Merge branch 'connected-subchannel' into ping-ping-ping-ping-ping-ping-ping-ping-ping

38 files changed, 290 insertions, 457 deletions

diff --git a/src/core/census/grpc_filter.c b/src/core/census/grpc_filter.c
index 7a6ce30612..8f18cd503e 100644
--- a/src/core/census/grpc_filter.c
+++ b/src/core/census/grpc_filter.c
@@ -43,7 +43,6 @@
 #include <grpc/support/time.h>
 
 #include "src/core/channel/channel_stack.h"
-#include "src/core/channel/noop_filter.h"
 #include "src/core/statistics/census_interface.h"
 #include "src/core/statistics/census_rpc_stats.h"
 #include "src/core/transport/static_metadata.h"
diff --git a/src/core/channel/http_server_filter.c b/src/core/channel/http_server_filter.c
index 647621cc4f..ae8660da92 100644
--- a/src/core/channel/http_server_filter.c
+++ b/src/core/channel/http_server_filter.c
@@ -124,7 +124,6 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
        omitted */
     grpc_mdelem *authority = grpc_mdelem_from_metadata_strings(
         GRPC_MDSTR_AUTHORITY, GRPC_MDSTR_REF(md->value));
-    GRPC_MDELEM_UNREF(md);
     calld->seen_authority = 1;
     return authority;
   } else {
diff --git a/src/core/channel/noop_filter.c b/src/core/channel/noop_filter.c
deleted file mode 100644
index 2fbf1c06bb..0000000000
--- a/src/core/channel/noop_filter.c
+++ /dev/null
@@ -1,118 +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/channel/noop_filter.h"
-#include <grpc/support/log.h>
-
-typedef struct call_data {
-  int unused; /* C89 requires at least one struct element */
-} call_data;
-
-typedef struct channel_data {
-  int unused; /* C89 requires at least one struct element */
-} channel_data;
-
-/* used to silence 'variable not used' warnings */
-static void ignore_unused(void *ignored) {}
-
-static void noop_mutate_op(grpc_call_element *elem,
-                           grpc_transport_stream_op *op) {
-  /* grab pointers to our data from the call element */
-  call_data *calld = elem->call_data;
-  channel_data *channeld = elem->channel_data;
-
-  ignore_unused(calld);
-  ignore_unused(channeld);
-
-  /* do nothing */
-}
-
-/* Called either:
-     - in response to an API call (or similar) from above, to send something
-     - a network event (or similar) from below, to receive something
-   op contains type and call direction information, in addition to the data
-   that is being sent or received. */
-static void noop_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
-                                           grpc_call_element *elem,
-                                           grpc_transport_stream_op *op) {
-  noop_mutate_op(elem, op);
-
-  /* pass control down the stack */
-  grpc_call_next_op(exec_ctx, elem, op);
-}
-
-/* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
-  /* grab pointers to our data from the call element */
-  call_data *calld = elem->call_data;
-  channel_data *channeld = elem->channel_data;
-
-  /* initialize members */
-  calld->unused = channeld->unused;
-}
-
-/* Destructor for call_data */
-static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_call_element *elem) {}
-
-/* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  /* The last filter tends to be implemented differently to
-     handle the case that there's no 'next' filter to call on the down
-     path */
-  GPR_ASSERT(!args->is_last);
-
-  /* initialize members */
-  channeld->unused = 0;
-}
-
-/* Destructor for channel data */
-static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
-                                 grpc_channel_element *elem) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  ignore_unused(channeld);
-}
-
-const grpc_channel_filter grpc_no_op_filter = {
-    noop_start_transport_stream_op, grpc_channel_next_op, sizeof(call_data),
-    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
-    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
-    grpc_call_next_get_peer, "no-op"};
diff --git a/src/core/channel/noop_filter.h b/src/core/channel/noop_filter.h
deleted file mode 100644
index ded9b33117..0000000000
--- a/src/core/channel/noop_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_INTERNAL_CORE_CHANNEL_NOOP_FILTER_H
-#define GRPC_INTERNAL_CORE_CHANNEL_NOOP_FILTER_H
-
-#include "src/core/channel/channel_stack.h"
-
-/* No-op filter: simply takes everything it's given, and passes it on to the
-   next filter. Exists simply as a starting point that others can take and
-   customize for their own filters */
-extern const grpc_channel_filter grpc_no_op_filter;
-
-#endif /* GRPC_INTERNAL_CORE_CHANNEL_NOOP_FILTER_H */
diff --git a/src/core/client_config/resolvers/dns_resolver.c b/src/core/client_config/resolvers/dns_resolver.c
index a467340ba2..28ca30b946 100644
--- a/src/core/client_config/resolvers/dns_resolver.c
+++ b/src/core/client_config/resolvers/dns_resolver.c
@@ -40,7 +40,6 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/client_config/lb_policy_registry.h"
-#include "src/core/client_config/subchannel_factory_decorators/add_channel_arg.h"
 #include "src/core/iomgr/resolve_address.h"
 #include "src/core/support/string.h"
 
diff --git a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c
deleted file mode 100644
index 585e465fa4..0000000000
--- a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.c
+++ /dev/null
@@ -1,43 +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/client_config/subchannel_factory_decorators/add_channel_arg.h"
-#include "src/core/client_config/subchannel_factory_decorators/merge_channel_args.h"
-
-grpc_subchannel_factory *grpc_subchannel_factory_add_channel_arg(
-    grpc_subchannel_factory *input, const grpc_arg *arg) {
-  grpc_channel_args args;
-  args.num_args = 1;
-  args.args = (grpc_arg *)arg;
-  return grpc_subchannel_factory_merge_channel_args(input, &args);
-}
diff --git a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h b/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h
deleted file mode 100644
index 76a535ebed..0000000000
--- a/src/core/client_config/subchannel_factory_decorators/add_channel_arg.h
+++ /dev/null
@@ -1,46 +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_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H
-#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H
-
-#include "src/core/client_config/subchannel_factory.h"
-
-/** Takes a subchannel factory, returns a new one that mutates incoming
-    channel_args by adding a new argument; ownership of input, arg is retained
-    by the caller. */
-grpc_subchannel_factory *grpc_subchannel_factory_add_channel_arg(
-    grpc_subchannel_factory *input, const grpc_arg *arg);
-
-#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_ADD_CHANNEL_ARG_H \
-        */
diff --git a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c
deleted file mode 100644
index cd25fdcf0f..0000000000
--- a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.c
+++ /dev/null
@@ -1,86 +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/client_config/subchannel_factory_decorators/merge_channel_args.h"
-#include <grpc/support/alloc.h>
-#include "src/core/channel/channel_args.h"
-
-typedef struct {
-  grpc_subchannel_factory base;
-  gpr_refcount refs;
-  grpc_subchannel_factory *wrapped;
-  grpc_channel_args *merge_args;
-} merge_args_factory;
-
-static void merge_args_factory_ref(grpc_subchannel_factory *scf) {
-  merge_args_factory *f = (merge_args_factory *)scf;
-  gpr_ref(&f->refs);
-}
-
-static void merge_args_factory_unref(grpc_exec_ctx *exec_ctx,
-                                     grpc_subchannel_factory *scf) {
-  merge_args_factory *f = (merge_args_factory *)scf;
-  if (gpr_unref(&f->refs)) {
-    grpc_subchannel_factory_unref(exec_ctx, f->wrapped);
-    grpc_channel_args_destroy(f->merge_args);
-    gpr_free(f);
-  }
-}
-
-static grpc_subchannel *merge_args_factory_create_subchannel(
-    grpc_exec_ctx *exec_ctx, grpc_subchannel_factory *scf,
-    grpc_subchannel_args *args) {
-  merge_args_factory *f = (merge_args_factory *)scf;
-  grpc_channel_args *final_args =
-      grpc_channel_args_merge(args->args, f->merge_args);
-  grpc_subchannel *s;
-  args->args = final_args;
-  s = grpc_subchannel_factory_create_subchannel(exec_ctx, f->wrapped, args);
-  grpc_channel_args_destroy(final_args);
-  return s;
-}
-
-static const grpc_subchannel_factory_vtable merge_args_factory_vtable = {
-    merge_args_factory_ref, merge_args_factory_unref,
-    merge_args_factory_create_subchannel};
-
-grpc_subchannel_factory *grpc_subchannel_factory_merge_channel_args(
-    grpc_subchannel_factory *input, const grpc_channel_args *args) {
-  merge_args_factory *f = gpr_malloc(sizeof(*f));
-  f->base.vtable = &merge_args_factory_vtable;
-  gpr_ref_init(&f->refs, 1);
-  grpc_subchannel_factory_ref(input);
-  f->wrapped = input;
-  f->merge_args = grpc_channel_args_copy(args);
-  return &f->base;
-}
diff --git a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h b/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h
deleted file mode 100644
index a9e1691871..0000000000
--- a/src/core/client_config/subchannel_factory_decorators/merge_channel_args.h
+++ /dev/null
@@ -1,46 +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_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H
-#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H
-
-#include "src/core/client_config/subchannel_factory.h"
-
-/** Takes a subchannel factory, returns a new one that mutates incoming
-    channel_args by adding a new argument; ownership of input, args is retained
-    by the caller. */
-grpc_subchannel_factory *grpc_subchannel_factory_merge_channel_args(
-    grpc_subchannel_factory *input, const grpc_channel_args *args);
-
-#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_DECORATORS_MERGE_CHANNEL_ARGS_H \
-        */
diff --git a/src/core/compression/message_compress.c b/src/core/compression/message_compress.c
index 209c1f0ff1..a723c47819 100644
--- a/src/core/compression/message_compress.c
+++ b/src/core/compression/message_compress.c
@@ -91,6 +91,14 @@ error:
   return 0;
 }
 
+static void *zalloc_gpr(void* opaque, unsigned int items, unsigned int size) {
+  return gpr_malloc(items * size);
+}
+
+static void zfree_gpr(void* opaque, void *address) {
+  gpr_free(address);
+}
+
 static int zlib_compress(gpr_slice_buffer* input, gpr_slice_buffer* output,
                          int gzip) {
   z_stream zs;
@@ -99,6 +107,8 @@ static int zlib_compress(gpr_slice_buffer* input, gpr_slice_buffer* output,
   size_t count_before = output->count;
   size_t length_before = output->length;
   memset(&zs, 0, sizeof(zs));
+  zs.zalloc = zalloc_gpr;
+  zs.zfree = zfree_gpr;
   r = deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 15 | (gzip ? 16 : 0),
                    8, Z_DEFAULT_STRATEGY);
   if (r != Z_OK) {
@@ -125,6 +135,8 @@ static int zlib_decompress(gpr_slice_buffer* input, gpr_slice_buffer* output,
   size_t count_before = output->count;
   size_t length_before = output->length;
   memset(&zs, 0, sizeof(zs));
+  zs.zalloc = zalloc_gpr;
+  zs.zfree = zfree_gpr;
   r = inflateInit2(&zs, 15 | (gzip ? 16 : 0));
   if (r != Z_OK) {
     gpr_log(GPR_ERROR, "inflateInit2 returns %d", r);
@@ -150,7 +162,7 @@ static int copy(gpr_slice_buffer* input, gpr_slice_buffer* output) {
   return 1;
 }
 
-int compress_inner(grpc_compression_algorithm algorithm,
+static int compress_inner(grpc_compression_algorithm algorithm,
                    gpr_slice_buffer* input, gpr_slice_buffer* output) {
   switch (algorithm) {
     case GRPC_COMPRESS_NONE:
diff --git a/src/core/iomgr/tcp_server_posix.c b/src/core/iomgr/tcp_server_posix.c
index a89ee02d34..b758702da8 100644
--- a/src/core/iomgr/tcp_server_posix.c
+++ b/src/core/iomgr/tcp_server_posix.c
@@ -411,7 +411,6 @@ static grpc_tcp_listener *add_socket_to_server(grpc_tcp_server *s, int fd,
 
 grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
                                             const void *addr, size_t addr_len) {
-  int allocated_port = -1;
   grpc_tcp_listener *sp;
   grpc_tcp_listener *sp2 = NULL;
   int fd;
@@ -464,14 +463,13 @@ grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
     addr_len = sizeof(wild6);
     fd = grpc_create_dualstack_socket(addr, SOCK_STREAM, 0, &dsmode);
     sp = add_socket_to_server(s, fd, addr, addr_len);
-    allocated_port = sp->port;
     if (fd >= 0 && dsmode == GRPC_DSMODE_DUALSTACK) {
       goto done;
     }
 
     /* If we didn't get a dualstack socket, also listen on 0.0.0.0. */
-    if (port == 0 && allocated_port > 0) {
-      grpc_sockaddr_set_port((struct sockaddr *)&wild4, allocated_port);
+    if (port == 0 && sp != NULL) {
+      grpc_sockaddr_set_port((struct sockaddr *)&wild4, sp->port);
       sp2 = sp;
     }
     addr = (struct sockaddr *)&wild4;
@@ -488,8 +486,8 @@ grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
     addr_len = sizeof(addr4_copy);
   }
   sp = add_socket_to_server(s, fd, addr, addr_len);
-  sp->sibling = sp2;
-  if (sp2) sp2->is_sibling = 1;
+  if (sp != NULL) sp->sibling = sp2;
+  if (sp2 != NULL) sp2->is_sibling = 1;
 
 done:
   gpr_free(allocated_addr);
diff --git a/src/core/iomgr/tcp_windows.c b/src/core/iomgr/tcp_windows.c
index 5ff78231bd..6915cb2f49 100644
--- a/src/core/iomgr/tcp_windows.c
+++ b/src/core/iomgr/tcp_windows.c
@@ -197,7 +197,7 @@ static void win_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
 
   tcp->read_slice = gpr_slice_malloc(8192);
 
-  buffer.len = GPR_SLICE_LENGTH(tcp->read_slice);
+  buffer.len = (ULONG)GPR_SLICE_LENGTH(tcp->read_slice);  // we know slice size fits in 32bit.
   buffer.buf = (char *)GPR_SLICE_START_PTR(tcp->read_slice);
 
   TCP_REF(tcp, "read");
@@ -273,6 +273,7 @@ static void win_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
   WSABUF local_buffers[16];
   WSABUF *allocated = NULL;
   WSABUF *buffers = local_buffers;
+  size_t len;
 
   if (tcp->shutting_down) {
     grpc_exec_ctx_enqueue(exec_ctx, cb, 0);
@@ -281,19 +282,21 @@ static void win_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
 
   tcp->write_cb = cb;
   tcp->write_slices = slices;
-
+  GPR_ASSERT(tcp->write_slices->count <= UINT_MAX);
   if (tcp->write_slices->count > GPR_ARRAY_SIZE(local_buffers)) {
     buffers = (WSABUF *)gpr_malloc(sizeof(WSABUF) * tcp->write_slices->count);
     allocated = buffers;
   }
 
   for (i = 0; i < tcp->write_slices->count; i++) {
-    buffers[i].len = GPR_SLICE_LENGTH(tcp->write_slices->slices[i]);
+    len = GPR_SLICE_LENGTH(tcp->write_slices->slices[i]);
+    GPR_ASSERT(len <= ULONG_MAX);
+    buffers[i].len = (ULONG) len;
     buffers[i].buf = (char *)GPR_SLICE_START_PTR(tcp->write_slices->slices[i]);
   }
 
   /* First, let's try a synchronous, non-blocking write. */
-  status = WSASend(socket->socket, buffers, tcp->write_slices->count,
+  status = WSASend(socket->socket, buffers, (DWORD)tcp->write_slices->count,
                    &bytes_sent, 0, NULL, NULL);
   info->wsa_error = status == 0 ? 0 : WSAGetLastError();
 
@@ -322,7 +325,7 @@ static void win_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
   /* If we got a WSAEWOULDBLOCK earlier, then we need to re-do the same
      operation, this time asynchronously. */
   memset(&socket->write_info.overlapped, 0, sizeof(OVERLAPPED));
-  status = WSASend(socket->socket, buffers, tcp->write_slices->count,
+  status = WSASend(socket->socket, buffers, (DWORD)tcp->write_slices->count,
                    &bytes_sent, 0, &socket->write_info.overlapped, NULL);
   if (allocated) gpr_free(allocated);
 
diff --git a/src/core/security/credentials.h b/src/core/security/credentials.h
index 6d45895e77..3cd652cd57 100644
--- a/src/core/security/credentials.h
+++ b/src/core/security/credentials.h
@@ -93,6 +93,14 @@ typedef enum {
 /* It is the caller's responsibility to gpr_free the result if not NULL. */
 char *grpc_get_well_known_google_credentials_file_path(void);
 
+/* Implementation function for the different platforms. */
+char *grpc_get_well_known_google_credentials_file_path_impl(void);
+
+/* Override for testing only. Not thread-safe */
+typedef char *(*grpc_well_known_credentials_path_getter)(void);
+void grpc_override_well_known_credentials_path_getter(
+    grpc_well_known_credentials_path_getter getter);
+
 /* --- grpc_channel_credentials. --- */
 
 typedef struct {
@@ -201,6 +209,7 @@ grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
     const struct grpc_httpcli_response *response,
     grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime);
+
 void grpc_flush_cached_google_default_credentials(void);
 
 /* Metadata-only credentials with the specified key and value where
diff --git a/src/core/security/credentials_posix.c b/src/core/security/credentials_posix.c
index 20f67a7f14..0c92bd4a96 100644
--- a/src/core/security/credentials_posix.c
+++ b/src/core/security/credentials_posix.c
@@ -44,7 +44,7 @@
 #include "src/core/support/env.h"
 #include "src/core/support/string.h"
 
-char *grpc_get_well_known_google_credentials_file_path(void) {
+char *grpc_get_well_known_google_credentials_file_path_impl(void) {
   char *result = NULL;
   char *home = gpr_getenv("HOME");
   if (home == NULL) {
diff --git a/src/core/security/credentials_win32.c b/src/core/security/credentials_win32.c
index 92dfd9bdfe..8ee9f706a1 100644
--- a/src/core/security/credentials_win32.c
+++ b/src/core/security/credentials_win32.c
@@ -44,7 +44,7 @@
 #include "src/core/support/env.h"
 #include "src/core/support/string.h"
 
-char *grpc_get_well_known_google_credentials_file_path(void) {
+char *grpc_get_well_known_google_credentials_file_path_impl(void) {
   char *result = NULL;
   char *appdata_path = gpr_getenv("APPDATA");
   if (appdata_path == NULL) {
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index 6a54fe4e47..5385e41130 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -241,5 +241,20 @@ void grpc_flush_cached_google_default_credentials(void) {
     grpc_channel_credentials_unref(default_credentials);
     default_credentials = NULL;
   }
+  compute_engine_detection_done = 0;
   gpr_mu_unlock(&g_mu);
 }
+
+/* -- Well known credentials path. -- */
+
+static grpc_well_known_credentials_path_getter creds_path_getter = NULL;
+
+char *grpc_get_well_known_google_credentials_file_path(void) {
+  if (creds_path_getter != NULL) return creds_path_getter();
+  return grpc_get_well_known_google_credentials_file_path_impl();
+}
+
+void grpc_override_well_known_credentials_path_getter(
+    grpc_well_known_credentials_path_getter getter) {
+  creds_path_getter = getter;
+}
diff --git a/src/core/security/json_token.c b/src/core/security/json_token.c
index 021912f333..92775d885d 100644
--- a/src/core/security/json_token.c
+++ b/src/core/security/json_token.c
@@ -215,8 +215,8 @@ static char *encoded_jwt_claim(const grpc_auth_json_key *json_key,
     gpr_log(GPR_INFO, "Cropping token lifetime to maximum allowed value.");
     expiration = gpr_time_add(now, grpc_max_auth_token_lifetime);
   }
-  gpr_ltoa(now.tv_sec, now_str);
-  gpr_ltoa(expiration.tv_sec, expiration_str);
+  gpr_int64toa(now.tv_sec, now_str);
+  gpr_int64toa(expiration.tv_sec, expiration_str);
 
   child =
       create_child(NULL, json, "iss", json_key->client_email, GRPC_JSON_STRING);
diff --git a/src/core/support/alloc.c b/src/core/support/alloc.c
index bfcb77956b..ca72379b1d 100644
--- a/src/core/support/alloc.c
+++ b/src/core/support/alloc.c
@@ -34,13 +34,27 @@
 #include <grpc/support/alloc.h>
 
 #include <stdlib.h>
+#include <grpc/support/log.h>
 #include <grpc/support/port_platform.h>
 #include "src/core/profiling/timers.h"
 
+static gpr_allocation_functions g_alloc_functions = {malloc, realloc, free};
+
+gpr_allocation_functions gpr_get_allocation_functions() {
+  return g_alloc_functions;
+}
+
+void gpr_set_allocation_functions(gpr_allocation_functions functions) {
+  GPR_ASSERT(functions.malloc_fn != NULL);
+  GPR_ASSERT(functions.realloc_fn != NULL);
+  GPR_ASSERT(functions.free_fn != NULL);
+  g_alloc_functions = functions;
+}
+
 void *gpr_malloc(size_t size) {
   void *p;
   GPR_TIMER_BEGIN("gpr_malloc", 0);
-  p = malloc(size);
+  p = g_alloc_functions.malloc_fn(size);
   if (!p) {
     abort();
   }
@@ -50,13 +64,13 @@ void *gpr_malloc(size_t size) {
 
 void gpr_free(void *p) {
   GPR_TIMER_BEGIN("gpr_free", 0);
-  free(p);
+  g_alloc_functions.free_fn(p);
   GPR_TIMER_END("gpr_free", 0);
 }
 
 void *gpr_realloc(void *p, size_t size) {
   GPR_TIMER_BEGIN("gpr_realloc", 0);
-  p = realloc(p, size);
+  p = g_alloc_functions.realloc_fn(p, size);
   if (!p) {
     abort();
   }
diff --git a/src/core/support/string.c b/src/core/support/string.c
index e0ffeb8a4a..46a7ca3d46 100644
--- a/src/core/support/string.c
+++ b/src/core/support/string.c
@@ -153,8 +153,8 @@ void gpr_reverse_bytes(char *str, int len) {
 }
 
 int gpr_ltoa(long value, char *string) {
+  long sign;
   int i = 0;
-  int neg = value < 0;
 
   if (value == 0) {
     string[0] = '0';
@@ -162,12 +162,33 @@ int gpr_ltoa(long value, char *string) {
     return 1;
   }
 
-  if (neg) value = -value;
+  sign = value < 0 ? -1 : 1;
   while (value) {
-    string[i++] = (char)('0' + value % 10);
+    string[i++] = (char)('0' + sign * (value % 10));
     value /= 10;
   }
-  if (neg) string[i++] = '-';
+  if (sign < 0) string[i++] = '-';
+  gpr_reverse_bytes(string, i);
+  string[i] = 0;
+  return i;
+}
+
+int gpr_int64toa(gpr_int64 value, char *string) {
+  gpr_int64 sign;
+  int i = 0;
+
+  if (value == 0) {
+    string[0] = '0';
+    string[1] = 0;
+    return 1;
+  }
+
+  sign = value < 0 ? -1 : 1;
+  while (value) {
+    string[i++] = (char)('0' + sign * (value % 10));
+    value /= 10;
+  }
+  if (sign < 0) string[i++] = '-';
   gpr_reverse_bytes(string, i);
   string[i] = 0;
   return i;
diff --git a/src/core/support/string.h b/src/core/support/string.h
index a28e00fd3e..9b604ac5bf 100644
--- a/src/core/support/string.h
+++ b/src/core/support/string.h
@@ -70,6 +70,16 @@ int gpr_parse_bytes_to_uint32(const char *data, size_t length,
    output must be at least GPR_LTOA_MIN_BUFSIZE bytes long. */
 int gpr_ltoa(long value, char *output);
 
+/* Minimum buffer size for calling int64toa */
+#define GPR_INT64TOA_MIN_BUFSIZE (3 * sizeof(gpr_int64))
+
+/* Convert an int64 to a string in base 10; returns the length of the
+output string (or 0 on failure).
+output must be at least GPR_INT64TOA_MIN_BUFSIZE bytes long.
+NOTE: This function ensures sufficient bit width even on Win x64,
+where long is 32bit is size.*/
+int gpr_int64toa(gpr_int64 value, char *output);
+
 /* Reverse a run of bytes */
 void gpr_reverse_bytes(char *str, int len);
 
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index b4959069c6..573a0e742f 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -112,7 +112,7 @@ grpc_channel *grpc_channel_create_from_filters(
         }
       } else if (0 == strcmp(args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
         if (args->args[i].type != GRPC_ARG_STRING) {
-          gpr_log(GPR_ERROR, "%s: must be an string",
+          gpr_log(GPR_ERROR, "%s ignored: it must be a string",
                   GRPC_ARG_DEFAULT_AUTHORITY);
         } else {
           if (channel->default_authority) {
@@ -125,13 +125,14 @@ grpc_channel *grpc_channel_create_from_filters(
       } else if (0 ==
                  strcmp(args->args[i].key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
         if (args->args[i].type != GRPC_ARG_STRING) {
-          gpr_log(GPR_ERROR, "%s: must be an string",
+          gpr_log(GPR_ERROR, "%s ignored: it must be a string",
                   GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
         } else {
           if (channel->default_authority) {
             /* other ways of setting this (notably ssl) take precedence */
-            gpr_log(GPR_ERROR, "%s: default host already set some other way",
-                    GRPC_ARG_DEFAULT_AUTHORITY);
+            gpr_log(GPR_ERROR,
+                    "%s ignored: default host already set some other way",
+                    GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
           } else {
             channel->default_authority = grpc_mdelem_from_strings(
                 ":authority", args->args[i].value.string);
diff --git a/src/core/surface/channel_create.c b/src/core/surface/channel_create.c
index 8970b56eea..97ec23408f 100644
--- a/src/core/surface/channel_create.c
+++ b/src/core/surface/channel_create.c
@@ -217,6 +217,9 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
   GRPC_CHANNEL_INTERNAL_REF(f->master, "subchannel_factory");
   resolver = grpc_resolver_create(target, &f->base);
   if (!resolver) {
+    GRPC_CHANNEL_INTERNAL_UNREF(&exec_ctx, f->master, "subchannel_factory");
+    grpc_subchannel_factory_unref(&exec_ctx, &f->base);
+    grpc_exec_ctx_finish(&exec_ctx);
     return NULL;
   }
 
diff --git a/src/core/surface/init.c b/src/core/surface/init.c
index e0106d8f2b..82027af651 100644
--- a/src/core/surface/init.c
+++ b/src/core/surface/init.c
@@ -147,6 +147,7 @@ void grpc_shutdown(void) {
     gpr_timers_global_destroy();
     grpc_tracer_shutdown();
     grpc_resolver_registry_shutdown();
+    grpc_lb_policy_registry_shutdown();
     for (i = 0; i < g_number_of_plugins; i++) {
       if (g_all_of_the_plugins[i].destroy != NULL) {
         g_all_of_the_plugins[i].destroy();
diff --git a/src/core/transport/chttp2/frame_settings.c b/src/core/transport/chttp2/frame_settings.c
index d7c9f7ed69..f03fb45908 100644
--- a/src/core/transport/chttp2/frame_settings.c
+++ b/src/core/transport/chttp2/frame_settings.c
@@ -44,6 +44,8 @@
 #include "src/core/transport/chttp2/http2_errors.h"
 #include "src/core/transport/chttp2_transport.h"
 
+#define MAX_MAX_HEADER_LIST_SIZE (1024*1024*1024)
+
 /* HTTP/2 mandated initial connection settings */
 const grpc_chttp2_setting_parameters
     grpc_chttp2_settings_parameters[GRPC_CHTTP2_NUM_SETTINGS] = {
@@ -60,7 +62,7 @@ const grpc_chttp2_setting_parameters
          GRPC_CHTTP2_FLOW_CONTROL_ERROR},
         {"MAX_FRAME_SIZE", 16384, 16384, 16777215,
          GRPC_CHTTP2_DISCONNECT_ON_INVALID_VALUE, GRPC_CHTTP2_PROTOCOL_ERROR},
-        {"MAX_HEADER_LIST_SIZE", 0xffffffffu, 0, 0xffffffffu,
+        {"MAX_HEADER_LIST_SIZE", MAX_MAX_HEADER_LIST_SIZE, 0, MAX_MAX_HEADER_LIST_SIZE,
          GRPC_CHTTP2_CLAMP_INVALID_VALUE, GRPC_CHTTP2_PROTOCOL_ERROR},
 };
 
diff --git a/src/core/transport/chttp2/hpack_parser.c b/src/core/transport/chttp2/hpack_parser.c
index 30f0d469e3..fea0000896 100644
--- a/src/core/transport/chttp2/hpack_parser.c
+++ b/src/core/transport/chttp2/hpack_parser.c
@@ -1066,7 +1066,7 @@ static int parse_value4(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
 error:
   gpr_log(GPR_ERROR,
           "integer overflow in hpack integer decoding: have 0x%08x, "
-          "got byte 0x%02x",
+          "got byte 0x%02x on byte 5",
           *p->parsing.value, *cur);
   return parse_error(p, cur, end);
 }
@@ -1091,7 +1091,8 @@ static int parse_value5up(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
 
   gpr_log(GPR_ERROR,
           "integer overflow in hpack integer decoding: have 0x%08x, "
-          "got byte 0x%02x sometime after byte 4");
+          "got byte 0x%02x sometime after byte 5",
+          *p->parsing.value, *cur);
   return parse_error(p, cur, end);
 }
 
diff --git a/src/core/transport/chttp2/parsing.c b/src/core/transport/chttp2/parsing.c
index eb2cb6b4c2..7604e7b681 100644
--- a/src/core/transport/chttp2/parsing.c
+++ b/src/core/transport/chttp2/parsing.c
@@ -604,7 +604,7 @@ static void on_initial_header(void *tp, grpc_mdelem *md) {
                                       cached_timeout)) {
         gpr_log(GPR_ERROR, "Ignoring bad timeout value '%s'",
                 grpc_mdstr_as_c_string(md->value));
-        *cached_timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
+        *cached_timeout = gpr_inf_future(GPR_TIMESPAN);
       }
       grpc_mdelem_set_user_data(md, free_timeout, cached_timeout);
     }
diff --git a/src/core/transport/chttp2/timeout_encoding.c b/src/core/transport/chttp2/timeout_encoding.c
index 8a9b290ecb..cf81c18a20 100644
--- a/src/core/transport/chttp2/timeout_encoding.c
+++ b/src/core/transport/chttp2/timeout_encoding.c
@@ -36,6 +36,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <grpc/support/port_platform.h>
 #include "src/core/support/string.h"
 
 static int round_up(int x, int divisor) {
@@ -57,13 +58,13 @@ static int round_up_to_three_sig_figs(int x) {
 /* encode our minimum viable timeout value */
 static void enc_tiny(char *buffer) { memcpy(buffer, "1n", 3); }
 
-static void enc_ext(char *buffer, long value, char ext) {
-  int n = gpr_ltoa(value, buffer);
+static void enc_ext(char *buffer, gpr_int64 value, char ext) {
+  int n = gpr_int64toa(value, buffer);
   buffer[n] = ext;
   buffer[n + 1] = 0;
 }
 
-static void enc_seconds(char *buffer, long sec) {
+static void enc_seconds(char *buffer, gpr_int64 sec) {
   if (sec % 3600 == 0) {
     enc_ext(buffer, sec / 3600, 'H');
   } else if (sec % 60 == 0) {
diff --git a/src/core/transport/chttp2/varint.h b/src/core/transport/chttp2/varint.h
index 4dfcc76773..970d1e17e2 100644
--- a/src/core/transport/chttp2/varint.h
+++ b/src/core/transport/chttp2/varint.h
@@ -50,7 +50,8 @@ void grpc_chttp2_hpack_write_varint_tail(gpr_uint32 tail_value,
 /* maximum value that can be bitpacked with the opcode if the opcode has a
    prefix
    of length prefix_bits */
-#define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) ((1 << (8 - (prefix_bits))) - 1)
+#define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \
+  ((gpr_uint32)((1 << (8 - (prefix_bits))) - 1))
 
 /* length required to bitpack a value */
 #define GRPC_CHTTP2_VARINT_LENGTH(n, prefix_bits) \
@@ -65,7 +66,7 @@ void grpc_chttp2_hpack_write_varint_tail(gpr_uint32 tail_value,
     if ((length) == 1u) {                                                     \
       (tgt)[0] = (gpr_uint8)((prefix_or) | (n));                              \
     } else {                                                                  \
-      (tgt)[0] = (prefix_or) | GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits);        \
+      (tgt)[0] = (prefix_or) | (gpr_uint8)GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits);        \
       grpc_chttp2_hpack_write_varint_tail(                                    \
           (n)-GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits), (tgt) + 1, (length)-1); \
     }                                                                         \
diff --git a/src/cpp/proto/proto_utils.cc b/src/cpp/proto/proto_utils.cc
index b1330fde7f..898a1d4f58 100644
--- a/src/cpp/proto/proto_utils.cc
+++ b/src/cpp/proto/proto_utils.cc
@@ -33,6 +33,8 @@
 
 #include <grpc++/impl/proto_utils.h>
 
+#include <climits>
+
 #include <grpc/grpc.h>
 #include <grpc/byte_buffer.h>
 #include <grpc/byte_buffer_reader.h>
@@ -70,7 +72,9 @@ class GrpcBufferWriter GRPC_FINAL
       slice_ = gpr_slice_malloc(block_size_);
     }
     *data = GPR_SLICE_START_PTR(slice_);
-    byte_count_ += * size = GPR_SLICE_LENGTH(slice_);
+    // On win x64, int is only 32bit
+    GPR_ASSERT(GPR_SLICE_LENGTH(slice_) <= INT_MAX);
+    byte_count_ += * size = (int)GPR_SLICE_LENGTH(slice_);
     gpr_slice_buffer_add(slice_buffer_, slice_);
     return true;
   }
@@ -124,7 +128,9 @@ class GrpcBufferReader GRPC_FINAL
     }
     gpr_slice_unref(slice_);
     *data = GPR_SLICE_START_PTR(slice_);
-    byte_count_ += * size = GPR_SLICE_LENGTH(slice_);
+    // On win x64, int is only 32bit
+    GPR_ASSERT(GPR_SLICE_LENGTH(slice_) <= INT_MAX);
+    byte_count_ += * size = (int)GPR_SLICE_LENGTH(slice_);
     return true;
   }
 
diff --git a/src/csharp/Grpc.Core.Tests/ChannelTest.cs b/src/csharp/Grpc.Core.Tests/ChannelTest.cs
index f4ae9abefd..ed0ec14df5 100644
--- a/src/csharp/Grpc.Core.Tests/ChannelTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ChannelTest.cs
@@ -48,6 +48,17 @@ namespace Grpc.Core.Tests
         }
 
         [Test]
+        public void Constructor_RejectsDuplicateOptions()
+        {
+            var options = new ChannelOption[]
+            {
+                new ChannelOption(ChannelOptions.PrimaryUserAgentString, "ABC"),
+                new ChannelOption(ChannelOptions.PrimaryUserAgentString, "XYZ")
+            };
+            Assert.Throws(typeof(ArgumentException), () => new Channel("127.0.0.1", ChannelCredentials.Insecure, options));
+        }
+
+        [Test]
         public void State_IdleAfterCreation()
         {
             var channel = new Channel("localhost", ChannelCredentials.Insecure);
diff --git a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
index 25a5a27c8e..b683751bc0 100644
--- a/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
+++ b/src/csharp/Grpc.Core.Tests/ClientServerTest.cs
@@ -201,7 +201,7 @@ namespace Grpc.Core.Tests
             Assert.AreEqual(headers[1].Key, trailers[1].Key);
             CollectionAssert.AreEqual(headers[1].ValueBytes, trailers[1].ValueBytes);
         }
-            
+
         [Test]
         public void UnknownMethodHandler()
         {
@@ -219,18 +219,6 @@ namespace Grpc.Core.Tests
         }
 
         [Test]
-        public void UserAgentStringPresent()
-        {
-            helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
-            {
-                return context.RequestHeaders.Where(entry => entry.Key == "user-agent").Single().Value;
-            });
-
-            string userAgent = Calls.BlockingUnaryCall(helper.CreateUnaryCall(), "abc");
-            Assert.IsTrue(userAgent.StartsWith("grpc-csharp/"));
-        }
-
-        [Test]
         public void PeerInfoPresent()
         {
             helper.UnaryHandler = new UnaryServerMethod<string, string>(async (request, context) =>
diff --git a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
index e5ffa31989..70b83f7fb1 100644
--- a/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
+++ b/src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj
@@ -64,6 +64,7 @@
       <Link>Version.cs</Link>
     </Compile>
     <Compile Include="CallCredentialsTest.cs" />
+    <Compile Include="UserAgentStringTest.cs" />
     <Compile Include="FakeCredentials.cs" />
     <Compile Include="MarshallingErrorsTest.cs" />
     <Compile Include="ChannelCredentialsTest.cs" />
diff --git a/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs b/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs
index 567e04eddc..3047314345 100644
--- a/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs
+++ b/src/csharp/Grpc.Core.Tests/MockServiceHelper.cs
@@ -32,6 +32,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
@@ -52,6 +53,7 @@ namespace Grpc.Core.Tests
 
         readonly string host;
         readonly ServerServiceDefinition serviceDefinition;
+        readonly IEnumerable<ChannelOption> channelOptions;
 
         readonly Method<string, string> unaryMethod;
         readonly Method<string, string> clientStreamingMethod;
@@ -66,9 +68,10 @@ namespace Grpc.Core.Tests
         Server server;
         Channel channel;
 
-        public MockServiceHelper(string host = null, Marshaller<string> marshaller = null)
+        public MockServiceHelper(string host = null, Marshaller<string> marshaller = null, IEnumerable<ChannelOption> channelOptions = null)
         {
             this.host = host ?? "localhost";
+            this.channelOptions = channelOptions;
             marshaller = marshaller ?? Marshallers.StringMarshaller;
 
             unaryMethod = new Method<string, string>(
@@ -154,7 +157,7 @@ namespace Grpc.Core.Tests
         {
             if (channel == null)
             {
-                channel = new Channel(Host, GetServer().Ports.Single().BoundPort, ChannelCredentials.Insecure);
+                channel = new Channel(Host, GetServer().Ports.Single().BoundPort, ChannelCredentials.Insecure, channelOptions);
             }
             return channel;
         }
diff --git a/src/csharp/Grpc.Core.Tests/UserAgentStringTest.cs b/src/csharp/Grpc.Core.Tests/UserAgentStringTest.cs
new file mode 100644
index 0000000000..cc830086a6
--- /dev/null
+++ b/src/csharp/Grpc.Core.Tests/UserAgentStringTest.cs
@@ -0,0 +1,101 @@
+#region Copyright notice and license
+
+// 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.
+
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using Grpc.Core.Profiling;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+
+namespace Grpc.Core.Tests
+{
+    public class UserAgentStringTest
+    {
+        const string Host = "127.0.0.1";
+
+        MockServiceHelper helper;
+        Server server;
+        Channel channel;
+
+        [TearDown]
+        public void Cleanup()
+        {
+            channel.ShutdownAsync().Wait();
+            server.ShutdownAsync().Wait();
+        }
+
+        [Test]
+        public void DefaultUserAgentString()
+        {
+            helper = new MockServiceHelper(Host);
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
+            {
+                var userAgentString = context.RequestHeaders.First(m => (m.Key == "user-agent")).Value;
+                var parts = userAgentString.Split(new [] {' '}, 2);
+                Assert.AreEqual(string.Format("grpc-csharp/{0}", VersionInfo.CurrentVersion), parts[0]);
+                Assert.IsTrue(parts[1].StartsWith("grpc-c/"));
+                return Task.FromResult("PASS");
+            });
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), ""));
+        }
+
+        [Test]
+        public void ApplicationUserAgentString()
+        {
+            helper = new MockServiceHelper(Host,
+                channelOptions: new[] { new ChannelOption(ChannelOptions.PrimaryUserAgentString, "XYZ") });
+            server = helper.GetServer();
+            server.Start();
+            channel = helper.GetChannel();
+            
+            channel = helper.GetChannel();
+            helper.UnaryHandler = new UnaryServerMethod<string, string>((request, context) =>
+            {
+                var userAgentString = context.RequestHeaders.First(m => (m.Key == "user-agent")).Value;
+                var parts = userAgentString.Split(new[] { ' ' }, 3);
+                Assert.AreEqual("XYZ", parts[0]);
+                return Task.FromResult("PASS");
+            });
+            Assert.AreEqual("PASS", Calls.BlockingUnaryCall(helper.CreateUnaryCall(), ""));
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index ec60354639..d8d43c7998 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -32,8 +32,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Runtime.InteropServices;
-using System.Threading;
 using System.Threading.Tasks;
 
 using Grpc.Core.Internal;
@@ -57,7 +55,7 @@ namespace Grpc.Core
         readonly string target;
         readonly GrpcEnvironment environment;
         readonly ChannelSafeHandle handle;
-        readonly List<ChannelOption> options;
+        readonly Dictionary<string, ChannelOption> options;
 
         bool shutdownRequested;
 
@@ -71,12 +69,12 @@ namespace Grpc.Core
         public Channel(string target, ChannelCredentials credentials, IEnumerable<ChannelOption> options = null)
         {
             this.target = Preconditions.CheckNotNull(target, "target");
+            this.options = CreateOptionsDictionary(options);
+            EnsureUserAgentChannelOption(this.options);
             this.environment = GrpcEnvironment.AddRef();
-            this.options = options != null ? new List<ChannelOption>(options) : new List<ChannelOption>();
 
-            EnsureUserAgentChannelOption(this.options);
             using (var nativeCredentials = credentials.ToNativeCredentials())
-            using (var nativeChannelArgs = ChannelOptions.CreateChannelArgs(this.options))
+            using (var nativeChannelArgs = ChannelOptions.CreateChannelArgs(this.options.Values))
             {
                 if (nativeCredentials != null)
                 {
@@ -233,18 +231,36 @@ namespace Grpc.Core
             activeCallCounter.Decrement();
         }
 
-        private static void EnsureUserAgentChannelOption(List<ChannelOption> options)
+        private static void EnsureUserAgentChannelOption(Dictionary<string, ChannelOption> options)
         {
-            if (!options.Any((option) => option.Name == ChannelOptions.PrimaryUserAgentString))
+            var key = ChannelOptions.PrimaryUserAgentString;
+            var userAgentString = "";
+
+            ChannelOption option;
+            if (options.TryGetValue(key, out option))
             {
-                options.Add(new ChannelOption(ChannelOptions.PrimaryUserAgentString, GetUserAgentString()));
-            }
+                // user-provided userAgentString needs to be at the beginning
+                userAgentString = option.StringValue + " ";
+            };
+
+            // TODO(jtattermusch): it would be useful to also provide .NET/mono version.
+            userAgentString += string.Format("grpc-csharp/{0}", VersionInfo.CurrentVersion);
+
+            options[ChannelOptions.PrimaryUserAgentString] = new ChannelOption(key, userAgentString);
         }
 
-        private static string GetUserAgentString()
+        private static Dictionary<string, ChannelOption> CreateOptionsDictionary(IEnumerable<ChannelOption> options)
         {
-            // TODO(jtattermusch): it would be useful to also provide .NET/mono version.
-            return string.Format("grpc-csharp/{0}", VersionInfo.CurrentVersion);
+            var dict = new Dictionary<string, ChannelOption>();
+            if (options == null)
+            {
+                return dict;
+            }
+            foreach (var option in options)
+            {
+                dict.Add(option.Name, option);
+            }
+            return dict;
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/ChannelOptions.cs b/src/csharp/Grpc.Core/ChannelOptions.cs
index f5ef63af54..d70673cf78 100644
--- a/src/csharp/Grpc.Core/ChannelOptions.cs
+++ b/src/csharp/Grpc.Core/ChannelOptions.cs
@@ -169,7 +169,7 @@ namespace Grpc.Core
         /// Creates native object for a collection of channel options.
         /// </summary>
         /// <returns>The native channel arguments.</returns>
-        internal static ChannelArgsSafeHandle CreateChannelArgs(List<ChannelOption> options)
+        internal static ChannelArgsSafeHandle CreateChannelArgs(ICollection<ChannelOption> options)
         {
             if (options == null || options.Count == 0)
             {
@@ -179,9 +179,9 @@ namespace Grpc.Core
             try
             {
                 nativeArgs = ChannelArgsSafeHandle.Create(options.Count);
-                for (int i = 0; i < options.Count; i++)
+                int i = 0;
+                foreach (var option in options)
                 {
-                    var option = options[i];
                     if (option.Type == ChannelOption.OptionType.Integer)
                     {
                         nativeArgs.SetInteger(i, option.Name, option.IntValue);
@@ -194,6 +194,7 @@ namespace Grpc.Core
                     {
                         throw new InvalidOperationException("Unknown option type");
                     }
+                    i++;
                 }
                 return nativeArgs;
             }
diff --git a/src/ruby/pb/test/client.rb b/src/ruby/pb/test/client.rb
index 30550d6cc0..329e2dc98b 100755
--- a/src/ruby/pb/test/client.rb
+++ b/src/ruby/pb/test/client.rb
@@ -160,7 +160,7 @@ end
 # produces a string of null chars (\0) of length l.
 def nulls(l)
   fail 'requires #{l} to be +ve' if l < 0
-  [].pack('x' * l).force_encoding('utf-8')
+  [].pack('x' * l).force_encoding('ascii-8bit')
 end
 
 # a PingPongPlayer implements the ping pong bidi test.
diff --git a/src/ruby/pb/test/server.rb b/src/ruby/pb/test/server.rb
index 67877a191f..851e815222 100755
--- a/src/ruby/pb/test/server.rb
+++ b/src/ruby/pb/test/server.rb
@@ -126,7 +126,7 @@ end
 # produces a string of null chars (\0) of length l.
 def nulls(l)
   fail 'requires #{l} to be +ve' if l < 0
-  [].pack('x' * l).force_encoding('utf-8')
+  [].pack('x' * l).force_encoding('ascii-8bit')
 end
 
 # A EnumeratorQueue wraps a Queue yielding the items added to it via each_item.