) {
-  (void)view;
-  abort();
-}
-
-void census_view_delete(census_view *view) {
-  (void)view;
-  abort();
-}
-
-const census_view_data *census_view_get_data(const census_view *view) {
-  (void)view;
-  abort();
-}
-
-size_t census_view_metric(const census_view *view) {
-  (void)view;
-  abort();
-}
-
-size_t census_view_naggregations(const census_view *view) {
-  (void)view;
-  abort();
-}
-
-void census_view_reset(census_view *view) {
-  (void)view;
-  abort();
-}
diff --git a/src/core/lib/census/rpc_metric_id.h b/src/core/lib/census/rpc_metric_id.h
deleted file mode 100644
index 0f05b7de8a..0000000000
--- a/src/core/lib/census/rpc_metric_id.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CENSUS_RPC_METRIC_ID_H
-#define GRPC_CORE_LIB_CENSUS_RPC_METRIC_ID_H
-
-/* Metric ID's used for RPC measurements. */
-/* Count of client requests sent. */
-#define CENSUS_METRIC_RPC_CLIENT_REQUESTS ((uint32_t)0)
-/* Count of server requests sent. */
-#define CENSUS_METRIC_RPC_SERVER_REQUESTS ((uint32_t)1)
-/* Client error counts. */
-#define CENSUS_METRIC_RPC_CLIENT_ERRORS ((uint32_t)2)
-/* Server error counts. */
-#define CENSUS_METRIC_RPC_SERVER_ERRORS ((uint32_t)3)
-/* Client side request latency. */
-#define CENSUS_METRIC_RPC_CLIENT_LATENCY ((uint32_t)4)
-/* Server side request latency. */
-#define CENSUS_METRIC_RPC_SERVER_LATENCY ((uint32_t)5)
-
-#endif /* GRPC_CORE_LIB_CENSUS_RPC_METRIC_ID_H */
diff --git a/src/core/lib/census/tracing.c b/src/core/lib/census/tracing.c
deleted file mode 100644
index 3b5d6dab2b..0000000000
--- a/src/core/lib/census/tracing.c
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/census.h>
-
-/* TODO(aveitch): These are all placeholder implementations. */
-
-int census_trace_mask(const census_context *context) {
-  return CENSUS_TRACE_MASK_NONE;
-}
-
-void census_set_trace_mask(int trace_mask) {}
-
-void census_trace_print(census_context *context, uint32_t type,
-                        const char *buffer, size_t n) {}
diff --git a/src/core/lib/client_config/resolver_registry.c b/src/core/lib/client_config/resolver_registry.c
index e8432d165a..5f3db273b5 100644
--- a/src/core/lib/client_config/resolver_registry.c
+++ b/src/core/lib/client_config/resolver_registry.c
@@ -70,14 +70,11 @@ void grpc_register_resolver_type(grpc_resolver_factory *factory) {
   g_all_of_the_resolvers[g_number_of_resolvers++] = factory;
 }
 
-static grpc_resolver_factory *lookup_factory(grpc_uri *uri) {
+static grpc_resolver_factory *lookup_factory(const char *name) {
   int i;
 
-  /* handling NULL uri's here simplifies grpc_resolver_create */
-  if (!uri) return NULL;
-
   for (i = 0; i < g_number_of_resolvers; i++) {
-    if (0 == strcmp(uri->scheme, g_all_of_the_resolvers[i]->vtable->scheme)) {
+    if (0 == strcmp(name, g_all_of_the_resolvers[i]->vtable->scheme)) {
       return g_all_of_the_resolvers[i];
     }
   }
@@ -85,6 +82,17 @@ static grpc_resolver_factory *lookup_factory(grpc_uri *uri) {
   return NULL;
 }
 
+grpc_resolver_factory *grpc_resolver_factory_lookup(const char *name) {
+  grpc_resolver_factory *f = lookup_factory(name);
+  if (f) grpc_resolver_factory_ref(f);
+  return f;
+}
+
+static grpc_resolver_factory *lookup_factory_by_uri(grpc_uri *uri) {
+  if (!uri) return NULL;
+  return lookup_factory(uri->scheme);
+}
+
 static grpc_resolver_factory *resolve_factory(const char *target,
                                               grpc_uri **uri) {
   char *tmp;
@@ -92,13 +100,13 @@ static grpc_resolver_factory *resolve_factory(const char *target,
 
   GPR_ASSERT(uri != NULL);
   *uri = grpc_uri_parse(target, 1);
-  factory = lookup_factory(*uri);
+  factory = lookup_factory_by_uri(*uri);
   if (factory == NULL) {
     if (g_default_resolver_prefix != NULL) {
       grpc_uri_destroy(*uri);
       gpr_asprintf(&tmp, "%s%s", g_default_resolver_prefix, target);
       *uri = grpc_uri_parse(tmp, 1);
-      factory = lookup_factory(*uri);
+      factory = lookup_factory_by_uri(*uri);
       if (factory == NULL) {
         grpc_uri_destroy(grpc_uri_parse(target, 0));
         grpc_uri_destroy(grpc_uri_parse(tmp, 0));
diff --git a/src/core/lib/client_config/resolver_registry.h b/src/core/lib/client_config/resolver_registry.h
index 330cb7f544..36c4f2fe03 100644
--- a/src/core/lib/client_config/resolver_registry.h
+++ b/src/core/lib/client_config/resolver_registry.h
@@ -58,6 +58,10 @@ void grpc_register_resolver_type(grpc_resolver_factory *factory);
 grpc_resolver *grpc_resolver_create(
     const char *target, grpc_subchannel_factory *subchannel_factory);
 
+/** Find a resolver factory given a name and return an (owned-by-the-caller)
+ *  reference to it */
+grpc_resolver_factory *grpc_resolver_factory_lookup(const char *name);
+
 /** Given a target, return a (freshly allocated with gpr_malloc) string
     representing the default authority to pass from a client. */
 char *grpc_get_default_authority(const char *target);
diff --git a/src/core/lib/client_config/resolvers/dns_resolver.c b/src/core/lib/client_config/resolvers/dns_resolver.c
deleted file mode 100644
index ad586aa7e4..0000000000
--- a/src/core/lib/client_config/resolvers/dns_resolver.c
+++ /dev/null
@@ -1,294 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/client_config/resolvers/dns_resolver.h"
-
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/host_port.h>
-#include <grpc/support/string_util.h>
-
-#include "src/core/lib/client_config/lb_policy_registry.h"
-#include "src/core/lib/iomgr/resolve_address.h"
-#include "src/core/lib/iomgr/timer.h"
-#include "src/core/lib/support/backoff.h"
-#include "src/core/lib/support/string.h"
-
-#define BACKOFF_MULTIPLIER 1.6
-#define BACKOFF_JITTER 0.2
-#define BACKOFF_MIN_SECONDS 1
-#define BACKOFF_MAX_SECONDS 120
-
-typedef struct {
-  /** base class: must be first */
-  grpc_resolver base;
-  /** refcount */
-  gpr_refcount refs;
-  /** name to resolve */
-  char *name;
-  /** default port to use */
-  char *default_port;
-  /** subchannel factory */
-  grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy name */
-  char *lb_policy_name;
-
-  /** mutex guarding the rest of the state */
-  gpr_mu mu;
-  /** are we currently resolving? */
-  int resolving;
-  /** which version of resolved_config have we published? */
-  int published_version;
-  /** which version of resolved_config is current? */
-  int resolved_version;
-  /** pending next completion, or NULL */
-  grpc_closure *next_completion;
-  /** target config address for next completion */
-  grpc_client_config **target_config;
-  /** current (fully resolved) config */
-  grpc_client_config *resolved_config;
-  /** retry timer */
-  bool have_retry_timer;
-  grpc_timer retry_timer;
-  /** retry backoff state */
-  gpr_backoff backoff_state;
-} dns_resolver;
-
-static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-
-static void dns_start_resolving_locked(dns_resolver *r);
-static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                         dns_resolver *r);
-
-static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r,
-                     grpc_client_config **target_config,
-                     grpc_closure *on_complete);
-
-static const grpc_resolver_vtable dns_resolver_vtable = {
-    dns_destroy, dns_shutdown, dns_channel_saw_error, dns_next};
-
-static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver) {
-  dns_resolver *r = (dns_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  if (r->have_retry_timer) {
-    grpc_timer_cancel(exec_ctx, &r->retry_timer);
-  }
-  if (r->next_completion != NULL) {
-    *r->target_config = NULL;
-    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
-    r->next_completion = NULL;
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx,
-                                  grpc_resolver *resolver) {
-  dns_resolver *r = (dns_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  if (!r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
-    dns_start_resolving_locked(r);
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
-                     grpc_client_config **target_config,
-                     grpc_closure *on_complete) {
-  dns_resolver *r = (dns_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(!r->next_completion);
-  r->next_completion = on_complete;
-  r->target_config = target_config;
-  if (r->resolved_version == 0 && !r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
-    dns_start_resolving_locked(r);
-  } else {
-    dns_maybe_finish_next_locked(exec_ctx, r);
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void dns_on_retry_timer(grpc_exec_ctx *exec_ctx, void *arg,
-                               bool success) {
-  dns_resolver *r = arg;
-
-  gpr_mu_lock(&r->mu);
-  r->have_retry_timer = false;
-  if (success) {
-    if (!r->resolving) {
-      dns_start_resolving_locked(r);
-    }
-  }
-  gpr_mu_unlock(&r->mu);
-
-  GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "retry-timer");
-}
-
-static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
-                            grpc_resolved_addresses *addresses) {
-  dns_resolver *r = arg;
-  grpc_client_config *config = NULL;
-  grpc_lb_policy *lb_policy;
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(r->resolving);
-  r->resolving = 0;
-  if (addresses != NULL) {
-    grpc_lb_policy_args lb_policy_args;
-    config = grpc_client_config_create();
-    memset(&lb_policy_args, 0, sizeof(lb_policy_args));
-    lb_policy_args.addresses = addresses;
-    lb_policy_args.subchannel_factory = r->subchannel_factory;
-    lb_policy =
-        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
-    if (lb_policy != NULL) {
-      grpc_client_config_set_lb_policy(config, lb_policy);
-      GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
-    }
-    grpc_resolved_addresses_destroy(addresses);
-  } else {
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
-    gpr_timespec timeout = gpr_time_sub(next_try, now);
-    gpr_log(GPR_DEBUG, "dns resolution failed: retrying in %d.%09d seconds",
-            timeout.tv_sec, timeout.tv_nsec);
-    GPR_ASSERT(!r->have_retry_timer);
-    r->have_retry_timer = true;
-    GRPC_RESOLVER_REF(&r->base, "retry-timer");
-    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, dns_on_retry_timer, r,
-                    now);
-  }
-  if (r->resolved_config) {
-    grpc_client_config_unref(exec_ctx, r->resolved_config);
-  }
-  r->resolved_config = config;
-  r->resolved_version++;
-  dns_maybe_finish_next_locked(exec_ctx, r);
-  gpr_mu_unlock(&r->mu);
-
-  GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "dns-resolving");
-}
-
-static void dns_start_resolving_locked(dns_resolver *r) {
-  GRPC_RESOLVER_REF(&r->base, "dns-resolving");
-  GPR_ASSERT(!r->resolving);
-  r->resolving = 1;
-  grpc_resolve_address(r->name, r->default_port, dns_on_resolved, r);
-}
-
-static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                         dns_resolver *r) {
-  if (r->next_completion != NULL &&
-      r->resolved_version != r->published_version) {
-    *r->target_config = r->resolved_config;
-    if (r->resolved_config) {
-      grpc_client_config_ref(r->resolved_config);
-    }
-    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
-    r->next_completion = NULL;
-    r->published_version = r->resolved_version;
-  }
-}
-
-static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
-  dns_resolver *r = (dns_resolver *)gr;
-  gpr_mu_destroy(&r->mu);
-  if (r->resolved_config) {
-    grpc_client_config_unref(exec_ctx, r->resolved_config);
-  }
-  grpc_subchannel_factory_unref(exec_ctx, r->subchannel_factory);
-  gpr_free(r->name);
-  gpr_free(r->default_port);
-  gpr_free(r->lb_policy_name);
-  gpr_free(r);
-}
-
-static grpc_resolver *dns_create(grpc_resolver_args *args,
-                                 const char *default_port,
-                                 const char *lb_policy_name) {
-  dns_resolver *r;
-  const char *path = args->uri->path;
-
-  if (0 != strcmp(args->uri->authority, "")) {
-    gpr_log(GPR_ERROR, "authority based dns uri's not supported");
-    return NULL;
-  }
-
-  if (path[0] == '/') ++path;
-
-  r = gpr_malloc(sizeof(dns_resolver));
-  memset(r, 0, sizeof(*r));
-  gpr_ref_init(&r->refs, 1);
-  gpr_mu_init(&r->mu);
-  grpc_resolver_init(&r->base, &dns_resolver_vtable);
-  r->name = gpr_strdup(path);
-  r->default_port = gpr_strdup(default_port);
-  r->subchannel_factory = args->subchannel_factory;
-  gpr_backoff_init(&r->backoff_state, BACKOFF_MULTIPLIER, BACKOFF_JITTER,
-                   BACKOFF_MIN_SECONDS * 1000, BACKOFF_MAX_SECONDS * 1000);
-  grpc_subchannel_factory_ref(r->subchannel_factory);
-  r->lb_policy_name = gpr_strdup(lb_policy_name);
-  return &r->base;
-}
-
-/*
- * FACTORY
- */
-
-static void dns_factory_ref(grpc_resolver_factory *factory) {}
-
-static void dns_factory_unref(grpc_resolver_factory *factory) {}
-
-static grpc_resolver *dns_factory_create_resolver(
-    grpc_resolver_factory *factory, grpc_resolver_args *args) {
-  return dns_create(args, "https", "pick_first");
-}
-
-char *dns_factory_get_default_host_name(grpc_resolver_factory *factory,
-                                        grpc_uri *uri) {
-  const char *path = uri->path;
-  if (path[0] == '/') ++path;
-  return gpr_strdup(path);
-}
-
-static const grpc_resolver_factory_vtable dns_factory_vtable = {
-    dns_factory_ref, dns_factory_unref, dns_factory_create_resolver,
-    dns_factory_get_default_host_name, "dns"};
-static grpc_resolver_factory dns_resolver_factory = {&dns_factory_vtable};
-
-grpc_resolver_factory *grpc_dns_resolver_factory_create() {
-  return &dns_resolver_factory;
-}
diff --git a/src/core/lib/client_config/resolvers/dns_resolver.h b/src/core/lib/client_config/resolvers/dns_resolver.h
deleted file mode 100644
index de41961ea9..0000000000
--- a/src/core/lib/client_config/resolvers/dns_resolver.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H
-#define GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H
-
-#include "src/core/lib/client_config/resolver_factory.h"
-
-/** Create a dns resolver factory */
-grpc_resolver_factory *grpc_dns_resolver_factory_create(void);
-
-#endif /* GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H */
diff --git a/src/core/lib/client_config/resolvers/sockaddr_resolver.c b/src/core/lib/client_config/resolvers/sockaddr_resolver.c
deleted file mode 100644
index 0e2656d033..0000000000
--- a/src/core/lib/client_config/resolvers/sockaddr_resolver.c
+++ /dev/null
@@ -1,354 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/client_config/resolvers/sockaddr_resolver.h"
-
-#include <stdio.h>
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/host_port.h>
-#include <grpc/support/string_util.h>
-
-#include "src/core/lib/client_config/lb_policy_registry.h"
-#include "src/core/lib/iomgr/resolve_address.h"
-#include "src/core/lib/iomgr/unix_sockets_posix.h"
-#include "src/core/lib/support/string.h"
-
-typedef struct {
-  /** base class: must be first */
-  grpc_resolver base;
-  /** refcount */
-  gpr_refcount refs;
-  /** subchannel factory */
-  grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy name */
-  char *lb_policy_name;
-
-  /** the addresses that we've 'resolved' */
-  grpc_resolved_addresses *addresses;
-
-  /** mutex guarding the rest of the state */
-  gpr_mu mu;
-  /** have we published? */
-  int published;
-  /** pending next completion, or NULL */
-  grpc_closure *next_completion;
-  /** target config address for next completion */
-  grpc_client_config **target_config;
-} sockaddr_resolver;
-
-static void sockaddr_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-
-static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                              sockaddr_resolver *r);
-
-static void sockaddr_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-static void sockaddr_channel_saw_error(grpc_exec_ctx *exec_ctx,
-                                       grpc_resolver *r);
-static void sockaddr_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r,
-                          grpc_client_config **target_config,
-                          grpc_closure *on_complete);
-
-static const grpc_resolver_vtable sockaddr_resolver_vtable = {
-    sockaddr_destroy, sockaddr_shutdown, sockaddr_channel_saw_error,
-    sockaddr_next};
-
-static void sockaddr_shutdown(grpc_exec_ctx *exec_ctx,
-                              grpc_resolver *resolver) {
-  sockaddr_resolver *r = (sockaddr_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  if (r->next_completion != NULL) {
-    *r->target_config = NULL;
-    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
-    r->next_completion = NULL;
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void sockaddr_channel_saw_error(grpc_exec_ctx *exec_ctx,
-                                       grpc_resolver *resolver) {
-  sockaddr_resolver *r = (sockaddr_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  r->published = 0;
-  sockaddr_maybe_finish_next_locked(exec_ctx, r);
-  gpr_mu_unlock(&r->mu);
-}
-
-static void sockaddr_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
-                          grpc_client_config **target_config,
-                          grpc_closure *on_complete) {
-  sockaddr_resolver *r = (sockaddr_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(!r->next_completion);
-  r->next_completion = on_complete;
-  r->target_config = target_config;
-  sockaddr_maybe_finish_next_locked(exec_ctx, r);
-  gpr_mu_unlock(&r->mu);
-}
-
-static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                              sockaddr_resolver *r) {
-  if (r->next_completion != NULL && !r->published) {
-    grpc_client_config *cfg = grpc_client_config_create();
-    grpc_lb_policy_args lb_policy_args;
-    memset(&lb_policy_args, 0, sizeof(lb_policy_args));
-    lb_policy_args.addresses = r->addresses;
-    lb_policy_args.subchannel_factory = r->subchannel_factory;
-    grpc_lb_policy *lb_policy =
-        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
-    grpc_client_config_set_lb_policy(cfg, lb_policy);
-    GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "sockaddr");
-    r->published = 1;
-    *r->target_config = cfg;
-    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
-    r->next_completion = NULL;
-  }
-}
-
-static void sockaddr_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
-  sockaddr_resolver *r = (sockaddr_resolver *)gr;
-  gpr_mu_destroy(&r->mu);
-  grpc_subchannel_factory_unref(exec_ctx, r->subchannel_factory);
-  grpc_resolved_addresses_destroy(r->addresses);
-  gpr_free(r->lb_policy_name);
-  gpr_free(r);
-}
-
-static char *ip_get_default_authority(grpc_uri *uri) {
-  const char *path = uri->path;
-  if (path[0] == '/') ++path;
-  return gpr_strdup(path);
-}
-
-static char *ipv4_get_default_authority(grpc_resolver_factory *factory,
-                                        grpc_uri *uri) {
-  return ip_get_default_authority(uri);
-}
-
-static char *ipv6_get_default_authority(grpc_resolver_factory *factory,
-                                        grpc_uri *uri) {
-  return ip_get_default_authority(uri);
-}
-
-static int parse_ipv4(grpc_uri *uri, struct sockaddr_storage *addr,
-                      size_t *len) {
-  const char *host_port = uri->path;
-  char *host;
-  char *port;
-  int port_num;
-  int result = 0;
-  struct sockaddr_in *in = (struct sockaddr_in *)addr;
-
-  if (*host_port == '/') ++host_port;
-  if (!gpr_split_host_port(host_port, &host, &port)) {
-    return 0;
-  }
-
-  memset(in, 0, sizeof(*in));
-  *len = sizeof(*in);
-  in->sin_family = AF_INET;
-  if (inet_pton(AF_INET, host, &in->sin_addr) == 0) {
-    gpr_log(GPR_ERROR, "invalid ipv4 address: '%s'", host);
-    goto done;
-  }
-
-  if (port != NULL) {
-    if (sscanf(port, "%d", &port_num) != 1 || port_num < 0 ||
-        port_num > 65535) {
-      gpr_log(GPR_ERROR, "invalid ipv4 port: '%s'", port);
-      goto done;
-    }
-    in->sin_port = htons((uint16_t)port_num);
-  } else {
-    gpr_log(GPR_ERROR, "no port given for ipv4 scheme");
-    goto done;
-  }
-
-  result = 1;
-done:
-  gpr_free(host);
-  gpr_free(port);
-  return result;
-}
-
-static int parse_ipv6(grpc_uri *uri, struct sockaddr_storage *addr,
-                      size_t *len) {
-  const char *host_port = uri->path;
-  char *host;
-  char *port;
-  int port_num;
-  int result = 0;
-  struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)addr;
-
-  if (*host_port == '/') ++host_port;
-  if (!gpr_split_host_port(host_port, &host, &port)) {
-    return 0;
-  }
-
-  memset(in6, 0, sizeof(*in6));
-  *len = sizeof(*in6);
-  in6->sin6_family = AF_INET6;
-  if (inet_pton(AF_INET6, host, &in6->sin6_addr) == 0) {
-    gpr_log(GPR_ERROR, "invalid ipv6 address: '%s'", host);
-    goto done;
-  }
-
-  if (port != NULL) {
-    if (sscanf(port, "%d", &port_num) != 1 || port_num < 0 ||
-        port_num > 65535) {
-      gpr_log(GPR_ERROR, "invalid ipv6 port: '%s'", port);
-      goto done;
-    }
-    in6->sin6_port = htons((uint16_t)port_num);
-  } else {
-    gpr_log(GPR_ERROR, "no port given for ipv6 scheme");
-    goto done;
-  }
-
-  result = 1;
-done:
-  gpr_free(host);
-  gpr_free(port);
-  return result;
-}
-
-static void do_nothing(void *ignored) {}
-
-static grpc_resolver *sockaddr_create(
-    grpc_resolver_args *args, const char *default_lb_policy_name,
-    int parse(grpc_uri *uri, struct sockaddr_storage *dst, size_t *len)) {
-  int errors_found = 0; /* GPR_FALSE */
-  sockaddr_resolver *r;
-  gpr_slice path_slice;
-  gpr_slice_buffer path_parts;
-
-  if (0 != strcmp(args->uri->authority, "")) {
-    gpr_log(GPR_ERROR, "authority based uri's not supported by the %s scheme",
-            args->uri->scheme);
-    return NULL;
-  }
-
-  r = gpr_malloc(sizeof(sockaddr_resolver));
-  memset(r, 0, sizeof(*r));
-
-  r->lb_policy_name = NULL;
-  if (0 != strcmp(args->uri->query, "")) {
-    gpr_slice query_slice;
-    gpr_slice_buffer query_parts;
-
-    query_slice =
-        gpr_slice_new(args->uri->query, strlen(args->uri->query), do_nothing);
-    gpr_slice_buffer_init(&query_parts);
-    gpr_slice_split(query_slice, "=", &query_parts);
-    GPR_ASSERT(query_parts.count == 2);
-    if (0 == gpr_slice_str_cmp(query_parts.slices[0], "lb_policy")) {
-      r->lb_policy_name = gpr_dump_slice(query_parts.slices[1], GPR_DUMP_ASCII);
-    }
-    gpr_slice_buffer_destroy(&query_parts);
-    gpr_slice_unref(query_slice);
-  }
-  if (r->lb_policy_name == NULL) {
-    r->lb_policy_name = gpr_strdup(default_lb_policy_name);
-  }
-
-  path_slice =
-      gpr_slice_new(args->uri->path, strlen(args->uri->path), do_nothing);
-  gpr_slice_buffer_init(&path_parts);
-
-  gpr_slice_split(path_slice, ",", &path_parts);
-  r->addresses = gpr_malloc(sizeof(grpc_resolved_addresses));
-  r->addresses->naddrs = path_parts.count;
-  r->addresses->addrs =
-      gpr_malloc(sizeof(grpc_resolved_address) * r->addresses->naddrs);
-
-  for (size_t i = 0; i < r->addresses->naddrs; i++) {
-    grpc_uri ith_uri = *args->uri;
-    char *part_str = gpr_dump_slice(path_parts.slices[i], GPR_DUMP_ASCII);
-    ith_uri.path = part_str;
-    if (!parse(&ith_uri,
-               (struct sockaddr_storage *)(&r->addresses->addrs[i].addr),
-               &r->addresses->addrs[i].len)) {
-      errors_found = 1; /* GPR_TRUE */
-    }
-    gpr_free(part_str);
-    if (errors_found) break;
-  }
-
-  gpr_slice_buffer_destroy(&path_parts);
-  gpr_slice_unref(path_slice);
-  if (errors_found) {
-    gpr_free(r->lb_policy_name);
-    grpc_resolved_addresses_destroy(r->addresses);
-    gpr_free(r);
-    return NULL;
-  }
-
-  gpr_ref_init(&r->refs, 1);
-  gpr_mu_init(&r->mu);
-  grpc_resolver_init(&r->base, &sockaddr_resolver_vtable);
-  r->subchannel_factory = args->subchannel_factory;
-  grpc_subchannel_factory_ref(r->subchannel_factory);
-
-  return &r->base;
-}
-
-/*
- * FACTORY
- */
-
-static void sockaddr_factory_ref(grpc_resolver_factory *factory) {}
-
-static void sockaddr_factory_unref(grpc_resolver_factory *factory) {}
-
-#define DECL_FACTORY(name, prefix)                                          \
-  static grpc_resolver *name##_factory_create_resolver(                     \
-      grpc_resolver_factory *factory, grpc_resolver_args *args) {           \
-    return sockaddr_create(args, "pick_first", prefix##parse_##name);       \
-  }                                                                         \
-  static const grpc_resolver_factory_vtable name##_factory_vtable = {       \
-      sockaddr_factory_ref, sockaddr_factory_unref,                         \
-      name##_factory_create_resolver, prefix##name##_get_default_authority, \
-      #name};                                                               \
-  static grpc_resolver_factory name##_resolver_factory = {                  \
-      &name##_factory_vtable};                                              \
-  grpc_resolver_factory *grpc_##name##_resolver_factory_create() {          \
-    return &name##_resolver_factory;                                        \
-  }
-
-#ifdef GPR_HAVE_UNIX_SOCKET
-DECL_FACTORY(unix, grpc_)
-#endif
-DECL_FACTORY(ipv4, ) DECL_FACTORY(ipv6, )
diff --git a/src/core/lib/client_config/resolvers/sockaddr_resolver.h b/src/core/lib/client_config/resolvers/sockaddr_resolver.h
deleted file mode 100644
index a8b208176c..0000000000
--- a/src/core/lib/client_config/resolvers/sockaddr_resolver.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_SOCKADDR_RESOLVER_H
-#define GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_SOCKADDR_RESOLVER_H
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/client_config/resolver_factory.h"
-
-grpc_resolver_factory *grpc_ipv4_resolver_factory_create(void);
-
-grpc_resolver_factory *grpc_ipv6_resolver_factory_create(void);
-
-#ifdef GPR_POSIX_SOCKET
-/** Create a unix resolver factory */
-grpc_resolver_factory *grpc_unix_resolver_factory_create(void);
-#endif
-
-#endif /* GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_SOCKADDR_RESOLVER_H */
diff --git a/src/core/lib/client_config/resolvers/zookeeper_resolver.c b/src/core/lib/client_config/resolvers/zookeeper_resolver.c
deleted file mode 100644
index a66c9925f0..0000000000
--- a/src/core/lib/client_config/resolvers/zookeeper_resolver.c
+++ /dev/null
@@ -1,514 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/client_config/resolvers/zookeeper_resolver.h"
-
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
-
-#include <grpc/grpc_zookeeper.h>
-#include <zookeeper/zookeeper.h>
-
-#include "src/core/lib/client_config/lb_policy_registry.h"
-#include "src/core/lib/client_config/resolver_registry.h"
-#include "src/core/lib/iomgr/resolve_address.h"
-#include "src/core/lib/json/json.h"
-#include "src/core/lib/support/string.h"
-#include "src/core/lib/surface/api_trace.h"
-
-/** Zookeeper session expiration time in milliseconds */
-#define GRPC_ZOOKEEPER_SESSION_TIMEOUT 15000
-
-typedef struct {
-  /** base class: must be first */
-  grpc_resolver base;
-  /** refcount */
-  gpr_refcount refs;
-  /** name to resolve */
-  char *name;
-  /** subchannel factory */
-  grpc_subchannel_factory *subchannel_factory;
-  /** load balancing policy name */
-  char *lb_policy_name;
-
-  /** mutex guarding the rest of the state */
-  gpr_mu mu;
-  /** are we currently resolving? */
-  int resolving;
-  /** which version of resolved_config have we published? */
-  int published_version;
-  /** which version of resolved_config is current? */
-  int resolved_version;
-  /** pending next completion, or NULL */
-  grpc_closure *next_completion;
-  /** target config address for next completion */
-  grpc_client_config **target_config;
-  /** current (fully resolved) config */
-  grpc_client_config *resolved_config;
-
-  /** zookeeper handle */
-  zhandle_t *zookeeper_handle;
-  /** zookeeper resolved addresses */
-  grpc_resolved_addresses *resolved_addrs;
-  /** total number of addresses to be resolved */
-  int resolved_total;
-  /** number of addresses resolved */
-  int resolved_num;
-} zookeeper_resolver;
-
-static void zookeeper_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-
-static void zookeeper_start_resolving_locked(zookeeper_resolver *r);
-static void zookeeper_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                               zookeeper_resolver *r);
-
-static void zookeeper_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
-static void zookeeper_channel_saw_error(grpc_exec_ctx *exec_ctx,
-                                        grpc_resolver *r);
-static void zookeeper_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r,
-                           grpc_client_config **target_config,
-                           grpc_closure *on_complete);
-
-static const grpc_resolver_vtable zookeeper_resolver_vtable = {
-    zookeeper_destroy, zookeeper_shutdown, zookeeper_channel_saw_error,
-    zookeeper_next};
-
-static void zookeeper_shutdown(grpc_exec_ctx *exec_ctx,
-                               grpc_resolver *resolver) {
-  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
-  grpc_closure *call = NULL;
-  gpr_mu_lock(&r->mu);
-  if (r->next_completion != NULL) {
-    *r->target_config = NULL;
-    call = r->next_completion;
-    r->next_completion = NULL;
-  }
-  zookeeper_close(r->zookeeper_handle);
-  gpr_mu_unlock(&r->mu);
-  if (call != NULL) {
-    call->cb(exec_ctx, call->cb_arg, 1);
-  }
-}
-
-static void zookeeper_channel_saw_error(grpc_exec_ctx *exec_ctx,
-                                        grpc_resolver *resolver) {
-  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  if (r->resolving == 0) {
-    zookeeper_start_resolving_locked(r);
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-static void zookeeper_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
-                           grpc_client_config **target_config,
-                           grpc_closure *on_complete) {
-  zookeeper_resolver *r = (zookeeper_resolver *)resolver;
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(r->next_completion == NULL);
-  r->next_completion = on_complete;
-  r->target_config = target_config;
-  if (r->resolved_version == 0 && r->resolving == 0) {
-    zookeeper_start_resolving_locked(r);
-  } else {
-    zookeeper_maybe_finish_next_locked(exec_ctx, r);
-  }
-  gpr_mu_unlock(&r->mu);
-}
-
-/** Zookeeper global watcher for connection management
-    TODO: better connection management besides logs */
-static void zookeeper_global_watcher(zhandle_t *zookeeper_handle, int type,
-                                     int state, const char *path,
-                                     void *watcher_ctx) {
-  if (type == ZOO_SESSION_EVENT) {
-    if (state == ZOO_EXPIRED_SESSION_STATE) {
-      gpr_log(GPR_ERROR, "Zookeeper session expired");
-    } else if (state == ZOO_AUTH_FAILED_STATE) {
-      gpr_log(GPR_ERROR, "Zookeeper authentication failed");
-    }
-  }
-}
-
-/** Zookeeper watcher triggered by changes to watched nodes
-    Once triggered, it tries to resolve again to get updated addresses */
-static void zookeeper_watcher(zhandle_t *zookeeper_handle, int type, int state,
-                              const char *path, void *watcher_ctx) {
-  if (watcher_ctx != NULL) {
-    zookeeper_resolver *r = (zookeeper_resolver *)watcher_ctx;
-    if (state == ZOO_CONNECTED_STATE) {
-      gpr_mu_lock(&r->mu);
-      if (r->resolving == 0) {
-        zookeeper_start_resolving_locked(r);
-      }
-      gpr_mu_unlock(&r->mu);
-    }
-  }
-}
-
-/** Callback function after getting all resolved addresses
-    Creates a subchannel for each address */
-static void zookeeper_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
-                                  grpc_resolved_addresses *addresses) {
-  zookeeper_resolver *r = arg;
-  grpc_client_config *config = NULL;
-  grpc_lb_policy *lb_policy;
-
-  if (addresses != NULL) {
-    grpc_lb_policy_args lb_policy_args;
-    config = grpc_client_config_create();
-
-    lb_policy_args.addresses = addresses;
-    lb_policy_args.subchannel_factory = r->subchannel_factory;
-    lb_policy =
-        grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
-
-    if (lb_policy != NULL) {
-      grpc_client_config_set_lb_policy(config, lb_policy);
-      GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
-    }
-    grpc_resolved_addresses_destroy(addresses);
-  }
-  gpr_mu_lock(&r->mu);
-  GPR_ASSERT(r->resolving == 1);
-  r->resolving = 0;
-  if (r->resolved_config != NULL) {
-    grpc_client_config_unref(exec_ctx, r->resolved_config);
-  }
-  r->resolved_config = config;
-  r->resolved_version++;
-  zookeeper_maybe_finish_next_locked(exec_ctx, r);
-  gpr_mu_unlock(&r->mu);
-
-  GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "zookeeper-resolving");
-}
-
-/** Callback function for each DNS resolved address */
-static void zookeeper_dns_resolved(grpc_exec_ctx *exec_ctx, void *arg,
-                                   grpc_resolved_addresses *addresses) {
-  size_t i;
-  zookeeper_resolver *r = arg;
-  int resolve_done = 0;
-
-  gpr_mu_lock(&r->mu);
-  r->resolved_num++;
-  r->resolved_addrs->addrs =
-      gpr_realloc(r->resolved_addrs->addrs,
-                  sizeof(grpc_resolved_address) *
-                      (r->resolved_addrs->naddrs + addresses->naddrs));
-  for (i = 0; i < addresses->naddrs; i++) {
-    memcpy(r->resolved_addrs->addrs[i + r->resolved_addrs->naddrs].addr,
-           addresses->addrs[i].addr, addresses->addrs[i].len);
-    r->resolved_addrs->addrs[i + r->resolved_addrs->naddrs].len =
-        addresses->addrs[i].len;
-  }
-
-  r->resolved_addrs->naddrs += addresses->naddrs;
-  grpc_resolved_addresses_destroy(addresses);
-
-  /** Wait for all addresses to be resolved */
-  resolve_done = (r->resolved_num == r->resolved_total);
-  gpr_mu_unlock(&r->mu);
-  if (resolve_done) {
-    zookeeper_on_resolved(exec_ctx, r, r->resolved_addrs);
-  }
-}
-
-/** Parses JSON format address of a zookeeper node */
-static char *zookeeper_parse_address(const char *value, size_t value_len) {
-  grpc_json *json;
-  grpc_json *cur;
-  const char *host;
-  const char *port;
-  char *buffer;
-  char *address = NULL;
-
-  buffer = gpr_malloc(value_len);
-  memcpy(buffer, value, value_len);
-  json = grpc_json_parse_string_with_len(buffer, value_len);
-  if (json != NULL) {
-    host = NULL;
-    port = NULL;
-    for (cur = json->child; cur != NULL; cur = cur->next) {
-      if (!strcmp(cur->key, "host")) {
-        host = cur->value;
-        if (port != NULL) {
-          break;
-        }
-      } else if (!strcmp(cur->key, "port")) {
-        port = cur->value;
-        if (host != NULL) {
-          break;
-        }
-      }
-    }
-    if (host != NULL && port != NULL) {
-      gpr_asprintf(&address, "%s:%s", host, port);
-    }
-    grpc_json_destroy(json);
-  }
-  gpr_free(buffer);
-
-  return address;
-}
-
-static void zookeeper_get_children_node_completion(int rc, const char *value,
-                                                   int value_len,
-                                                   const struct Stat *stat,
-                                                   const void *arg) {
-  char *address = NULL;
-  zookeeper_resolver *r = (zookeeper_resolver *)arg;
-  int resolve_done = 0;
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-
-  if (rc != 0) {
-    gpr_log(GPR_ERROR, "Error in getting a child node of %s", r->name);
-    grpc_exec_ctx_finish(&exec_ctx);
-    return;
-  }
-
-  address = zookeeper_parse_address(value, (size_t)value_len);
-  if (address != NULL) {
-    /** Further resolves address by DNS */
-    grpc_resolve_address(address, NULL, zookeeper_dns_resolved, r);
-    gpr_free(address);
-  } else {
-    gpr_log(GPR_ERROR, "Error in resolving a child node of %s", r->name);
-    gpr_mu_lock(&r->mu);
-    r->resolved_total--;
-    resolve_done = (r->resolved_num == r->resolved_total);
-    gpr_mu_unlock(&r->mu);
-    if (resolve_done) {
-      zookeeper_on_resolved(&exec_ctx, r, r->resolved_addrs);
-    }
-  }
-
-  grpc_exec_ctx_finish(&exec_ctx);
-}
-
-static void zookeeper_get_children_completion(
-    int rc, const struct String_vector *children, const void *arg) {
-  char *path;
-  int status;
-  int i;
-  zookeeper_resolver *r = (zookeeper_resolver *)arg;
-
-  if (rc != 0) {
-    gpr_log(GPR_ERROR, "Error in getting zookeeper children of %s", r->name);
-    return;
-  }
-
-  if (children->count == 0) {
-    gpr_log(GPR_ERROR, "Error in resolving zookeeper address %s", r->name);
-    return;
-  }
-
-  r->resolved_addrs = gpr_malloc(sizeof(grpc_resolved_addresses));
-  r->resolved_addrs->addrs = NULL;
-  r->resolved_addrs->naddrs = 0;
-  r->resolved_total = children->count;
-
-  /** TODO: Replace expensive heap allocation with stack
-      if we can get maximum length of zookeeper path */
-  for (i = 0; i < children->count; i++) {
-    gpr_asprintf(&path, "%s/%s", r->name, children->data[i]);
-    status = zoo_awget(r->zookeeper_handle, path, zookeeper_watcher, r,
-                       zookeeper_get_children_node_completion, r);
-    gpr_free(path);
-    if (status != 0) {
-      gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", path);
-    }
-  }
-}
-
-static void zookeeper_get_node_completion(int rc, const char *value,
-                                          int value_len,
-                                          const struct Stat *stat,
-                                          const void *arg) {
-  int status;
-  char *address = NULL;
-  zookeeper_resolver *r = (zookeeper_resolver *)arg;
-  r->resolved_addrs = NULL;
-  r->resolved_total = 0;
-  r->resolved_num = 0;
-
-  if (rc != 0) {
-    gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", r->name);
-    return;
-  }
-
-  /** If zookeeper node of path r->name does not have address
-      (i.e. service node), get its children */
-  address = zookeeper_parse_address(value, (size_t)value_len);
-  if (address != NULL) {
-    r->resolved_addrs = gpr_malloc(sizeof(grpc_resolved_addresses));
-    r->resolved_addrs->addrs = NULL;
-    r->resolved_addrs->naddrs = 0;
-    r->resolved_total = 1;
-    /** Further resolves address by DNS */
-    grpc_resolve_address(address, NULL, zookeeper_dns_resolved, r);
-    gpr_free(address);
-    return;
-  }
-
-  status = zoo_awget_children(r->zookeeper_handle, r->name, zookeeper_watcher,
-                              r, zookeeper_get_children_completion, r);
-  if (status != 0) {
-    gpr_log(GPR_ERROR, "Error in getting zookeeper children of %s", r->name);
-  }
-}
-
-static void zookeeper_resolve_address(zookeeper_resolver *r) {
-  int status;
-  status = zoo_awget(r->zookeeper_handle, r->name, zookeeper_watcher, r,
-                     zookeeper_get_node_completion, r);
-  if (status != 0) {
-    gpr_log(GPR_ERROR, "Error in getting zookeeper node %s", r->name);
-  }
-}
-
-static void zookeeper_start_resolving_locked(zookeeper_resolver *r) {
-  GRPC_RESOLVER_REF(&r->base, "zookeeper-resolving");
-  GPR_ASSERT(r->resolving == 0);
-  r->resolving = 1;
-  zookeeper_resolve_address(r);
-}
-
-static void zookeeper_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
-                                               zookeeper_resolver *r) {
-  if (r->next_completion != NULL &&
-      r->resolved_version != r->published_version) {
-    *r->target_config = r->resolved_config;
-    if (r->resolved_config != NULL) {
-      grpc_client_config_ref(r->resolved_config);
-    }
-    grpc_exec_ctx_enqueue(exec_ctx, r->next_completion, true, NULL);
-    r->next_completion = NULL;
-    r->published_version = r->resolved_version;
-  }
-}
-
-static void zookeeper_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
-  zookeeper_resolver *r = (zookeeper_resolver *)gr;
-  gpr_mu_destroy(&r->mu);
-  if (r->resolved_config != NULL) {
-    grpc_client_config_unref(exec_ctx, r->resolved_config);
-  }
-  grpc_subchannel_factory_unref(exec_ctx, r->subchannel_factory);
-  gpr_free(r->name);
-  gpr_free(r->lb_policy_name);
-  gpr_free(r);
-}
-
-static grpc_resolver *zookeeper_create(grpc_resolver_args *args,
-                                       const char *lb_policy_name) {
-  zookeeper_resolver *r;
-  size_t length;
-  char *path = args->uri->path;
-
-  if (0 == strcmp(args->uri->authority, "")) {
-    gpr_log(GPR_ERROR, "No authority specified in zookeeper uri");
-    return NULL;
-  }
-
-  /** Removes the trailing slash if exists */
-  length = strlen(path);
-  if (length > 1 && path[length - 1] == '/') {
-    path[length - 1] = 0;
-  }
-
-  r = gpr_malloc(sizeof(zookeeper_resolver));
-  memset(r, 0, sizeof(*r));
-  gpr_ref_init(&r->refs, 1);
-  gpr_mu_init(&r->mu);
-  grpc_resolver_init(&r->base, &zookeeper_resolver_vtable);
-  r->name = gpr_strdup(path);
-
-  r->subchannel_factory = args->subchannel_factory;
-  grpc_subchannel_factory_ref(r->subchannel_factory);
-
-  r->lb_policy_name = gpr_strdup(lb_policy_name);
-
-  /** Initializes zookeeper client */
-  zoo_set_debug_level(ZOO_LOG_LEVEL_WARN);
-  r->zookeeper_handle =
-      zookeeper_init(args->uri->authority, zookeeper_global_watcher,
-                     GRPC_ZOOKEEPER_SESSION_TIMEOUT, 0, 0, 0);
-  if (r->zookeeper_handle == NULL) {
-    gpr_log(GPR_ERROR, "Unable to connect to zookeeper server");
-    return NULL;
-  }
-
-  return &r->base;
-}
-
-static void zookeeper_plugin_init() {
-  grpc_register_resolver_type(grpc_zookeeper_resolver_factory_create());
-}
-
-void grpc_zookeeper_register() {
-  GRPC_API_TRACE("grpc_zookeeper_register(void)", 0, ());
-  grpc_register_plugin(zookeeper_plugin_init, NULL);
-}
-
-/*
- * FACTORY
- */
-
-static void zookeeper_factory_ref(grpc_resolver_factory *factory) {}
-
-static void zookeeper_factory_unref(grpc_resolver_factory *factory) {}
-
-static char *zookeeper_factory_get_default_hostname(
-    grpc_resolver_factory *factory, grpc_uri *uri) {
-  return NULL;
-}
-
-static grpc_resolver *zookeeper_factory_create_resolver(
-    grpc_resolver_factory *factory, grpc_resolver_args *args) {
-  return zookeeper_create(args, "pick_first");
-}
-
-static const grpc_resolver_factory_vtable zookeeper_factory_vtable = {
-    zookeeper_factory_ref, zookeeper_factory_unref,
-    zookeeper_factory_create_resolver, zookeeper_factory_get_default_hostname,
-    "zookeeper"};
-
-static grpc_resolver_factory zookeeper_resolver_factory = {
-    &zookeeper_factory_vtable};
-
-grpc_resolver_factory *grpc_zookeeper_resolver_factory_create() {
-  return &zookeeper_resolver_factory;
-}
diff --git a/src/core/lib/client_config/resolvers/zookeeper_resolver.h b/src/core/lib/client_config/resolvers/zookeeper_resolver.h
deleted file mode 100644
index a067bd0bdb..0000000000
--- a/src/core/lib/client_config/resolvers/zookeeper_resolver.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_ZOOKEEPER_RESOLVER_H
-#define GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_ZOOKEEPER_RESOLVER_H
-
-#include "src/core/lib/client_config/resolver_factory.h"
-
-/** Create a zookeeper resolver factory */
-grpc_resolver_factory *grpc_zookeeper_resolver_factory_create(void);
-
-#endif /* GRPC_CORE_LIB_CLIENT_CONFIG_RESOLVERS_ZOOKEEPER_RESOLVER_H */
diff --git a/src/core/lib/client_config/uri_parser.c b/src/core/lib/client_config/uri_parser.c
index b4ee763735..6bec70da2d 100644
--- a/src/core/lib/client_config/uri_parser.c
+++ b/src/core/lib/client_config/uri_parser.c
@@ -38,8 +38,12 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/port_platform.h>
+#include <grpc/support/slice.h>
+#include <grpc/support/slice_buffer.h>
 #include <grpc/support/string_util.h>
 
+#include "src/core/lib/support/string.h"
+
 /** a size_t default value... maps to all 1's */
 #define NOT_SET (~(size_t)0)
 
@@ -133,6 +137,51 @@ static int parse_fragment_or_query(const char *uri_text, size_t *i) {
   return 1;
 }
 
+static void do_nothing(void *ignored) {}
+static void parse_query_parts(grpc_uri *uri) {
+  static const char *QUERY_PARTS_SEPARATOR = "&";
+  static const char *QUERY_PARTS_VALUE_SEPARATOR = "=";
+  GPR_ASSERT(uri->query != NULL);
+  if (uri->query[0] == '\0') {
+    uri->query_parts = NULL;
+    uri->query_parts_values = NULL;
+    uri->num_query_parts = 0;
+    return;
+  }
+  gpr_slice query_slice =
+      gpr_slice_new(uri->query, strlen(uri->query), do_nothing);
+  gpr_slice_buffer query_parts; /* the &-separated elements of the query */
+  gpr_slice_buffer query_param_parts; /* the =-separated subelements */
+
+  gpr_slice_buffer_init(&query_parts);
+  gpr_slice_buffer_init(&query_param_parts);
+
+  gpr_slice_split(query_slice, QUERY_PARTS_SEPARATOR, &query_parts);
+  uri->query_parts = gpr_malloc(query_parts.count * sizeof(char *));
+  uri->query_parts_values = gpr_malloc(query_parts.count * sizeof(char *));
+  uri->num_query_parts = query_parts.count;
+  for (size_t i = 0; i < query_parts.count; i++) {
+    gpr_slice_split(query_parts.slices[i], QUERY_PARTS_VALUE_SEPARATOR,
+                    &query_param_parts);
+    GPR_ASSERT(query_param_parts.count > 0);
+    uri->query_parts[i] =
+        gpr_dump_slice(query_param_parts.slices[0], GPR_DUMP_ASCII);
+    if (query_param_parts.count > 1) {
+      /* TODO(dgq): only the first value after the separator is considered.
+       * Perhaps all chars after the first separator for the query part should
+       * be included, even if they include the separator. */
+      uri->query_parts_values[i] =
+          gpr_dump_slice(query_param_parts.slices[1], GPR_DUMP_ASCII);
+    } else {
+      uri->query_parts_values[i] = NULL;
+    }
+    gpr_slice_buffer_reset_and_unref(&query_param_parts);
+  }
+  gpr_slice_buffer_destroy(&query_parts);
+  gpr_slice_buffer_destroy(&query_param_parts);
+  gpr_slice_unref(query_slice);
+}
+
 grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors) {
   grpc_uri *uri;
   size_t scheme_begin = 0;
@@ -227,16 +276,35 @@ grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors) {
   uri->path = copy_component(uri_text, path_begin, path_end);
   uri->query = copy_component(uri_text, query_begin, query_end);
   uri->fragment = copy_component(uri_text, fragment_begin, fragment_end);
+  parse_query_parts(uri);
 
   return uri;
 }
 
+const char *grpc_uri_get_query_arg(const grpc_uri *uri, const char *key) {
+  GPR_ASSERT(key != NULL);
+  if (key[0] == '\0') return NULL;
+
+  for (size_t i = 0; i < uri->num_query_parts; ++i) {
+    if (0 == strcmp(key, uri->query_parts[i])) {
+      return uri->query_parts_values[i];
+    }
+  }
+  return NULL;
+}
+
 void grpc_uri_destroy(grpc_uri *uri) {
   if (!uri) return;
   gpr_free(uri->scheme);
   gpr_free(uri->authority);
   gpr_free(uri->path);
   gpr_free(uri->query);
+  for (size_t i = 0; i < uri->num_query_parts; ++i) {
+    gpr_free(uri->query_parts[i]);
+    gpr_free(uri->query_parts_values[i]);
+  }
+  gpr_free(uri->query_parts);
+  gpr_free(uri->query_parts_values);
   gpr_free(uri->fragment);
   gpr_free(uri);
 }
diff --git a/src/core/lib/client_config/uri_parser.h b/src/core/lib/client_config/uri_parser.h
index 4f8e809b2e..5d6785d293 100644
--- a/src/core/lib/client_config/uri_parser.h
+++ b/src/core/lib/client_config/uri_parser.h
@@ -34,17 +34,29 @@
 #ifndef GRPC_CORE_LIB_CLIENT_CONFIG_URI_PARSER_H
 #define GRPC_CORE_LIB_CLIENT_CONFIG_URI_PARSER_H
 
+#include <stddef.h>
+
 typedef struct {
   char *scheme;
   char *authority;
   char *path;
   char *query;
+  /** Query substrings separated by '&' */
+  char **query_parts;
+  /** Number of elements in \a query_parts and \a query_parts_values */
+  size_t num_query_parts;
+  /** Split each query part by '='. NULL if not present. */
+  char **query_parts_values;
   char *fragment;
 } grpc_uri;
 
 /** parse a uri, return NULL on failure */
 grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors);
 
+/** return the part of a query string after the '=' in "?key=xxx&...", or NULL
+ * if key is not present */
+const char *grpc_uri_get_query_arg(const grpc_uri *uri, const char *key);
+
 /** destroy a uri */
 void grpc_uri_destroy(grpc_uri *uri);
 
diff --git a/src/core/lib/iomgr/ev_poll_and_epoll_posix.c b/src/core/lib/iomgr/ev_poll_and_epoll_posix.c
new file mode 100644
index 0000000000..dba335490b
--- /dev/null
+++ b/src/core/lib/iomgr/ev_poll_and_epoll_posix.c
@@ -0,0 +1,1936 @@
+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+/* This file will be removed shortly: it's here to keep refactoring
+ * steps simple and auditable.
+ * It's the combination of the old files:
+ *  - fd_posix.{h,c}
+ *  - pollset_posix.{h,c}
+ *  - pullset_multipoller_with_{poll,epoll}.{h,c}
+ * The new version will be split into:
+ *  - ev_poll_posix.{h,c}
+ *  - ev_epoll_posix.{h,c}
+ */
+
+#include <grpc/support/port_platform.h>
+
+#ifdef GPR_POSIX_SOCKET
+
+#include "src/core/lib/iomgr/ev_poll_and_epoll_posix.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <poll.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/tls.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/iomgr/iomgr_internal.h"
+#include "src/core/lib/iomgr/wakeup_fd_posix.h"
+#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/block_annotate.h"
+
+/*******************************************************************************
+ * FD declarations
+ */
+
+typedef struct grpc_fd_watcher {
+  struct grpc_fd_watcher *next;
+  struct grpc_fd_watcher *prev;
+  grpc_pollset *pollset;
+  grpc_pollset_worker *worker;
+  grpc_fd *fd;
+} grpc_fd_watcher;
+
+struct grpc_fd {
+  int fd;
+  /* refst format:
+     bit0:   1=active/0=orphaned
+     bit1-n: refcount
+     meaning that mostly we ref by two to avoid altering the orphaned bit,
+     and just unref by 1 when we're ready to flag the object as orphaned */
+  gpr_atm refst;
+
+  gpr_mu mu;
+  int shutdown;
+  int closed;
+  int released;
+
+  /* The watcher list.
+
+     The following watcher related fields are protected by watcher_mu.
+
+     An fd_watcher is an ephemeral object created when an fd wants to
+     begin polling, and destroyed after the poll.
+
+     It denotes the fd's interest in whether to read poll or write poll
+     or both or neither on this fd.
+
+     If a watcher is asked to poll for reads or writes, the read_watcher
+     or write_watcher fields are set respectively. A watcher may be asked
+     to poll for both, in which case both fields will be set.
+
+     read_watcher and write_watcher may be NULL if no watcher has been
+     asked to poll for reads or writes.
+
+     If an fd_watcher is not asked to poll for reads or writes, it's added
+     to a linked list of inactive watchers, rooted at inactive_watcher_root.
+     If at a later time there becomes need of a poller to poll, one of
+     the inactive pollers may be kicked out of their poll loops to take
+     that responsibility. */
+  grpc_fd_watcher inactive_watcher_root;
+  grpc_fd_watcher *read_watcher;
+  grpc_fd_watcher *write_watcher;
+
+  grpc_closure *read_closure;
+  grpc_closure *write_closure;
+
+  struct grpc_fd *freelist_next;
+
+  grpc_closure *on_done_closure;
+
+  grpc_iomgr_object iomgr_object;
+};
+
+/* Begin polling on an fd.
+   Registers that the given pollset is interested in this fd - so that if read
+   or writability interest changes, the pollset can be kicked to pick up that
+   new interest.
+   Return value is:
+     (fd_needs_read? read_mask : 0) | (fd_needs_write? write_mask : 0)
+   i.e. a combination of read_mask and write_mask determined by the fd's current
+   interest in said events.
+   Polling strategies that do not need to alter their behavior depending on the
+   fd's current interest (such as epoll) do not need to call this function.
+   MUST NOT be called with a pollset lock taken */
+static uint32_t fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
+                              grpc_pollset_worker *worker, uint32_t read_mask,
+                              uint32_t write_mask, grpc_fd_watcher *rec);
+/* Complete polling previously started with fd_begin_poll
+   MUST NOT be called with a pollset lock taken
+   if got_read or got_write are 1, also does the become_{readable,writable} as
+   appropriate. */
+static void fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *rec,
+                        int got_read, int got_write);
+
+/* Return 1 if this fd is orphaned, 0 otherwise */
+static bool fd_is_orphaned(grpc_fd *fd);
+
+/* Reference counting for fds */
+/*#define GRPC_FD_REF_COUNT_DEBUG*/
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+static void fd_ref(grpc_fd *fd, const char *reason, const char *file, int line);
+static void fd_unref(grpc_fd *fd, const char *reason, const char *file,
+                     int line);
+#define GRPC_FD_REF(fd, reason) fd_ref(fd, reason, __FILE__, __LINE__)
+#define GRPC_FD_UNREF(fd, reason) fd_unref(fd, reason, __FILE__, __LINE__)
+#else
+static void fd_ref(grpc_fd *fd);
+static void fd_unref(grpc_fd *fd);
+#define GRPC_FD_REF(fd, reason) fd_ref(fd)
+#define GRPC_FD_UNREF(fd, reason) fd_unref(fd)
+#endif
+
+static void fd_global_init(void);
+static void fd_global_shutdown(void);
+
+#define CLOSURE_NOT_READY ((grpc_closure *)0)
+#define CLOSURE_READY ((grpc_closure *)1)
+
+/*******************************************************************************
+ * pollset declarations
+ */
+
+typedef struct grpc_pollset_vtable grpc_pollset_vtable;
+
+typedef struct grpc_cached_wakeup_fd {
+  grpc_wakeup_fd fd;
+  struct grpc_cached_wakeup_fd *next;
+} grpc_cached_wakeup_fd;
+
+struct grpc_pollset_worker {
+  grpc_cached_wakeup_fd *wakeup_fd;
+  int reevaluate_polling_on_wakeup;
+  int kicked_specifically;
+  struct grpc_pollset_worker *next;
+  struct grpc_pollset_worker *prev;
+};
+
+struct grpc_pollset {
+  /* pollsets under posix can mutate representation as fds are added and
+     removed.
+     For example, we may choose a poll() based implementation on linux for
+     few fds, and an epoll() based implementation for many fds */
+  const grpc_pollset_vtable *vtable;
+  gpr_mu mu;
+  grpc_pollset_worker root_worker;
+  int in_flight_cbs;
+  int shutting_down;
+  int called_shutdown;
+  int kicked_without_pollers;
+  grpc_closure *shutdown_done;
+  grpc_closure_list idle_jobs;
+  union {
+    int fd;
+    void *ptr;
+  } data;
+  /* Local cache of eventfds for workers */
+  grpc_cached_wakeup_fd *local_wakeup_cache;
+};
+
+struct grpc_pollset_vtable {
+  void (*add_fd)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                 struct grpc_fd *fd, int and_unlock_pollset);
+  void (*maybe_work_and_unlock)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                                grpc_pollset_worker *worker,
+                                gpr_timespec deadline, gpr_timespec now);
+  void (*finish_shutdown)(grpc_pollset *pollset);
+  void (*destroy)(grpc_pollset *pollset);
+};
+
+/* Add an fd to a pollset */
+static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                           struct grpc_fd *fd);
+
+static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
+                               grpc_pollset_set *pollset_set, grpc_fd *fd);
+
+/* Convert a timespec to milliseconds:
+   - very small or negative poll times are clamped to zero to do a
+     non-blocking poll (which becomes spin polling)
+   - other small values are rounded up to one millisecond
+   - longer than a millisecond polls are rounded up to the next nearest
+     millisecond to avoid spinning
+   - infinite timeouts are converted to -1 */
+static int poll_deadline_to_millis_timeout(gpr_timespec deadline,
+                                           gpr_timespec now);
+
+/* Allow kick to wakeup the currently polling worker */
+#define GRPC_POLLSET_CAN_KICK_SELF 1
+/* Force the wakee to repoll when awoken */
+#define GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP 2
+/* As per pollset_kick, with an extended set of flags (defined above)
+   -- mostly for fd_posix's use. */
+static void pollset_kick_ext(grpc_pollset *p,
+                             grpc_pollset_worker *specific_worker,
+                             uint32_t flags);
+
+/* turn a pollset into a multipoller: platform specific */
+typedef void (*platform_become_multipoller_type)(grpc_exec_ctx *exec_ctx,
+                                                 grpc_pollset *pollset,
+                                                 struct grpc_fd **fds,
+                                                 size_t fd_count);
+static platform_become_multipoller_type platform_become_multipoller;
+
+/* Return 1 if the pollset has active threads in pollset_work (pollset must
+ * be locked) */
+static int pollset_has_workers(grpc_pollset *pollset);
+
+static void remove_fd_from_all_epoll_sets(int fd);
+
+/*******************************************************************************
+ * pollset_set definitions
+ */
+
+struct grpc_pollset_set {
+  gpr_mu mu;
+
+  size_t pollset_count;
+  size_t pollset_capacity;
+  grpc_pollset **pollsets;
+
+  size_t pollset_set_count;
+  size_t pollset_set_capacity;
+  struct grpc_pollset_set **pollset_sets;
+
+  size_t fd_count;
+  size_t fd_capacity;
+  grpc_fd **fds;
+};
+
+/*******************************************************************************
+ * fd_posix.c
+ */
+
+/* We need to keep a freelist not because of any concerns of malloc performance
+ * but instead so that implementations with multiple threads in (for example)
+ * epoll_wait deal with the race between pollset removal and incoming poll
+ * notifications.
+ *
+ * The problem is that the poller ultimately holds a reference to this
+ * object, so it is very difficult to know when is safe to free it, at least
+ * without some expensive synchronization.
+ *
+ * If we keep the object freelisted, in the worst case losing this race just
+ * becomes a spurious read notification on a reused fd.
+ */
+/* TODO(klempner): We could use some form of polling generation count to know
+ * when these are safe to free. */
+/* TODO(klempner): Consider disabling freelisting if we don't have multiple
+ * threads in poll on the same fd */
+/* TODO(klempner): Batch these allocations to reduce fragmentation */
+static grpc_fd *fd_freelist = NULL;
+static gpr_mu fd_freelist_mu;
+
+static void freelist_fd(grpc_fd *fd) {
+  gpr_mu_lock(&fd_freelist_mu);
+  fd->freelist_next = fd_freelist;
+  fd_freelist = fd;
+  grpc_iomgr_unregister_object(&fd->iomgr_object);
+  gpr_mu_unlock(&fd_freelist_mu);
+}
+
+static grpc_fd *alloc_fd(int fd) {
+  grpc_fd *r = NULL;
+  gpr_mu_lock(&fd_freelist_mu);
+  if (fd_freelist != NULL) {
+    r = fd_freelist;
+    fd_freelist = fd_freelist->freelist_next;
+  }
+  gpr_mu_unlock(&fd_freelist_mu);
+  if (r == NULL) {
+    r = gpr_malloc(sizeof(grpc_fd));
+    gpr_mu_init(&r->mu);
+  }
+
+  gpr_mu_lock(&r->mu);
+  gpr_atm_rel_store(&r->refst, 1);
+  r->shutdown = 0;
+  r->read_closure = CLOSURE_NOT_READY;
+  r->write_closure = CLOSURE_NOT_READY;
+  r->fd = fd;
+  r->inactive_watcher_root.next = r->inactive_watcher_root.prev =
+      &r->inactive_watcher_root;
+  r->freelist_next = NULL;
+  r->read_watcher = r->write_watcher = NULL;
+  r->on_done_closure = NULL;
+  r->closed = 0;
+  r->released = 0;
+  gpr_mu_unlock(&r->mu);
+  return r;
+}
+
+static void destroy(grpc_fd *fd) {
+  gpr_mu_destroy(&fd->mu);
+  gpr_free(fd);
+}
+
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+#define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__)
+#define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__)
+static void ref_by(grpc_fd *fd, int n, const char *reason, const char *file,
+                   int line) {
+  gpr_log(GPR_DEBUG, "FD %d %p   ref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
+          gpr_atm_no_barrier_load(&fd->refst),
+          gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line);
+#else
+#define REF_BY(fd, n, reason) ref_by(fd, n)
+#define UNREF_BY(fd, n, reason) unref_by(fd, n)
+static void ref_by(grpc_fd *fd, int n) {
+#endif
+  GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0);
+}
+
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+static void unref_by(grpc_fd *fd, int n, const char *reason, const char *file,
+                     int line) {
+  gpr_atm old;
+  gpr_log(GPR_DEBUG, "FD %d %p unref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
+          gpr_atm_no_barrier_load(&fd->refst),
+          gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line);
+#else
+static void unref_by(grpc_fd *fd, int n) {
+  gpr_atm old;
+#endif
+  old = gpr_atm_full_fetch_add(&fd->refst, -n);
+  if (old == n) {
+    freelist_fd(fd);
+  } else {
+    GPR_ASSERT(old > n);
+  }
+}
+
+static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); }
+
+static void fd_global_shutdown(void) {
+  gpr_mu_lock(&fd_freelist_mu);
+  gpr_mu_unlock(&fd_freelist_mu);
+  while (fd_freelist != NULL) {
+    grpc_fd *fd = fd_freelist;
+    fd_freelist = fd_freelist->freelist_next;
+    destroy(fd);
+  }
+  gpr_mu_destroy(&fd_freelist_mu);
+}
+
+static grpc_fd *fd_create(int fd, const char *name) {
+  grpc_fd *r = alloc_fd(fd);
+  char *name2;
+  gpr_asprintf(&name2, "%s fd=%d", name, fd);
+  grpc_iomgr_register_object(&r->iomgr_object, name2);
+  gpr_free(name2);
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+  gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, r, name);
+#endif
+  return r;
+}
+
+static bool fd_is_orphaned(grpc_fd *fd) {
+  return (gpr_atm_acq_load(&fd->refst) & 1) == 0;
+}
+
+static void pollset_kick_locked(grpc_fd_watcher *watcher) {
+  gpr_mu_lock(&watcher->pollset->mu);
+  GPR_ASSERT(watcher->worker);
+  pollset_kick_ext(watcher->pollset, watcher->worker,
+                   GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP);
+  gpr_mu_unlock(&watcher->pollset->mu);
+}
+
+static void maybe_wake_one_watcher_locked(grpc_fd *fd) {
+  if (fd->inactive_watcher_root.next != &fd->inactive_watcher_root) {
+    pollset_kick_locked(fd->inactive_watcher_root.next);
+  } else if (fd->read_watcher) {
+    pollset_kick_locked(fd->read_watcher);
+  } else if (fd->write_watcher) {
+    pollset_kick_locked(fd->write_watcher);
+  }
+}
+
+static void wake_all_watchers_locked(grpc_fd *fd) {
+  grpc_fd_watcher *watcher;
+  for (watcher = fd->inactive_watcher_root.next;
+       watcher != &fd->inactive_watcher_root; watcher = watcher->next) {
+    pollset_kick_locked(watcher);
+  }
+  if (fd->read_watcher) {
+    pollset_kick_locked(fd->read_watcher);
+  }
+  if (fd->write_watcher && fd->write_watcher != fd->read_watcher) {
+    pollset_kick_locked(fd->write_watcher);
+  }
+}
+
+static int has_watchers(grpc_fd *fd) {
+  return fd->read_watcher != NULL || fd->write_watcher != NULL ||
+         fd->inactive_watcher_root.next != &fd->inactive_watcher_root;
+}
+
+static void close_fd_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
+  fd->closed = 1;
+  if (!fd->released) {
+    close(fd->fd);
+  } else {
+    remove_fd_from_all_epoll_sets(fd->fd);
+  }
+  grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, true, NULL);
+}
+
+static int fd_wrapped_fd(grpc_fd *fd) {
+  if (fd->released || fd->closed) {
+    return -1;
+  } else {
+    return fd->fd;
+  }
+}
+
+static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                      grpc_closure *on_done, int *release_fd,
+                      const char *reason) {
+  fd->on_done_closure = on_done;
+  fd->released = release_fd != NULL;
+  if (!fd->released) {
+    shutdown(fd->fd, SHUT_RDWR);
+  } else {
+    *release_fd = fd->fd;
+  }
+  gpr_mu_lock(&fd->mu);
+  REF_BY(fd, 1, reason); /* remove active status, but keep referenced */
+  if (!has_watchers(fd)) {
+    close_fd_locked(exec_ctx, fd);
+  } else {
+    wake_all_watchers_locked(fd);
+  }
+  gpr_mu_unlock(&fd->mu);
+  UNREF_BY(fd, 2, reason); /* drop the reference */
+}
+
+/* increment refcount by two to avoid changing the orphan bit */
+#ifdef GRPC_FD_REF_COUNT_DEBUG
+static void fd_ref(grpc_fd *fd, const char *reason, const char *file,
+                   int line) {
+  ref_by(fd, 2, reason, file, line);
+}
+
+static void fd_unref(grpc_fd *fd, const char *reason, const char *file,
+                     int line) {
+  unref_by(fd, 2, reason, file, line);
+}
+#else
+static void fd_ref(grpc_fd *fd) { ref_by(fd, 2); }
+
+static void fd_unref(grpc_fd *fd) { unref_by(fd, 2); }
+#endif
+
+static void notify_on_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                             grpc_closure **st, grpc_closure *closure) {
+  if (*st == CLOSURE_NOT_READY) {
+    /* not ready ==> switch to a waiting state by setting the closure */
+    *st = closure;
+  } else if (*st == CLOSURE_READY) {
+    /* already ready ==> queue the closure to run immediately */
+    *st = CLOSURE_NOT_READY;
+    grpc_exec_ctx_enqueue(exec_ctx, closure, !fd->shutdown, NULL);
+    maybe_wake_one_watcher_locked(fd);
+  } else {
+    /* upcallptr was set to a different closure.  This is an error! */
+    gpr_log(GPR_ERROR,
+            "User called a notify_on function with a previous callback still "
+            "pending");
+    abort();
+  }
+}
+
+/* returns 1 if state becomes not ready */
+static int set_ready_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                            grpc_closure **st) {
+  if (*st == CLOSURE_READY) {
+    /* duplicate ready ==> ignore */
+    return 0;
+  } else if (*st == CLOSURE_NOT_READY) {
+    /* not ready, and not waiting ==> flag ready */
+    *st = CLOSURE_READY;
+    return 0;
+  } else {
+    /* waiting ==> queue closure */
+    grpc_exec_ctx_enqueue(exec_ctx, *st, !fd->shutdown, NULL);
+    *st = CLOSURE_NOT_READY;
+    return 1;
+  }
+}
+
+static void fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
+  gpr_mu_lock(&fd->mu);
+  GPR_ASSERT(!fd->shutdown);
+  fd->shutdown = 1;
+  set_ready_locked(exec_ctx, fd, &fd->read_closure);
+  set_ready_locked(exec_ctx, fd, &fd->write_closure);
+  gpr_mu_unlock(&fd->mu);
+}
+
+static void fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                              grpc_closure *closure) {
+  gpr_mu_lock(&fd->mu);
+  notify_on_locked(exec_ctx, fd, &fd->read_closure, closure);
+  gpr_mu_unlock(&fd->mu);
+}
+
+static void fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                               grpc_closure *closure) {
+  gpr_mu_lock(&fd->mu);
+  notify_on_locked(exec_ctx, fd, &fd->write_closure, closure);
+  gpr_mu_unlock(&fd->mu);
+}
+
+static uint32_t fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
+                              grpc_pollset_worker *worker, uint32_t read_mask,
+                              uint32_t write_mask, grpc_fd_watcher *watcher) {
+  uint32_t mask = 0;
+  grpc_closure *cur;
+  int requested;
+  /* keep track of pollers that have requested our events, in case they change
+   */
+  GRPC_FD_REF(fd, "poll");
+
+  gpr_mu_lock(&fd->mu);
+
+  /* if we are shutdown, then don't add to the watcher set */
+  if (fd->shutdown) {
+    watcher->fd = NULL;
+    watcher->pollset = NULL;
+    watcher->worker = NULL;
+    gpr_mu_unlock(&fd->mu);
+    GRPC_FD_UNREF(fd, "poll");
+    return 0;
+  }
+
+  /* if there is nobody polling for read, but we need to, then start doing so */
+  cur = fd->read_closure;
+  requested = cur != CLOSURE_READY;
+  if (read_mask && fd->read_watcher == NULL && requested) {
+    fd->read_watcher = watcher;
+    mask |= read_mask;
+  }
+  /* if there is nobody polling for write, but we need to, then start doing so
+   */
+  cur = fd->write_closure;
+  requested = cur != CLOSURE_READY;
+  if (write_mask && fd->write_watcher == NULL && requested) {
+    fd->write_watcher = watcher;
+    mask |= write_mask;
+  }
+  /* if not polling, remember this watcher in case we need someone to later */
+  if (mask == 0 && worker != NULL) {
+    watcher->next = &fd->inactive_watcher_root;
+    watcher->prev = watcher->next->prev;
+    watcher->next->prev = watcher->prev->next = watcher;
+  }
+  watcher->pollset = pollset;
+  watcher->worker = worker;
+  watcher->fd = fd;
+  gpr_mu_unlock(&fd->mu);
+
+  return mask;
+}
+
+static void fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *watcher,
+                        int got_read, int got_write) {
+  int was_polling = 0;
+  int kick = 0;
+  grpc_fd *fd = watcher->fd;
+
+  if (fd == NULL) {
+    return;
+  }
+
+  gpr_mu_lock(&fd->mu);
+
+  if (watcher == fd->read_watcher) {
+    /* remove read watcher, kick if we still need a read */
+    was_polling = 1;
+    if (!got_read) {
+      kick = 1;
+    }
+    fd->read_watcher = NULL;
+  }
+  if (watcher == fd->write_watcher) {
+    /* remove write watcher, kick if we still need a write */
+    was_polling = 1;
+    if (!got_write) {
+      kick = 1;
+    }
+    fd->write_watcher = NULL;
+  }
+  if (!was_polling && watcher->worker != NULL) {
+    /* remove from inactive list */
+    watcher->next->prev = watcher->prev;
+    watcher->prev->next = watcher->next;
+  }
+  if (got_read) {
+    if (set_ready_locked(exec_ctx, fd, &fd->read_closure)) {
+      kick = 1;
+    }
+  }
+  if (got_write) {
+    if (set_ready_locked(exec_ctx, fd, &fd->write_closure)) {
+      kick = 1;
+    }
+  }
+  if (kick) {
+    maybe_wake_one_watcher_locked(fd);
+  }
+  if (fd_is_orphaned(fd) && !has_watchers(fd) && !fd->closed) {
+    close_fd_locked(exec_ctx, fd);
+  }
+  gpr_mu_unlock(&fd->mu);
+
+  GRPC_FD_UNREF(fd, "poll");
+}
+
+/*******************************************************************************
+ * pollset_posix.c
+ */
+
+GPR_TLS_DECL(g_current_thread_poller);
+GPR_TLS_DECL(g_current_thread_worker);
+
+/** The alarm system needs to be able to wakeup 'some poller' sometimes
+ *  (specifically when a new alarm needs to be triggered earlier than the next
+ *  alarm 'epoch').
+ *  This wakeup_fd gives us something to alert on when such a case occurs. */
+grpc_wakeup_fd grpc_global_wakeup_fd;
+
+static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev->next = worker->next;
+  worker->next->prev = worker->prev;
+}
+
+static int pollset_has_workers(grpc_pollset *p) {
+  return p->root_worker.next != &p->root_worker;
+}
+
+static grpc_pollset_worker *pop_front_worker(grpc_pollset *p) {
+  if (pollset_has_workers(p)) {
+    grpc_pollset_worker *w = p->root_worker.next;
+    remove_worker(p, w);
+    return w;
+  } else {
+    return NULL;
+  }
+}
+
+static void push_back_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->next = &p->root_worker;
+  worker->prev = worker->next->prev;
+  worker->prev->next = worker->next->prev = worker;
+}
+
+static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
+  worker->prev = &p->root_worker;
+  worker->next = worker->prev->next;
+  worker->prev->next = worker->next->prev = worker;
+}
+
+static void pollset_kick_ext(grpc_pollset *p,
+                             grpc_pollset_worker *specific_worker,
+                             uint32_t flags) {
+  GPR_TIMER_BEGIN("pollset_kick_ext", 0);
+
+  /* pollset->mu already held */
+  if (specific_worker != NULL) {
+    if (specific_worker == GRPC_POLLSET_KICK_BROADCAST) {
+      GPR_TIMER_BEGIN("pollset_kick_ext.broadcast", 0);
+      GPR_ASSERT((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) == 0);
+      for (specific_worker = p->root_worker.next;
+           specific_worker != &p->root_worker;
+           specific_worker = specific_worker->next) {
+        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
+      }
+      p->kicked_without_pollers = 1;
+      GPR_TIMER_END("pollset_kick_ext.broadcast", 0);
+    } else if (gpr_tls_get(&g_current_thread_worker) !=
+               (intptr_t)specific_worker) {
+      GPR_TIMER_MARK("different_thread_worker", 0);
+      if ((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) != 0) {
+        specific_worker->reevaluate_polling_on_wakeup = 1;
+      }
+      specific_worker->kicked_specifically = 1;
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
+    } else if ((flags & GRPC_POLLSET_CAN_KICK_SELF) != 0) {
+      GPR_TIMER_MARK("kick_yoself", 0);
+      if ((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) != 0) {
+        specific_worker->reevaluate_polling_on_wakeup = 1;
+      }
+      specific_worker->kicked_specifically = 1;
+      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
+    }
+  } else if (gpr_tls_get(&g_current_thread_poller) != (intptr_t)p) {
+    GPR_ASSERT((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) == 0);
+    GPR_TIMER_MARK("kick_anonymous", 0);
+    specific_worker = pop_front_worker(p);
+    if (specific_worker != NULL) {
+      if (gpr_tls_get(&g_current_thread_worker) == (intptr_t)specific_worker) {
+        GPR_TIMER_MARK("kick_anonymous_not_self", 0);
+        push_back_worker(p, specific_worker);
+        specific_worker = pop_front_worker(p);
+        if ((flags & GRPC_POLLSET_CAN_KICK_SELF) == 0 &&
+            gpr_tls_get(&g_current_thread_worker) ==
+                (intptr_t)specific_worker) {
+          push_back_worker(p, specific_worker);
+          specific_worker = NULL;
+        }
+      }
+      if (specific_worker != NULL) {
+        GPR_TIMER_MARK("finally_kick", 0);
+        push_back_worker(p, specific_worker);
+        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
+      }
+    } else {
+      GPR_TIMER_MARK("kicked_no_pollers", 0);
+      p->kicked_without_pollers = 1;
+    }
+  }
+
+  GPR_TIMER_END("pollset_kick_ext", 0);
+}
+
+static void pollset_kick(grpc_pollset *p,
+                         grpc_pollset_worker *specific_worker) {
+  pollset_kick_ext(p, specific_worker, 0);
+}
+
+/* global state management */
+
+static void pollset_global_init(void) {
+  gpr_tls_init(&g_current_thread_poller);
+  gpr_tls_init(&g_current_thread_worker);
+  grpc_wakeup_fd_global_init();
+  grpc_wakeup_fd_init(&grpc_global_wakeup_fd);
+}
+
+static void pollset_global_shutdown(void) {
+  grpc_wakeup_fd_destroy(&grpc_global_wakeup_fd);
+  gpr_tls_destroy(&g_current_thread_poller);
+  gpr_tls_destroy(&g_current_thread_worker);
+  grpc_wakeup_fd_global_destroy();
+}
+
+static void kick_poller(void) { grpc_wakeup_fd_wakeup(&grpc_global_wakeup_fd); }
+
+/* main interface */
+
+static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null);
+
+static void pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
+  gpr_mu_init(&pollset->mu);
+  *mu = &pollset->mu;
+  pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
+  pollset->in_flight_cbs = 0;
+  pollset->shutting_down = 0;
+  pollset->called_shutdown = 0;
+  pollset->kicked_without_pollers = 0;
+  pollset->idle_jobs.head = pollset->idle_jobs.tail = NULL;
+  pollset->local_wakeup_cache = NULL;
+  pollset->kicked_without_pollers = 0;
+  become_basic_pollset(pollset, NULL);
+}
+
+static void pollset_destroy(grpc_pollset *pollset) {
+  GPR_ASSERT(pollset->in_flight_cbs == 0);
+  GPR_ASSERT(!pollset_has_workers(pollset));
+  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
+  pollset->vtable->destroy(pollset);
+  while (pollset->local_wakeup_cache) {
+    grpc_cached_wakeup_fd *next = pollset->local_wakeup_cache->next;
+    grpc_wakeup_fd_destroy(&pollset->local_wakeup_cache->fd);
+    gpr_free(pollset->local_wakeup_cache);
+    pollset->local_wakeup_cache = next;
+  }
+  gpr_mu_destroy(&pollset->mu);
+}
+
+static void pollset_reset(grpc_pollset *pollset) {
+  GPR_ASSERT(pollset->shutting_down);
+  GPR_ASSERT(pollset->in_flight_cbs == 0);
+  GPR_ASSERT(!pollset_has_workers(pollset));
+  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
+  pollset->vtable->destroy(pollset);
+  pollset->shutting_down = 0;
+  pollset->called_shutdown = 0;
+  pollset->kicked_without_pollers = 0;
+  become_basic_pollset(pollset, NULL);
+}
+
+static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                           grpc_fd *fd) {
+  gpr_mu_lock(&pollset->mu);
+  pollset->vtable->add_fd(exec_ctx, pollset, fd, 1);
+/* the following (enabled only in debug) will reacquire and then release
+   our lock - meaning that if the unlocking flag passed to add_fd above is
+   not respected, the code will deadlock (in a way that we have a chance of
+   debugging) */
+#ifndef NDEBUG
+  gpr_mu_lock(&pollset->mu);
+  gpr_mu_unlock(&pollset->mu);
+#endif
+}
+
+static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
+  GPR_ASSERT(grpc_closure_list_empty(pollset->idle_jobs));
+  pollset->vtable->finish_shutdown(pollset);
+  grpc_exec_ctx_enqueue(exec_ctx, pollset->shutdown_done, true, NULL);
+}
+
+static void pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                         grpc_pollset_worker **worker_hdl, gpr_timespec now,
+                         gpr_timespec deadline) {
+  grpc_pollset_worker worker;
+  *worker_hdl = &worker;
+
+  /* pollset->mu already held */
+  int added_worker = 0;
+  int locked = 1;
+  int queued_work = 0;
+  int keep_polling = 0;
+  GPR_TIMER_BEGIN("pollset_work", 0);
+  /* this must happen before we (potentially) drop pollset->mu */
+  worker.next = worker.prev = NULL;
+  worker.reevaluate_polling_on_wakeup = 0;
+  if (pollset->local_wakeup_cache != NULL) {
+    worker.wakeup_fd = pollset->local_wakeup_cache;
+    pollset->local_wakeup_cache = worker.wakeup_fd->next;
+  } else {
+    worker.wakeup_fd = gpr_malloc(sizeof(*worker.wakeup_fd));
+    grpc_wakeup_fd_init(&worker.wakeup_fd->fd);
+  }
+  worker.kicked_specifically = 0;
+  /* If there's work waiting for the pollset to be idle, and the
+     pollset is idle, then do that work */
+  if (!pollset_has_workers(pollset) &&
+      !grpc_closure_list_empty(pollset->idle_jobs)) {
+    GPR_TIMER_MARK("pollset_work.idle_jobs", 0);
+    grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
+    goto done;
+  }
+  /* If we're shutting down then we don't execute any extended work */
+  if (pollset->shutting_down) {
+    GPR_TIMER_MARK("pollset_work.shutting_down", 0);
+    goto done;
+  }
+  /* Give do_promote priority so we don't starve it out */
+  if (pollset->in_flight_cbs) {
+    GPR_TIMER_MARK("pollset_work.in_flight_cbs", 0);
+    gpr_mu_unlock(&pollset->mu);
+    locked = 0;
+    goto done;
+  }
+  /* Start polling, and keep doing so while we're being asked to
+     re-evaluate our pollers (this allows poll() based pollers to
+     ensure they don't miss wakeups) */
+  keep_polling = 1;
+  while (keep_polling) {
+    keep_polling = 0;
+    if (!pollset->kicked_without_pollers) {
+      if (!added_worker) {
+        push_front_worker(pollset, &worker);
+        added_worker = 1;
+        gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker);
+      }
+      gpr_tls_set(&g_current_thread_poller, (intptr_t)pollset);
+      GPR_TIMER_BEGIN("maybe_work_and_unlock", 0);
+      pollset->vtable->maybe_work_and_unlock(exec_ctx, pollset, &worker,
+                                             deadline, now);
+      GPR_TIMER_END("maybe_work_and_unlock", 0);
+      locked = 0;
+      gpr_tls_set(&g_current_thread_poller, 0);
+    } else {
+      GPR_TIMER_MARK("pollset_work.kicked_without_pollers", 0);
+      pollset->kicked_without_pollers = 0;
+    }
+  /* Finished execution - start cleaning up.
+     Note that we may arrive here from outside the enclosing while() loop.
+     In that case we won't loop though as we haven't added worker to the
+     worker list, which means nobody could ask us to re-evaluate polling). */
+  done:
+    if (!locked) {
+      queued_work |= grpc_exec_ctx_flush(exec_ctx);
+      gpr_mu_lock(&pollset->mu);
+      locked = 1;
+    }
+    /* If we're forced to re-evaluate polling (via pollset_kick with
+       GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) then we land here and force
+       a loop */
+    if (worker.reevaluate_polling_on_wakeup) {
+      worker.reevaluate_polling_on_wakeup = 0;
+      pollset->kicked_without_pollers = 0;
+      if (queued_work || worker.kicked_specifically) {
+        /* If there's queued work on the list, then set the deadline to be
+           immediate so we get back out of the polling loop quickly */
+        deadline = gpr_inf_past(GPR_CLOCK_MONOTONIC);
+      }
+      keep_polling = 1;
+    }
+  }
+  if (added_worker) {
+    remove_worker(pollset, &worker);
+    gpr_tls_set(&g_current_thread_worker, 0);
+  }
+  /* release wakeup fd to the local pool */
+  worker.wakeup_fd->next = pollset->local_wakeup_cache;
+  pollset->local_wakeup_cache = worker.wakeup_fd;
+  /* check shutdown conditions */
+  if (pollset->shutting_down) {
+    if (pollset_has_workers(pollset)) {
+      pollset_kick(pollset, NULL);
+    } else if (!pollset->called_shutdown && pollset->in_flight_cbs == 0) {
+      pollset->called_shutdown = 1;
+      gpr_mu_unlock(&pollset->mu);
+      finish_shutdown(exec_ctx, pollset);
+      grpc_exec_ctx_flush(exec_ctx);
+      /* Continuing to access pollset here is safe -- it is the caller's
+       * responsibility to not destroy when it has outstanding calls to
+       * pollset_work.
+       * TODO(dklempner): Can we refactor the shutdown logic to avoid this? */
+      gpr_mu_lock(&pollset->mu);
+    } else if (!grpc_closure_list_empty(pollset->idle_jobs)) {
+      grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
+      gpr_mu_unlock(&pollset->mu);
+      grpc_exec_ctx_flush(exec_ctx);
+      gpr_mu_lock(&pollset->mu);
+    }
+  }
+  *worker_hdl = NULL;
+  GPR_TIMER_END("pollset_work", 0);
+}
+
+static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                             grpc_closure *closure) {
+  GPR_ASSERT(!pollset->shutting_down);
+  pollset->shutting_down = 1;
+  pollset->shutdown_done = closure;
+  pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
+  if (!pollset_has_workers(pollset)) {
+    grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
+  }
+  if (!pollset->called_shutdown && pollset->in_flight_cbs == 0 &&
+      !pollset_has_workers(pollset)) {
+    pollset->called_shutdown = 1;
+    finish_shutdown(exec_ctx, pollset);
+  }
+}
+
+static int poll_deadline_to_millis_timeout(gpr_timespec deadline,
+                                           gpr_timespec now) {
+  gpr_timespec timeout;
+  static const int64_t max_spin_polling_us = 10;
+  if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) == 0) {
+    return -1;
+  }
+  if (gpr_time_cmp(deadline, gpr_time_add(now, gpr_time_from_micros(
+                                                   max_spin_polling_us,
+                                                   GPR_TIMESPAN))) <= 0) {
+    return 0;
+  }
+  timeout = gpr_time_sub(deadline, now);
+  return gpr_time_to_millis(gpr_time_add(
+      timeout, gpr_time_from_nanos(GPR_NS_PER_MS - 1, GPR_TIMESPAN)));
+}
+
+/*
+ * basic_pollset - a vtable that provides polling for zero or one file
+ *                 descriptor via poll()
+ */
+
+typedef struct grpc_unary_promote_args {
+  const grpc_pollset_vtable *original_vtable;
+  grpc_pollset *pollset;
+  grpc_fd *fd;
+  grpc_closure promotion_closure;
+} grpc_unary_promote_args;
+
+static void basic_do_promote(grpc_exec_ctx *exec_ctx, void *args,
+                             bool success) {
+  grpc_unary_promote_args *up_args = args;
+  const grpc_pollset_vtable *original_vtable = up_args->original_vtable;
+  grpc_pollset *pollset = up_args->pollset;
+  grpc_fd *fd = up_args->fd;
+
+  /*
+   * This is quite tricky. There are a number of cases to keep in mind here:
+   * 1. fd may have been orphaned
+   * 2. The pollset may no longer be a unary poller (and we can't let case #1
+   * leak to other pollset types!)
+   * 3. pollset's fd (which may have changed) may have been orphaned
+   * 4. The pollset may be shutting down.
+   */
+
+  gpr_mu_lock(&pollset->mu);
+  /* First we need to ensure that nobody is polling concurrently */
+  GPR_ASSERT(!pollset_has_workers(pollset));
+
+  gpr_free(up_args);
+  /* At this point the pollset may no longer be a unary poller. In that case
+   * we should just call the right add function and be done. */
+  /* TODO(klempner): If we're not careful this could cause infinite recursion.
+   * That's not a problem for now because empty_pollset has a trivial poller
+   * and we don't have any mechanism to unbecome multipoller. */
+  pollset->in_flight_cbs--;
+  if (pollset->shutting_down) {
+    /* We don't care about this pollset anymore. */
+    if (pollset->in_flight_cbs == 0 && !pollset->called_shutdown) {
+      pollset->called_shutdown = 1;
+      finish_shutdown(exec_ctx, pollset);
+    }
+  } else if (fd_is_orphaned(fd)) {
+    /* Don't try to add it to anything, we'll drop our ref on it below */
+  } else if (pollset->vtable != original_vtable) {
+    pollset->vtable->add_fd(exec_ctx, pollset, fd, 0);
+  } else if (fd != pollset->data.ptr) {
+    grpc_fd *fds[2];
+    fds[0] = pollset->data.ptr;
+    fds[1] = fd;
+
+    if (fds[0] && !fd_is_orphaned(fds[0])) {
+      platform_become_multipoller(exec_ctx, pollset, fds, GPR_ARRAY_SIZE(fds));
+      GRPC_FD_UNREF(fds[0], "basicpoll");
+    } else {
+      /* old fd is orphaned and we haven't cleaned it up until now, so remain a
+       * unary poller */
+      /* Note that it is possible that fds[1] is also orphaned at this point.
+       * That's okay, we'll correct it at the next add or poll. */
+      if (fds[0]) GRPC_FD_UNREF(fds[0], "basicpoll");
+      pollset->data.ptr = fd;
+      GRPC_FD_REF(fd, "basicpoll");
+    }
+  }
+
+  gpr_mu_unlock(&pollset->mu);
+
+  /* Matching ref in basic_pollset_add_fd */
+  GRPC_FD_UNREF(fd, "basicpoll_add");
+}
+
+static void basic_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                                 grpc_fd *fd, int and_unlock_pollset) {
+  grpc_unary_promote_args *up_args;
+  GPR_ASSERT(fd);
+  if (fd == pollset->data.ptr) goto exit;
+
+  if (!pollset_has_workers(pollset)) {
+    /* Fast path -- no in flight cbs */
+    /* TODO(klempner): Comment this out and fix any test failures or establish
+     * they are due to timing issues */
+    grpc_fd *fds[2];
+    fds[0] = pollset->data.ptr;
+    fds[1] = fd;
+
+    if (fds[0] == NULL) {
+      pollset->data.ptr = fd;
+      GRPC_FD_REF(fd, "basicpoll");
+    } else if (!fd_is_orphaned(fds[0])) {
+      platform_become_multipoller(exec_ctx, pollset, fds, GPR_ARRAY_SIZE(fds));
+      GRPC_FD_UNREF(fds[0], "basicpoll");
+    } else {
+      /* old fd is orphaned and we haven't cleaned it up until now, so remain a
+       * unary poller */
+      GRPC_FD_UNREF(fds[0], "basicpoll");
+      pollset->data.ptr = fd;
+      GRPC_FD_REF(fd, "basicpoll");
+    }
+    goto exit;
+  }
+
+  /* Now we need to promote. This needs to happen when we're not polling. Since
+   * this may be called from poll, the wait needs to happen asynchronously. */
+  GRPC_FD_REF(fd, "basicpoll_add");
+  pollset->in_flight_cbs++;
+  up_args = gpr_malloc(sizeof(*up_args));
+  up_args->fd = fd;
+  up_args->original_vtable = pollset->vtable;
+  up_args->pollset = pollset;
+  up_args->promotion_closure.cb = basic_do_promote;
+  up_args->promotion_closure.cb_arg = up_args;
+
+  grpc_closure_list_add(&pollset->idle_jobs, &up_args->promotion_closure, 1);
+  pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
+
+exit:
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
+}
+
+static void basic_pollset_maybe_work_and_unlock(grpc_exec_ctx *exec_ctx,
+                                                grpc_pollset *pollset,
+                                                grpc_pollset_worker *worker,
+                                                gpr_timespec deadline,
+                                                gpr_timespec now) {
+#define POLLOUT_CHECK (POLLOUT | POLLHUP | POLLERR)
+#define POLLIN_CHECK (POLLIN | POLLHUP | POLLERR)
+
+  struct pollfd pfd[3];
+  grpc_fd *fd;
+  grpc_fd_watcher fd_watcher;
+  int timeout;
+  int r;
+  nfds_t nfds;
+
+  fd = pollset->data.ptr;
+  if (fd && fd_is_orphaned(fd)) {
+    GRPC_FD_UNREF(fd, "basicpoll");
+    fd = pollset->data.ptr = NULL;
+  }
+  timeout = poll_deadline_to_millis_timeout(deadline, now);
+  pfd[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
+  pfd[0].events = POLLIN;
+  pfd[0].revents = 0;
+  pfd[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
+  pfd[1].events = POLLIN;
+  pfd[1].revents = 0;
+  nfds = 2;
+  if (fd) {
+    pfd[2].fd = fd->fd;
+    pfd[2].revents = 0;
+    GRPC_FD_REF(fd, "basicpoll_begin");
+    gpr_mu_unlock(&pollset->mu);
+    pfd[2].events =
+        (short)fd_begin_poll(fd, pollset, worker, POLLIN, POLLOUT, &fd_watcher);
+    if (pfd[2].events != 0) {
+      nfds++;
+    }
+  } else {
+    gpr_mu_unlock(&pollset->mu);
+  }
+
+  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
+     even going into the blocking annotation if possible */
+  /* poll fd count (argument 2) is shortened by one if we have no events
+     to poll on - such that it only includes the kicker */
+  GPR_TIMER_BEGIN("poll", 0);
+  GRPC_SCHEDULING_START_BLOCKING_REGION;
+  r = grpc_poll_function(pfd, nfds, timeout);
+  GRPC_SCHEDULING_END_BLOCKING_REGION;
+  GPR_TIMER_END("poll", 0);
+
+  if (r < 0) {
+    if (errno != EINTR) {
+      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    }
+    if (fd) {
+      fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
+    }
+  } else if (r == 0) {
+    if (fd) {
+      fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
+    }
+  } else {
+    if (pfd[0].revents & POLLIN_CHECK) {
+      grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
+    }
+    if (pfd[1].revents & POLLIN_CHECK) {
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
+    }
+    if (nfds > 2) {
+      fd_end_poll(exec_ctx, &fd_watcher, pfd[2].revents & POLLIN_CHECK,
+                  pfd[2].revents & POLLOUT_CHECK);
+    } else if (fd) {
+      fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
+    }
+  }
+
+  if (fd) {
+    GRPC_FD_UNREF(fd, "basicpoll_begin");
+  }
+}
+
+static void basic_pollset_destroy(grpc_pollset *pollset) {
+  if (pollset->data.ptr != NULL) {
+    GRPC_FD_UNREF(pollset->data.ptr, "basicpoll");
+    pollset->data.ptr = NULL;
+  }
+}
+
+static const grpc_pollset_vtable basic_pollset = {
+    basic_pollset_add_fd, basic_pollset_maybe_work_and_unlock,
+    basic_pollset_destroy, basic_pollset_destroy};
+
+static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null) {
+  pollset->vtable = &basic_pollset;
+  pollset->data.ptr = fd_or_null;
+  if (fd_or_null != NULL) {
+    GRPC_FD_REF(fd_or_null, "basicpoll");
+  }
+}
+
+/*******************************************************************************
+ * pollset_multipoller_with_poll_posix.c
+ */
+
+#ifndef GPR_LINUX_MULTIPOLL_WITH_EPOLL
+
+typedef struct {
+  /* all polled fds */
+  size_t fd_count;
+  size_t fd_capacity;
+  grpc_fd **fds;
+  /* fds that have been removed from the pollset explicitly */
+  size_t del_count;
+  size_t del_capacity;
+  grpc_fd **dels;
+} poll_hdr;
+
+static void multipoll_with_poll_pollset_add_fd(grpc_exec_ctx *exec_ctx,
+                                               grpc_pollset *pollset,
+                                               grpc_fd *fd,
+                                               int and_unlock_pollset) {
+  size_t i;
+  poll_hdr *h = pollset->data.ptr;
+  /* TODO(ctiller): this is O(num_fds^2); maybe switch to a hash set here */
+  for (i = 0; i < h->fd_count; i++) {
+    if (h->fds[i] == fd) goto exit;
+  }
+  if (h->fd_count == h->fd_capacity) {
+    h->fd_capacity = GPR_MAX(h->fd_capacity + 8, h->fd_count * 3 / 2);
+    h->fds = gpr_realloc(h->fds, sizeof(grpc_fd *) * h->fd_capacity);
+  }
+  h->fds[h->fd_count++] = fd;
+  GRPC_FD_REF(fd, "multipoller");
+exit:
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+  }
+}
+
+static void multipoll_with_poll_pollset_maybe_work_and_unlock(
+    grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_pollset_worker *worker,
+    gpr_timespec deadline, gpr_timespec now) {
+#define POLLOUT_CHECK (POLLOUT | POLLHUP | POLLERR)
+#define POLLIN_CHECK (POLLIN | POLLHUP | POLLERR)
+
+  int timeout;
+  int r;
+  size_t i, j, fd_count;
+  nfds_t pfd_count;
+  poll_hdr *h;
+  /* TODO(ctiller): inline some elements to avoid an allocation */
+  grpc_fd_watcher *watchers;
+  struct pollfd *pfds;
+
+  h = pollset->data.ptr;
+  timeout = poll_deadline_to_millis_timeout(deadline, now);
+  /* TODO(ctiller): perform just one malloc here if we exceed the inline case */
+  pfds = gpr_malloc(sizeof(*pfds) * (h->fd_count + 2));
+  watchers = gpr_malloc(sizeof(*watchers) * (h->fd_count + 2));
+  fd_count = 0;
+  pfd_count = 2;
+  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
+  pfds[0].events = POLLIN;
+  pfds[0].revents = 0;
+  pfds[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
+  pfds[1].events = POLLIN;
+  pfds[1].revents = 0;
+  for (i = 0; i < h->fd_count; i++) {
+    int remove = fd_is_orphaned(h->fds[i]);
+    for (j = 0; !remove && j < h->del_count; j++) {
+      if (h->fds[i] == h->dels[j]) remove = 1;
+    }
+    if (remove) {
+      GRPC_FD_UNREF(h->fds[i], "multipoller");
+    } else {
+      h->fds[fd_count++] = h->fds[i];
+      watchers[pfd_count].fd = h->fds[i];
+      GRPC_FD_REF(watchers[pfd_count].fd, "multipoller_start");
+      pfds[pfd_count].fd = h->fds[i]->fd;
+      pfds[pfd_count].revents = 0;
+      pfd_count++;
+    }
+  }
+  for (j = 0; j < h->del_count; j++) {
+    GRPC_FD_UNREF(h->dels[j], "multipoller_del");
+  }
+  h->del_count = 0;
+  h->fd_count = fd_count;
+  gpr_mu_unlock(&pollset->mu);
+
+  for (i = 2; i < pfd_count; i++) {
+    grpc_fd *fd = watchers[i].fd;
+    pfds[i].events = (short)fd_begin_poll(fd, pollset, worker, POLLIN, POLLOUT,
+                                          &watchers[i]);
+    GRPC_FD_UNREF(fd, "multipoller_start");
+  }
+
+  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
+     even going into the blocking annotation if possible */
+  GRPC_SCHEDULING_START_BLOCKING_REGION;
+  r = grpc_poll_function(pfds, pfd_count, timeout);
+  GRPC_SCHEDULING_END_BLOCKING_REGION;
+
+  if (r < 0) {
+    if (errno != EINTR) {
+      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    }
+    for (i = 2; i < pfd_count; i++) {
+      fd_end_poll(exec_ctx, &watchers[i], 0, 0);
+    }
+  } else if (r == 0) {
+    for (i = 2; i < pfd_count; i++) {
+      fd_end_poll(exec_ctx, &watchers[i], 0, 0);
+    }
+  } else {
+    if (pfds[0].revents & POLLIN_CHECK) {
+      grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
+    }
+    if (pfds[1].revents & POLLIN_CHECK) {
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
+    }
+    for (i = 2; i < pfd_count; i++) {
+      if (watchers[i].fd == NULL) {
+        fd_end_poll(exec_ctx, &watchers[i], 0, 0);
+        continue;
+      }
+      fd_end_poll(exec_ctx, &watchers[i], pfds[i].revents & POLLIN_CHECK,
+                  pfds[i].revents & POLLOUT_CHECK);
+    }
+  }
+
+  gpr_free(pfds);
+  gpr_free(watchers);
+}
+
+static void multipoll_with_poll_pollset_finish_shutdown(grpc_pollset *pollset) {
+  size_t i;
+  poll_hdr *h = pollset->data.ptr;
+  for (i = 0; i < h->fd_count; i++) {
+    GRPC_FD_UNREF(h->fds[i], "multipoller");
+  }
+  for (i = 0; i < h->del_count; i++) {
+    GRPC_FD_UNREF(h->dels[i], "multipoller_del");
+  }
+  h->fd_count = 0;
+  h->del_count = 0;
+}
+
+static void multipoll_with_poll_pollset_destroy(grpc_pollset *pollset) {
+  poll_hdr *h = pollset->data.ptr;
+  multipoll_with_poll_pollset_finish_shutdown(pollset);
+  gpr_free(h->fds);
+  gpr_free(h->dels);
+  gpr_free(h);
+}
+
+static const grpc_pollset_vtable multipoll_with_poll_pollset = {
+    multipoll_with_poll_pollset_add_fd,
+    multipoll_with_poll_pollset_maybe_work_and_unlock,
+    multipoll_with_poll_pollset_finish_shutdown,
+    multipoll_with_poll_pollset_destroy};
+
+static void poll_become_multipoller(grpc_exec_ctx *exec_ctx,
+                                    grpc_pollset *pollset, grpc_fd **fds,
+                                    size_t nfds) {
+  size_t i;
+  poll_hdr *h = gpr_malloc(sizeof(poll_hdr));
+  pollset->vtable = &multipoll_with_poll_pollset;
+  pollset->data.ptr = h;
+  h->fd_count = nfds;
+  h->fd_capacity = nfds;
+  h->fds = gpr_malloc(nfds * sizeof(grpc_fd *));
+  h->del_count = 0;
+  h->del_capacity = 0;
+  h->dels = NULL;
+  for (i = 0; i < nfds; i++) {
+    h->fds[i] = fds[i];
+    GRPC_FD_REF(fds[i], "multipoller");
+  }
+}
+
+#endif /* !GPR_LINUX_MULTIPOLL_WITH_EPOLL */
+
+/*******************************************************************************
+ * pollset_multipoller_with_epoll_posix.c
+ */
+
+#ifdef GPR_LINUX_MULTIPOLL_WITH_EPOLL
+
+#include <errno.h>
+#include <poll.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/iomgr/ev_posix.h"
+#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/support/block_annotate.h"
+
+static void set_ready(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure **st) {
+  /* only one set_ready can be active at once (but there may be a racing
+     notify_on) */
+  gpr_mu_lock(&fd->mu);
+  set_ready_locked(exec_ctx, fd, st);
+  gpr_mu_unlock(&fd->mu);
+}
+
+static void fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
+  set_ready(exec_ctx, fd, &fd->read_closure);
+}
+
+static void fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
+  set_ready(exec_ctx, fd, &fd->write_closure);
+}
+
+struct epoll_fd_list {
+  int *epoll_fds;
+  size_t count;
+  size_t capacity;
+};
+
+static struct epoll_fd_list epoll_fd_global_list;
+static gpr_once init_epoll_fd_list_mu = GPR_ONCE_INIT;
+static gpr_mu epoll_fd_list_mu;
+
+static void init_mu(void) { gpr_mu_init(&epoll_fd_list_mu); }
+
+static void add_epoll_fd_to_global_list(int epoll_fd) {
+  gpr_once_init(&init_epoll_fd_list_mu, init_mu);
+
+  gpr_mu_lock(&epoll_fd_list_mu);
+  if (epoll_fd_global_list.count == epoll_fd_global_list.capacity) {
+    epoll_fd_global_list.capacity =
+        GPR_MAX((size_t)8, epoll_fd_global_list.capacity * 2);
+    epoll_fd_global_list.epoll_fds =
+        gpr_realloc(epoll_fd_global_list.epoll_fds,
+                    epoll_fd_global_list.capacity * sizeof(int));
+  }
+  epoll_fd_global_list.epoll_fds[epoll_fd_global_list.count++] = epoll_fd;
+  gpr_mu_unlock(&epoll_fd_list_mu);
+}
+
+static void remove_epoll_fd_from_global_list(int epoll_fd) {
+  gpr_mu_lock(&epoll_fd_list_mu);
+  GPR_ASSERT(epoll_fd_global_list.count > 0);
+  for (size_t i = 0; i < epoll_fd_global_list.count; i++) {
+    if (epoll_fd == epoll_fd_global_list.epoll_fds[i]) {
+      epoll_fd_global_list.epoll_fds[i] =
+          epoll_fd_global_list.epoll_fds[--(epoll_fd_global_list.count)];
+      break;
+    }
+  }
+  gpr_mu_unlock(&epoll_fd_list_mu);
+}
+
+static void remove_fd_from_all_epoll_sets(int fd) {
+  int err;
+  gpr_once_init(&init_epoll_fd_list_mu, init_mu);
+  gpr_mu_lock(&epoll_fd_list_mu);
+  if (epoll_fd_global_list.count == 0) {
+    gpr_mu_unlock(&epoll_fd_list_mu);
+    return;
+  }
+  for (size_t i = 0; i < epoll_fd_global_list.count; i++) {
+    err = epoll_ctl(epoll_fd_global_list.epoll_fds[i], EPOLL_CTL_DEL, fd, NULL);
+    if (err < 0 && errno != ENOENT) {
+      gpr_log(GPR_ERROR, "epoll_ctl del for %d failed: %s", fd,
+              strerror(errno));
+    }
+  }
+  gpr_mu_unlock(&epoll_fd_list_mu);
+}
+
+typedef struct {
+  grpc_pollset *pollset;
+  grpc_fd *fd;
+  grpc_closure closure;
+} delayed_add;
+
+typedef struct { int epoll_fd; } epoll_hdr;
+
+static void finally_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                           grpc_fd *fd) {
+  epoll_hdr *h = pollset->data.ptr;
+  struct epoll_event ev;
+  int err;
+  grpc_fd_watcher watcher;
+
+  /* We pretend to be polling whilst adding an fd to keep the fd from being
+     closed during the add. This may result in a spurious wakeup being assigned
+     to this pollset whilst adding, but that should be benign. */
+  GPR_ASSERT(fd_begin_poll(fd, pollset, NULL, 0, 0, &watcher) == 0);
+  if (watcher.fd != NULL) {
+    ev.events = (uint32_t)(EPOLLIN | EPOLLOUT | EPOLLET);
+    ev.data.ptr = fd;
+    err = epoll_ctl(h->epoll_fd, EPOLL_CTL_ADD, fd->fd, &ev);
+    if (err < 0) {
+      /* FDs may be added to a pollset multiple times, so EEXIST is normal. */
+      if (errno != EEXIST) {
+        gpr_log(GPR_ERROR, "epoll_ctl add for %d failed: %s", fd->fd,
+                strerror(errno));
+      }
+    }
+  }
+  fd_end_poll(exec_ctx, &watcher, 0, 0);
+}
+
+static void perform_delayed_add(grpc_exec_ctx *exec_ctx, void *arg,
+                                bool iomgr_status) {
+  delayed_add *da = arg;
+
+  if (!fd_is_orphaned(da->fd)) {
+    finally_add_fd(exec_ctx, da->pollset, da->fd);
+  }
+
+  gpr_mu_lock(&da->pollset->mu);
+  da->pollset->in_flight_cbs--;
+  if (da->pollset->shutting_down) {
+    /* We don't care about this pollset anymore. */
+    if (da->pollset->in_flight_cbs == 0 && !da->pollset->called_shutdown) {
+      da->pollset->called_shutdown = 1;
+      grpc_exec_ctx_enqueue(exec_ctx, da->pollset->shutdown_done, true, NULL);
+    }
+  }
+  gpr_mu_unlock(&da->pollset->mu);
+
+  GRPC_FD_UNREF(da->fd, "delayed_add");
+
+  gpr_free(da);
+}
+
+static void multipoll_with_epoll_pollset_add_fd(grpc_exec_ctx *exec_ctx,
+                                                grpc_pollset *pollset,
+                                                grpc_fd *fd,
+                                                int and_unlock_pollset) {
+  if (and_unlock_pollset) {
+    gpr_mu_unlock(&pollset->mu);
+    finally_add_fd(exec_ctx, pollset, fd);
+  } else {
+    delayed_add *da = gpr_malloc(sizeof(*da));
+    da->pollset = pollset;
+    da->fd = fd;
+    GRPC_FD_REF(fd, "delayed_add");
+    grpc_closure_init(&da->closure, perform_delayed_add, da);
+    pollset->in_flight_cbs++;
+    grpc_exec_ctx_enqueue(exec_ctx, &da->closure, true, NULL);
+  }
+}
+
+/* TODO(klempner): We probably want to turn this down a bit */
+#define GRPC_EPOLL_MAX_EVENTS 1000
+
+static void multipoll_with_epoll_pollset_maybe_work_and_unlock(
+    grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_pollset_worker *worker,
+    gpr_timespec deadline, gpr_timespec now) {
+  struct epoll_event ep_ev[GRPC_EPOLL_MAX_EVENTS];
+  int ep_rv;
+  int poll_rv;
+  epoll_hdr *h = pollset->data.ptr;
+  int timeout_ms;
+  struct pollfd pfds[2];
+
+  /* If you want to ignore epoll's ability to sanely handle parallel pollers,
+   * for a more apples-to-apples performance comparison with poll, add a
+   * if (pollset->counter != 0) { return 0; }
+   * here.
+   */
+
+  gpr_mu_unlock(&pollset->mu);
+
+  timeout_ms = poll_deadline_to_millis_timeout(deadline, now);
+
+  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
+  pfds[0].events = POLLIN;
+  pfds[0].revents = 0;
+  pfds[1].fd = h->epoll_fd;
+  pfds[1].events = POLLIN;
+  pfds[1].revents = 0;
+
+  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
+     even going into the blocking annotation if possible */
+  GPR_TIMER_BEGIN("poll", 0);
+  GRPC_SCHEDULING_START_BLOCKING_REGION;
+  poll_rv = grpc_poll_function(pfds, 2, timeout_ms);
+  GRPC_SCHEDULING_END_BLOCKING_REGION;
+  GPR_TIMER_END("poll", 0);
+
+  if (poll_rv < 0) {
+    if (errno != EINTR) {
+      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
+    }
+  } else if (poll_rv == 0) {
+    /* do nothing */
+  } else {
+    if (pfds[0].revents) {
+      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
+    }
+    if (pfds[1].revents) {
+      do {
+        /* The following epoll_wait never blocks; it has a timeout of 0 */
+        ep_rv = epoll_wait(h->epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, 0);
+        if (ep_rv < 0) {
+          if (errno != EINTR) {
+            gpr_log(GPR_ERROR, "epoll_wait() failed: %s", strerror(errno));
+          }
+        } else {
+          int i;
+          for (i = 0; i < ep_rv; ++i) {
+            grpc_fd *fd = ep_ev[i].data.ptr;
+            /* TODO(klempner): We might want to consider making err and pri
+             * separate events */
+            int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP);
+            int read_ev = ep_ev[i].events & (EPOLLIN | EPOLLPRI);
+            int write_ev = ep_ev[i].events & EPOLLOUT;
+            if (fd == NULL) {
+              grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
+            } else {
+              if (read_ev || cancel) {
+                fd_become_readable(exec_ctx, fd);
+              }
+              if (write_ev || cancel) {
+                fd_become_writable(exec_ctx, fd);
+              }
+            }
+          }
+        }
+      } while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
+    }
+  }
+}
+
+static void multipoll_with_epoll_pollset_finish_shutdown(
+    grpc_pollset *pollset) {}
+
+static void multipoll_with_epoll_pollset_destroy(grpc_pollset *pollset) {
+  epoll_hdr *h = pollset->data.ptr;
+  close(h->epoll_fd);
+  remove_epoll_fd_from_global_list(h->epoll_fd);
+  gpr_free(h);
+}
+
+static const grpc_pollset_vtable multipoll_with_epoll_pollset = {
+    multipoll_with_epoll_pollset_add_fd,
+    multipoll_with_epoll_pollset_maybe_work_and_unlock,
+    multipoll_with_epoll_pollset_finish_shutdown,
+    multipoll_with_epoll_pollset_destroy};
+
+static void epoll_become_multipoller(grpc_exec_ctx *exec_ctx,
+                                     grpc_pollset *pollset, grpc_fd **fds,
+                                     size_t nfds) {
+  size_t i;
+  epoll_hdr *h = gpr_malloc(sizeof(epoll_hdr));
+  struct epoll_event ev;
+  int err;
+
+  pollset->vtable = &multipoll_with_epoll_pollset;
+  pollset->data.ptr = h;
+  h->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+  if (h->epoll_fd < 0) {
+    /* TODO(klempner): Fall back to poll here, especially on ENOSYS */
+    gpr_log(GPR_ERROR, "epoll_create1 failed: %s", strerror(errno));
+    abort();
+  }
+  add_epoll_fd_to_global_list(h->epoll_fd);
+
+  ev.events = (uint32_t)(EPOLLIN | EPOLLET);
+  ev.data.ptr = NULL;
+  err = epoll_ctl(h->epoll_fd, EPOLL_CTL_ADD,
+                  GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd), &ev);
+  if (err < 0) {
+    gpr_log(GPR_ERROR, "epoll_ctl add for %d failed: %s",
+            GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd),
+            strerror(errno));
+  }
+
+  for (i = 0; i < nfds; i++) {
+    multipoll_with_epoll_pollset_add_fd(exec_ctx, pollset, fds[i], 0);
+  }
+}
+
+#else /* GPR_LINUX_MULTIPOLL_WITH_EPOLL */
+
+static void remove_fd_from_all_epoll_sets(int fd) {}
+
+#endif /* GPR_LINUX_MULTIPOLL_WITH_EPOLL */
+
+/*******************************************************************************
+ * pollset_set_posix.c
+ */
+
+static grpc_pollset_set *pollset_set_create(void) {
+  grpc_pollset_set *pollset_set = gpr_malloc(sizeof(*pollset_set));
+  memset(pollset_set, 0, sizeof(*pollset_set));
+  gpr_mu_init(&pollset_set->mu);
+  return pollset_set;
+}
+
+static void pollset_set_destroy(grpc_pollset_set *pollset_set) {
+  size_t i;
+  gpr_mu_destroy(&pollset_set->mu);
+  for (i = 0; i < pollset_set->fd_count; i++) {
+    GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
+  }
+  gpr_free(pollset_set->pollsets);
+  gpr_free(pollset_set->pollset_sets);
+  gpr_free(pollset_set->fds);
+  gpr_free(pollset_set);
+}
+
+static void pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
+                                    grpc_pollset_set *pollset_set,
+                                    grpc_pollset *pollset) {
+  size_t i, j;
+  gpr_mu_lock(&pollset_set->mu);
+  if (pollset_set->pollset_count == pollset_set->pollset_capacity) {
+    pollset_set->pollset_capacity =
+        GPR_MAX(8, 2 * pollset_set->pollset_capacity);
+    pollset_set->pollsets =
+        gpr_realloc(pollset_set->pollsets, pollset_set->pollset_capacity *
+                                               sizeof(*pollset_set->pollsets));
+  }
+  pollset_set->pollsets[pollset_set->pollset_count++] = pollset;
+  for (i = 0, j = 0; i < pollset_set->fd_count; i++) {
+    if (fd_is_orphaned(pollset_set->fds[i])) {
+      GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
+    } else {
+      pollset_add_fd(exec_ctx, pollset, pollset_set->fds[i]);
+      pollset_set->fds[j++] = pollset_set->fds[i];
+    }
+  }
+  pollset_set->fd_count = j;
+  gpr_mu_unlock(&pollset_set->mu);
+}
+
+static void pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
+                                    grpc_pollset_set *pollset_set,
+                                    grpc_pollset *pollset) {
+  size_t i;
+  gpr_mu_lock(&pollset_set->mu);
+  for (i = 0; i < pollset_set->pollset_count; i++) {
+    if (pollset_set->pollsets[i] == pollset) {
+      pollset_set->pollset_count--;
+      GPR_SWAP(grpc_pollset *, pollset_set->pollsets[i],
+               pollset_set->pollsets[pollset_set->pollset_count]);
+      break;
+    }
+  }
+  gpr_mu_unlock(&pollset_set->mu);
+}
+
+static void pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx,
+                                        grpc_pollset_set *bag,
+                                        grpc_pollset_set *item) {
+  size_t i, j;
+  gpr_mu_lock(&bag->mu);
+  if (bag->pollset_set_count == bag->pollset_set_capacity) {
+    bag->pollset_set_capacity = GPR_MAX(8, 2 * bag->pollset_set_capacity);
+    bag->pollset_sets =
+        gpr_realloc(bag->pollset_sets,
+                    bag->pollset_set_capacity * sizeof(*bag->pollset_sets));
+  }
+  bag->pollset_sets[bag->pollset_set_count++] = item;
+  for (i = 0, j = 0; i < bag->fd_count; i++) {
+    if (fd_is_orphaned(bag->fds[i])) {
+      GRPC_FD_UNREF(bag->fds[i], "pollset_set");
+    } else {
+      pollset_set_add_fd(exec_ctx, item, bag->fds[i]);
+      bag->fds[j++] = bag->fds[i];
+    }
+  }
+  bag->fd_count = j;
+  gpr_mu_unlock(&bag->mu);
+}
+
+static void pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx,
+                                        grpc_pollset_set *bag,
+                                        grpc_pollset_set *item) {
+  size_t i;
+  gpr_mu_lock(&bag->mu);
+  for (i = 0; i < bag->pollset_set_count; i++) {
+    if (bag->pollset_sets[i] == item) {
+      bag->pollset_set_count--;
+      GPR_SWAP(grpc_pollset_set *, bag->pollset_sets[i],
+               bag->pollset_sets[bag->pollset_set_count]);
+      break;
+    }
+  }
+  gpr_mu_unlock(&bag->mu);
+}
+
+static void pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
+                               grpc_pollset_set *pollset_set, grpc_fd *fd) {
+  size_t i;
+  gpr_mu_lock(&pollset_set->mu);
+  if (pollset_set->fd_count == pollset_set->fd_capacity) {
+    pollset_set->fd_capacity = GPR_MAX(8, 2 * pollset_set->fd_capacity);
+    pollset_set->fds = gpr_realloc(
+        pollset_set->fds, pollset_set->fd_capacity * sizeof(*pollset_set->fds));
+  }
+  GRPC_FD_REF(fd, "pollset_set");
+  pollset_set->fds[pollset_set->fd_count++] = fd;
+  for (i = 0; i < pollset_set->pollset_count; i++) {
+    pollset_add_fd(exec_ctx, pollset_set->pollsets[i], fd);
+  }
+  for (i = 0; i < pollset_set->pollset_set_count; i++) {
+    pollset_set_add_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
+  }
+  gpr_mu_unlock(&pollset_set->mu);
+}
+
+static void pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
+                               grpc_pollset_set *pollset_set, grpc_fd *fd) {
+  size_t i;
+  gpr_mu_lock(&pollset_set->mu);
+  for (i = 0; i < pollset_set->fd_count; i++) {
+    if (pollset_set->fds[i] == fd) {
+      pollset_set->fd_count--;
+      GPR_SWAP(grpc_fd *, pollset_set->fds[i],
+               pollset_set->fds[pollset_set->fd_count]);
+      GRPC_FD_UNREF(fd, "pollset_set");
+      break;
+    }
+  }
+  for (i = 0; i < pollset_set->pollset_set_count; i++) {
+    pollset_set_del_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
+  }
+  gpr_mu_unlock(&pollset_set->mu);
+}
+
+/*******************************************************************************
+ * event engine binding
+ */
+
+static void shutdown_engine(void) {
+  fd_global_shutdown();
+  pollset_global_shutdown();
+}
+
+static const grpc_event_engine_vtable vtable = {
+    .pollset_size = sizeof(grpc_pollset),
+
+    .fd_create = fd_create,
+    .fd_wrapped_fd = fd_wrapped_fd,
+    .fd_orphan = fd_orphan,
+    .fd_shutdown = fd_shutdown,
+    .fd_notify_on_read = fd_notify_on_read,
+    .fd_notify_on_write = fd_notify_on_write,
+
+    .pollset_init = pollset_init,
+    .pollset_shutdown = pollset_shutdown,
+    .pollset_reset = pollset_reset,
+    .pollset_destroy = pollset_destroy,
+    .pollset_work = pollset_work,
+    .pollset_kick = pollset_kick,
+    .pollset_add_fd = pollset_add_fd,
+
+    .pollset_set_create = pollset_set_create,
+    .pollset_set_destroy = pollset_set_destroy,
+    .pollset_set_add_pollset = pollset_set_add_pollset,
+    .pollset_set_del_pollset = pollset_set_del_pollset,
+    .pollset_set_add_pollset_set = pollset_set_add_pollset_set,
+    .pollset_set_del_pollset_set = pollset_set_del_pollset_set,
+    .pollset_set_add_fd = pollset_set_add_fd,
+    .pollset_set_del_fd = pollset_set_del_fd,
+
+    .kick_poller = kick_poller,
+
+    .shutdown_engine = shutdown_engine,
+};
+
+const grpc_event_engine_vtable *grpc_init_poll_and_epoll_posix(void) {
+#ifdef GPR_LINUX_MULTIPOLL_WITH_EPOLL
+  platform_become_multipoller = epoll_become_multipoller;
+#else
+  platform_become_multipoller = poll_become_multipoller;
+#endif
+  fd_global_init();
+  pollset_global_init();
+  return &vtable;
+}
+
+#endif
diff --git a/src/core/lib/census/grpc_plugin.h b/src/core/lib/iomgr/ev_poll_and_epoll_posix.h
index 4d642a65c7..06d6dbf29d 100644
--- a/src/core/lib/census/grpc_plugin.h
+++ b/src/core/lib/iomgr/ev_poll_and_epoll_posix.h
@@ -31,10 +31,11 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_CENSUS_GRPC_PLUGIN_H
-#define GRPC_CORE_LIB_CENSUS_GRPC_PLUGIN_H
+#ifndef GRPC_CORE_LIB_IOMGR_EV_POLL_AND_EPOLL_POSIX_H
+#define GRPC_CORE_LIB_IOMGR_EV_POLL_AND_EPOLL_POSIX_H
 
-void census_grpc_plugin_init(void);
-void census_grpc_plugin_destroy(void);
+#include "src/core/lib/iomgr/ev_posix.h"
 
-#endif /* GRPC_CORE_LIB_CENSUS_GRPC_PLUGIN_H */
+const grpc_event_engine_vtable *grpc_init_poll_and_epoll_posix(void);
+
+#endif /* GRPC_CORE_LIB_IOMGR_EV_POLL_AND_EPOLL_POSIX_H */
diff --git a/src/core/lib/iomgr/ev_posix.c b/src/core/lib/iomgr/ev_posix.c
new file mode 100644
index 0000000000..235a7df08d
--- /dev/null
+++ b/src/core/lib/iomgr/ev_posix.c
@@ -0,0 +1,165 @@
+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#ifdef GPR_POSIX_SOCKET
+
+#include "src/core/lib/iomgr/ev_posix.h"
+
+#include <grpc/support/log.h>
+
+#include "src/core/lib/iomgr/ev_poll_and_epoll_posix.h"
+
+static const grpc_event_engine_vtable *g_event_engine;
+
+grpc_poll_function_type grpc_poll_function = poll;
+grpc_wakeup_fd grpc_global_wakeup_fd;
+
+void grpc_event_engine_init(void) {
+  if ((g_event_engine = grpc_init_poll_and_epoll_posix())) {
+    return;
+  }
+  gpr_log(GPR_ERROR, "No event engine could be initialized");
+  abort();
+}
+
+void grpc_event_engine_shutdown(void) { g_event_engine->shutdown_engine(); }
+
+grpc_fd *grpc_fd_create(int fd, const char *name) {
+  return g_event_engine->fd_create(fd, name);
+}
+
+int grpc_fd_wrapped_fd(grpc_fd *fd) {
+  return g_event_engine->fd_wrapped_fd(fd);
+}
+
+void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
+                    int *release_fd, const char *reason) {
+  g_event_engine->fd_orphan(exec_ctx, fd, on_done, release_fd, reason);
+}
+
+void grpc_fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
+  g_event_engine->fd_shutdown(exec_ctx, fd);
+}
+
+void grpc_fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                            grpc_closure *closure) {
+  g_event_engine->fd_notify_on_read(exec_ctx, fd, closure);
+}
+
+void grpc_fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                             grpc_closure *closure) {
+  g_event_engine->fd_notify_on_write(exec_ctx, fd, closure);
+}
+
+size_t grpc_pollset_size(void) { return g_event_engine->pollset_size; }
+
+void grpc_pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
+  g_event_engine->pollset_init(pollset, mu);
+}
+
+void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                           grpc_closure *closure) {
+  g_event_engine->pollset_shutdown(exec_ctx, pollset, closure);
+}
+
+void grpc_pollset_reset(grpc_pollset *pollset) {
+  g_event_engine->pollset_reset(pollset);
+}
+
+void grpc_pollset_destroy(grpc_pollset *pollset) {
+  g_event_engine->pollset_destroy(pollset);
+}
+
+void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                       grpc_pollset_worker **worker, gpr_timespec now,
+                       gpr_timespec deadline) {
+  g_event_engine->pollset_work(exec_ctx, pollset, worker, now, deadline);
+}
+
+void grpc_pollset_kick(grpc_pollset *pollset,
+                       grpc_pollset_worker *specific_worker) {
+  g_event_engine->pollset_kick(pollset, specific_worker);
+}
+
+void grpc_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                         struct grpc_fd *fd) {
+  g_event_engine->pollset_add_fd(exec_ctx, pollset, fd);
+}
+
+grpc_pollset_set *grpc_pollset_set_create(void) {
+  return g_event_engine->pollset_set_create();
+}
+
+void grpc_pollset_set_destroy(grpc_pollset_set *pollset_set) {
+  g_event_engine->pollset_set_destroy(pollset_set);
+}
+
+void grpc_pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
+                                  grpc_pollset_set *pollset_set,
+                                  grpc_pollset *pollset) {
+  g_event_engine->pollset_set_add_pollset(exec_ctx, pollset_set, pollset);
+}
+
+void grpc_pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
+                                  grpc_pollset_set *pollset_set,
+                                  grpc_pollset *pollset) {
+  g_event_engine->pollset_set_del_pollset(exec_ctx, pollset_set, pollset);
+}
+
+void grpc_pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx,
+                                      grpc_pollset_set *bag,
+                                      grpc_pollset_set *item) {
+  g_event_engine->pollset_set_add_pollset_set(exec_ctx, bag, item);
+}
+
+void grpc_pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx,
+                                      grpc_pollset_set *bag,
+                                      grpc_pollset_set *item) {
+  g_event_engine->pollset_set_del_pollset_set(exec_ctx, bag, item);
+}
+
+void grpc_pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd) {
+  g_event_engine->pollset_set_add_fd(exec_ctx, pollset_set, fd);
+}
+
+void grpc_pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd) {
+  g_event_engine->pollset_set_del_fd(exec_ctx, pollset_set, fd);
+}
+
+void grpc_kick_poller(void) { g_event_engine->kick_poller(); }
+
+#endif  // GPR_POSIX_SOCKET
diff --git a/src/core/lib/iomgr/ev_posix.h b/src/core/lib/iomgr/ev_posix.h
new file mode 100644
index 0000000000..9d27b2bcda
--- /dev/null
+++ b/src/core/lib/iomgr/ev_posix.h
@@ -0,0 +1,158 @@
+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_IOMGR_EV_POSIX_H
+#define GRPC_CORE_LIB_IOMGR_EV_POSIX_H
+
+#include <poll.h>
+
+#include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/iomgr/pollset.h"
+#include "src/core/lib/iomgr/pollset_set.h"
+#include "src/core/lib/iomgr/wakeup_fd_posix.h"
+
+typedef struct grpc_fd grpc_fd;
+
+typedef struct grpc_event_engine_vtable {
+  size_t pollset_size;
+
+  grpc_fd *(*fd_create)(int fd, const char *name);
+  int (*fd_wrapped_fd)(grpc_fd *fd);
+  void (*fd_orphan)(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
+                    int *release_fd, const char *reason);
+  void (*fd_shutdown)(grpc_exec_ctx *exec_ctx, grpc_fd *fd);
+  void (*fd_notify_on_read)(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                            grpc_closure *closure);
+  void (*fd_notify_on_write)(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                             grpc_closure *closure);
+
+  void (*pollset_init)(grpc_pollset *pollset, gpr_mu **mu);
+  void (*pollset_shutdown)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                           grpc_closure *closure);
+  void (*pollset_reset)(grpc_pollset *pollset);
+  void (*pollset_destroy)(grpc_pollset *pollset);
+  void (*pollset_work)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                       grpc_pollset_worker **worker, gpr_timespec now,
+                       gpr_timespec deadline);
+  void (*pollset_kick)(grpc_pollset *pollset,
+                       grpc_pollset_worker *specific_worker);
+  void (*pollset_add_fd)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                         struct grpc_fd *fd);
+
+  grpc_pollset_set *(*pollset_set_create)(void);
+  void (*pollset_set_destroy)(grpc_pollset_set *pollset_set);
+  void (*pollset_set_add_pollset)(grpc_exec_ctx *exec_ctx,
+                                  grpc_pollset_set *pollset_set,
+                                  grpc_pollset *pollset);
+  void (*pollset_set_del_pollset)(grpc_exec_ctx *exec_ctx,
+                                  grpc_pollset_set *pollset_set,
+                                  grpc_pollset *pollset);
+  void (*pollset_set_add_pollset_set)(grpc_exec_ctx *exec_ctx,
+                                      grpc_pollset_set *bag,
+                                      grpc_pollset_set *item);
+  void (*pollset_set_del_pollset_set)(grpc_exec_ctx *exec_ctx,
+                                      grpc_pollset_set *bag,
+                                      grpc_pollset_set *item);
+  void (*pollset_set_add_fd)(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd);
+  void (*pollset_set_del_fd)(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd);
+
+  void (*kick_poller)(void);
+
+  void (*shutdown_engine)(void);
+} grpc_event_engine_vtable;
+
+void grpc_event_engine_init(void);
+void grpc_event_engine_shutdown(void);
+
+/* Create a wrapped file descriptor.
+   Requires fd is a non-blocking file descriptor.
+   This takes ownership of closing fd. */
+grpc_fd *grpc_fd_create(int fd, const char *name);
+
+/* Return the wrapped fd, or -1 if it has been released or closed. */
+int grpc_fd_wrapped_fd(grpc_fd *fd);
+
+/* Releases fd to be asynchronously destroyed.
+   on_done is called when the underlying file descriptor is definitely close()d.
+   If on_done is NULL, no callback will be made.
+   If release_fd is not NULL, it's set to fd and fd will not be closed.
+   Requires: *fd initialized; no outstanding notify_on_read or
+   notify_on_write.
+   MUST NOT be called with a pollset lock taken */
+void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
+                    int *release_fd, const char *reason);
+
+/* Cause any current callbacks to error out with GRPC_CALLBACK_CANCELLED. */
+void grpc_fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd);
+
+/* Register read interest, causing read_cb to be called once when fd becomes
+   readable, on deadline specified by deadline, or on shutdown triggered by
+   grpc_fd_shutdown.
+   read_cb will be called with read_cb_arg when *fd becomes readable.
+   read_cb is Called with status of GRPC_CALLBACK_SUCCESS if readable,
+   GRPC_CALLBACK_TIMED_OUT if the call timed out,
+   and CANCELLED if the call was cancelled.
+
+   Requires:This method must not be called before the read_cb for any previous
+   call runs. Edge triggered events are used whenever they are supported by the
+   underlying platform. This means that users must drain fd in read_cb before
+   calling notify_on_read again. Users are also expected to handle spurious
+   events, i.e read_cb is called while nothing can be readable from fd  */
+void grpc_fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                            grpc_closure *closure);
+
+/* Exactly the same semantics as above, except based on writable events.  */
+void grpc_fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
+                             grpc_closure *closure);
+
+/* pollset_posix functions */
+
+/* Add an fd to a pollset */
+void grpc_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
+                         struct grpc_fd *fd);
+
+/* pollset_set_posix functions */
+
+void grpc_pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd);
+void grpc_pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
+                             grpc_pollset_set *pollset_set, grpc_fd *fd);
+
+/* override to allow tests to hook poll() usage */
+typedef int (*grpc_poll_function_type)(struct pollfd *, nfds_t, int);
+extern grpc_poll_function_type grpc_poll_function;
+extern grpc_wakeup_fd grpc_global_wakeup_fd;
+
+#endif /* GRPC_CORE_LIB_IOMGR_EV_POSIX_H */
diff --git a/src/core/lib/iomgr/fd_posix.c b/src/core/lib/iomgr/fd_posix.c
deleted file mode 100644
index 1397302658..0000000000
--- a/src/core/lib/iomgr/fd_posix.c
+++ /dev/null
@@ -1,454 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_POSIX_SOCKET
-
-#include "src/core/lib/iomgr/fd_posix.h"
-
-#include <assert.h>
-#include <sys/socket.h>
-#include <unistd.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/useful.h>
-
-#include "src/core/lib/iomgr/pollset_posix.h"
-
-#define CLOSURE_NOT_READY ((grpc_closure *)0)
-#define CLOSURE_READY ((grpc_closure *)1)
-
-/* We need to keep a freelist not because of any concerns of malloc performance
- * but instead so that implementations with multiple threads in (for example)
- * epoll_wait deal with the race between pollset removal and incoming poll
- * notifications.
- *
- * The problem is that the poller ultimately holds a reference to this
- * object, so it is very difficult to know when is safe to free it, at least
- * without some expensive synchronization.
- *
- * If we keep the object freelisted, in the worst case losing this race just
- * becomes a spurious read notification on a reused fd.
- */
-/* TODO(klempner): We could use some form of polling generation count to know
- * when these are safe to free. */
-/* TODO(klempner): Consider disabling freelisting if we don't have multiple
- * threads in poll on the same fd */
-/* TODO(klempner): Batch these allocations to reduce fragmentation */
-static grpc_fd *fd_freelist = NULL;
-static gpr_mu fd_freelist_mu;
-
-static void freelist_fd(grpc_fd *fd) {
-  gpr_mu_lock(&fd_freelist_mu);
-  fd->freelist_next = fd_freelist;
-  fd_freelist = fd;
-  grpc_iomgr_unregister_object(&fd->iomgr_object);
-  gpr_mu_unlock(&fd_freelist_mu);
-}
-
-static grpc_fd *alloc_fd(int fd) {
-  grpc_fd *r = NULL;
-  gpr_mu_lock(&fd_freelist_mu);
-  if (fd_freelist != NULL) {
-    r = fd_freelist;
-    fd_freelist = fd_freelist->freelist_next;
-  }
-  gpr_mu_unlock(&fd_freelist_mu);
-  if (r == NULL) {
-    r = gpr_malloc(sizeof(grpc_fd));
-    gpr_mu_init(&r->mu);
-  }
-
-  gpr_mu_lock(&r->mu);
-  r->shutdown = 0;
-  r->read_closure = CLOSURE_NOT_READY;
-  r->write_closure = CLOSURE_NOT_READY;
-  r->fd = fd;
-  r->inactive_watcher_root.next = r->inactive_watcher_root.prev =
-      &r->inactive_watcher_root;
-  r->freelist_next = NULL;
-  r->read_watcher = r->write_watcher = NULL;
-  r->on_done_closure = NULL;
-  r->closed = 0;
-  r->released = 0;
-  gpr_atm_rel_store(&r->refst, 1);
-  gpr_mu_unlock(&r->mu);
-
-  return r;
-}
-
-static void destroy(grpc_fd *fd) {
-  gpr_mu_destroy(&fd->mu);
-  gpr_free(fd);
-}
-
-#ifdef GRPC_FD_REF_COUNT_DEBUG
-#define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__)
-#define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__)
-static void ref_by(grpc_fd *fd, int n, const char *reason, const char *file,
-                   int line) {
-  gpr_log(GPR_DEBUG, "FD %d %p   ref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
-          gpr_atm_no_barrier_load(&fd->refst),
-          gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line);
-#else
-#define REF_BY(fd, n, reason) ref_by(fd, n)
-#define UNREF_BY(fd, n, reason) unref_by(fd, n)
-static void ref_by(grpc_fd *fd, int n) {
-#endif
-  GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0);
-}
-
-#ifdef GRPC_FD_REF_COUNT_DEBUG
-static void unref_by(grpc_fd *fd, int n, const char *reason, const char *file,
-                     int line) {
-  gpr_atm old;
-  gpr_log(GPR_DEBUG, "FD %d %p unref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
-          gpr_atm_no_barrier_load(&fd->refst),
-          gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line);
-#else
-static void unref_by(grpc_fd *fd, int n) {
-  gpr_atm old;
-#endif
-  old = gpr_atm_full_fetch_add(&fd->refst, -n);
-  if (old == n) {
-    freelist_fd(fd);
-  } else {
-    GPR_ASSERT(old > n);
-  }
-}
-
-void grpc_fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); }
-
-void grpc_fd_global_shutdown(void) {
-  gpr_mu_lock(&fd_freelist_mu);
-  gpr_mu_unlock(&fd_freelist_mu);
-  while (fd_freelist != NULL) {
-    grpc_fd *fd = fd_freelist;
-    fd_freelist = fd_freelist->freelist_next;
-    destroy(fd);
-  }
-  gpr_mu_destroy(&fd_freelist_mu);
-}
-
-grpc_fd *grpc_fd_create(int fd, const char *name) {
-  grpc_fd *r = alloc_fd(fd);
-  char *name2;
-  gpr_asprintf(&name2, "%s fd=%d", name, fd);
-  grpc_iomgr_register_object(&r->iomgr_object, name2);
-  gpr_free(name2);
-#ifdef GRPC_FD_REF_COUNT_DEBUG
-  gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, r, name);
-#endif
-  return r;
-}
-
-int grpc_fd_is_orphaned(grpc_fd *fd) {
-  return (gpr_atm_acq_load(&fd->refst) & 1) == 0;
-}
-
-static void pollset_kick_locked(grpc_fd_watcher *watcher) {
-  gpr_mu_lock(&watcher->pollset->mu);
-  GPR_ASSERT(watcher->worker);
-  grpc_pollset_kick_ext(watcher->pollset, watcher->worker,
-                        GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP);
-  gpr_mu_unlock(&watcher->pollset->mu);
-}
-
-static void maybe_wake_one_watcher_locked(grpc_fd *fd) {
-  if (fd->inactive_watcher_root.next != &fd->inactive_watcher_root) {
-    pollset_kick_locked(fd->inactive_watcher_root.next);
-  } else if (fd->read_watcher) {
-    pollset_kick_locked(fd->read_watcher);
-  } else if (fd->write_watcher) {
-    pollset_kick_locked(fd->write_watcher);
-  }
-}
-
-static void wake_all_watchers_locked(grpc_fd *fd) {
-  grpc_fd_watcher *watcher;
-  for (watcher = fd->inactive_watcher_root.next;
-       watcher != &fd->inactive_watcher_root; watcher = watcher->next) {
-    pollset_kick_locked(watcher);
-  }
-  if (fd->read_watcher) {
-    pollset_kick_locked(fd->read_watcher);
-  }
-  if (fd->write_watcher && fd->write_watcher != fd->read_watcher) {
-    pollset_kick_locked(fd->write_watcher);
-  }
-}
-
-static int has_watchers(grpc_fd *fd) {
-  return fd->read_watcher != NULL || fd->write_watcher != NULL ||
-         fd->inactive_watcher_root.next != &fd->inactive_watcher_root;
-}
-
-static void close_fd_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
-  fd->closed = 1;
-  if (!fd->released) {
-    close(fd->fd);
-  } else {
-    grpc_remove_fd_from_all_epoll_sets(fd->fd);
-  }
-  grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, true, NULL);
-}
-
-int grpc_fd_wrapped_fd(grpc_fd *fd) {
-  if (fd->released || fd->closed) {
-    return -1;
-  } else {
-    return fd->fd;
-  }
-}
-
-void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
-                    int *release_fd, const char *reason) {
-  fd->on_done_closure = on_done;
-  fd->released = release_fd != NULL;
-  if (!fd->released) {
-    shutdown(fd->fd, SHUT_RDWR);
-  } else {
-    *release_fd = fd->fd;
-  }
-  gpr_mu_lock(&fd->mu);
-  REF_BY(fd, 1, reason); /* remove active status, but keep referenced */
-  if (!has_watchers(fd)) {
-    close_fd_locked(exec_ctx, fd);
-  } else {
-    wake_all_watchers_locked(fd);
-  }
-  gpr_mu_unlock(&fd->mu);
-  UNREF_BY(fd, 2, reason); /* drop the reference */
-}
-
-/* increment refcount by two to avoid changing the orphan bit */
-#ifdef GRPC_FD_REF_COUNT_DEBUG
-void grpc_fd_ref(grpc_fd *fd, const char *reason, const char *file, int line) {
-  ref_by(fd, 2, reason, file, line);
-}
-
-void grpc_fd_unref(grpc_fd *fd, const char *reason, const char *file,
-                   int line) {
-  unref_by(fd, 2, reason, file, line);
-}
-#else
-void grpc_fd_ref(grpc_fd *fd) { ref_by(fd, 2); }
-
-void grpc_fd_unref(grpc_fd *fd) { unref_by(fd, 2); }
-#endif
-
-static void notify_on_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                             grpc_closure **st, grpc_closure *closure) {
-  if (*st == CLOSURE_NOT_READY) {
-    /* not ready ==> switch to a waiting state by setting the closure */
-    *st = closure;
-  } else if (*st == CLOSURE_READY) {
-    /* already ready ==> queue the closure to run immediately */
-    *st = CLOSURE_NOT_READY;
-    grpc_exec_ctx_enqueue(exec_ctx, closure, !fd->shutdown, NULL);
-    maybe_wake_one_watcher_locked(fd);
-  } else {
-    /* upcallptr was set to a different closure.  This is an error! */
-    gpr_log(GPR_ERROR,
-            "User called a notify_on function with a previous callback still "
-            "pending");
-    abort();
-  }
-}
-
-/* returns 1 if state becomes not ready */
-static int set_ready_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                            grpc_closure **st) {
-  if (*st == CLOSURE_READY) {
-    /* duplicate ready ==> ignore */
-    return 0;
-  } else if (*st == CLOSURE_NOT_READY) {
-    /* not ready, and not waiting ==> flag ready */
-    *st = CLOSURE_READY;
-    return 0;
-  } else {
-    /* waiting ==> queue closure */
-    grpc_exec_ctx_enqueue(exec_ctx, *st, !fd->shutdown, NULL);
-    *st = CLOSURE_NOT_READY;
-    return 1;
-  }
-}
-
-static void set_ready(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure **st) {
-  /* only one set_ready can be active at once (but there may be a racing
-     notify_on) */
-  gpr_mu_lock(&fd->mu);
-  set_ready_locked(exec_ctx, fd, st);
-  gpr_mu_unlock(&fd->mu);
-}
-
-void grpc_fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
-  gpr_mu_lock(&fd->mu);
-  GPR_ASSERT(!fd->shutdown);
-  fd->shutdown = 1;
-  set_ready_locked(exec_ctx, fd, &fd->read_closure);
-  set_ready_locked(exec_ctx, fd, &fd->write_closure);
-  gpr_mu_unlock(&fd->mu);
-}
-
-void grpc_fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                            grpc_closure *closure) {
-  gpr_mu_lock(&fd->mu);
-  notify_on_locked(exec_ctx, fd, &fd->read_closure, closure);
-  gpr_mu_unlock(&fd->mu);
-}
-
-void grpc_fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                             grpc_closure *closure) {
-  gpr_mu_lock(&fd->mu);
-  notify_on_locked(exec_ctx, fd, &fd->write_closure, closure);
-  gpr_mu_unlock(&fd->mu);
-}
-
-uint32_t grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
-                            grpc_pollset_worker *worker, uint32_t read_mask,
-                            uint32_t write_mask, grpc_fd_watcher *watcher) {
-  uint32_t mask = 0;
-  grpc_closure *cur;
-  int requested;
-  /* keep track of pollers that have requested our events, in case they change
-   */
-  GRPC_FD_REF(fd, "poll");
-
-  gpr_mu_lock(&fd->mu);
-
-  /* if we are shutdown, then don't add to the watcher set */
-  if (fd->shutdown) {
-    watcher->fd = NULL;
-    watcher->pollset = NULL;
-    watcher->worker = NULL;
-    gpr_mu_unlock(&fd->mu);
-    GRPC_FD_UNREF(fd, "poll");
-    return 0;
-  }
-
-  /* if there is nobody polling for read, but we need to, then start doing so */
-  cur = fd->read_closure;
-  requested = cur != CLOSURE_READY;
-  if (read_mask && fd->read_watcher == NULL && requested) {
-    fd->read_watcher = watcher;
-    mask |= read_mask;
-  }
-  /* if there is nobody polling for write, but we need to, then start doing so
-   */
-  cur = fd->write_closure;
-  requested = cur != CLOSURE_READY;
-  if (write_mask && fd->write_watcher == NULL && requested) {
-    fd->write_watcher = watcher;
-    mask |= write_mask;
-  }
-  /* if not polling, remember this watcher in case we need someone to later */
-  if (mask == 0 && worker != NULL) {
-    watcher->next = &fd->inactive_watcher_root;
-    watcher->prev = watcher->next->prev;
-    watcher->next->prev = watcher->prev->next = watcher;
-  }
-  watcher->pollset = pollset;
-  watcher->worker = worker;
-  watcher->fd = fd;
-  gpr_mu_unlock(&fd->mu);
-
-  return mask;
-}
-
-void grpc_fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *watcher,
-                      int got_read, int got_write) {
-  int was_polling = 0;
-  int kick = 0;
-  grpc_fd *fd = watcher->fd;
-
-  if (fd == NULL) {
-    return;
-  }
-
-  gpr_mu_lock(&fd->mu);
-
-  if (watcher == fd->read_watcher) {
-    /* remove read watcher, kick if we still need a read */
-    was_polling = 1;
-    if (!got_read) {
-      kick = 1;
-    }
-    fd->read_watcher = NULL;
-  }
-  if (watcher == fd->write_watcher) {
-    /* remove write watcher, kick if we still need a write */
-    was_polling = 1;
-    if (!got_write) {
-      kick = 1;
-    }
-    fd->write_watcher = NULL;
-  }
-  if (!was_polling && watcher->worker != NULL) {
-    /* remove from inactive list */
-    watcher->next->prev = watcher->prev;
-    watcher->prev->next = watcher->next;
-  }
-  if (got_read) {
-    if (set_ready_locked(exec_ctx, fd, &fd->read_closure)) {
-      kick = 1;
-    }
-  }
-  if (got_write) {
-    if (set_ready_locked(exec_ctx, fd, &fd->write_closure)) {
-      kick = 1;
-    }
-  }
-  if (kick) {
-    maybe_wake_one_watcher_locked(fd);
-  }
-  if (grpc_fd_is_orphaned(fd) && !has_watchers(fd) && !fd->closed) {
-    close_fd_locked(exec_ctx, fd);
-  }
-  gpr_mu_unlock(&fd->mu);
-
-  GRPC_FD_UNREF(fd, "poll");
-}
-
-void grpc_fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
-  set_ready(exec_ctx, fd, &fd->read_closure);
-}
-
-void grpc_fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
-  set_ready(exec_ctx, fd, &fd->write_closure);
-}
-
-#endif
diff --git a/src/core/lib/iomgr/fd_posix.h b/src/core/lib/iomgr/fd_posix.h
deleted file mode 100644
index dc389ba743..0000000000
--- a/src/core/lib/iomgr/fd_posix.h
+++ /dev/null
@@ -1,192 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_IOMGR_FD_POSIX_H
-#define GRPC_CORE_LIB_IOMGR_FD_POSIX_H
-
-#include <grpc/support/atm.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/time.h>
-#include "src/core/lib/iomgr/iomgr_internal.h"
-#include "src/core/lib/iomgr/pollset.h"
-
-typedef struct grpc_fd grpc_fd;
-
-typedef struct grpc_fd_watcher {
-  struct grpc_fd_watcher *next;
-  struct grpc_fd_watcher *prev;
-  grpc_pollset *pollset;
-  grpc_pollset_worker *worker;
-  grpc_fd *fd;
-} grpc_fd_watcher;
-
-struct grpc_fd {
-  int fd;
-  /* refst format:
-     bit0:   1=active/0=orphaned
-     bit1-n: refcount
-     meaning that mostly we ref by two to avoid altering the orphaned bit,
-     and just unref by 1 when we're ready to flag the object as orphaned */
-  gpr_atm refst;
-
-  gpr_mu mu;
-  int shutdown;
-  int closed;
-  int released;
-
-  /* The watcher list.
-
-     The following watcher related fields are protected by watcher_mu.
-
-     An fd_watcher is an ephemeral object created when an fd wants to
-     begin polling, and destroyed after the poll.
-
-     It denotes the fd's interest in whether to read poll or write poll
-     or both or neither on this fd.
-
-     If a watcher is asked to poll for reads or writes, the read_watcher
-     or write_watcher fields are set respectively. A watcher may be asked
-     to poll for both, in which case both fields will be set.
-
-     read_watcher and write_watcher may be NULL if no watcher has been
-     asked to poll for reads or writes.
-
-     If an fd_watcher is not asked to poll for reads or writes, it's added
-     to a linked list of inactive watchers, rooted at inactive_watcher_root.
-     If at a later time there becomes need of a poller to poll, one of
-     the inactive pollers may be kicked out of their poll loops to take
-     that responsibility. */
-  grpc_fd_watcher inactive_watcher_root;
-  grpc_fd_watcher *read_watcher;
-  grpc_fd_watcher *write_watcher;
-
-  grpc_closure *read_closure;
-  grpc_closure *write_closure;
-
-  struct grpc_fd *freelist_next;
-
-  grpc_closure *on_done_closure;
-
-  grpc_iomgr_object iomgr_object;
-};
-
-/* Create a wrapped file descriptor.
-   Requires fd is a non-blocking file descriptor.
-   This takes ownership of closing fd. */
-grpc_fd *grpc_fd_create(int fd, const char *name);
-
-/* Return the wrapped fd, or -1 if it has been released or closed. */
-int grpc_fd_wrapped_fd(grpc_fd *fd);
-
-/* Releases fd to be asynchronously destroyed.
-   on_done is called when the underlying file descriptor is definitely close()d.
-   If on_done is NULL, no callback will be made.
-   If release_fd is not NULL, it's set to fd and fd will not be closed.
-   Requires: *fd initialized; no outstanding notify_on_read or
-   notify_on_write.
-   MUST NOT be called with a pollset lock taken */
-void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
-                    int *release_fd, const char *reason);
-
-/* Begin polling on an fd.
-   Registers that the given pollset is interested in this fd - so that if read
-   or writability interest changes, the pollset can be kicked to pick up that
-   new interest.
-   Return value is:
-     (fd_needs_read? read_mask : 0) | (fd_needs_write? write_mask : 0)
-   i.e. a combination of read_mask and write_mask determined by the fd's current
-   interest in said events.
-   Polling strategies that do not need to alter their behavior depending on the
-   fd's current interest (such as epoll) do not need to call this function.
-   MUST NOT be called with a pollset lock taken */
-uint32_t grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
-                            grpc_pollset_worker *worker, uint32_t read_mask,
-                            uint32_t write_mask, grpc_fd_watcher *rec);
-/* Complete polling previously started with grpc_fd_begin_poll
-   MUST NOT be called with a pollset lock taken
-   if got_read or got_write are 1, also does the become_{readable,writable} as
-   appropriate. */
-void grpc_fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *rec,
-                      int got_read, int got_write);
-
-/* Return 1 if this fd is orphaned, 0 otherwise */
-int grpc_fd_is_orphaned(grpc_fd *fd);
-
-/* Cause any current callbacks to error out with GRPC_CALLBACK_CANCELLED. */
-void grpc_fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd);
-
-/* Register read interest, causing read_cb to be called once when fd becomes
-   readable, on deadline specified by deadline, or on shutdown triggered by
-   grpc_fd_shutdown.
-   read_cb will be called with read_cb_arg when *fd becomes readable.
-   read_cb is Called with status of GRPC_CALLBACK_SUCCESS if readable,
-   GRPC_CALLBACK_TIMED_OUT if the call timed out,
-   and CANCELLED if the call was cancelled.
-
-   Requires:This method must not be called before the read_cb for any previous
-   call runs. Edge triggered events are used whenever they are supported by the
-   underlying platform. This means that users must drain fd in read_cb before
-   calling notify_on_read again. Users are also expected to handle spurious
-   events, i.e read_cb is called while nothing can be readable from fd  */
-void grpc_fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                            grpc_closure *closure);
-
-/* Exactly the same semantics as above, except based on writable events.  */
-void grpc_fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
-                             grpc_closure *closure);
-
-/* Notification from the poller to an fd that it has become readable or
-   writable.
-   If allow_synchronous_callback is 1, allow running the fd callback inline
-   in this callstack, otherwise register an asynchronous callback and return */
-void grpc_fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd);
-void grpc_fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd);
-
-/* Reference counting for fds */
-/*#define GRPC_FD_REF_COUNT_DEBUG*/
-#ifdef GRPC_FD_REF_COUNT_DEBUG
-void grpc_fd_ref(grpc_fd *fd, const char *reason, const char *file, int line);
-void grpc_fd_unref(grpc_fd *fd, const char *reason, const char *file, int line);
-#define GRPC_FD_REF(fd, reason) grpc_fd_ref(fd, reason, __FILE__, __LINE__)
-#define GRPC_FD_UNREF(fd, reason) grpc_fd_unref(fd, reason, __FILE__, __LINE__)
-#else
-void grpc_fd_ref(grpc_fd *fd);
-void grpc_fd_unref(grpc_fd *fd);
-#define GRPC_FD_REF(fd, reason) grpc_fd_ref(fd)
-#define GRPC_FD_UNREF(fd, reason) grpc_fd_unref(fd)
-#endif
-
-void grpc_fd_global_init(void);
-void grpc_fd_global_shutdown(void);
-
-#endif /* GRPC_CORE_LIB_IOMGR_FD_POSIX_H */
diff --git a/src/core/lib/iomgr/iomgr.c b/src/core/lib/iomgr/iomgr.c
index f1868cc96b..60cef8ba77 100644
--- a/src/core/lib/iomgr/iomgr.c
+++ b/src/core/lib/iomgr/iomgr.c
@@ -63,7 +63,6 @@ void grpc_iomgr_init(void) {
   g_root_object.next = g_root_object.prev = &g_root_object;
   g_root_object.name = "root";
   grpc_iomgr_platform_init();
-  grpc_pollset_global_init();
 }
 
 static size_t count_objects(void) {
@@ -138,7 +137,6 @@ void grpc_iomgr_shutdown(void) {
   gpr_mu_lock(&g_mu);
   gpr_mu_unlock(&g_mu);
 
-  grpc_pollset_global_shutdown();
   grpc_iomgr_platform_shutdown();
   grpc_exec_ctx_global_shutdown();
   gpr_mu_destroy(&g_mu);
diff --git a/src/core/lib/iomgr/iomgr_internal.h b/src/core/lib/iomgr/iomgr_internal.h
index 87d5a3d672..805be1f1e4 100644
--- a/src/core/lib/iomgr/iomgr_internal.h
+++ b/src/core/lib/iomgr/iomgr_internal.h
@@ -36,7 +36,6 @@
 
 #include <stdbool.h>
 
-#include <grpc/support/sync.h>
 #include "src/core/lib/iomgr/iomgr.h"
 
 typedef struct grpc_iomgr_object {
@@ -45,9 +44,6 @@ typedef struct grpc_iomgr_object {
   struct grpc_iomgr_object *prev;
 } grpc_iomgr_object;
 
-void grpc_pollset_global_init(void);
-void grpc_pollset_global_shutdown(void);
-
 void grpc_iomgr_register_object(grpc_iomgr_object *obj, const char *name);
 void grpc_iomgr_unregister_object(grpc_iomgr_object *obj);
 
diff --git a/src/core/lib/iomgr/iomgr_posix.c b/src/core/lib/iomgr/iomgr_posix.c
index 5d909bd220..016c501f75 100644
--- a/src/core/lib/iomgr/iomgr_posix.c
+++ b/src/core/lib/iomgr/iomgr_posix.c
@@ -36,17 +36,17 @@
 #ifdef GPR_POSIX_SOCKET
 
 #include "src/core/lib/debug/trace.h"
-#include "src/core/lib/iomgr/fd_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/iomgr/iomgr_posix.h"
 #include "src/core/lib/iomgr/tcp_posix.h"
 
 void grpc_iomgr_platform_init(void) {
-  grpc_fd_global_init();
+  grpc_event_engine_init();
   grpc_register_tracer("tcp", &grpc_tcp_trace);
 }
 
 void grpc_iomgr_platform_flush(void) {}
 
-void grpc_iomgr_platform_shutdown(void) { grpc_fd_global_shutdown(); }
+void grpc_iomgr_platform_shutdown(void) { grpc_event_engine_shutdown(); }
 
 #endif /* GRPC_POSIX_SOCKET */
diff --git a/src/core/lib/iomgr/iomgr_windows.c b/src/core/lib/iomgr/iomgr_windows.c
index 25c88425c4..398517fc75 100644
--- a/src/core/lib/iomgr/iomgr_windows.c
+++ b/src/core/lib/iomgr/iomgr_windows.c
@@ -41,6 +41,7 @@
 
 #include "src/core/lib/iomgr/iocp_windows.h"
 #include "src/core/lib/iomgr/iomgr.h"
+#include "src/core/lib/iomgr/pollset_windows.h"
 #include "src/core/lib/iomgr/socket_windows.h"
 
 /* Windows' io manager is going to be fully designed using IO completion
@@ -61,11 +62,13 @@ static void winsock_shutdown(void) {
 void grpc_iomgr_platform_init(void) {
   winsock_init();
   grpc_iocp_init();
+  grpc_pollset_global_init();
 }
 
 void grpc_iomgr_platform_flush(void) { grpc_iocp_flush(); }
 
 void grpc_iomgr_platform_shutdown(void) {
+  grpc_pollset_global_shutdown();
   grpc_iocp_shutdown();
   winsock_shutdown();
 }
diff --git a/src/core/lib/iomgr/pollset_multipoller_with_epoll.c b/src/core/lib/iomgr/pollset_multipoller_with_epoll.c
deleted file mode 100644
index 04d912e94d..0000000000
--- a/src/core/lib/iomgr/pollset_multipoller_with_epoll.c
+++ /dev/null
@@ -1,324 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_LINUX_MULTIPOLL_WITH_EPOLL
-
-#include <errno.h>
-#include <poll.h>
-#include <string.h>
-#include <sys/epoll.h>
-#include <unistd.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/useful.h>
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
-#include "src/core/lib/profiling/timers.h"
-#include "src/core/lib/support/block_annotate.h"
-
-struct epoll_fd_list {
-  int *epoll_fds;
-  size_t count;
-  size_t capacity;
-};
-
-static struct epoll_fd_list epoll_fd_global_list;
-static gpr_once init_epoll_fd_list_mu = GPR_ONCE_INIT;
-static gpr_mu epoll_fd_list_mu;
-
-static void init_mu(void) { gpr_mu_init(&epoll_fd_list_mu); }
-
-static void add_epoll_fd_to_global_list(int epoll_fd) {
-  gpr_once_init(&init_epoll_fd_list_mu, init_mu);
-
-  gpr_mu_lock(&epoll_fd_list_mu);
-  if (epoll_fd_global_list.count == epoll_fd_global_list.capacity) {
-    epoll_fd_global_list.capacity =
-        GPR_MAX((size_t)8, epoll_fd_global_list.capacity * 2);
-    epoll_fd_global_list.epoll_fds =
-        gpr_realloc(epoll_fd_global_list.epoll_fds,
-                    epoll_fd_global_list.capacity * sizeof(int));
-  }
-  epoll_fd_global_list.epoll_fds[epoll_fd_global_list.count++] = epoll_fd;
-  gpr_mu_unlock(&epoll_fd_list_mu);
-}
-
-static void remove_epoll_fd_from_global_list(int epoll_fd) {
-  gpr_mu_lock(&epoll_fd_list_mu);
-  GPR_ASSERT(epoll_fd_global_list.count > 0);
-  for (size_t i = 0; i < epoll_fd_global_list.count; i++) {
-    if (epoll_fd == epoll_fd_global_list.epoll_fds[i]) {
-      epoll_fd_global_list.epoll_fds[i] =
-          epoll_fd_global_list.epoll_fds[--(epoll_fd_global_list.count)];
-      break;
-    }
-  }
-  gpr_mu_unlock(&epoll_fd_list_mu);
-}
-
-void grpc_remove_fd_from_all_epoll_sets(int fd) {
-  int err;
-  gpr_once_init(&init_epoll_fd_list_mu, init_mu);
-  gpr_mu_lock(&epoll_fd_list_mu);
-  if (epoll_fd_global_list.count == 0) {
-    gpr_mu_unlock(&epoll_fd_list_mu);
-    return;
-  }
-  for (size_t i = 0; i < epoll_fd_global_list.count; i++) {
-    err = epoll_ctl(epoll_fd_global_list.epoll_fds[i], EPOLL_CTL_DEL, fd, NULL);
-    if (err < 0 && errno != ENOENT) {
-      gpr_log(GPR_ERROR, "epoll_ctl del for %d failed: %s", fd,
-              strerror(errno));
-    }
-  }
-  gpr_mu_unlock(&epoll_fd_list_mu);
-}
-
-typedef struct {
-  grpc_pollset *pollset;
-  grpc_fd *fd;
-  grpc_closure closure;
-} delayed_add;
-
-typedef struct { int epoll_fd; } pollset_hdr;
-
-static void finally_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                           grpc_fd *fd) {
-  pollset_hdr *h = pollset->data.ptr;
-  struct epoll_event ev;
-  int err;
-  grpc_fd_watcher watcher;
-
-  /* We pretend to be polling whilst adding an fd to keep the fd from being
-     closed during the add. This may result in a spurious wakeup being assigned
-     to this pollset whilst adding, but that should be benign. */
-  GPR_ASSERT(grpc_fd_begin_poll(fd, pollset, NULL, 0, 0, &watcher) == 0);
-  if (watcher.fd != NULL) {
-    ev.events = (uint32_t)(EPOLLIN | EPOLLOUT | EPOLLET);
-    ev.data.ptr = fd;
-    err = epoll_ctl(h->epoll_fd, EPOLL_CTL_ADD, fd->fd, &ev);
-    if (err < 0) {
-      /* FDs may be added to a pollset multiple times, so EEXIST is normal. */
-      if (errno != EEXIST) {
-        gpr_log(GPR_ERROR, "epoll_ctl add for %d failed: %s", fd->fd,
-                strerror(errno));
-      }
-    }
-  }
-  grpc_fd_end_poll(exec_ctx, &watcher, 0, 0);
-}
-
-static void perform_delayed_add(grpc_exec_ctx *exec_ctx, void *arg,
-                                bool iomgr_status) {
-  delayed_add *da = arg;
-
-  if (!grpc_fd_is_orphaned(da->fd)) {
-    finally_add_fd(exec_ctx, da->pollset, da->fd);
-  }
-
-  gpr_mu_lock(&da->pollset->mu);
-  da->pollset->in_flight_cbs--;
-  if (da->pollset->shutting_down) {
-    /* We don't care about this pollset anymore. */
-    if (da->pollset->in_flight_cbs == 0 && !da->pollset->called_shutdown) {
-      da->pollset->called_shutdown = 1;
-      grpc_exec_ctx_enqueue(exec_ctx, da->pollset->shutdown_done, true, NULL);
-    }
-  }
-  gpr_mu_unlock(&da->pollset->mu);
-
-  GRPC_FD_UNREF(da->fd, "delayed_add");
-
-  gpr_free(da);
-}
-
-static void multipoll_with_epoll_pollset_add_fd(grpc_exec_ctx *exec_ctx,
-                                                grpc_pollset *pollset,
-                                                grpc_fd *fd,
-                                                int and_unlock_pollset) {
-  if (and_unlock_pollset) {
-    gpr_mu_unlock(&pollset->mu);
-    finally_add_fd(exec_ctx, pollset, fd);
-  } else {
-    delayed_add *da = gpr_malloc(sizeof(*da));
-    da->pollset = pollset;
-    da->fd = fd;
-    GRPC_FD_REF(fd, "delayed_add");
-    grpc_closure_init(&da->closure, perform_delayed_add, da);
-    pollset->in_flight_cbs++;
-    grpc_exec_ctx_enqueue(exec_ctx, &da->closure, true, NULL);
-  }
-}
-
-/* TODO(klempner): We probably want to turn this down a bit */
-#define GRPC_EPOLL_MAX_EVENTS 1000
-
-static void multipoll_with_epoll_pollset_maybe_work_and_unlock(
-    grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_pollset_worker *worker,
-    gpr_timespec deadline, gpr_timespec now) {
-  struct epoll_event ep_ev[GRPC_EPOLL_MAX_EVENTS];
-  int ep_rv;
-  int poll_rv;
-  pollset_hdr *h = pollset->data.ptr;
-  int timeout_ms;
-  struct pollfd pfds[2];
-
-  /* If you want to ignore epoll's ability to sanely handle parallel pollers,
-   * for a more apples-to-apples performance comparison with poll, add a
-   * if (pollset->counter != 0) { return 0; }
-   * here.
-   */
-
-  gpr_mu_unlock(&pollset->mu);
-
-  timeout_ms = grpc_poll_deadline_to_millis_timeout(deadline, now);
-
-  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
-  pfds[0].events = POLLIN;
-  pfds[0].revents = 0;
-  pfds[1].fd = h->epoll_fd;
-  pfds[1].events = POLLIN;
-  pfds[1].revents = 0;
-
-  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
-     even going into the blocking annotation if possible */
-  GPR_TIMER_BEGIN("poll", 0);
-  GRPC_SCHEDULING_START_BLOCKING_REGION;
-  poll_rv = grpc_poll_function(pfds, 2, timeout_ms);
-  GRPC_SCHEDULING_END_BLOCKING_REGION;
-  GPR_TIMER_END("poll", 0);
-
-  if (poll_rv < 0) {
-    if (errno != EINTR) {
-      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
-    }
-  } else if (poll_rv == 0) {
-    /* do nothing */
-  } else {
-    if (pfds[0].revents) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
-    }
-    if (pfds[1].revents) {
-      do {
-        /* The following epoll_wait never blocks; it has a timeout of 0 */
-        ep_rv = epoll_wait(h->epoll_fd, ep_ev, GRPC_EPOLL_MAX_EVENTS, 0);
-        if (ep_rv < 0) {
-          if (errno != EINTR) {
-            gpr_log(GPR_ERROR, "epoll_wait() failed: %s", strerror(errno));
-          }
-        } else {
-          int i;
-          for (i = 0; i < ep_rv; ++i) {
-            grpc_fd *fd = ep_ev[i].data.ptr;
-            /* TODO(klempner): We might want to consider making err and pri
-             * separate events */
-            int cancel = ep_ev[i].events & (EPOLLERR | EPOLLHUP);
-            int read_ev = ep_ev[i].events & (EPOLLIN | EPOLLPRI);
-            int write_ev = ep_ev[i].events & EPOLLOUT;
-            if (fd == NULL) {
-              grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
-            } else {
-              if (read_ev || cancel) {
-                grpc_fd_become_readable(exec_ctx, fd);
-              }
-              if (write_ev || cancel) {
-                grpc_fd_become_writable(exec_ctx, fd);
-              }
-            }
-          }
-        }
-      } while (ep_rv == GRPC_EPOLL_MAX_EVENTS);
-    }
-  }
-}
-
-static void multipoll_with_epoll_pollset_finish_shutdown(
-    grpc_pollset *pollset) {}
-
-static void multipoll_with_epoll_pollset_destroy(grpc_pollset *pollset) {
-  pollset_hdr *h = pollset->data.ptr;
-  close(h->epoll_fd);
-  remove_epoll_fd_from_global_list(h->epoll_fd);
-  gpr_free(h);
-}
-
-static const grpc_pollset_vtable multipoll_with_epoll_pollset = {
-    multipoll_with_epoll_pollset_add_fd,
-    multipoll_with_epoll_pollset_maybe_work_and_unlock,
-    multipoll_with_epoll_pollset_finish_shutdown,
-    multipoll_with_epoll_pollset_destroy};
-
-static void epoll_become_multipoller(grpc_exec_ctx *exec_ctx,
-                                     grpc_pollset *pollset, grpc_fd **fds,
-                                     size_t nfds) {
-  size_t i;
-  pollset_hdr *h = gpr_malloc(sizeof(pollset_hdr));
-  struct epoll_event ev;
-  int err;
-
-  pollset->vtable = &multipoll_with_epoll_pollset;
-  pollset->data.ptr = h;
-  h->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
-  if (h->epoll_fd < 0) {
-    /* TODO(klempner): Fall back to poll here, especially on ENOSYS */
-    gpr_log(GPR_ERROR, "epoll_create1 failed: %s", strerror(errno));
-    abort();
-  }
-  add_epoll_fd_to_global_list(h->epoll_fd);
-
-  ev.events = (uint32_t)(EPOLLIN | EPOLLET);
-  ev.data.ptr = NULL;
-  err = epoll_ctl(h->epoll_fd, EPOLL_CTL_ADD,
-                  GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd), &ev);
-  if (err < 0) {
-    gpr_log(GPR_ERROR, "epoll_ctl add for %d failed: %s",
-            GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd),
-            strerror(errno));
-  }
-
-  for (i = 0; i < nfds; i++) {
-    multipoll_with_epoll_pollset_add_fd(exec_ctx, pollset, fds[i], 0);
-  }
-}
-
-grpc_platform_become_multipoller_type grpc_platform_become_multipoller =
-    epoll_become_multipoller;
-
-#else /* GPR_LINUX_MULTIPOLL_WITH_EPOLL */
-
-void grpc_remove_fd_from_all_epoll_sets(int fd) {}
-
-#endif /* GPR_LINUX_MULTIPOLL_WITH_EPOLL */
diff --git a/src/core/lib/iomgr/pollset_multipoller_with_poll_posix.c b/src/core/lib/iomgr/pollset_multipoller_with_poll_posix.c
deleted file mode 100644
index 7668bf63f5..0000000000
--- a/src/core/lib/iomgr/pollset_multipoller_with_poll_posix.c
+++ /dev/null
@@ -1,234 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_POSIX_SOCKET
-
-#include "src/core/lib/iomgr/pollset_posix.h"
-
-#include <errno.h>
-#include <poll.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/useful.h>
-
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/iomgr_internal.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
-#include "src/core/lib/support/block_annotate.h"
-
-typedef struct {
-  /* all polled fds */
-  size_t fd_count;
-  size_t fd_capacity;
-  grpc_fd **fds;
-  /* fds that have been removed from the pollset explicitly */
-  size_t del_count;
-  size_t del_capacity;
-  grpc_fd **dels;
-} pollset_hdr;
-
-static void multipoll_with_poll_pollset_add_fd(grpc_exec_ctx *exec_ctx,
-                                               grpc_pollset *pollset,
-                                               grpc_fd *fd,
-                                               int and_unlock_pollset) {
-  size_t i;
-  pollset_hdr *h = pollset->data.ptr;
-  /* TODO(ctiller): this is O(num_fds^2); maybe switch to a hash set here */
-  for (i = 0; i < h->fd_count; i++) {
-    if (h->fds[i] == fd) goto exit;
-  }
-  if (h->fd_count == h->fd_capacity) {
-    h->fd_capacity = GPR_MAX(h->fd_capacity + 8, h->fd_count * 3 / 2);
-    h->fds = gpr_realloc(h->fds, sizeof(grpc_fd *) * h->fd_capacity);
-  }
-  h->fds[h->fd_count++] = fd;
-  GRPC_FD_REF(fd, "multipoller");
-exit:
-  if (and_unlock_pollset) {
-    gpr_mu_unlock(&pollset->mu);
-  }
-}
-
-static void multipoll_with_poll_pollset_maybe_work_and_unlock(
-    grpc_exec_ctx *exec_ctx, grpc_pollset *pollset, grpc_pollset_worker *worker,
-    gpr_timespec deadline, gpr_timespec now) {
-#define POLLOUT_CHECK (POLLOUT | POLLHUP | POLLERR)
-#define POLLIN_CHECK (POLLIN | POLLHUP | POLLERR)
-
-  int timeout;
-  int r;
-  size_t i, j, fd_count;
-  nfds_t pfd_count;
-  pollset_hdr *h;
-  /* TODO(ctiller): inline some elements to avoid an allocation */
-  grpc_fd_watcher *watchers;
-  struct pollfd *pfds;
-
-  h = pollset->data.ptr;
-  timeout = grpc_poll_deadline_to_millis_timeout(deadline, now);
-  /* TODO(ctiller): perform just one malloc here if we exceed the inline case */
-  pfds = gpr_malloc(sizeof(*pfds) * (h->fd_count + 2));
-  watchers = gpr_malloc(sizeof(*watchers) * (h->fd_count + 2));
-  fd_count = 0;
-  pfd_count = 2;
-  pfds[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
-  pfds[0].events = POLLIN;
-  pfds[0].revents = 0;
-  pfds[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
-  pfds[1].events = POLLIN;
-  pfds[1].revents = 0;
-  for (i = 0; i < h->fd_count; i++) {
-    int remove = grpc_fd_is_orphaned(h->fds[i]);
-    for (j = 0; !remove && j < h->del_count; j++) {
-      if (h->fds[i] == h->dels[j]) remove = 1;
-    }
-    if (remove) {
-      GRPC_FD_UNREF(h->fds[i], "multipoller");
-    } else {
-      h->fds[fd_count++] = h->fds[i];
-      watchers[pfd_count].fd = h->fds[i];
-      GRPC_FD_REF(watchers[pfd_count].fd, "multipoller_start");
-      pfds[pfd_count].fd = h->fds[i]->fd;
-      pfds[pfd_count].revents = 0;
-      pfd_count++;
-    }
-  }
-  for (j = 0; j < h->del_count; j++) {
-    GRPC_FD_UNREF(h->dels[j], "multipoller_del");
-  }
-  h->del_count = 0;
-  h->fd_count = fd_count;
-  gpr_mu_unlock(&pollset->mu);
-
-  for (i = 2; i < pfd_count; i++) {
-    grpc_fd *fd = watchers[i].fd;
-    pfds[i].events = (short)grpc_fd_begin_poll(fd, pollset, worker, POLLIN,
-                                               POLLOUT, &watchers[i]);
-    GRPC_FD_UNREF(fd, "multipoller_start");
-  }
-
-  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
-     even going into the blocking annotation if possible */
-  GRPC_SCHEDULING_START_BLOCKING_REGION;
-  r = grpc_poll_function(pfds, pfd_count, timeout);
-  GRPC_SCHEDULING_END_BLOCKING_REGION;
-
-  if (r < 0) {
-    if (errno != EINTR) {
-      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
-    }
-    for (i = 2; i < pfd_count; i++) {
-      grpc_fd_end_poll(exec_ctx, &watchers[i], 0, 0);
-    }
-  } else if (r == 0) {
-    for (i = 2; i < pfd_count; i++) {
-      grpc_fd_end_poll(exec_ctx, &watchers[i], 0, 0);
-    }
-  } else {
-    if (pfds[0].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
-    }
-    if (pfds[1].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
-    }
-    for (i = 2; i < pfd_count; i++) {
-      if (watchers[i].fd == NULL) {
-        grpc_fd_end_poll(exec_ctx, &watchers[i], 0, 0);
-        continue;
-      }
-      grpc_fd_end_poll(exec_ctx, &watchers[i], pfds[i].revents & POLLIN_CHECK,
-                       pfds[i].revents & POLLOUT_CHECK);
-    }
-  }
-
-  gpr_free(pfds);
-  gpr_free(watchers);
-}
-
-static void multipoll_with_poll_pollset_finish_shutdown(grpc_pollset *pollset) {
-  size_t i;
-  pollset_hdr *h = pollset->data.ptr;
-  for (i = 0; i < h->fd_count; i++) {
-    GRPC_FD_UNREF(h->fds[i], "multipoller");
-  }
-  for (i = 0; i < h->del_count; i++) {
-    GRPC_FD_UNREF(h->dels[i], "multipoller_del");
-  }
-  h->fd_count = 0;
-  h->del_count = 0;
-}
-
-static void multipoll_with_poll_pollset_destroy(grpc_pollset *pollset) {
-  pollset_hdr *h = pollset->data.ptr;
-  multipoll_with_poll_pollset_finish_shutdown(pollset);
-  gpr_free(h->fds);
-  gpr_free(h->dels);
-  gpr_free(h);
-}
-
-static const grpc_pollset_vtable multipoll_with_poll_pollset = {
-    multipoll_with_poll_pollset_add_fd,
-    multipoll_with_poll_pollset_maybe_work_and_unlock,
-    multipoll_with_poll_pollset_finish_shutdown,
-    multipoll_with_poll_pollset_destroy};
-
-void grpc_poll_become_multipoller(grpc_exec_ctx *exec_ctx,
-                                  grpc_pollset *pollset, grpc_fd **fds,
-                                  size_t nfds) {
-  size_t i;
-  pollset_hdr *h = gpr_malloc(sizeof(pollset_hdr));
-  pollset->vtable = &multipoll_with_poll_pollset;
-  pollset->data.ptr = h;
-  h->fd_count = nfds;
-  h->fd_capacity = nfds;
-  h->fds = gpr_malloc(nfds * sizeof(grpc_fd *));
-  h->del_count = 0;
-  h->del_capacity = 0;
-  h->dels = NULL;
-  for (i = 0; i < nfds; i++) {
-    h->fds[i] = fds[i];
-    GRPC_FD_REF(fds[i], "multipoller");
-  }
-}
-
-#endif /* GPR_POSIX_SOCKET */
-
-#ifdef GPR_POSIX_MULTIPOLL_WITH_POLL
-grpc_platform_become_multipoller_type grpc_platform_become_multipoller =
-    grpc_poll_become_multipoller;
-#endif
diff --git a/src/core/lib/iomgr/pollset_posix.c b/src/core/lib/iomgr/pollset_posix.c
deleted file mode 100644
index 84a9153034..0000000000
--- a/src/core/lib/iomgr/pollset_posix.c
+++ /dev/null
@@ -1,633 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_POSIX_SOCKET
-
-#include "src/core/lib/iomgr/pollset_posix.h"
-
-#include <errno.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/thd.h>
-#include <grpc/support/tls.h>
-#include <grpc/support/useful.h>
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/iomgr_internal.h"
-#include "src/core/lib/iomgr/socket_utils_posix.h"
-#include "src/core/lib/profiling/timers.h"
-#include "src/core/lib/support/block_annotate.h"
-
-GPR_TLS_DECL(g_current_thread_poller);
-GPR_TLS_DECL(g_current_thread_worker);
-
-/** Default poll() function - a pointer so that it can be overridden by some
- *  tests */
-grpc_poll_function_type grpc_poll_function = poll;
-
-/** The alarm system needs to be able to wakeup 'some poller' sometimes
- *  (specifically when a new alarm needs to be triggered earlier than the next
- *  alarm 'epoch').
- *  This wakeup_fd gives us something to alert on when such a case occurs. */
-grpc_wakeup_fd grpc_global_wakeup_fd;
-
-static void remove_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
-  worker->prev->next = worker->next;
-  worker->next->prev = worker->prev;
-}
-
-int grpc_pollset_has_workers(grpc_pollset *p) {
-  return p->root_worker.next != &p->root_worker;
-}
-
-static grpc_pollset_worker *pop_front_worker(grpc_pollset *p) {
-  if (grpc_pollset_has_workers(p)) {
-    grpc_pollset_worker *w = p->root_worker.next;
-    remove_worker(p, w);
-    return w;
-  } else {
-    return NULL;
-  }
-}
-
-static void push_back_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
-  worker->next = &p->root_worker;
-  worker->prev = worker->next->prev;
-  worker->prev->next = worker->next->prev = worker;
-}
-
-static void push_front_worker(grpc_pollset *p, grpc_pollset_worker *worker) {
-  worker->prev = &p->root_worker;
-  worker->next = worker->prev->next;
-  worker->prev->next = worker->next->prev = worker;
-}
-
-size_t grpc_pollset_size(void) { return sizeof(grpc_pollset); }
-
-void grpc_pollset_kick_ext(grpc_pollset *p,
-                           grpc_pollset_worker *specific_worker,
-                           uint32_t flags) {
-  GPR_TIMER_BEGIN("grpc_pollset_kick_ext", 0);
-
-  /* pollset->mu already held */
-  if (specific_worker != NULL) {
-    if (specific_worker == GRPC_POLLSET_KICK_BROADCAST) {
-      GPR_TIMER_BEGIN("grpc_pollset_kick_ext.broadcast", 0);
-      GPR_ASSERT((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) == 0);
-      for (specific_worker = p->root_worker.next;
-           specific_worker != &p->root_worker;
-           specific_worker = specific_worker->next) {
-        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
-      }
-      p->kicked_without_pollers = 1;
-      GPR_TIMER_END("grpc_pollset_kick_ext.broadcast", 0);
-    } else if (gpr_tls_get(&g_current_thread_worker) !=
-               (intptr_t)specific_worker) {
-      GPR_TIMER_MARK("different_thread_worker", 0);
-      if ((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) != 0) {
-        specific_worker->reevaluate_polling_on_wakeup = 1;
-      }
-      specific_worker->kicked_specifically = 1;
-      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
-    } else if ((flags & GRPC_POLLSET_CAN_KICK_SELF) != 0) {
-      GPR_TIMER_MARK("kick_yoself", 0);
-      if ((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) != 0) {
-        specific_worker->reevaluate_polling_on_wakeup = 1;
-      }
-      specific_worker->kicked_specifically = 1;
-      grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
-    }
-  } else if (gpr_tls_get(&g_current_thread_poller) != (intptr_t)p) {
-    GPR_ASSERT((flags & GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) == 0);
-    GPR_TIMER_MARK("kick_anonymous", 0);
-    specific_worker = pop_front_worker(p);
-    if (specific_worker != NULL) {
-      if (gpr_tls_get(&g_current_thread_worker) == (intptr_t)specific_worker) {
-        GPR_TIMER_MARK("kick_anonymous_not_self", 0);
-        push_back_worker(p, specific_worker);
-        specific_worker = pop_front_worker(p);
-        if ((flags & GRPC_POLLSET_CAN_KICK_SELF) == 0 &&
-            gpr_tls_get(&g_current_thread_worker) ==
-                (intptr_t)specific_worker) {
-          push_back_worker(p, specific_worker);
-          specific_worker = NULL;
-        }
-      }
-      if (specific_worker != NULL) {
-        GPR_TIMER_MARK("finally_kick", 0);
-        push_back_worker(p, specific_worker);
-        grpc_wakeup_fd_wakeup(&specific_worker->wakeup_fd->fd);
-      }
-    } else {
-      GPR_TIMER_MARK("kicked_no_pollers", 0);
-      p->kicked_without_pollers = 1;
-    }
-  }
-
-  GPR_TIMER_END("grpc_pollset_kick_ext", 0);
-}
-
-void grpc_pollset_kick(grpc_pollset *p, grpc_pollset_worker *specific_worker) {
-  grpc_pollset_kick_ext(p, specific_worker, 0);
-}
-
-/* global state management */
-
-void grpc_pollset_global_init(void) {
-  gpr_tls_init(&g_current_thread_poller);
-  gpr_tls_init(&g_current_thread_worker);
-  grpc_wakeup_fd_global_init();
-  grpc_wakeup_fd_init(&grpc_global_wakeup_fd);
-}
-
-void grpc_pollset_global_shutdown(void) {
-  grpc_wakeup_fd_destroy(&grpc_global_wakeup_fd);
-  gpr_tls_destroy(&g_current_thread_poller);
-  gpr_tls_destroy(&g_current_thread_worker);
-  grpc_wakeup_fd_global_destroy();
-}
-
-void grpc_kick_poller(void) { grpc_wakeup_fd_wakeup(&grpc_global_wakeup_fd); }
-
-/* main interface */
-
-static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null);
-
-void grpc_pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
-  gpr_mu_init(&pollset->mu);
-  *mu = &pollset->mu;
-  pollset->root_worker.next = pollset->root_worker.prev = &pollset->root_worker;
-  pollset->in_flight_cbs = 0;
-  pollset->shutting_down = 0;
-  pollset->called_shutdown = 0;
-  pollset->kicked_without_pollers = 0;
-  pollset->idle_jobs.head = pollset->idle_jobs.tail = NULL;
-  pollset->local_wakeup_cache = NULL;
-  pollset->kicked_without_pollers = 0;
-  become_basic_pollset(pollset, NULL);
-}
-
-void grpc_pollset_destroy(grpc_pollset *pollset) {
-  GPR_ASSERT(pollset->in_flight_cbs == 0);
-  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
-  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
-  pollset->vtable->destroy(pollset);
-  while (pollset->local_wakeup_cache) {
-    grpc_cached_wakeup_fd *next = pollset->local_wakeup_cache->next;
-    grpc_wakeup_fd_destroy(&pollset->local_wakeup_cache->fd);
-    gpr_free(pollset->local_wakeup_cache);
-    pollset->local_wakeup_cache = next;
-  }
-}
-
-void grpc_pollset_reset(grpc_pollset *pollset) {
-  GPR_ASSERT(pollset->shutting_down);
-  GPR_ASSERT(pollset->in_flight_cbs == 0);
-  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
-  GPR_ASSERT(pollset->idle_jobs.head == pollset->idle_jobs.tail);
-  pollset->vtable->destroy(pollset);
-  pollset->shutting_down = 0;
-  pollset->called_shutdown = 0;
-  pollset->kicked_without_pollers = 0;
-  become_basic_pollset(pollset, NULL);
-}
-
-void grpc_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                         grpc_fd *fd) {
-  gpr_mu_lock(&pollset->mu);
-  pollset->vtable->add_fd(exec_ctx, pollset, fd, 1);
-/* the following (enabled only in debug) will reacquire and then release
-   our lock - meaning that if the unlocking flag passed to add_fd above is
-   not respected, the code will deadlock (in a way that we have a chance of
-   debugging) */
-#ifndef NDEBUG
-  gpr_mu_lock(&pollset->mu);
-  gpr_mu_unlock(&pollset->mu);
-#endif
-}
-
-static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
-  GPR_ASSERT(grpc_closure_list_empty(pollset->idle_jobs));
-  pollset->vtable->finish_shutdown(pollset);
-  grpc_exec_ctx_enqueue(exec_ctx, pollset->shutdown_done, true, NULL);
-}
-
-void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                       grpc_pollset_worker **worker_hdl, gpr_timespec now,
-                       gpr_timespec deadline) {
-  grpc_pollset_worker worker;
-  *worker_hdl = &worker;
-
-  /* pollset->mu already held */
-  int added_worker = 0;
-  int locked = 1;
-  int queued_work = 0;
-  int keep_polling = 0;
-  GPR_TIMER_BEGIN("grpc_pollset_work", 0);
-  /* this must happen before we (potentially) drop pollset->mu */
-  worker.next = worker.prev = NULL;
-  worker.reevaluate_polling_on_wakeup = 0;
-  if (pollset->local_wakeup_cache != NULL) {
-    worker.wakeup_fd = pollset->local_wakeup_cache;
-    pollset->local_wakeup_cache = worker.wakeup_fd->next;
-  } else {
-    worker.wakeup_fd = gpr_malloc(sizeof(*worker.wakeup_fd));
-    grpc_wakeup_fd_init(&worker.wakeup_fd->fd);
-  }
-  worker.kicked_specifically = 0;
-  /* If there's work waiting for the pollset to be idle, and the
-     pollset is idle, then do that work */
-  if (!grpc_pollset_has_workers(pollset) &&
-      !grpc_closure_list_empty(pollset->idle_jobs)) {
-    GPR_TIMER_MARK("grpc_pollset_work.idle_jobs", 0);
-    grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
-    goto done;
-  }
-  /* If we're shutting down then we don't execute any extended work */
-  if (pollset->shutting_down) {
-    GPR_TIMER_MARK("grpc_pollset_work.shutting_down", 0);
-    goto done;
-  }
-  /* Give do_promote priority so we don't starve it out */
-  if (pollset->in_flight_cbs) {
-    GPR_TIMER_MARK("grpc_pollset_work.in_flight_cbs", 0);
-    gpr_mu_unlock(&pollset->mu);
-    locked = 0;
-    goto done;
-  }
-  /* Start polling, and keep doing so while we're being asked to
-     re-evaluate our pollers (this allows poll() based pollers to
-     ensure they don't miss wakeups) */
-  keep_polling = 1;
-  while (keep_polling) {
-    keep_polling = 0;
-    if (!pollset->kicked_without_pollers) {
-      if (!added_worker) {
-        push_front_worker(pollset, &worker);
-        added_worker = 1;
-        gpr_tls_set(&g_current_thread_worker, (intptr_t)&worker);
-      }
-      gpr_tls_set(&g_current_thread_poller, (intptr_t)pollset);
-      GPR_TIMER_BEGIN("maybe_work_and_unlock", 0);
-      pollset->vtable->maybe_work_and_unlock(exec_ctx, pollset, &worker,
-                                             deadline, now);
-      GPR_TIMER_END("maybe_work_and_unlock", 0);
-      locked = 0;
-      gpr_tls_set(&g_current_thread_poller, 0);
-    } else {
-      GPR_TIMER_MARK("grpc_pollset_work.kicked_without_pollers", 0);
-      pollset->kicked_without_pollers = 0;
-    }
-  /* Finished execution - start cleaning up.
-     Note that we may arrive here from outside the enclosing while() loop.
-     In that case we won't loop though as we haven't added worker to the
-     worker list, which means nobody could ask us to re-evaluate polling). */
-  done:
-    if (!locked) {
-      queued_work |= grpc_exec_ctx_flush(exec_ctx);
-      gpr_mu_lock(&pollset->mu);
-      locked = 1;
-    }
-    /* If we're forced to re-evaluate polling (via grpc_pollset_kick with
-       GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP) then we land here and force
-       a loop */
-    if (worker.reevaluate_polling_on_wakeup) {
-      worker.reevaluate_polling_on_wakeup = 0;
-      pollset->kicked_without_pollers = 0;
-      if (queued_work || worker.kicked_specifically) {
-        /* If there's queued work on the list, then set the deadline to be
-           immediate so we get back out of the polling loop quickly */
-        deadline = gpr_inf_past(GPR_CLOCK_MONOTONIC);
-      }
-      keep_polling = 1;
-    }
-  }
-  if (added_worker) {
-    remove_worker(pollset, &worker);
-    gpr_tls_set(&g_current_thread_worker, 0);
-  }
-  /* release wakeup fd to the local pool */
-  worker.wakeup_fd->next = pollset->local_wakeup_cache;
-  pollset->local_wakeup_cache = worker.wakeup_fd;
-  /* check shutdown conditions */
-  if (pollset->shutting_down) {
-    if (grpc_pollset_has_workers(pollset)) {
-      grpc_pollset_kick(pollset, NULL);
-    } else if (!pollset->called_shutdown && pollset->in_flight_cbs == 0) {
-      pollset->called_shutdown = 1;
-      gpr_mu_unlock(&pollset->mu);
-      finish_shutdown(exec_ctx, pollset);
-      grpc_exec_ctx_flush(exec_ctx);
-      /* Continuing to access pollset here is safe -- it is the caller's
-       * responsibility to not destroy when it has outstanding calls to
-       * grpc_pollset_work.
-       * TODO(dklempner): Can we refactor the shutdown logic to avoid this? */
-      gpr_mu_lock(&pollset->mu);
-    } else if (!grpc_closure_list_empty(pollset->idle_jobs)) {
-      grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
-      gpr_mu_unlock(&pollset->mu);
-      grpc_exec_ctx_flush(exec_ctx);
-      gpr_mu_lock(&pollset->mu);
-    }
-  }
-  *worker_hdl = NULL;
-  GPR_TIMER_END("grpc_pollset_work", 0);
-}
-
-void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                           grpc_closure *closure) {
-  GPR_ASSERT(!pollset->shutting_down);
-  pollset->shutting_down = 1;
-  pollset->shutdown_done = closure;
-  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
-  if (!grpc_pollset_has_workers(pollset)) {
-    grpc_exec_ctx_enqueue_list(exec_ctx, &pollset->idle_jobs, NULL);
-  }
-  if (!pollset->called_shutdown && pollset->in_flight_cbs == 0 &&
-      !grpc_pollset_has_workers(pollset)) {
-    pollset->called_shutdown = 1;
-    finish_shutdown(exec_ctx, pollset);
-  }
-}
-
-int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
-                                         gpr_timespec now) {
-  gpr_timespec timeout;
-  static const int64_t max_spin_polling_us = 10;
-  if (gpr_time_cmp(deadline, gpr_inf_future(deadline.clock_type)) == 0) {
-    return -1;
-  }
-  if (gpr_time_cmp(deadline, gpr_time_add(now, gpr_time_from_micros(
-                                                   max_spin_polling_us,
-                                                   GPR_TIMESPAN))) <= 0) {
-    return 0;
-  }
-  timeout = gpr_time_sub(deadline, now);
-  return gpr_time_to_millis(gpr_time_add(
-      timeout, gpr_time_from_nanos(GPR_NS_PER_MS - 1, GPR_TIMESPAN)));
-}
-
-/*
- * basic_pollset - a vtable that provides polling for zero or one file
- *                 descriptor via poll()
- */
-
-typedef struct grpc_unary_promote_args {
-  const grpc_pollset_vtable *original_vtable;
-  grpc_pollset *pollset;
-  grpc_fd *fd;
-  grpc_closure promotion_closure;
-} grpc_unary_promote_args;
-
-static void basic_do_promote(grpc_exec_ctx *exec_ctx, void *args,
-                             bool success) {
-  grpc_unary_promote_args *up_args = args;
-  const grpc_pollset_vtable *original_vtable = up_args->original_vtable;
-  grpc_pollset *pollset = up_args->pollset;
-  grpc_fd *fd = up_args->fd;
-
-  /*
-   * This is quite tricky. There are a number of cases to keep in mind here:
-   * 1. fd may have been orphaned
-   * 2. The pollset may no longer be a unary poller (and we can't let case #1
-   * leak to other pollset types!)
-   * 3. pollset's fd (which may have changed) may have been orphaned
-   * 4. The pollset may be shutting down.
-   */
-
-  gpr_mu_lock(&pollset->mu);
-  /* First we need to ensure that nobody is polling concurrently */
-  GPR_ASSERT(!grpc_pollset_has_workers(pollset));
-
-  gpr_free(up_args);
-  /* At this point the pollset may no longer be a unary poller. In that case
-   * we should just call the right add function and be done. */
-  /* TODO(klempner): If we're not careful this could cause infinite recursion.
-   * That's not a problem for now because empty_pollset has a trivial poller
-   * and we don't have any mechanism to unbecome multipoller. */
-  pollset->in_flight_cbs--;
-  if (pollset->shutting_down) {
-    /* We don't care about this pollset anymore. */
-    if (pollset->in_flight_cbs == 0 && !pollset->called_shutdown) {
-      pollset->called_shutdown = 1;
-      finish_shutdown(exec_ctx, pollset);
-    }
-  } else if (grpc_fd_is_orphaned(fd)) {
-    /* Don't try to add it to anything, we'll drop our ref on it below */
-  } else if (pollset->vtable != original_vtable) {
-    pollset->vtable->add_fd(exec_ctx, pollset, fd, 0);
-  } else if (fd != pollset->data.ptr) {
-    grpc_fd *fds[2];
-    fds[0] = pollset->data.ptr;
-    fds[1] = fd;
-
-    if (fds[0] && !grpc_fd_is_orphaned(fds[0])) {
-      grpc_platform_become_multipoller(exec_ctx, pollset, fds,
-                                       GPR_ARRAY_SIZE(fds));
-      GRPC_FD_UNREF(fds[0], "basicpoll");
-    } else {
-      /* old fd is orphaned and we haven't cleaned it up until now, so remain a
-       * unary poller */
-      /* Note that it is possible that fds[1] is also orphaned at this point.
-       * That's okay, we'll correct it at the next add or poll. */
-      if (fds[0]) GRPC_FD_UNREF(fds[0], "basicpoll");
-      pollset->data.ptr = fd;
-      GRPC_FD_REF(fd, "basicpoll");
-    }
-  }
-
-  gpr_mu_unlock(&pollset->mu);
-
-  /* Matching ref in basic_pollset_add_fd */
-  GRPC_FD_UNREF(fd, "basicpoll_add");
-}
-
-static void basic_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                                 grpc_fd *fd, int and_unlock_pollset) {
-  grpc_unary_promote_args *up_args;
-  GPR_ASSERT(fd);
-  if (fd == pollset->data.ptr) goto exit;
-
-  if (!grpc_pollset_has_workers(pollset)) {
-    /* Fast path -- no in flight cbs */
-    /* TODO(klempner): Comment this out and fix any test failures or establish
-     * they are due to timing issues */
-    grpc_fd *fds[2];
-    fds[0] = pollset->data.ptr;
-    fds[1] = fd;
-
-    if (fds[0] == NULL) {
-      pollset->data.ptr = fd;
-      GRPC_FD_REF(fd, "basicpoll");
-    } else if (!grpc_fd_is_orphaned(fds[0])) {
-      grpc_platform_become_multipoller(exec_ctx, pollset, fds,
-                                       GPR_ARRAY_SIZE(fds));
-      GRPC_FD_UNREF(fds[0], "basicpoll");
-    } else {
-      /* old fd is orphaned and we haven't cleaned it up until now, so remain a
-       * unary poller */
-      GRPC_FD_UNREF(fds[0], "basicpoll");
-      pollset->data.ptr = fd;
-      GRPC_FD_REF(fd, "basicpoll");
-    }
-    goto exit;
-  }
-
-  /* Now we need to promote. This needs to happen when we're not polling. Since
-   * this may be called from poll, the wait needs to happen asynchronously. */
-  GRPC_FD_REF(fd, "basicpoll_add");
-  pollset->in_flight_cbs++;
-  up_args = gpr_malloc(sizeof(*up_args));
-  up_args->fd = fd;
-  up_args->original_vtable = pollset->vtable;
-  up_args->pollset = pollset;
-  up_args->promotion_closure.cb = basic_do_promote;
-  up_args->promotion_closure.cb_arg = up_args;
-
-  grpc_closure_list_add(&pollset->idle_jobs, &up_args->promotion_closure, 1);
-  grpc_pollset_kick(pollset, GRPC_POLLSET_KICK_BROADCAST);
-
-exit:
-  if (and_unlock_pollset) {
-    gpr_mu_unlock(&pollset->mu);
-  }
-}
-
-static void basic_pollset_maybe_work_and_unlock(grpc_exec_ctx *exec_ctx,
-                                                grpc_pollset *pollset,
-                                                grpc_pollset_worker *worker,
-                                                gpr_timespec deadline,
-                                                gpr_timespec now) {
-#define POLLOUT_CHECK (POLLOUT | POLLHUP | POLLERR)
-#define POLLIN_CHECK (POLLIN | POLLHUP | POLLERR)
-
-  struct pollfd pfd[3];
-  grpc_fd *fd;
-  grpc_fd_watcher fd_watcher;
-  int timeout;
-  int r;
-  nfds_t nfds;
-
-  fd = pollset->data.ptr;
-  if (fd && grpc_fd_is_orphaned(fd)) {
-    GRPC_FD_UNREF(fd, "basicpoll");
-    fd = pollset->data.ptr = NULL;
-  }
-  timeout = grpc_poll_deadline_to_millis_timeout(deadline, now);
-  pfd[0].fd = GRPC_WAKEUP_FD_GET_READ_FD(&grpc_global_wakeup_fd);
-  pfd[0].events = POLLIN;
-  pfd[0].revents = 0;
-  pfd[1].fd = GRPC_WAKEUP_FD_GET_READ_FD(&worker->wakeup_fd->fd);
-  pfd[1].events = POLLIN;
-  pfd[1].revents = 0;
-  nfds = 2;
-  if (fd) {
-    pfd[2].fd = fd->fd;
-    pfd[2].revents = 0;
-    GRPC_FD_REF(fd, "basicpoll_begin");
-    gpr_mu_unlock(&pollset->mu);
-    pfd[2].events = (short)grpc_fd_begin_poll(fd, pollset, worker, POLLIN,
-                                              POLLOUT, &fd_watcher);
-    if (pfd[2].events != 0) {
-      nfds++;
-    }
-  } else {
-    gpr_mu_unlock(&pollset->mu);
-  }
-
-  /* TODO(vpai): Consider first doing a 0 timeout poll here to avoid
-     even going into the blocking annotation if possible */
-  /* poll fd count (argument 2) is shortened by one if we have no events
-     to poll on - such that it only includes the kicker */
-  GPR_TIMER_BEGIN("poll", 0);
-  GRPC_SCHEDULING_START_BLOCKING_REGION;
-  r = grpc_poll_function(pfd, nfds, timeout);
-  GRPC_SCHEDULING_END_BLOCKING_REGION;
-  GPR_TIMER_END("poll", 0);
-
-  if (r < 0) {
-    if (errno != EINTR) {
-      gpr_log(GPR_ERROR, "poll() failed: %s", strerror(errno));
-    }
-    if (fd) {
-      grpc_fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
-    }
-  } else if (r == 0) {
-    if (fd) {
-      grpc_fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
-    }
-  } else {
-    if (pfd[0].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&grpc_global_wakeup_fd);
-    }
-    if (pfd[1].revents & POLLIN_CHECK) {
-      grpc_wakeup_fd_consume_wakeup(&worker->wakeup_fd->fd);
-    }
-    if (nfds > 2) {
-      grpc_fd_end_poll(exec_ctx, &fd_watcher, pfd[2].revents & POLLIN_CHECK,
-                       pfd[2].revents & POLLOUT_CHECK);
-    } else if (fd) {
-      grpc_fd_end_poll(exec_ctx, &fd_watcher, 0, 0);
-    }
-  }
-
-  if (fd) {
-    GRPC_FD_UNREF(fd, "basicpoll_begin");
-  }
-}
-
-static void basic_pollset_destroy(grpc_pollset *pollset) {
-  if (pollset->data.ptr != NULL) {
-    GRPC_FD_UNREF(pollset->data.ptr, "basicpoll");
-    pollset->data.ptr = NULL;
-  }
-}
-
-static const grpc_pollset_vtable basic_pollset = {
-    basic_pollset_add_fd, basic_pollset_maybe_work_and_unlock,
-    basic_pollset_destroy, basic_pollset_destroy};
-
-static void become_basic_pollset(grpc_pollset *pollset, grpc_fd *fd_or_null) {
-  pollset->vtable = &basic_pollset;
-  pollset->data.ptr = fd_or_null;
-  if (fd_or_null != NULL) {
-    GRPC_FD_REF(fd_or_null, "basicpoll");
-  }
-}
-
-#endif /* GPR_POSIX_POLLSET */
diff --git a/src/core/lib/iomgr/pollset_posix.h b/src/core/lib/iomgr/pollset_posix.h
deleted file mode 100644
index f53ef8855c..0000000000
--- a/src/core/lib/iomgr/pollset_posix.h
+++ /dev/null
@@ -1,153 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_IOMGR_POLLSET_POSIX_H
-#define GRPC_CORE_LIB_IOMGR_POLLSET_POSIX_H
-
-#include <poll.h>
-
-#include <grpc/support/sync.h>
-
-#include "src/core/lib/iomgr/exec_ctx.h"
-#include "src/core/lib/iomgr/iomgr.h"
-#include "src/core/lib/iomgr/pollset.h"
-#include "src/core/lib/iomgr/wakeup_fd_posix.h"
-
-typedef struct grpc_pollset_vtable grpc_pollset_vtable;
-
-/* forward declare only in this file to avoid leaking impl details via
-   pollset.h; real users of grpc_fd should always include 'fd_posix.h' and not
-   use the struct tag */
-struct grpc_fd;
-
-typedef struct grpc_cached_wakeup_fd {
-  grpc_wakeup_fd fd;
-  struct grpc_cached_wakeup_fd *next;
-} grpc_cached_wakeup_fd;
-
-struct grpc_pollset_worker {
-  grpc_cached_wakeup_fd *wakeup_fd;
-  int reevaluate_polling_on_wakeup;
-  int kicked_specifically;
-  struct grpc_pollset_worker *next;
-  struct grpc_pollset_worker *prev;
-};
-
-struct grpc_pollset {
-  /* pollsets under posix can mutate representation as fds are added and
-     removed.
-     For example, we may choose a poll() based implementation on linux for
-     few fds, and an epoll() based implementation for many fds */
-  const grpc_pollset_vtable *vtable;
-  gpr_mu mu;
-  grpc_pollset_worker root_worker;
-  int in_flight_cbs;
-  int shutting_down;
-  int called_shutdown;
-  int kicked_without_pollers;
-  grpc_closure *shutdown_done;
-  grpc_closure_list idle_jobs;
-  union {
-    int fd;
-    void *ptr;
-  } data;
-  /* Local cache of eventfds for workers */
-  grpc_cached_wakeup_fd *local_wakeup_cache;
-};
-
-struct grpc_pollset_vtable {
-  void (*add_fd)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                 struct grpc_fd *fd, int and_unlock_pollset);
-  void (*maybe_work_and_unlock)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                                grpc_pollset_worker *worker,
-                                gpr_timespec deadline, gpr_timespec now);
-  void (*finish_shutdown)(grpc_pollset *pollset);
-  void (*destroy)(grpc_pollset *pollset);
-};
-
-/* Add an fd to a pollset */
-void grpc_pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
-                         struct grpc_fd *fd);
-
-/* Returns the fd to listen on for kicks */
-int grpc_kick_read_fd(grpc_pollset *p);
-/* Call after polling has been kicked to leave the kicked state */
-void grpc_kick_drain(grpc_pollset *p);
-
-/* Convert a timespec to milliseconds:
-   - very small or negative poll times are clamped to zero to do a
-     non-blocking poll (which becomes spin polling)
-   - other small values are rounded up to one millisecond
-   - longer than a millisecond polls are rounded up to the next nearest
-     millisecond to avoid spinning
-   - infinite timeouts are converted to -1 */
-int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
-                                         gpr_timespec now);
-
-/* Allow kick to wakeup the currently polling worker */
-#define GRPC_POLLSET_CAN_KICK_SELF 1
-/* Force the wakee to repoll when awoken */
-#define GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP 2
-/* As per grpc_pollset_kick, with an extended set of flags (defined above)
-   -- mostly for fd_posix's use. */
-void grpc_pollset_kick_ext(grpc_pollset *p,
-                           grpc_pollset_worker *specific_worker,
-                           uint32_t flags);
-
-/* turn a pollset into a multipoller: platform specific */
-typedef void (*grpc_platform_become_multipoller_type)(grpc_exec_ctx *exec_ctx,
-                                                      grpc_pollset *pollset,
-                                                      struct grpc_fd **fds,
-                                                      size_t fd_count);
-extern grpc_platform_become_multipoller_type grpc_platform_become_multipoller;
-
-void grpc_poll_become_multipoller(grpc_exec_ctx *exec_ctx,
-                                  grpc_pollset *pollset, struct grpc_fd **fds,
-                                  size_t fd_count);
-
-/* Return 1 if the pollset has active threads in grpc_pollset_work (pollset must
- * be locked) */
-int grpc_pollset_has_workers(grpc_pollset *pollset);
-
-void grpc_remove_fd_from_all_epoll_sets(int fd);
-
-/* override to allow tests to hook poll() usage */
-/* NOTE: Any changes to grpc_poll_function must take place when the gRPC
-   is certainly not doing any polling anywhere.
-   Otherwise, there might be a race between changing the variable and actually
-   doing a polling operation */
-typedef int (*grpc_poll_function_type)(struct pollfd *, nfds_t, int);
-extern grpc_poll_function_type grpc_poll_function;
-extern grpc_wakeup_fd grpc_global_wakeup_fd;
-
-#endif /* GRPC_CORE_LIB_IOMGR_POLLSET_POSIX_H */
diff --git a/src/core/lib/iomgr/pollset_set_posix.c b/src/core/lib/iomgr/pollset_set_posix.c
deleted file mode 100644
index ef85075f38..0000000000
--- a/src/core/lib/iomgr/pollset_set_posix.c
+++ /dev/null
@@ -1,202 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#ifdef GPR_POSIX_SOCKET
-
-#include <stdlib.h>
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/useful.h>
-
-#include "src/core/lib/iomgr/pollset_posix.h"
-#include "src/core/lib/iomgr/pollset_set_posix.h"
-
-struct grpc_pollset_set {
-  gpr_mu mu;
-
-  size_t pollset_count;
-  size_t pollset_capacity;
-  grpc_pollset **pollsets;
-
-  size_t pollset_set_count;
-  size_t pollset_set_capacity;
-  struct grpc_pollset_set **pollset_sets;
-
-  size_t fd_count;
-  size_t fd_capacity;
-  grpc_fd **fds;
-};
-
-grpc_pollset_set *grpc_pollset_set_create(void) {
-  grpc_pollset_set *pollset_set = gpr_malloc(sizeof(*pollset_set));
-  memset(pollset_set, 0, sizeof(*pollset_set));
-  gpr_mu_init(&pollset_set->mu);
-  return pollset_set;
-}
-
-void grpc_pollset_set_destroy(grpc_pollset_set *pollset_set) {
-  size_t i;
-  gpr_mu_destroy(&pollset_set->mu);
-  for (i = 0; i < pollset_set->fd_count; i++) {
-    GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
-  }
-  gpr_free(pollset_set->pollsets);
-  gpr_free(pollset_set->pollset_sets);
-  gpr_free(pollset_set->fds);
-  gpr_free(pollset_set);
-}
-
-void grpc_pollset_set_add_pollset(grpc_exec_ctx *exec_ctx,
-                                  grpc_pollset_set *pollset_set,
-                                  grpc_pollset *pollset) {
-  size_t i, j;
-  gpr_mu_lock(&pollset_set->mu);
-  if (pollset_set->pollset_count == pollset_set->pollset_capacity) {
-    pollset_set->pollset_capacity =
-        GPR_MAX(8, 2 * pollset_set->pollset_capacity);
-    pollset_set->pollsets =
-        gpr_realloc(pollset_set->pollsets, pollset_set->pollset_capacity *
-                                               sizeof(*pollset_set->pollsets));
-  }
-  pollset_set->pollsets[pollset_set->pollset_count++] = pollset;
-  for (i = 0, j = 0; i < pollset_set->fd_count; i++) {
-    if (grpc_fd_is_orphaned(pollset_set->fds[i])) {
-      GRPC_FD_UNREF(pollset_set->fds[i], "pollset_set");
-    } else {
-      grpc_pollset_add_fd(exec_ctx, pollset, pollset_set->fds[i]);
-      pollset_set->fds[j++] = pollset_set->fds[i];
-    }
-  }
-  pollset_set->fd_count = j;
-  gpr_mu_unlock(&pollset_set->mu);
-}
-
-void grpc_pollset_set_del_pollset(grpc_exec_ctx *exec_ctx,
-                                  grpc_pollset_set *pollset_set,
-                                  grpc_pollset *pollset) {
-  size_t i;
-  gpr_mu_lock(&pollset_set->mu);
-  for (i = 0; i < pollset_set->pollset_count; i++) {
-    if (pollset_set->pollsets[i] == pollset) {
-      pollset_set->pollset_count--;
-      GPR_SWAP(grpc_pollset *, pollset_set->pollsets[i],
-               pollset_set->pollsets[pollset_set->pollset_count]);
-      break;
-    }
-  }
-  gpr_mu_unlock(&pollset_set->mu);
-}
-
-void grpc_pollset_set_add_pollset_set(grpc_exec_ctx *exec_ctx,
-                                      grpc_pollset_set *bag,
-                                      grpc_pollset_set *item) {
-  size_t i, j;
-  gpr_mu_lock(&bag->mu);
-  if (bag->pollset_set_count == bag->pollset_set_capacity) {
-    bag->pollset_set_capacity = GPR_MAX(8, 2 * bag->pollset_set_capacity);
-    bag->pollset_sets =
-        gpr_realloc(bag->pollset_sets,
-                    bag->pollset_set_capacity * sizeof(*bag->pollset_sets));
-  }
-  bag->pollset_sets[bag->pollset_set_count++] = item;
-  for (i = 0, j = 0; i < bag->fd_count; i++) {
-    if (grpc_fd_is_orphaned(bag->fds[i])) {
-      GRPC_FD_UNREF(bag->fds[i], "pollset_set");
-    } else {
-      grpc_pollset_set_add_fd(exec_ctx, item, bag->fds[i]);
-      bag->fds[j++] = bag->fds[i];
-    }
-  }
-  bag->fd_count = j;
-  gpr_mu_unlock(&bag->mu);
-}
-
-void grpc_pollset_set_del_pollset_set(grpc_exec_ctx *exec_ctx,
-                                      grpc_pollset_set *bag,
-                                      grpc_pollset_set *item) {
-  size_t i;
-  gpr_mu_lock(&bag->mu);
-  for (i = 0; i < bag->pollset_set_count; i++) {
-    if (bag->pollset_sets[i] == item) {
-      bag->pollset_set_count--;
-      GPR_SWAP(grpc_pollset_set *, bag->pollset_sets[i],
-               bag->pollset_sets[bag->pollset_set_count]);
-      break;
-    }
-  }
-  gpr_mu_unlock(&bag->mu);
-}
-
-void grpc_pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
-                             grpc_pollset_set *pollset_set, grpc_fd *fd) {
-  size_t i;
-  gpr_mu_lock(&pollset_set->mu);
-  if (pollset_set->fd_count == pollset_set->fd_capacity) {
-    pollset_set->fd_capacity = GPR_MAX(8, 2 * pollset_set->fd_capacity);
-    pollset_set->fds = gpr_realloc(
-        pollset_set->fds, pollset_set->fd_capacity * sizeof(*pollset_set->fds));
-  }
-  GRPC_FD_REF(fd, "pollset_set");
-  pollset_set->fds[pollset_set->fd_count++] = fd;
-  for (i = 0; i < pollset_set->pollset_count; i++) {
-    grpc_pollset_add_fd(exec_ctx, pollset_set->pollsets[i], fd);
-  }
-  for (i = 0; i < pollset_set->pollset_set_count; i++) {
-    grpc_pollset_set_add_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
-  }
-  gpr_mu_unlock(&pollset_set->mu);
-}
-
-void grpc_pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
-                             grpc_pollset_set *pollset_set, grpc_fd *fd) {
-  size_t i;
-  gpr_mu_lock(&pollset_set->mu);
-  for (i = 0; i < pollset_set->fd_count; i++) {
-    if (pollset_set->fds[i] == fd) {
-      pollset_set->fd_count--;
-      GPR_SWAP(grpc_fd *, pollset_set->fds[i],
-               pollset_set->fds[pollset_set->fd_count]);
-      GRPC_FD_UNREF(fd, "pollset_set");
-      break;
-    }
-  }
-  for (i = 0; i < pollset_set->pollset_set_count; i++) {
-    grpc_pollset_set_del_fd(exec_ctx, pollset_set->pollset_sets[i], fd);
-  }
-  gpr_mu_unlock(&pollset_set->mu);
-}
-
-#endif /* GPR_POSIX_SOCKET */
diff --git a/src/core/lib/iomgr/pollset_set_posix.h b/src/core/lib/iomgr/pollset_set_posix.h
deleted file mode 100644
index e23e974921..0000000000
--- a/src/core/lib/iomgr/pollset_set_posix.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_IOMGR_POLLSET_SET_POSIX_H
-#define GRPC_CORE_LIB_IOMGR_POLLSET_SET_POSIX_H
-
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/pollset_set.h"
-
-void grpc_pollset_set_add_fd(grpc_exec_ctx *exec_ctx,
-                             grpc_pollset_set *pollset_set, grpc_fd *fd);
-void grpc_pollset_set_del_fd(grpc_exec_ctx *exec_ctx,
-                             grpc_pollset_set *pollset_set, grpc_fd *fd);
-
-#endif /* GRPC_CORE_LIB_IOMGR_POLLSET_SET_POSIX_H */
diff --git a/src/core/lib/iomgr/pollset_windows.c b/src/core/lib/iomgr/pollset_windows.c
index c2e7f647b5..bff5c586f8 100644
--- a/src/core/lib/iomgr/pollset_windows.c
+++ b/src/core/lib/iomgr/pollset_windows.c
@@ -47,7 +47,7 @@ gpr_mu grpc_polling_mu;
 static grpc_pollset_worker *g_active_poller;
 static grpc_pollset_worker g_global_root_worker;
 
-void grpc_pollset_global_init() {
+void grpc_pollset_global_init(void) {
   gpr_mu_init(&grpc_polling_mu);
   g_active_poller = NULL;
   g_global_root_worker.links[GRPC_POLLSET_WORKER_LINK_GLOBAL].next =
@@ -55,7 +55,7 @@ void grpc_pollset_global_init() {
           &g_global_root_worker;
 }
 
-void grpc_pollset_global_shutdown() { gpr_mu_destroy(&grpc_polling_mu); }
+void grpc_pollset_global_shutdown(void) { gpr_mu_destroy(&grpc_polling_mu); }
 
 static void remove_worker(grpc_pollset_worker *worker,
                           grpc_pollset_worker_link_type type) {
diff --git a/src/core/lib/iomgr/pollset_windows.h b/src/core/lib/iomgr/pollset_windows.h
index fef0e87b71..2642013afc 100644
--- a/src/core/lib/iomgr/pollset_windows.h
+++ b/src/core/lib/iomgr/pollset_windows.h
@@ -72,4 +72,7 @@ struct grpc_pollset {
   grpc_closure *on_shutdown;
 };
 
+void grpc_pollset_global_init(void);
+void grpc_pollset_global_shutdown(void);
+
 #endif /* GRPC_CORE_LIB_IOMGR_POLLSET_WINDOWS_H */
diff --git a/src/core/lib/iomgr/tcp_client_posix.c b/src/core/lib/iomgr/tcp_client_posix.c
index 77718a5b5c..6430cb629f 100644
--- a/src/core/lib/iomgr/tcp_client_posix.c
+++ b/src/core/lib/iomgr/tcp_client_posix.c
@@ -47,9 +47,8 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
+#include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/iomgr/iomgr_posix.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
-#include "src/core/lib/iomgr/pollset_set_posix.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/socket_utils_posix.h"
 #include "src/core/lib/iomgr/tcp_posix.h"
@@ -140,7 +139,8 @@ static void on_writable(grpc_exec_ctx *exec_ctx, void *acp, bool success) {
   if (success) {
     do {
       so_error_size = sizeof(so_error);
-      err = getsockopt(fd->fd, SOL_SOCKET, SO_ERROR, &so_error, &so_error_size);
+      err = getsockopt(grpc_fd_wrapped_fd(fd), SOL_SOCKET, SO_ERROR, &so_error,
+                       &so_error_size);
     } while (err < 0 && errno == EINTR);
     if (err < 0) {
       gpr_log(GPR_ERROR, "failed to connect to '%s': getsockopt(ERROR): %s",
diff --git a/src/core/lib/iomgr/tcp_client_windows.c b/src/core/lib/iomgr/tcp_client_windows.c
index 1f0f2e3925..7d78beb15a 100644
--- a/src/core/lib/iomgr/tcp_client_windows.c
+++ b/src/core/lib/iomgr/tcp_client_windows.c
@@ -103,7 +103,8 @@ static void on_connect(grpc_exec_ctx *exec_ctx, void *acp, bool from_iocp) {
     GPR_ASSERT(transfered_bytes == 0);
     if (!wsa_success) {
       char *utf8_message = gpr_format_message(WSAGetLastError());
-      gpr_log(GPR_ERROR, "on_connect error: %s", utf8_message);
+      gpr_log(GPR_ERROR, "on_connect error connecting to '%s': %s",
+              ac->addr_name, utf8_message);
       gpr_free(utf8_message);
     } else {
       *ep = grpc_tcp_create(ac->socket, ac->addr_name);
diff --git a/src/core/lib/iomgr/tcp_posix.c b/src/core/lib/iomgr/tcp_posix.c
index 33ec29a411..7210aef5d5 100644
--- a/src/core/lib/iomgr/tcp_posix.c
+++ b/src/core/lib/iomgr/tcp_posix.c
@@ -52,8 +52,7 @@
 #include <grpc/support/time.h>
 
 #include "src/core/lib/debug/trace.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
-#include "src/core/lib/iomgr/pollset_set_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/support/string.h"
 
@@ -454,7 +453,7 @@ grpc_endpoint *grpc_tcp_create(grpc_fd *em_fd, size_t slice_size,
   grpc_tcp *tcp = (grpc_tcp *)gpr_malloc(sizeof(grpc_tcp));
   tcp->base.vtable = &vtable;
   tcp->peer_string = gpr_strdup(peer_string);
-  tcp->fd = em_fd->fd;
+  tcp->fd = grpc_fd_wrapped_fd(em_fd);
   tcp->read_cb = NULL;
   tcp->write_cb = NULL;
   tcp->release_fd_cb = NULL;
diff --git a/src/core/lib/iomgr/tcp_posix.h b/src/core/lib/iomgr/tcp_posix.h
index acce56467a..99125836d6 100644
--- a/src/core/lib/iomgr/tcp_posix.h
+++ b/src/core/lib/iomgr/tcp_posix.h
@@ -45,7 +45,7 @@
 */
 
 #include "src/core/lib/iomgr/endpoint.h"
-#include "src/core/lib/iomgr/fd_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 
 #define GRPC_TCP_DEFAULT_READ_SLICE_SIZE 8192
 
diff --git a/src/core/lib/iomgr/tcp_server_posix.c b/src/core/lib/iomgr/tcp_server_posix.c
index 76aeb1c2f0..cfb5251684 100644
--- a/src/core/lib/iomgr/tcp_server_posix.c
+++ b/src/core/lib/iomgr/tcp_server_posix.c
@@ -59,7 +59,6 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
-#include "src/core/lib/iomgr/pollset_posix.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/socket_utils_posix.h"
diff --git a/src/core/lib/iomgr/udp_server.c b/src/core/lib/iomgr/udp_server.c
index 2d8220a9b1..a0b9709be5 100644
--- a/src/core/lib/iomgr/udp_server.c
+++ b/src/core/lib/iomgr/udp_server.c
@@ -60,12 +60,10 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/socket_utils_posix.h"
-#include "src/core/lib/iomgr/unix_sockets_posix.h"
 #include "src/core/lib/support/string.h"
 
 #define INIT_PORT_CAP 2
diff --git a/src/core/lib/iomgr/udp_server.h b/src/core/lib/iomgr/udp_server.h
index b0ca15101f..d8cf957a22 100644
--- a/src/core/lib/iomgr/udp_server.h
+++ b/src/core/lib/iomgr/udp_server.h
@@ -35,7 +35,7 @@
 #define GRPC_CORE_LIB_IOMGR_UDP_SERVER_H
 
 #include "src/core/lib/iomgr/endpoint.h"
-#include "src/core/lib/iomgr/fd_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 
 /* Forward decl of struct grpc_server */
 /* This is not typedef'ed to avoid a typedef-redefinition error */
diff --git a/src/core/lib/iomgr/workqueue_posix.c b/src/core/lib/iomgr/workqueue_posix.c
index 9d68d9e16a..80e7a0b206 100644
--- a/src/core/lib/iomgr/workqueue_posix.c
+++ b/src/core/lib/iomgr/workqueue_posix.c
@@ -43,8 +43,7 @@
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
 
-#include "src/core/lib/iomgr/fd_posix.h"
-#include "src/core/lib/iomgr/pollset_posix.h"
+#include "src/core/lib/iomgr/ev_posix.h"
 
 static void on_readable(grpc_exec_ctx *exec_ctx, void *arg, bool success);
 
diff --git a/src/core/lib/json/json_reader.c b/src/core/lib/json/json_reader.c
index d09cee54f2..bc04bccc65 100644
--- a/src/core/lib/json/json_reader.c
+++ b/src/core/lib/json/json_reader.c
@@ -180,6 +180,13 @@ grpc_json_reader_status grpc_json_reader_run(grpc_json_reader *reader) {
           case GRPC_JSON_STATE_VALUE_NUMBER_WITH_DECIMAL:
           case GRPC_JSON_STATE_VALUE_NUMBER_ZERO:
           case GRPC_JSON_STATE_VALUE_NUMBER_EPM:
+            if (reader->depth == 0) {
+              return GRPC_JSON_PARSE_ERROR;
+            } else if ((c == '}') && !reader->in_object) {
+              return GRPC_JSON_PARSE_ERROR;
+            } else if ((c == ']') && !reader->in_array) {
+              return GRPC_JSON_PARSE_ERROR;
+            }
             success = (uint32_t)json_reader_set_number(reader);
             if (!success) return GRPC_JSON_PARSE_ERROR;
             json_reader_string_clear(reader);
@@ -195,8 +202,10 @@ grpc_json_reader_status grpc_json_reader_run(grpc_json_reader *reader) {
               }
               if (reader->in_object) {
                 reader->state = GRPC_JSON_STATE_OBJECT_KEY_BEGIN;
-              } else {
+              } else if (reader->in_array) {
                 reader->state = GRPC_JSON_STATE_VALUE_BEGIN;
+              } else {
+                return GRPC_JSON_PARSE_ERROR;
               }
             } else {
               if (reader->depth-- == 0) return GRPC_JSON_PARSE_ERROR;
diff --git a/src/core/lib/statistics/census_init.c b/src/core/lib/statistics/census_init.c
deleted file mode 100644
index 7a8b8b660a..0000000000
--- a/src/core/lib/statistics/census_init.c
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/statistics/census_interface.h"
-
-#include <grpc/support/log.h>
-#include "src/core/lib/statistics/census_rpc_stats.h"
-#include "src/core/lib/statistics/census_tracing.h"
-
-void census_init(void) {
-  census_tracing_init();
-  census_stats_store_init();
-}
-
-void census_shutdown(void) {
-  census_stats_store_shutdown();
-  census_tracing_shutdown();
-}
diff --git a/src/core/lib/statistics/census_interface.h b/src/core/lib/statistics/census_interface.h
deleted file mode 100644
index 4dce81b0c7..0000000000
--- a/src/core/lib/statistics/census_interface.h
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_CENSUS_INTERFACE_H
-#define GRPC_CORE_LIB_STATISTICS_CENSUS_INTERFACE_H
-
-#include <grpc/support/port_platform.h>
-
-/* Maximum length of an individual census trace annotation. */
-#define CENSUS_MAX_ANNOTATION_LENGTH 200
-
-/* Structure of a census op id. Define as structure because 64bit integer is not
-   available on every platform for C89. */
-typedef struct census_op_id {
-  uint32_t upper;
-  uint32_t lower;
-} census_op_id;
-
-typedef struct census_rpc_stats census_rpc_stats;
-
-/* Initializes Census library. No-op if Census is already initialized. */
-void census_init(void);
-
-/* Shutdown Census Library. */
-void census_shutdown(void);
-
-/* Annotates grpc method name on a census_op_id. The method name has the format
-   of <full quantified rpc service name>/<rpc function name>. Returns 0 iff
-   op_id and method_name are all valid. op_id is valid after its creation and
-   before calling census_tracing_end_op().
-
-   TODO(hongyu): Figure out valid characters set for service name and command
-   name and document requirements here.*/
-int census_add_method_tag(census_op_id op_id, const char *method_name);
-
-/* Annotates tracing information to a specific op_id.
-   Up to CENSUS_MAX_ANNOTATION_LENGTH bytes are recorded. */
-void census_tracing_print(census_op_id op_id, const char *annotation);
-
-/* Starts tracing for an RPC. Returns a locally unique census_op_id */
-census_op_id census_tracing_start_op(void);
-
-/* Ends tracing. Calling this function will invalidate the input op_id. */
-void census_tracing_end_op(census_op_id op_id);
-
-#endif /* GRPC_CORE_LIB_STATISTICS_CENSUS_INTERFACE_H */
diff --git a/src/core/lib/statistics/census_log.c b/src/core/lib/statistics/census_log.c
deleted file mode 100644
index 782b34e3a1..0000000000
--- a/src/core/lib/statistics/census_log.c
+++ /dev/null
@@ -1,603 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-/* Available log space is divided up in blocks of
-   CENSUS_LOG_2_MAX_RECORD_SIZE bytes. A block can be in one of the
-   following three data structures:
-   - Free blocks (free_block_list)
-   - Blocks with unread data (dirty_block_list)
-   - Blocks currently attached to cores (core_local_blocks[])
-
-   census_log_start_write() moves a block from core_local_blocks[] to the
-   end of dirty_block_list when block:
-   - is out-of-space OR
-   - has an incomplete record (an incomplete record occurs when a thread calls
-     census_log_start_write() and is context-switched before calling
-     census_log_end_write()
-   So, blocks in dirty_block_list are ordered, from oldest to newest, by time
-   when block is detached from the core.
-
-   census_log_read_next() first iterates over dirty_block_list and then
-   core_local_blocks[]. It moves completely read blocks from dirty_block_list
-   to free_block_list. Blocks in core_local_blocks[] are not freed, even when
-   completely read.
-
-   If log is configured to discard old records and free_block_list is empty,
-   census_log_start_write() iterates over dirty_block_list to allocate a
-   new block. It moves the oldest available block (no pending read/write) to
-   core_local_blocks[].
-
-   core_local_block_struct is used to implement a map from core id to the block
-   associated with that core. This mapping is advisory. It is possible that the
-   block returned by this mapping is no longer associated with that core. This
-   mapping is updated, lazily, by census_log_start_write().
-
-   Locking in block struct:
-
-   Exclusive g_log.lock must be held before calling any functions operatong on
-   block structs except census_log_start_write() and
-   census_log_end_write().
-
-   Writes to a block are serialized via writer_lock.
-   census_log_start_write() acquires this lock and
-   census_log_end_write() releases it. On failure to acquire the lock,
-   writer allocates a new block for the current core and updates
-   core_local_block accordingly.
-
-   Simultaneous read and write access is allowed. Reader can safely read up to
-   committed bytes (bytes_committed).
-
-   reader_lock protects the block, currently being read, from getting recycled.
-   start_read() acquires reader_lock and end_read() releases the lock.
-
-   Read/write access to a block is disabled via try_disable_access(). It returns
-   with both writer_lock and reader_lock held. These locks are subsequently
-   released by enable_access() to enable access to the block.
-
-   A note on naming: Most function/struct names are prepended by cl_
-   (shorthand for census_log). Further, functions that manipulate structures
-   include the name of the structure, which will be passed as the first
-   argument. E.g. cl_block_initialize() will initialize a cl_block.
-*/
-#include "src/core/lib/statistics/census_log.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/atm.h>
-#include <grpc/support/cpu.h>
-#include <grpc/support/log.h>
-#include <grpc/support/port_platform.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/useful.h>
-#include <string.h>
-
-/* End of platform specific code */
-
-typedef struct census_log_block_list_struct {
-  struct census_log_block_list_struct *next;
-  struct census_log_block_list_struct *prev;
-  struct census_log_block *block;
-} cl_block_list_struct;
-
-typedef struct census_log_block {
-  /* Pointer to underlying buffer */
-  char *buffer;
-  gpr_atm writer_lock;
-  gpr_atm reader_lock;
-  /* Keeps completely written bytes. Declared atomic because accessed
-     simultaneously by reader and writer. */
-  gpr_atm bytes_committed;
-  /* Bytes already read */
-  int32_t bytes_read;
-  /* Links for list */
-  cl_block_list_struct link;
-/* We want this structure to be cacheline aligned. We assume the following
-   sizes for the various parts on 32/64bit systems:
-   type                 32b size    64b size
-   char*                   4           8
-   3x gpr_atm             12          24
-   int32_t               4           8 (assumes padding)
-   cl_block_list_struct   12          24
-   TOTAL                  32          64
-
-   Depending on the size of our cacheline and the architecture, we
-   selectively add char buffering to this structure. The size is checked
-   via assert in census_log_initialize(). */
-#if defined(GPR_ARCH_64)
-#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 64)
-#else
-#if defined(GPR_ARCH_32)
-#define CL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 32)
-#else
-#error "Unknown architecture"
-#endif
-#endif
-#if CL_BLOCK_PAD_SIZE > 0
-  char padding[CL_BLOCK_PAD_SIZE];
-#endif
-} cl_block;
-
-/* A list of cl_blocks, doubly-linked through cl_block::link. */
-typedef struct census_log_block_list {
-  int32_t count;           /* Number of items in list. */
-  cl_block_list_struct ht; /* head/tail of linked list. */
-} cl_block_list;
-
-/* Cacheline aligned block pointers to avoid false sharing. Block pointer must
-   be initialized via set_block(), before calling other functions */
-typedef struct census_log_core_local_block {
-  gpr_atm block;
-/* Ensure cachline alignment: we assume sizeof(gpr_atm) == 4 or 8 */
-#if defined(GPR_ARCH_64)
-#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 8)
-#else
-#if defined(GPR_ARCH_32)
-#define CL_CORE_LOCAL_BLOCK_PAD_SIZE (GPR_CACHELINE_SIZE - 4)
-#else
-#error "Unknown architecture"
-#endif
-#endif
-#if CL_CORE_LOCAL_BLOCK_PAD_SIZE > 0
-  char padding[CL_CORE_LOCAL_BLOCK_PAD_SIZE];
-#endif
-} cl_core_local_block;
-
-struct census_log {
-  int discard_old_records;
-  /* Number of cores (aka hardware-contexts) */
-  unsigned num_cores;
-  /* number of CENSUS_LOG_2_MAX_RECORD_SIZE blocks in log */
-  int32_t num_blocks;
-  cl_block *blocks;                       /* Block metadata. */
-  cl_core_local_block *core_local_blocks; /* Keeps core to block mappings. */
-  gpr_mu lock;
-  int initialized; /* has log been initialized? */
-  /* Keeps the state of the reader iterator. A value of 0 indicates that
-     iterator has reached the end. census_log_init_reader() resets the
-     value to num_core to restart iteration. */
-  uint32_t read_iterator_state;
-  /* Points to the block being read. If non-NULL, the block is locked for
-     reading (block_being_read_->reader_lock is held). */
-  cl_block *block_being_read;
-  /* A non-zero value indicates that log is full. */
-  gpr_atm is_full;
-  char *buffer;
-  cl_block_list free_block_list;
-  cl_block_list dirty_block_list;
-  gpr_atm out_of_space_count;
-};
-
-/* Single internal log */
-static struct census_log g_log;
-
-/* Functions that operate on an atomic memory location used as a lock */
-
-/* Returns non-zero if lock is acquired */
-static int cl_try_lock(gpr_atm *lock) { return gpr_atm_acq_cas(lock, 0, 1); }
-
-static void cl_unlock(gpr_atm *lock) { gpr_atm_rel_store(lock, 0); }
-
-/* Functions that operate on cl_core_local_block's */
-
-static void cl_core_local_block_set_block(cl_core_local_block *clb,
-                                          cl_block *block) {
-  gpr_atm_rel_store(&clb->block, (gpr_atm)block);
-}
-
-static cl_block *cl_core_local_block_get_block(cl_core_local_block *clb) {
-  return (cl_block *)gpr_atm_acq_load(&clb->block);
-}
-
-/* Functions that operate on cl_block_list_struct's */
-
-static void cl_block_list_struct_initialize(cl_block_list_struct *bls,
-                                            cl_block *block) {
-  bls->next = bls->prev = bls;
-  bls->block = block;
-}
-
-/* Functions that operate on cl_block_list's */
-
-static void cl_block_list_initialize(cl_block_list *list) {
-  list->count = 0;
-  cl_block_list_struct_initialize(&list->ht, NULL);
-}
-
-/* Returns head of *this, or NULL if empty. */
-static cl_block *cl_block_list_head(cl_block_list *list) {
-  return list->ht.next->block;
-}
-
-/* Insert element *e after *pos. */
-static void cl_block_list_insert(cl_block_list *list, cl_block_list_struct *pos,
-                                 cl_block_list_struct *e) {
-  list->count++;
-  e->next = pos->next;
-  e->prev = pos;
-  e->next->prev = e;
-  e->prev->next = e;
-}
-
-/* Insert block at the head of the list */
-static void cl_block_list_insert_at_head(cl_block_list *list, cl_block *block) {
-  cl_block_list_insert(list, &list->ht, &block->link);
-}
-
-/* Insert block at the tail of the list */
-static void cl_block_list_insert_at_tail(cl_block_list *list, cl_block *block) {
-  cl_block_list_insert(list, list->ht.prev, &block->link);
-}
-
-/* Removes block *b. Requires *b be in the list. */
-static void cl_block_list_remove(cl_block_list *list, cl_block *b) {
-  list->count--;
-  b->link.next->prev = b->link.prev;
-  b->link.prev->next = b->link.next;
-}
-
-/* Functions that operate on cl_block's */
-
-static void cl_block_initialize(cl_block *block, char *buffer) {
-  block->buffer = buffer;
-  gpr_atm_rel_store(&block->writer_lock, 0);
-  gpr_atm_rel_store(&block->reader_lock, 0);
-  gpr_atm_rel_store(&block->bytes_committed, 0);
-  block->bytes_read = 0;
-  cl_block_list_struct_initialize(&block->link, block);
-}
-
-/* Guards against exposing partially written buffer to the reader. */
-static void cl_block_set_bytes_committed(cl_block *block,
-                                         int32_t bytes_committed) {
-  gpr_atm_rel_store(&block->bytes_committed, bytes_committed);
-}
-
-static int32_t cl_block_get_bytes_committed(cl_block *block) {
-  return gpr_atm_acq_load(&block->bytes_committed);
-}
-
-/* Tries to disable future read/write access to this block. Succeeds if:
-   - no in-progress write AND
-   - no in-progress read AND
-   - 'discard_data' set to true OR no unread data
-   On success, clears the block state and returns with writer_lock_ and
-   reader_lock_ held. These locks are released by a subsequent
-   cl_block_access_enable() call. */
-static int cl_block_try_disable_access(cl_block *block, int discard_data) {
-  if (!cl_try_lock(&block->writer_lock)) {
-    return 0;
-  }
-  if (!cl_try_lock(&block->reader_lock)) {
-    cl_unlock(&block->writer_lock);
-    return 0;
-  }
-  if (!discard_data &&
-      (block->bytes_read != cl_block_get_bytes_committed(block))) {
-    cl_unlock(&block->reader_lock);
-    cl_unlock(&block->writer_lock);
-    return 0;
-  }
-  cl_block_set_bytes_committed(block, 0);
-  block->bytes_read = 0;
-  return 1;
-}
-
-static void cl_block_enable_access(cl_block *block) {
-  cl_unlock(&block->reader_lock);
-  cl_unlock(&block->writer_lock);
-}
-
-/* Returns with writer_lock held. */
-static void *cl_block_start_write(cl_block *block, size_t size) {
-  int32_t bytes_committed;
-  if (!cl_try_lock(&block->writer_lock)) {
-    return NULL;
-  }
-  bytes_committed = cl_block_get_bytes_committed(block);
-  if (bytes_committed + size > CENSUS_LOG_MAX_RECORD_SIZE) {
-    cl_unlock(&block->writer_lock);
-    return NULL;
-  }
-  return block->buffer + bytes_committed;
-}
-
-/* Releases writer_lock and increments committed bytes by 'bytes_written'.
-  'bytes_written' must be <= 'size' specified in the corresponding
-  StartWrite() call. This function is thread-safe. */
-static void cl_block_end_write(cl_block *block, size_t bytes_written) {
-  cl_block_set_bytes_committed(
-      block, cl_block_get_bytes_committed(block) + bytes_written);
-  cl_unlock(&block->writer_lock);
-}
-
-/* Returns a pointer to the first unread byte in buffer. The number of bytes
-   available are returned in 'bytes_available'. Acquires reader lock that is
-   released by a subsequent cl_block_end_read() call. Returns NULL if:
-   - read in progress
-   - no data available */
-static void *cl_block_start_read(cl_block *block, size_t *bytes_available) {
-  void *record;
-  if (!cl_try_lock(&block->reader_lock)) {
-    return NULL;
-  }
-  /* bytes_committed may change from under us. Use bytes_available to update
-     bytes_read below. */
-  *bytes_available = cl_block_get_bytes_committed(block) - block->bytes_read;
-  if (*bytes_available == 0) {
-    cl_unlock(&block->reader_lock);
-    return NULL;
-  }
-  record = block->buffer + block->bytes_read;
-  block->bytes_read += *bytes_available;
-  return record;
-}
-
-static void cl_block_end_read(cl_block *block) {
-  cl_unlock(&block->reader_lock);
-}
-
-/* Internal functions operating on g_log */
-
-/* Allocates a new free block (or recycles an available dirty block if log is
-   configured to discard old records). Returns NULL if out-of-space. */
-static cl_block *cl_allocate_block(void) {
-  cl_block *block = cl_block_list_head(&g_log.free_block_list);
-  if (block != NULL) {
-    cl_block_list_remove(&g_log.free_block_list, block);
-    return block;
-  }
-  if (!g_log.discard_old_records) {
-    /* No free block and log is configured to keep old records. */
-    return NULL;
-  }
-  /* Recycle dirty block. Start from the oldest. */
-  for (block = cl_block_list_head(&g_log.dirty_block_list); block != NULL;
-       block = block->link.next->block) {
-    if (cl_block_try_disable_access(block, 1 /* discard data */)) {
-      cl_block_list_remove(&g_log.dirty_block_list, block);
-      return block;
-    }
-  }
-  return NULL;
-}
-
-/* Allocates a new block and updates core id => block mapping. 'old_block'
-   points to the block that the caller thinks is attached to
-   'core_id'. 'old_block' may be NULL. Returns non-zero if:
-   - allocated a new block OR
-   - 'core_id' => 'old_block' mapping changed (another thread allocated a
-     block before lock was acquired). */
-static int cl_allocate_core_local_block(int32_t core_id, cl_block *old_block) {
-  /* Now that we have the lock, check if core-local mapping has changed. */
-  cl_core_local_block *core_local_block = &g_log.core_local_blocks[core_id];
-  cl_block *block = cl_core_local_block_get_block(core_local_block);
-  if ((block != NULL) && (block != old_block)) {
-    return 1;
-  }
-  if (block != NULL) {
-    cl_core_local_block_set_block(core_local_block, NULL);
-    cl_block_list_insert_at_tail(&g_log.dirty_block_list, block);
-  }
-  block = cl_allocate_block();
-  if (block == NULL) {
-    gpr_atm_rel_store(&g_log.is_full, 1);
-    return 0;
-  }
-  cl_core_local_block_set_block(core_local_block, block);
-  cl_block_enable_access(block);
-  return 1;
-}
-
-static cl_block *cl_get_block(void *record) {
-  uintptr_t p = (uintptr_t)((char *)record - g_log.buffer);
-  uintptr_t index = p >> CENSUS_LOG_2_MAX_RECORD_SIZE;
-  return &g_log.blocks[index];
-}
-
-/* Gets the next block to read and tries to free 'prev' block (if not NULL).
-   Returns NULL if reached the end. */
-static cl_block *cl_next_block_to_read(cl_block *prev) {
-  cl_block *block = NULL;
-  if (g_log.read_iterator_state == g_log.num_cores) {
-    /* We are traversing dirty list; find the next dirty block. */
-    if (prev != NULL) {
-      /* Try to free the previous block if there is no unread data. This block
-         may have unread data if previously incomplete record completed between
-         read_next() calls. */
-      block = prev->link.next->block;
-      if (cl_block_try_disable_access(prev, 0 /* do not discard data */)) {
-        cl_block_list_remove(&g_log.dirty_block_list, prev);
-        cl_block_list_insert_at_head(&g_log.free_block_list, prev);
-        gpr_atm_rel_store(&g_log.is_full, 0);
-      }
-    } else {
-      block = cl_block_list_head(&g_log.dirty_block_list);
-    }
-    if (block != NULL) {
-      return block;
-    }
-    /* We are done with the dirty list; moving on to core-local blocks. */
-  }
-  while (g_log.read_iterator_state > 0) {
-    g_log.read_iterator_state--;
-    block = cl_core_local_block_get_block(
-        &g_log.core_local_blocks[g_log.read_iterator_state]);
-    if (block != NULL) {
-      return block;
-    }
-  }
-  return NULL;
-}
-
-/* External functions: primary stats_log interface */
-void census_log_initialize(size_t size_in_mb, int discard_old_records) {
-  int32_t ix;
-  /* Check cacheline alignment. */
-  GPR_ASSERT(sizeof(cl_block) % GPR_CACHELINE_SIZE == 0);
-  GPR_ASSERT(sizeof(cl_core_local_block) % GPR_CACHELINE_SIZE == 0);
-  GPR_ASSERT(!g_log.initialized);
-  g_log.discard_old_records = discard_old_records;
-  g_log.num_cores = gpr_cpu_num_cores();
-  /* Ensure at least as many blocks as there are cores. */
-  g_log.num_blocks = GPR_MAX(
-      g_log.num_cores, (size_in_mb << 20) >> CENSUS_LOG_2_MAX_RECORD_SIZE);
-  gpr_mu_init(&g_log.lock);
-  g_log.read_iterator_state = 0;
-  g_log.block_being_read = NULL;
-  gpr_atm_rel_store(&g_log.is_full, 0);
-  g_log.core_local_blocks = (cl_core_local_block *)gpr_malloc_aligned(
-      g_log.num_cores * sizeof(cl_core_local_block), GPR_CACHELINE_SIZE_LOG);
-  memset(g_log.core_local_blocks, 0,
-         g_log.num_cores * sizeof(cl_core_local_block));
-  g_log.blocks = (cl_block *)gpr_malloc_aligned(
-      g_log.num_blocks * sizeof(cl_block), GPR_CACHELINE_SIZE_LOG);
-  memset(g_log.blocks, 0, g_log.num_blocks * sizeof(cl_block));
-  g_log.buffer = gpr_malloc(g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
-  memset(g_log.buffer, 0, g_log.num_blocks * CENSUS_LOG_MAX_RECORD_SIZE);
-  cl_block_list_initialize(&g_log.free_block_list);
-  cl_block_list_initialize(&g_log.dirty_block_list);
-  for (ix = 0; ix < g_log.num_blocks; ++ix) {
-    cl_block *block = g_log.blocks + ix;
-    cl_block_initialize(block,
-                        g_log.buffer + (CENSUS_LOG_MAX_RECORD_SIZE * ix));
-    cl_block_try_disable_access(block, 1 /* discard data */);
-    cl_block_list_insert_at_tail(&g_log.free_block_list, block);
-  }
-  gpr_atm_rel_store(&g_log.out_of_space_count, 0);
-  g_log.initialized = 1;
-}
-
-void census_log_shutdown(void) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_destroy(&g_log.lock);
-  gpr_free_aligned(g_log.core_local_blocks);
-  g_log.core_local_blocks = NULL;
-  gpr_free_aligned(g_log.blocks);
-  g_log.blocks = NULL;
-  gpr_free(g_log.buffer);
-  g_log.buffer = NULL;
-  g_log.initialized = 0;
-}
-
-void *census_log_start_write(size_t size) {
-  /* Used to bound number of times block allocation is attempted. */
-  int32_t attempts_remaining = g_log.num_blocks;
-  /* TODO(aveitch): move this inside the do loop when current_cpu is fixed */
-  int32_t core_id = gpr_cpu_current_cpu();
-  GPR_ASSERT(g_log.initialized);
-  if (size > CENSUS_LOG_MAX_RECORD_SIZE) {
-    return NULL;
-  }
-  do {
-    int allocated;
-    void *record = NULL;
-    cl_block *block =
-        cl_core_local_block_get_block(&g_log.core_local_blocks[core_id]);
-    if (block && (record = cl_block_start_write(block, size))) {
-      return record;
-    }
-    /* Need to allocate a new block. We are here if:
-       - No block associated with the core OR
-       - Write in-progress on the block OR
-       - block is out of space */
-    if (gpr_atm_acq_load(&g_log.is_full)) {
-      gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
-      return NULL;
-    }
-    gpr_mu_lock(&g_log.lock);
-    allocated = cl_allocate_core_local_block(core_id, block);
-    gpr_mu_unlock(&g_log.lock);
-    if (!allocated) {
-      gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
-      return NULL;
-    }
-  } while (attempts_remaining--);
-  /* Give up. */
-  gpr_atm_no_barrier_fetch_add(&g_log.out_of_space_count, 1);
-  return NULL;
-}
-
-void census_log_end_write(void *record, size_t bytes_written) {
-  GPR_ASSERT(g_log.initialized);
-  cl_block_end_write(cl_get_block(record), bytes_written);
-}
-
-void census_log_init_reader(void) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_lock(&g_log.lock);
-  /* If a block is locked for reading unlock it. */
-  if (g_log.block_being_read != NULL) {
-    cl_block_end_read(g_log.block_being_read);
-    g_log.block_being_read = NULL;
-  }
-  g_log.read_iterator_state = g_log.num_cores;
-  gpr_mu_unlock(&g_log.lock);
-}
-
-const void *census_log_read_next(size_t *bytes_available) {
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_lock(&g_log.lock);
-  if (g_log.block_being_read != NULL) {
-    cl_block_end_read(g_log.block_being_read);
-  }
-  do {
-    g_log.block_being_read = cl_next_block_to_read(g_log.block_being_read);
-    if (g_log.block_being_read != NULL) {
-      void *record =
-          cl_block_start_read(g_log.block_being_read, bytes_available);
-      if (record != NULL) {
-        gpr_mu_unlock(&g_log.lock);
-        return record;
-      }
-    }
-  } while (g_log.block_being_read != NULL);
-  gpr_mu_unlock(&g_log.lock);
-  return NULL;
-}
-
-size_t census_log_remaining_space(void) {
-  size_t space;
-  GPR_ASSERT(g_log.initialized);
-  gpr_mu_lock(&g_log.lock);
-  if (g_log.discard_old_records) {
-    /* Remaining space is not meaningful; just return the entire log space. */
-    space = g_log.num_blocks << CENSUS_LOG_2_MAX_RECORD_SIZE;
-  } else {
-    space = g_log.free_block_list.count * CENSUS_LOG_MAX_RECORD_SIZE;
-  }
-  gpr_mu_unlock(&g_log.lock);
-  return space;
-}
-
-int census_log_out_of_space_count(void) {
-  GPR_ASSERT(g_log.initialized);
-  return gpr_atm_acq_load(&g_log.out_of_space_count);
-}
diff --git a/src/core/lib/statistics/census_log.h b/src/core/lib/statistics/census_log.h
deleted file mode 100644
index 6efcef49a4..0000000000
--- a/src/core/lib/statistics/census_log.h
+++ /dev/null
@@ -1,91 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_CENSUS_LOG_H
-#define GRPC_CORE_LIB_STATISTICS_CENSUS_LOG_H
-
-#include <stddef.h>
-
-/* Maximum record size, in bytes. */
-#define CENSUS_LOG_2_MAX_RECORD_SIZE 14 /* 2^14 = 16KB */
-#define CENSUS_LOG_MAX_RECORD_SIZE (1 << CENSUS_LOG_2_MAX_RECORD_SIZE)
-
-/* Initialize the statistics logging subsystem with the given log size. A log
-   size of 0 will result in the smallest possible log for the platform
-   (approximately CENSUS_LOG_MAX_RECORD_SIZE * gpr_cpu_num_cores()). If
-   discard_old_records is non-zero, then new records will displace older ones
-   when the log is full. This function must be called before any other
-   census_log functions.
-*/
-void census_log_initialize(size_t size_in_mb, int discard_old_records);
-
-/* Shutdown the logging subsystem. Caller must ensure that:
-   - no in progress or future call to any census_log functions
-   - no incomplete records
-*/
-void census_log_shutdown(void);
-
-/* Allocates and returns a 'size' bytes record and marks it in use. A
-   subsequent census_log_end_write() marks the record complete. The
-   'bytes_written' census_log_end_write() argument must be <=
-   'size'. Returns NULL if out-of-space AND:
-       - log is configured to keep old records OR
-       - all blocks are pinned by incomplete records.
-*/
-void *census_log_start_write(size_t size);
-
-void census_log_end_write(void *record, size_t bytes_written);
-
-/* census_log_read_next() iterates over blocks with data and for each block
-   returns a pointer to the first unread byte. The number of bytes that can be
-   read are returned in 'bytes_available'. Reader is expected to read all
-   available data. Reading the data consumes it i.e. it cannot be read again.
-   census_log_read_next() returns NULL if the end is reached i.e last block
-   is read. census_log_init_reader() starts the iteration or aborts the
-   current iteration.
-*/
-void census_log_init_reader(void);
-const void *census_log_read_next(size_t *bytes_available);
-
-/* Returns estimated remaining space across all blocks, in bytes. If log is
-   configured to discard old records, returns total log space. Otherwise,
-   returns space available in empty blocks (partially filled blocks are
-   treated as full).
-*/
-size_t census_log_remaining_space(void);
-
-/* Returns the number of times gprc_stats_log_start_write() failed due to
-   out-of-space. */
-int census_log_out_of_space_count(void);
-
-#endif /* GRPC_CORE_LIB_STATISTICS_CENSUS_LOG_H */
diff --git a/src/core/lib/statistics/census_rpc_stats.c b/src/core/lib/statistics/census_rpc_stats.c
deleted file mode 100644
index 33522e0f40..0000000000
--- a/src/core/lib/statistics/census_rpc_stats.c
+++ /dev/null
@@ -1,253 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/sync.h>
-#include "src/core/lib/statistics/census_interface.h"
-#include "src/core/lib/statistics/census_rpc_stats.h"
-#include "src/core/lib/statistics/census_tracing.h"
-#include "src/core/lib/statistics/hash_table.h"
-#include "src/core/lib/statistics/window_stats.h"
-#include "src/core/lib/support/murmur_hash.h"
-#include "src/core/lib/support/string.h"
-
-#define NUM_INTERVALS 3
-#define MINUTE_INTERVAL 0
-#define HOUR_INTERVAL 1
-#define TOTAL_INTERVAL 2
-
-/* for easier typing */
-typedef census_per_method_rpc_stats per_method_stats;
-
-/* Ensure mu is only initialized once. */
-static gpr_once g_stats_store_mu_init = GPR_ONCE_INIT;
-/* Guards two stats stores. */
-static gpr_mu g_mu;
-static census_ht *g_client_stats_store = NULL;
-static census_ht *g_server_stats_store = NULL;
-
-static void init_mutex(void) { gpr_mu_init(&g_mu); }
-
-static void init_mutex_once(void) {
-  gpr_once_init(&g_stats_store_mu_init, init_mutex);
-}
-
-static int cmp_str_keys(const void *k1, const void *k2) {
-  return strcmp((const char *)k1, (const char *)k2);
-}
-
-/* TODO(hongyu): replace it with cityhash64 */
-static uint64_t simple_hash(const void *k) {
-  size_t len = strlen(k);
-  uint64_t higher = gpr_murmur_hash3((const char *)k, len / 2, 0);
-  return higher << 32 |
-         gpr_murmur_hash3((const char *)k + len / 2, len - len / 2, 0);
-}
-
-static void delete_stats(void *stats) {
-  census_window_stats_destroy((struct census_window_stats *)stats);
-}
-
-static void delete_key(void *key) { gpr_free(key); }
-
-static const census_ht_option ht_opt = {
-    CENSUS_HT_POINTER /* key type */, 1999 /* n_of_buckets */,
-    simple_hash /* hash function */,  cmp_str_keys /* key comparator */,
-    delete_stats /* data deleter */,  delete_key /* key deleter */
-};
-
-static void init_rpc_stats(void *stats) {
-  memset(stats, 0, sizeof(census_rpc_stats));
-}
-
-static void stat_add_proportion(double p, void *base, const void *addme) {
-  census_rpc_stats *b = (census_rpc_stats *)base;
-  census_rpc_stats *a = (census_rpc_stats *)addme;
-  b->cnt += p * a->cnt;
-  b->rpc_error_cnt += p * a->rpc_error_cnt;
-  b->app_error_cnt += p * a->app_error_cnt;
-  b->elapsed_time_ms += p * a->elapsed_time_ms;
-  b->api_request_bytes += p * a->api_request_bytes;
-  b->wire_request_bytes += p * a->wire_request_bytes;
-  b->api_response_bytes += p * a->api_response_bytes;
-  b->wire_response_bytes += p * a->wire_response_bytes;
-}
-
-static void stat_add(void *base, const void *addme) {
-  stat_add_proportion(1.0, base, addme);
-}
-
-static gpr_timespec min_hour_total_intervals[3] = {
-    {60, 0}, {3600, 0}, {36000000, 0}};
-
-static const census_window_stats_stat_info window_stats_settings = {
-    sizeof(census_rpc_stats), init_rpc_stats, stat_add, stat_add_proportion};
-
-census_rpc_stats *census_rpc_stats_create_empty(void) {
-  census_rpc_stats *ret =
-      (census_rpc_stats *)gpr_malloc(sizeof(census_rpc_stats));
-  memset(ret, 0, sizeof(census_rpc_stats));
-  return ret;
-}
-
-void census_aggregated_rpc_stats_set_empty(census_aggregated_rpc_stats *data) {
-  int i = 0;
-  for (i = 0; i < data->num_entries; i++) {
-    if (data->stats[i].method != NULL) {
-      gpr_free((void *)data->stats[i].method);
-    }
-  }
-  if (data->stats != NULL) {
-    gpr_free(data->stats);
-  }
-  data->num_entries = 0;
-  data->stats = NULL;
-}
-
-static void record_stats(census_ht *store, census_op_id op_id,
-                         const census_rpc_stats *stats) {
-  gpr_mu_lock(&g_mu);
-  if (store != NULL) {
-    census_trace_obj *trace = NULL;
-    census_internal_lock_trace_store();
-    trace = census_get_trace_obj_locked(op_id);
-    if (trace != NULL) {
-      const char *method_name = census_get_trace_method_name(trace);
-      struct census_window_stats *window_stats = NULL;
-      census_ht_key key;
-      key.ptr = (void *)method_name;
-      window_stats = census_ht_find(store, key);
-      census_internal_unlock_trace_store();
-      if (window_stats == NULL) {
-        window_stats = census_window_stats_create(3, min_hour_total_intervals,
-                                                  30, &window_stats_settings);
-        key.ptr = gpr_strdup(key.ptr);
-        census_ht_insert(store, key, (void *)window_stats);
-      }
-      census_window_stats_add(window_stats, gpr_now(GPR_CLOCK_REALTIME), stats);
-    } else {
-      census_internal_unlock_trace_store();
-    }
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_record_rpc_client_stats(census_op_id op_id,
-                                    const census_rpc_stats *stats) {
-  record_stats(g_client_stats_store, op_id, stats);
-}
-
-void census_record_rpc_server_stats(census_op_id op_id,
-                                    const census_rpc_stats *stats) {
-  record_stats(g_server_stats_store, op_id, stats);
-}
-
-/* Get stats from input stats store */
-static void get_stats(census_ht *store, census_aggregated_rpc_stats *data) {
-  GPR_ASSERT(data != NULL);
-  if (data->num_entries != 0) {
-    census_aggregated_rpc_stats_set_empty(data);
-  }
-  gpr_mu_lock(&g_mu);
-  if (store != NULL) {
-    size_t n;
-    unsigned i, j;
-    gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
-    census_ht_kv *kv = census_ht_get_all_elements(store, &n);
-    if (kv != NULL) {
-      data->num_entries = n;
-      data->stats =
-          (per_method_stats *)gpr_malloc(sizeof(per_method_stats) * n);
-      for (i = 0; i < n; i++) {
-        census_window_stats_sums sums[NUM_INTERVALS];
-        for (j = 0; j < NUM_INTERVALS; j++) {
-          sums[j].statistic = (void *)census_rpc_stats_create_empty();
-        }
-        data->stats[i].method = gpr_strdup(kv[i].k.ptr);
-        census_window_stats_get_sums(kv[i].v, now, sums);
-        data->stats[i].minute_stats =
-            *(census_rpc_stats *)sums[MINUTE_INTERVAL].statistic;
-        data->stats[i].hour_stats =
-            *(census_rpc_stats *)sums[HOUR_INTERVAL].statistic;
-        data->stats[i].total_stats =
-            *(census_rpc_stats *)sums[TOTAL_INTERVAL].statistic;
-        for (j = 0; j < NUM_INTERVALS; j++) {
-          gpr_free(sums[j].statistic);
-        }
-      }
-      gpr_free(kv);
-    }
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_get_client_stats(census_aggregated_rpc_stats *data) {
-  get_stats(g_client_stats_store, data);
-}
-
-void census_get_server_stats(census_aggregated_rpc_stats *data) {
-  get_stats(g_server_stats_store, data);
-}
-
-void census_stats_store_init(void) {
-  init_mutex_once();
-  gpr_mu_lock(&g_mu);
-  if (g_client_stats_store == NULL && g_server_stats_store == NULL) {
-    g_client_stats_store = census_ht_create(&ht_opt);
-    g_server_stats_store = census_ht_create(&ht_opt);
-  } else {
-    gpr_log(GPR_ERROR, "Census stats store already initialized.");
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_stats_store_shutdown(void) {
-  init_mutex_once();
-  gpr_mu_lock(&g_mu);
-  if (g_client_stats_store != NULL) {
-    census_ht_destroy(g_client_stats_store);
-    g_client_stats_store = NULL;
-  } else {
-    gpr_log(GPR_ERROR, "Census server stats store not initialized.");
-  }
-  if (g_server_stats_store != NULL) {
-    census_ht_destroy(g_server_stats_store);
-    g_server_stats_store = NULL;
-  } else {
-    gpr_log(GPR_ERROR, "Census client stats store not initialized.");
-  }
-  gpr_mu_unlock(&g_mu);
-}
diff --git a/src/core/lib/statistics/census_rpc_stats.h b/src/core/lib/statistics/census_rpc_stats.h
deleted file mode 100644
index 3853642362..0000000000
--- a/src/core/lib/statistics/census_rpc_stats.h
+++ /dev/null
@@ -1,101 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_CENSUS_RPC_STATS_H
-#define GRPC_CORE_LIB_STATISTICS_CENSUS_RPC_STATS_H
-
-#include <grpc/support/port_platform.h>
-#include "src/core/lib/statistics/census_interface.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-struct census_rpc_stats {
-  uint64_t cnt;
-  uint64_t rpc_error_cnt;
-  uint64_t app_error_cnt;
-  double elapsed_time_ms;
-  double api_request_bytes;
-  double wire_request_bytes;
-  double api_response_bytes;
-  double wire_response_bytes;
-};
-
-/* Creates an empty rpc stats object on heap. */
-census_rpc_stats *census_rpc_stats_create_empty(void);
-
-typedef struct census_per_method_rpc_stats {
-  const char *method;
-  census_rpc_stats minute_stats; /* cumulative stats in the past minute */
-  census_rpc_stats hour_stats;   /* cumulative stats in the past hour */
-  census_rpc_stats total_stats;  /* cumulative stats from last gc */
-} census_per_method_rpc_stats;
-
-typedef struct census_aggregated_rpc_stats {
-  int num_entries;
-  census_per_method_rpc_stats *stats;
-} census_aggregated_rpc_stats;
-
-/* Initializes an aggregated rpc stats object to an empty state. */
-void census_aggregated_rpc_stats_set_empty(census_aggregated_rpc_stats *data);
-
-/* Records client side stats of a rpc. */
-void census_record_rpc_client_stats(census_op_id op_id,
-                                    const census_rpc_stats *stats);
-
-/* Records server side stats of a rpc. */
-void census_record_rpc_server_stats(census_op_id op_id,
-                                    const census_rpc_stats *stats);
-
-/* The following two functions are intended for inprocess query of
-   per-service per-method stats from grpc implementations. */
-
-/* Populates *data_map with server side aggregated per-service per-method
-   stats.
-   DO NOT CALL from outside of grpc code. */
-void census_get_server_stats(census_aggregated_rpc_stats *data_map);
-
-/* Populates *data_map with client side aggregated per-service per-method
-   stats.
-   DO NOT CALL from outside of grpc code. */
-void census_get_client_stats(census_aggregated_rpc_stats *data_map);
-
-void census_stats_store_init(void);
-void census_stats_store_shutdown(void);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* GRPC_CORE_LIB_STATISTICS_CENSUS_RPC_STATS_H */
diff --git a/src/core/lib/statistics/census_tracing.c b/src/core/lib/statistics/census_tracing.c
deleted file mode 100644
index ff71e796ad..0000000000
--- a/src/core/lib/statistics/census_tracing.c
+++ /dev/null
@@ -1,241 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/statistics/census_tracing.h"
-#include "src/core/lib/statistics/census_interface.h"
-
-#include <stdio.h>
-#include <string.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/port_platform.h>
-#include <grpc/support/sync.h>
-#include "src/core/lib/statistics/hash_table.h"
-#include "src/core/lib/support/string.h"
-
-void census_trace_obj_destroy(census_trace_obj *obj) {
-  census_trace_annotation *p = obj->annotations;
-  while (p != NULL) {
-    census_trace_annotation *next = p->next;
-    gpr_free(p);
-    p = next;
-  }
-  gpr_free(obj->method);
-  gpr_free(obj);
-}
-
-static void delete_trace_obj(void *obj) {
-  census_trace_obj_destroy((census_trace_obj *)obj);
-}
-
-static const census_ht_option ht_opt = {
-    CENSUS_HT_UINT64 /* key type */,
-    571 /* n_of_buckets */,
-    NULL /* hash */,
-    NULL /* compare_keys */,
-    delete_trace_obj /* delete data */,
-    NULL /* delete key */
-};
-
-static gpr_once g_init_mutex_once = GPR_ONCE_INIT;
-static gpr_mu g_mu; /* Guards following two static variables. */
-static census_ht *g_trace_store = NULL;
-static uint64_t g_id = 0;
-
-static census_ht_key op_id_as_key(census_op_id *id) {
-  return *(census_ht_key *)id;
-}
-
-static uint64_t op_id_2_uint64(census_op_id *id) {
-  uint64_t ret;
-  memcpy(&ret, id, sizeof(census_op_id));
-  return ret;
-}
-
-static void init_mutex(void) { gpr_mu_init(&g_mu); }
-
-static void init_mutex_once(void) {
-  gpr_once_init(&g_init_mutex_once, init_mutex);
-}
-
-census_op_id census_tracing_start_op(void) {
-  gpr_mu_lock(&g_mu);
-  {
-    census_trace_obj *ret = gpr_malloc(sizeof(census_trace_obj));
-    memset(ret, 0, sizeof(census_trace_obj));
-    g_id++;
-    memcpy(&ret->id, &g_id, sizeof(census_op_id));
-    ret->rpc_stats.cnt = 1;
-    ret->ts = gpr_now(GPR_CLOCK_REALTIME);
-    census_ht_insert(g_trace_store, op_id_as_key(&ret->id), (void *)ret);
-    gpr_log(GPR_DEBUG, "Start tracing for id %lu", g_id);
-    gpr_mu_unlock(&g_mu);
-    return ret->id;
-  }
-}
-
-int census_add_method_tag(census_op_id op_id, const char *method) {
-  int ret = 0;
-  census_trace_obj *trace = NULL;
-  gpr_mu_lock(&g_mu);
-  trace = census_ht_find(g_trace_store, op_id_as_key(&op_id));
-  if (trace == NULL) {
-    ret = 1;
-  } else {
-    trace->method = gpr_strdup(method);
-  }
-  gpr_mu_unlock(&g_mu);
-  return ret;
-}
-
-void census_tracing_print(census_op_id op_id, const char *anno_txt) {
-  census_trace_obj *trace = NULL;
-  gpr_mu_lock(&g_mu);
-  trace = census_ht_find(g_trace_store, op_id_as_key(&op_id));
-  if (trace != NULL) {
-    census_trace_annotation *anno = gpr_malloc(sizeof(census_trace_annotation));
-    anno->ts = gpr_now(GPR_CLOCK_REALTIME);
-    {
-      char *d = anno->txt;
-      const char *s = anno_txt;
-      int n = 0;
-      for (; n < CENSUS_MAX_ANNOTATION_LENGTH && *s != '\0'; ++n) {
-        *d++ = *s++;
-      }
-      *d = '\0';
-    }
-    anno->next = trace->annotations;
-    trace->annotations = anno;
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_tracing_end_op(census_op_id op_id) {
-  census_trace_obj *trace = NULL;
-  gpr_mu_lock(&g_mu);
-  trace = census_ht_find(g_trace_store, op_id_as_key(&op_id));
-  if (trace != NULL) {
-    trace->rpc_stats.elapsed_time_ms = gpr_timespec_to_micros(
-        gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), trace->ts));
-    gpr_log(GPR_DEBUG, "End tracing for id %lu, method %s, latency %f us",
-            op_id_2_uint64(&op_id), trace->method,
-            trace->rpc_stats.elapsed_time_ms);
-    census_ht_erase(g_trace_store, op_id_as_key(&op_id));
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_tracing_init(void) {
-  init_mutex_once();
-  gpr_mu_lock(&g_mu);
-  if (g_trace_store == NULL) {
-    g_id = 1;
-    g_trace_store = census_ht_create(&ht_opt);
-  } else {
-    gpr_log(GPR_ERROR, "Census trace store already initialized.");
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_tracing_shutdown(void) {
-  gpr_mu_lock(&g_mu);
-  if (g_trace_store != NULL) {
-    census_ht_destroy(g_trace_store);
-    g_trace_store = NULL;
-  } else {
-    gpr_log(GPR_ERROR, "Census trace store is not initialized.");
-  }
-  gpr_mu_unlock(&g_mu);
-}
-
-void census_internal_lock_trace_store(void) { gpr_mu_lock(&g_mu); }
-
-void census_internal_unlock_trace_store(void) { gpr_mu_unlock(&g_mu); }
-
-census_trace_obj *census_get_trace_obj_locked(census_op_id op_id) {
-  if (g_trace_store == NULL) {
-    gpr_log(GPR_ERROR, "Census trace store is not initialized.");
-    return NULL;
-  }
-  return (census_trace_obj *)census_ht_find(g_trace_store,
-                                            op_id_as_key(&op_id));
-}
-
-const char *census_get_trace_method_name(const census_trace_obj *trace) {
-  return trace->method;
-}
-
-static census_trace_annotation *dup_annotation_chain(
-    census_trace_annotation *from) {
-  census_trace_annotation *ret = NULL;
-  census_trace_annotation **to = &ret;
-  for (; from != NULL; from = from->next) {
-    *to = gpr_malloc(sizeof(census_trace_annotation));
-    memcpy(*to, from, sizeof(census_trace_annotation));
-    to = &(*to)->next;
-  }
-  return ret;
-}
-
-static census_trace_obj *trace_obj_dup(census_trace_obj *from) {
-  census_trace_obj *to = NULL;
-  GPR_ASSERT(from != NULL);
-  to = gpr_malloc(sizeof(census_trace_obj));
-  to->id = from->id;
-  to->ts = from->ts;
-  to->rpc_stats = from->rpc_stats;
-  to->method = gpr_strdup(from->method);
-  to->annotations = dup_annotation_chain(from->annotations);
-  return to;
-}
-
-census_trace_obj **census_get_active_ops(int *num_active_ops) {
-  census_trace_obj **ret = NULL;
-  gpr_mu_lock(&g_mu);
-  if (g_trace_store != NULL) {
-    size_t n = 0;
-    census_ht_kv *all_kvs = census_ht_get_all_elements(g_trace_store, &n);
-    *num_active_ops = (int)n;
-    if (n != 0) {
-      size_t i = 0;
-      ret = gpr_malloc(sizeof(census_trace_obj *) * n);
-      for (i = 0; i < n; i++) {
-        ret[i] = trace_obj_dup((census_trace_obj *)all_kvs[i].v);
-      }
-    }
-    gpr_free(all_kvs);
-  }
-  gpr_mu_unlock(&g_mu);
-  return ret;
-}
diff --git a/src/core/lib/statistics/census_tracing.h b/src/core/lib/statistics/census_tracing.h
deleted file mode 100644
index 7b2db1e008..0000000000
--- a/src/core/lib/statistics/census_tracing.h
+++ /dev/null
@@ -1,96 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_CENSUS_TRACING_H
-#define GRPC_CORE_LIB_STATISTICS_CENSUS_TRACING_H
-
-#include <grpc/support/time.h>
-#include "src/core/lib/statistics/census_rpc_stats.h"
-
-/* WARNING: The data structures and APIs provided by this file are for GRPC
-   library's internal use ONLY. They might be changed in backward-incompatible
-   ways and are not subject to any deprecation policy.
-   They are not recommended for external use.
- */
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* Struct for a trace annotation. */
-typedef struct census_trace_annotation {
-  gpr_timespec ts;                            /* timestamp of the annotation */
-  char txt[CENSUS_MAX_ANNOTATION_LENGTH + 1]; /* actual txt annotation */
-  struct census_trace_annotation *next;
-} census_trace_annotation;
-
-typedef struct census_trace_obj {
-  census_op_id id;
-  gpr_timespec ts;
-  census_rpc_stats rpc_stats;
-  char *method;
-  census_trace_annotation *annotations;
-} census_trace_obj;
-
-/* Deletes trace object. */
-void census_trace_obj_destroy(census_trace_obj *obj);
-
-/* Initializes trace store. This function is thread safe. */
-void census_tracing_init(void);
-
-/* Shutsdown trace store. This function is thread safe. */
-void census_tracing_shutdown(void);
-
-/* Gets trace obj corresponding to the input op_id. Returns NULL if trace store
-   is not initialized or trace obj is not found. Requires trace store being
-   locked before calling this function. */
-census_trace_obj *census_get_trace_obj_locked(census_op_id op_id);
-
-/* The following two functions acquire and release the trace store global lock.
-   They are for census internal use only. */
-void census_internal_lock_trace_store(void);
-void census_internal_unlock_trace_store(void);
-
-/* Gets method name associated with the input trace object. */
-const char *census_get_trace_method_name(const census_trace_obj *trace);
-
-/* Returns an array of pointers to trace objects of currently active operations
-   and fills in number of active operations. Returns NULL if there are no active
-   operations.
-   Caller owns the returned objects. */
-census_trace_obj **census_get_active_ops(int *num_active_ops);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* GRPC_CORE_LIB_STATISTICS_CENSUS_TRACING_H */
diff --git a/src/core/lib/statistics/hash_table.c b/src/core/lib/statistics/hash_table.c
deleted file mode 100644
index 79481c3eb1..0000000000
--- a/src/core/lib/statistics/hash_table.c
+++ /dev/null
@@ -1,303 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/statistics/hash_table.h"
-
-#include <stddef.h>
-#include <stdio.h>
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/port_platform.h>
-
-#define CENSUS_HT_NUM_BUCKETS 1999
-
-/* A single hash table data entry */
-typedef struct ht_entry {
-  census_ht_key key;
-  void *data;
-  struct ht_entry *next;
-} ht_entry;
-
-/* hash table bucket */
-typedef struct bucket {
-  /* NULL if bucket is empty */
-  ht_entry *next;
-  /* -1 if all buckets are empty. */
-  int32_t prev_non_empty_bucket;
-  /* -1 if all buckets are empty. */
-  int32_t next_non_empty_bucket;
-} bucket;
-
-struct unresizable_hash_table {
-  /* Number of entries in the table */
-  size_t size;
-  /* Number of buckets */
-  uint32_t num_buckets;
-  /* Array of buckets initialized at creation time. Memory consumption is
-     16 bytes per bucket on a 64-bit platform. */
-  bucket *buckets;
-  /* Index of the first non-empty bucket. -1 iff size == 0. */
-  int32_t first_non_empty_bucket;
-  /* Index of the last non_empty bucket. -1 iff size == 0. */
-  int32_t last_non_empty_bucket;
-  /* Immutable options of this hash table, initialized at creation time. */
-  census_ht_option options;
-};
-
-typedef struct entry_locator {
-  int32_t bucket_idx;
-  int is_first_in_chain;
-  int found;
-  ht_entry *prev_entry;
-} entry_locator;
-
-/* Asserts if option is not valid. */
-void check_options(const census_ht_option *option) {
-  GPR_ASSERT(option != NULL);
-  GPR_ASSERT(option->num_buckets > 0);
-  GPR_ASSERT(option->key_type == CENSUS_HT_UINT64 ||
-             option->key_type == CENSUS_HT_POINTER);
-  if (option->key_type == CENSUS_HT_UINT64) {
-    GPR_ASSERT(option->hash == NULL);
-  } else if (option->key_type == CENSUS_HT_POINTER) {
-    GPR_ASSERT(option->hash != NULL);
-    GPR_ASSERT(option->compare_keys != NULL);
-  }
-}
-
-#define REMOVE_NEXT(options, ptr) \
-  do {                            \
-    ht_entry *tmp = (ptr)->next;  \
-    (ptr)->next = tmp->next;      \
-    delete_entry(options, tmp);   \
-  } while (0)
-
-static void delete_entry(const census_ht_option *opt, ht_entry *p) {
-  if (opt->delete_data != NULL) {
-    opt->delete_data(p->data);
-  }
-  if (opt->delete_key != NULL) {
-    opt->delete_key(p->key.ptr);
-  }
-  gpr_free(p);
-}
-
-static uint64_t hash(const census_ht_option *opt, census_ht_key key) {
-  return opt->key_type == CENSUS_HT_UINT64 ? key.val : opt->hash(key.ptr);
-}
-
-census_ht *census_ht_create(const census_ht_option *option) {
-  int i;
-  census_ht *ret = NULL;
-  check_options(option);
-  ret = (census_ht *)gpr_malloc(sizeof(census_ht));
-  ret->size = 0;
-  ret->num_buckets = option->num_buckets;
-  ret->buckets = (bucket *)gpr_malloc(sizeof(bucket) * ret->num_buckets);
-  ret->options = *option;
-  /* initialize each bucket */
-  for (i = 0; i < ret->options.num_buckets; i++) {
-    ret->buckets[i].prev_non_empty_bucket = -1;
-    ret->buckets[i].next_non_empty_bucket = -1;
-    ret->buckets[i].next = NULL;
-  }
-  return ret;
-}
-
-static int32_t find_bucket_idx(const census_ht *ht, census_ht_key key) {
-  return hash(&ht->options, key) % ht->num_buckets;
-}
-
-static int keys_match(const census_ht_option *opt, const ht_entry *p,
-                      const census_ht_key key) {
-  GPR_ASSERT(opt->key_type == CENSUS_HT_UINT64 ||
-             opt->key_type == CENSUS_HT_POINTER);
-  if (opt->key_type == CENSUS_HT_UINT64) return p->key.val == key.val;
-  return !opt->compare_keys((p->key).ptr, key.ptr);
-}
-
-static entry_locator ht_find(const census_ht *ht, census_ht_key key) {
-  entry_locator loc = {0, 0, 0, NULL};
-  int32_t idx = 0;
-  ht_entry *ptr = NULL;
-  GPR_ASSERT(ht != NULL);
-  idx = find_bucket_idx(ht, key);
-  ptr = ht->buckets[idx].next;
-  if (ptr == NULL) {
-    /* bucket is empty */
-    return loc;
-  }
-  if (keys_match(&ht->options, ptr, key)) {
-    loc.bucket_idx = idx;
-    loc.is_first_in_chain = 1;
-    loc.found = 1;
-    return loc;
-  } else {
-    for (; ptr->next != NULL; ptr = ptr->next) {
-      if (keys_match(&ht->options, ptr->next, key)) {
-        loc.bucket_idx = idx;
-        loc.is_first_in_chain = 0;
-        loc.found = 1;
-        loc.prev_entry = ptr;
-        return loc;
-      }
-    }
-  }
-  /* Could not find the key */
-  return loc;
-}
-
-void *census_ht_find(const census_ht *ht, census_ht_key key) {
-  entry_locator loc = ht_find(ht, key);
-  if (loc.found == 0) {
-    return NULL;
-  }
-  return loc.is_first_in_chain ? ht->buckets[loc.bucket_idx].next->data
-                               : loc.prev_entry->next->data;
-}
-
-void census_ht_insert(census_ht *ht, census_ht_key key, void *data) {
-  int32_t idx = find_bucket_idx(ht, key);
-  ht_entry *ptr = NULL;
-  entry_locator loc = ht_find(ht, key);
-  if (loc.found) {
-    /* Replace old value with new value. */
-    ptr = loc.is_first_in_chain ? ht->buckets[loc.bucket_idx].next
-                                : loc.prev_entry->next;
-    if (ht->options.delete_data != NULL) {
-      ht->options.delete_data(ptr->data);
-    }
-    ptr->data = data;
-    return;
-  }
-
-  /* first entry in the table. */
-  if (ht->size == 0) {
-    ht->buckets[idx].next_non_empty_bucket = -1;
-    ht->buckets[idx].prev_non_empty_bucket = -1;
-    ht->first_non_empty_bucket = idx;
-    ht->last_non_empty_bucket = idx;
-  } else if (ht->buckets[idx].next == NULL) {
-    /* first entry in the bucket. */
-    ht->buckets[ht->last_non_empty_bucket].next_non_empty_bucket = idx;
-    ht->buckets[idx].prev_non_empty_bucket = ht->last_non_empty_bucket;
-    ht->buckets[idx].next_non_empty_bucket = -1;
-    ht->last_non_empty_bucket = idx;
-  }
-  ptr = (ht_entry *)gpr_malloc(sizeof(ht_entry));
-  ptr->key = key;
-  ptr->data = data;
-  ptr->next = ht->buckets[idx].next;
-  ht->buckets[idx].next = ptr;
-  ht->size++;
-}
-
-void census_ht_erase(census_ht *ht, census_ht_key key) {
-  entry_locator loc = ht_find(ht, key);
-  if (loc.found == 0) {
-    /* noop if not found */
-    return;
-  }
-  ht->size--;
-  if (loc.is_first_in_chain) {
-    bucket *b = &ht->buckets[loc.bucket_idx];
-    GPR_ASSERT(b->next != NULL);
-    /* The only entry in the bucket */
-    if (b->next->next == NULL) {
-      int prev = b->prev_non_empty_bucket;
-      int next = b->next_non_empty_bucket;
-      if (prev != -1) {
-        ht->buckets[prev].next_non_empty_bucket = next;
-      } else {
-        ht->first_non_empty_bucket = next;
-      }
-      if (next != -1) {
-        ht->buckets[next].prev_non_empty_bucket = prev;
-      } else {
-        ht->last_non_empty_bucket = prev;
-      }
-    }
-    REMOVE_NEXT(&ht->options, b);
-  } else {
-    GPR_ASSERT(loc.prev_entry->next != NULL);
-    REMOVE_NEXT(&ht->options, loc.prev_entry);
-  }
-}
-
-/* Returns NULL if input table is empty. */
-census_ht_kv *census_ht_get_all_elements(const census_ht *ht, size_t *num) {
-  census_ht_kv *ret = NULL;
-  int i = 0;
-  int32_t idx = -1;
-  GPR_ASSERT(ht != NULL && num != NULL);
-  *num = ht->size;
-  if (*num == 0) {
-    return NULL;
-  }
-
-  ret = (census_ht_kv *)gpr_malloc(sizeof(census_ht_kv) * ht->size);
-  idx = ht->first_non_empty_bucket;
-  while (idx >= 0) {
-    ht_entry *ptr = ht->buckets[idx].next;
-    for (; ptr != NULL; ptr = ptr->next) {
-      ret[i].k = ptr->key;
-      ret[i].v = ptr->data;
-      i++;
-    }
-    idx = ht->buckets[idx].next_non_empty_bucket;
-  }
-  return ret;
-}
-
-static void ht_delete_entry_chain(const census_ht_option *options,
-                                  ht_entry *first) {
-  if (first == NULL) {
-    return;
-  }
-  if (first->next != NULL) {
-    ht_delete_entry_chain(options, first->next);
-  }
-  delete_entry(options, first);
-}
-
-void census_ht_destroy(census_ht *ht) {
-  unsigned i;
-  for (i = 0; i < ht->num_buckets; ++i) {
-    ht_delete_entry_chain(&ht->options, ht->buckets[i].next);
-  }
-  gpr_free(ht->buckets);
-  gpr_free(ht);
-}
-
-size_t census_ht_get_size(const census_ht *ht) { return ht->size; }
diff --git a/src/core/lib/statistics/hash_table.h b/src/core/lib/statistics/hash_table.h
deleted file mode 100644
index 45984a1c41..0000000000
--- a/src/core/lib/statistics/hash_table.h
+++ /dev/null
@@ -1,131 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_HASH_TABLE_H
-#define GRPC_CORE_LIB_STATISTICS_HASH_TABLE_H
-
-#include <stddef.h>
-
-#include <grpc/support/port_platform.h>
-
-/* A chain based hash table with fixed number of buckets.
-   Your probably shouldn't use this code directly. It is implemented for the
-   use case in census trace store and stats store, where number of entries in
-   the table is in the scale of upto several thousands, entries are added and
-   removed from the table very frequently (~100k/s), the frequency of find()
-   operations is roughly several times of the frequency of insert() and erase()
-   Comparing to find(), the insert(), erase() and get_all_entries() operations
-   are much less freqent (<1/s).
-
-   Per bucket memory overhead is about (8 + sizeof(intptr_t) bytes.
-   Per entry memory overhead is about (8 + 2 * sizeof(intptr_t) bytes.
-
-   All functions are not thread-safe. Synchronization will be provided in the
-   upper layer (in trace store and stats store).
-*/
-
-/* Opaque hash table struct */
-typedef struct unresizable_hash_table census_ht;
-
-/* Currently, the hash_table can take two types of keys. (uint64 for trace
-   store and const char* for stats store). */
-typedef union {
-  uint64_t val;
-  void *ptr;
-} census_ht_key;
-
-typedef enum census_ht_key_type {
-  CENSUS_HT_UINT64 = 0,
-  CENSUS_HT_POINTER = 1
-} census_ht_key_type;
-
-typedef struct census_ht_option {
-  /* Type of hash key */
-  census_ht_key_type key_type;
-  /* Desired number of buckets, preferably a prime number */
-  int32_t num_buckets;
-  /* Fucntion to calculate uint64 hash value of the key. Only takes effect if
-     key_type is POINTER. */
-  uint64_t (*hash)(const void *);
-  /* Function to compare two keys, returns 0 iff equal. Only takes effect if
-     key_type is POINTER */
-  int (*compare_keys)(const void *k1, const void *k2);
-  /* Value deleter. NULL if no specialized delete function is needed. */
-  void (*delete_data)(void *);
-  /* Key deleter. NULL if table does not own the key. (e.g. key is part of the
-     value or key is not owned by the table.) */
-  void (*delete_key)(void *);
-} census_ht_option;
-
-/* Creates a hashtable with fixed number of buckets according to the settings
-   specified in 'options' arg. Function pointers "hash" and "compare_keys" must
-   be provided if key_type is POINTER. Asserts if fail to create. */
-census_ht *census_ht_create(const census_ht_option *options);
-
-/* Deletes hash table instance. Frees all dynamic memory owned by ht.*/
-void census_ht_destroy(census_ht *ht);
-
-/* Inserts the input key-val pair into hash_table. If an entry with the same key
-   exists in the table, the corresponding value will be overwritten by the input
-   val. */
-void census_ht_insert(census_ht *ht, census_ht_key key, void *val);
-
-/* Returns pointer to data, returns NULL if not found. */
-void *census_ht_find(const census_ht *ht, census_ht_key key);
-
-/* Erase hash table entry with input key. Noop if key is not found. */
-void census_ht_erase(census_ht *ht, census_ht_key key);
-
-typedef struct census_ht_kv {
-  census_ht_key k;
-  void *v;
-} census_ht_kv;
-
-/* Returns an array of pointers to all values in the hash table. Order of the
-   elements can be arbitrary. Sets 'num' to the size of returned array. Caller
-   owns returned array. */
-census_ht_kv *census_ht_get_all_elements(const census_ht *ht, size_t *num);
-
-/* Returns number of elements kept. */
-size_t census_ht_get_size(const census_ht *ht);
-
-/* Functor applied on each key-value pair while iterating through entries in the
-   table. The functor should not mutate data. */
-typedef void (*census_ht_itr_cb)(census_ht_key key, const void *val_ptr,
-                                 void *state);
-
-/* Iterates through all key-value pairs in the hash_table. The callback function
-   should not invalidate data entries. */
-uint64_t census_ht_for_all(const census_ht *ht, census_ht_itr_cb);
-
-#endif /* GRPC_CORE_LIB_STATISTICS_HASH_TABLE_H */
diff --git a/src/core/lib/statistics/window_stats.c b/src/core/lib/statistics/window_stats.c
deleted file mode 100644
index 9185e98d60..0000000000
--- a/src/core/lib/statistics/window_stats.c
+++ /dev/null
@@ -1,316 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/statistics/window_stats.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/time.h>
-#include <grpc/support/useful.h>
-#include <math.h>
-#include <stddef.h>
-#include <string.h>
-
-/* typedefs make typing long names easier. Use cws (for census_window_stats) */
-typedef census_window_stats_stat_info cws_stat_info;
-typedef struct census_window_stats_sum cws_sum;
-
-/* Each interval is composed of a number of buckets, which hold a count of
-   entries and a single statistic */
-typedef struct census_window_stats_bucket {
-  int64_t count;
-  void *statistic;
-} cws_bucket;
-
-/* Each interval has a set of buckets, and the variables needed to keep
-   track of their current state */
-typedef struct census_window_stats_interval_stats {
-  /* The buckets. There will be 'granularity' + 1 of these. */
-  cws_bucket *buckets;
-  /* Index of the bucket containing the smallest time interval. */
-  int bottom_bucket;
-  /* The smallest time storable in the current window. */
-  int64_t bottom;
-  /* The largest time storable in the current window + 1ns */
-  int64_t top;
-  /* The width of each bucket in ns. */
-  int64_t width;
-} cws_interval_stats;
-
-typedef struct census_window_stats {
-  /* Number of intervals. */
-  int nintervals;
-  /* Number of buckets in each interval. 'granularity' + 1. */
-  int nbuckets;
-  /* Record of stat_info. */
-  cws_stat_info stat_info;
-  /* Stats for each interval. */
-  cws_interval_stats *interval_stats;
-  /* The time the newset stat was recorded. */
-  int64_t newest_time;
-} window_stats;
-
-/* Calculate an actual bucket index from a logical index 'IDX'. Other
-   parameters supply information on the interval struct and overall stats. */
-#define BUCKET_IDX(IS, IDX, WSTATS) \
-  ((IS->bottom_bucket + (IDX)) % WSTATS->nbuckets)
-
-/* The maximum seconds value we can have in a valid timespec. More than this
-   will result in overflow in timespec_to_ns(). This works out to ~292 years.
-   TODO: consider using doubles instead of int64. */
-static int64_t max_seconds = (GPR_INT64_MAX - GPR_NS_PER_SEC) / GPR_NS_PER_SEC;
-
-static int64_t timespec_to_ns(const gpr_timespec ts) {
-  if (ts.tv_sec > max_seconds) {
-    return GPR_INT64_MAX - 1;
-  }
-  return ts.tv_sec * GPR_NS_PER_SEC + ts.tv_nsec;
-}
-
-static void cws_initialize_statistic(void *statistic,
-                                     const cws_stat_info *stat_info) {
-  if (stat_info->stat_initialize == NULL) {
-    memset(statistic, 0, stat_info->stat_size);
-  } else {
-    stat_info->stat_initialize(statistic);
-  }
-}
-
-/* Create and initialize a statistic */
-static void *cws_create_statistic(const cws_stat_info *stat_info) {
-  void *stat = gpr_malloc(stat_info->stat_size);
-  cws_initialize_statistic(stat, stat_info);
-  return stat;
-}
-
-window_stats *census_window_stats_create(int nintervals,
-                                         const gpr_timespec intervals[],
-                                         int granularity,
-                                         const cws_stat_info *stat_info) {
-  window_stats *ret;
-  int i;
-  /* validate inputs */
-  GPR_ASSERT(nintervals > 0 && granularity > 2 && intervals != NULL &&
-             stat_info != NULL);
-  for (i = 0; i < nintervals; i++) {
-    int64_t ns = timespec_to_ns(intervals[i]);
-    GPR_ASSERT(intervals[i].tv_sec >= 0 && intervals[i].tv_nsec >= 0 &&
-               intervals[i].tv_nsec < GPR_NS_PER_SEC && ns >= 100 &&
-               granularity * 10 <= ns);
-  }
-  /* Allocate and initialize relevant data structures */
-  ret = (window_stats *)gpr_malloc(sizeof(window_stats));
-  ret->nintervals = nintervals;
-  ret->nbuckets = granularity + 1;
-  ret->stat_info = *stat_info;
-  ret->interval_stats =
-      (cws_interval_stats *)gpr_malloc(nintervals * sizeof(cws_interval_stats));
-  for (i = 0; i < nintervals; i++) {
-    int64_t size_ns = timespec_to_ns(intervals[i]);
-    cws_interval_stats *is = ret->interval_stats + i;
-    cws_bucket *buckets = is->buckets =
-        (cws_bucket *)gpr_malloc(ret->nbuckets * sizeof(cws_bucket));
-    int b;
-    for (b = 0; b < ret->nbuckets; b++) {
-      buckets[b].statistic = cws_create_statistic(stat_info);
-      buckets[b].count = 0;
-    }
-    is->bottom_bucket = 0;
-    is->bottom = 0;
-    is->width = size_ns / granularity;
-    /* Check for possible overflow issues, and maximize interval size if the
-       user requested something large enough. */
-    if ((GPR_INT64_MAX - is->width) > size_ns) {
-      is->top = size_ns + is->width;
-    } else {
-      is->top = GPR_INT64_MAX;
-      is->width = GPR_INT64_MAX / (granularity + 1);
-    }
-    /* If size doesn't divide evenly, we can have a width slightly too small;
-       better to have it slightly large. */
-    if ((size_ns - (granularity + 1) * is->width) > 0) {
-      is->width += 1;
-    }
-  }
-  ret->newest_time = 0;
-  return ret;
-}
-
-/* When we try adding a measurement above the current interval range, we
-   need to "shift" the buckets sufficiently to cover the new range. */
-static void cws_shift_buckets(const window_stats *wstats,
-                              cws_interval_stats *is, int64_t when_ns) {
-  int i;
-  /* number of bucket time widths to "shift" */
-  int shift;
-  /* number of buckets to clear */
-  int nclear;
-  GPR_ASSERT(when_ns >= is->top);
-  /* number of bucket time widths to "shift" */
-  shift = ((when_ns - is->top) / is->width) + 1;
-  /* number of buckets to clear - limited by actual number of buckets */
-  nclear = GPR_MIN(shift, wstats->nbuckets);
-  for (i = 0; i < nclear; i++) {
-    int b = BUCKET_IDX(is, i, wstats);
-    is->buckets[b].count = 0;
-    cws_initialize_statistic(is->buckets[b].statistic, &wstats->stat_info);
-  }
-  /* adjust top/bottom times and current bottom bucket */
-  is->bottom_bucket = BUCKET_IDX(is, shift, wstats);
-  is->top += shift * is->width;
-  is->bottom += shift * is->width;
-}
-
-void census_window_stats_add(window_stats *wstats, const gpr_timespec when,
-                             const void *stat_value) {
-  int i;
-  int64_t when_ns = timespec_to_ns(when);
-  GPR_ASSERT(wstats->interval_stats != NULL);
-  for (i = 0; i < wstats->nintervals; i++) {
-    cws_interval_stats *is = wstats->interval_stats + i;
-    cws_bucket *bucket;
-    if (when_ns < is->bottom) { /* Below smallest time in interval: drop */
-      continue;
-    }
-    if (when_ns >= is->top) { /* above limit: shift buckets */
-      cws_shift_buckets(wstats, is, when_ns);
-    }
-    /* Add the stat. */
-    GPR_ASSERT(is->bottom <= when_ns && when_ns < is->top);
-    bucket = is->buckets +
-             BUCKET_IDX(is, (when_ns - is->bottom) / is->width, wstats);
-    bucket->count++;
-    wstats->stat_info.stat_add(bucket->statistic, stat_value);
-  }
-  if (when_ns > wstats->newest_time) {
-    wstats->newest_time = when_ns;
-  }
-}
-
-/* Add a specific bucket contents to an accumulating total. */
-static void cws_add_bucket_to_sum(cws_sum *sum, const cws_bucket *bucket,
-                                  const cws_stat_info *stat_info) {
-  sum->count += bucket->count;
-  stat_info->stat_add(sum->statistic, bucket->statistic);
-}
-
-/* Add a proportion to an accumulating sum. */
-static void cws_add_proportion_to_sum(double p, cws_sum *sum,
-                                      const cws_bucket *bucket,
-                                      const cws_stat_info *stat_info) {
-  sum->count += p * bucket->count;
-  stat_info->stat_add_proportion(p, sum->statistic, bucket->statistic);
-}
-
-void census_window_stats_get_sums(const window_stats *wstats,
-                                  const gpr_timespec when, cws_sum sums[]) {
-  int i;
-  int64_t when_ns = timespec_to_ns(when);
-  GPR_ASSERT(wstats->interval_stats != NULL);
-  for (i = 0; i < wstats->nintervals; i++) {
-    int when_bucket;
-    int new_bucket;
-    double last_proportion = 1.0;
-    double bottom_proportion;
-    cws_interval_stats *is = wstats->interval_stats + i;
-    cws_sum *sum = sums + i;
-    sum->count = 0;
-    cws_initialize_statistic(sum->statistic, &wstats->stat_info);
-    if (when_ns < is->bottom) {
-      continue;
-    }
-    if (when_ns >= is->top) {
-      cws_shift_buckets(wstats, is, when_ns);
-    }
-    /* Calculating the appropriate amount of which buckets to use can get
-       complicated. Essentially there are two cases:
-       1) if the "top" bucket (new_bucket, where the newest additions to the
-       stats recorded are entered) corresponds to 'when', then we need
-       to take a proportion of it - (if when < newest_time) or the full
-       thing. We also (possibly) need to take a corresponding
-       proportion of the bottom bucket.
-       2) Other cases, we just take a straight proportion.
-     */
-    when_bucket = (when_ns - is->bottom) / is->width;
-    new_bucket = (wstats->newest_time - is->bottom) / is->width;
-    if (new_bucket == when_bucket) {
-      int64_t bottom_bucket_time = is->bottom + when_bucket * is->width;
-      if (when_ns < wstats->newest_time) {
-        last_proportion = (double)(when_ns - bottom_bucket_time) /
-                          (double)(wstats->newest_time - bottom_bucket_time);
-        bottom_proportion =
-            (double)(is->width - (when_ns - bottom_bucket_time)) / is->width;
-      } else {
-        bottom_proportion =
-            (double)(is->width - (wstats->newest_time - bottom_bucket_time)) /
-            is->width;
-      }
-    } else {
-      last_proportion =
-          (double)(when_ns + 1 - is->bottom - when_bucket * is->width) /
-          is->width;
-      bottom_proportion = 1.0 - last_proportion;
-    }
-    cws_add_proportion_to_sum(last_proportion, sum,
-                              is->buckets + BUCKET_IDX(is, when_bucket, wstats),
-                              &wstats->stat_info);
-    if (when_bucket != 0) { /* last bucket isn't also bottom bucket */
-      int b;
-      /* Add all of "bottom" bucket if we are looking at a subset of the
-         full interval, or a proportion if we are adding full interval. */
-      cws_add_proportion_to_sum(
-          (when_bucket == wstats->nbuckets - 1 ? bottom_proportion : 1.0), sum,
-          is->buckets + is->bottom_bucket, &wstats->stat_info);
-      /* Add all the remaining buckets (everything but top and bottom). */
-      for (b = 1; b < when_bucket; b++) {
-        cws_add_bucket_to_sum(sum, is->buckets + BUCKET_IDX(is, b, wstats),
-                              &wstats->stat_info);
-      }
-    }
-  }
-}
-
-void census_window_stats_destroy(window_stats *wstats) {
-  int i;
-  GPR_ASSERT(wstats->interval_stats != NULL);
-  for (i = 0; i < wstats->nintervals; i++) {
-    int b;
-    for (b = 0; b < wstats->nbuckets; b++) {
-      gpr_free(wstats->interval_stats[i].buckets[b].statistic);
-    }
-    gpr_free(wstats->interval_stats[i].buckets);
-  }
-  gpr_free(wstats->interval_stats);
-  /* Ensure any use-after free triggers assert. */
-  wstats->interval_stats = NULL;
-  gpr_free(wstats);
-}
diff --git a/src/core/lib/statistics/window_stats.h b/src/core/lib/statistics/window_stats.h
deleted file mode 100644
index 629c08b8d5..0000000000
--- a/src/core/lib/statistics/window_stats.h
+++ /dev/null
@@ -1,173 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#ifndef GRPC_CORE_LIB_STATISTICS_WINDOW_STATS_H
-#define GRPC_CORE_LIB_STATISTICS_WINDOW_STATS_H
-
-#include <grpc/support/time.h>
-
-/* Keep rolling sums of a user-defined statistic (containing a number of
-   measurements) over a a number of time intervals ("windows"). For example,
-   you can use a window_stats object to answer questions such as
-   "Approximately how many RPCs/s did I receive over the past minute, and
-   approximately how many bytes did I send out over that period?".
-
-   The type of data to record, and the time intervals to keep are specified
-   when creating the object via a call to census_window_stats_create().
-
-   A window's interval is divided into one or more "buckets"; the interval
-   must be divisible by the number of buckets. Internally, these buckets
-   control the granularity of window_stats' measurements. Increasing the
-   number of buckets lets the object respond more quickly to changes in the
-   overall rate of data added into the object, at the cost of additional
-   memory usage.
-
-   Here's some code which keeps one minute/hour measurements for two values
-   (latency in seconds and bytes transferred), with each interval divided into
-   4 buckets.
-
-    typedef struct my_stat {
-      double latency;
-      int bytes;
-    } my_stat;
-
-    void add_my_stat(void* base, const void* addme) {
-      my_stat* b = (my_stat*)base;
-      const my_stat* a = (const my_stat*)addme;
-      b->latency += a->latency;
-      b->bytes += a->bytes;
-    }
-
-    void add_proportion_my_stat(double p, void* base, const void* addme) {
-      (my_stat*)result->latency += p * (const my_stat*)base->latency;
-      (my_stat*)result->bytes += p * (const my_stat*)base->bytes;
-    }
-
-    #define kNumIntervals 2
-    #define kMinInterval 0
-    #define kHourInterval 1
-    #define kNumBuckets 4
-
-    const struct census_window_stats_stat_info kMyStatInfo
-        = { sizeof(my_stat), NULL, add_my_stat, add_proportion_my_stat };
-    gpr_timespec intervals[kNumIntervals] = {{60, 0}, {3600, 0}};
-    my_stat stat;
-    my_stat sums[kNumIntervals];
-    census_window_stats_sums result[kNumIntervals];
-    struct census_window_stats* stats
-        = census_window_stats_create(kNumIntervals, intervals, kNumBuckets,
-                                     &kMyStatInfo);
-    // Record a new event, taking 15.3ms, transferring 1784 bytes.
-    stat.latency = 0.153;
-    stat.bytes = 1784;
-    census_window_stats_add(stats, gpr_now(GPR_CLOCK_REALTIME), &stat);
-    // Get sums and print them out
-    result[kMinInterval].statistic = &sums[kMinInterval];
-    result[kHourInterval].statistic = &sums[kHourInterval];
-    census_window_stats_get_sums(stats, gpr_now(GPR_CLOCK_REALTIME), result);
-    printf("%d events/min, average time %gs, average bytes %g\n",
-           result[kMinInterval].count,
-           (my_stat*)result[kMinInterval].statistic->latency /
-             result[kMinInterval].count,
-           (my_stat*)result[kMinInterval].statistic->bytes /
-             result[kMinInterval].count
-          );
-    printf("%d events/hr, average time %gs, average bytes %g\n",
-           result[kHourInterval].count,
-           (my_stat*)result[kHourInterval].statistic->latency /
-             result[kHourInterval].count,
-           (my_stat*)result[kHourInterval].statistic->bytes /
-             result[kHourInterval].count
-          );
-*/
-
-/* Opaque structure for representing window_stats object */
-struct census_window_stats;
-
-/* Information provided by API user on the information they want to record */
-typedef struct census_window_stats_stat_info {
-  /* Number of bytes in user-defined object. */
-  size_t stat_size;
-  /* Function to initialize a user-defined statistics object. If this is set
-   * to NULL, then the object will be zero-initialized. */
-  void (*stat_initialize)(void *stat);
-  /* Function to add one user-defined statistics object ('addme') to 'base' */
-  void (*stat_add)(void *base, const void *addme);
-  /* As for previous function, but only add a proportion 'p'. This API will
-     currently only use 'p' values in the range [0,1], but other values are
-     possible in the future, and should be supported. */
-  void (*stat_add_proportion)(double p, void *base, const void *addme);
-} census_window_stats_stat_info;
-
-/* Create a new window_stats object. 'nintervals' is the number of
-   'intervals', and must be >=1. 'granularity' is the number of buckets, with
-   a larger number using more memory, but providing greater accuracy of
-   results. 'granularity should be > 2. We also require that each interval be
-   at least 10 * 'granularity' nanoseconds in size. 'stat_info' contains
-   information about the statistic to be gathered. Intervals greater than ~192
-   years will be treated as essentially infinite in size. This function will
-   GPR_ASSERT() if the object cannot be created or any of the parameters have
-   invalid values. This function is thread-safe. */
-struct census_window_stats *census_window_stats_create(
-    int nintervals, const gpr_timespec intervals[], int granularity,
-    const census_window_stats_stat_info *stat_info);
-
-/* Add a new measurement (in 'stat_value'), as of a given time ('when').
-   This function is thread-compatible. */
-void census_window_stats_add(struct census_window_stats *wstats,
-                             const gpr_timespec when, const void *stat_value);
-
-/* Structure used to record a single intervals sum for a given statistic */
-typedef struct census_window_stats_sum {
-  /* Total count of samples. Note that because some internal interpolation
-     is performed, the count of samples returned for each interval may not be an
-     integral value. */
-  double count;
-  /* Sum for statistic */
-  void *statistic;
-} census_window_stats_sums;
-
-/* Retrieve a set of all values stored in a window_stats object 'wstats'. The
-   number of 'sums' MUST be the same as the number 'nintervals' used in
-   census_window_stats_create(). This function is thread-compatible. */
-void census_window_stats_get_sums(const struct census_window_stats *wstats,
-                                  const gpr_timespec when,
-                                  struct census_window_stats_sum sums[]);
-
-/* Destroy a window_stats object. Once this function has been called, the
-   object will no longer be usable from any of the above functions (and
-   calling them will most likely result in a NULL-pointer dereference or
-   assertion failure). This function is thread-compatible. */
-void census_window_stats_destroy(struct census_window_stats *wstats);
-
-#endif /* GRPC_CORE_LIB_STATISTICS_WINDOW_STATS_H */
diff --git a/src/core/lib/surface/init.c b/src/core/lib/surface/init.c
index 566b030912..aca4ce9d07 100644
--- a/src/core/lib/surface/init.c
+++ b/src/core/lib/surface/init.c
@@ -39,9 +39,7 @@
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/time.h>
-/* TODO(ctiller): find another way? - better not to include census here */
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
-#include "src/core/lib/census/grpc_plugin.h"
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/channel/client_channel.h"
 #include "src/core/lib/channel/compress_filter.h"
@@ -50,8 +48,6 @@
 #include "src/core/lib/channel/http_server_filter.h"
 #include "src/core/lib/client_config/lb_policy_registry.h"
 #include "src/core/lib/client_config/resolver_registry.h"
-#include "src/core/lib/client_config/resolvers/dns_resolver.h"
-#include "src/core/lib/client_config/resolvers/sockaddr_resolver.h"
 #include "src/core/lib/client_config/subchannel.h"
 #include "src/core/lib/client_config/subchannel_index.h"
 #include "src/core/lib/debug/trace.h"
@@ -85,8 +81,6 @@ static int g_initializations;
 static void do_basic_init(void) {
   gpr_mu_init(&g_init_mu);
   grpc_register_built_in_plugins();
-  /* TODO(ctiller): ideally remove this strict linkage */
-  grpc_register_plugin(census_grpc_plugin_init, census_grpc_plugin_destroy);
   g_initializations = 0;
 }
 
@@ -169,12 +163,6 @@ void grpc_init(void) {
     grpc_channel_init_init();
     grpc_lb_policy_registry_init();
     grpc_resolver_registry_init(GRPC_DEFAULT_NAME_PREFIX);
-    grpc_register_resolver_type(grpc_dns_resolver_factory_create());
-    grpc_register_resolver_type(grpc_ipv4_resolver_factory_create());
-    grpc_register_resolver_type(grpc_ipv6_resolver_factory_create());
-#ifdef GPR_HAVE_UNIX_SOCKET
-    grpc_register_resolver_type(grpc_unix_resolver_factory_create());
-#endif
     grpc_register_tracer("api", &grpc_api_trace);
     grpc_register_tracer("channel", &grpc_trace_channel);
     grpc_register_tracer("http", &grpc_http_trace);