Revert "Channel Tracing Implementation; Part 1"

14 files changed, 10 insertions, 592 deletions

diff --git a/src/core/ext/filters/client_channel/client_channel.cc b/src/core/ext/filters/client_channel/client_channel.cc
index bf3911e5ee..bbc5160bec 100644
--- a/src/core/ext/filters/client_channel/client_channel.cc
+++ b/src/core/ext/filters/client_channel/client_channel.cc
@@ -38,12 +38,12 @@
 #include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
 #include "src/core/ext/filters/client_channel/retry_throttle.h"
+#include "src/core/ext/filters/client_channel/status_util.h"
 #include "src/core/ext/filters/client_channel/subchannel.h"
 #include "src/core/ext/filters/deadline/deadline_filter.h"
 #include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
-#include "src/core/lib/channel/status_util.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/inlined_vector.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
diff --git a/src/core/ext/filters/client_channel/method_params.cc b/src/core/ext/filters/client_channel/method_params.cc
index 1f116bb67d..374b87e170 100644
--- a/src/core/ext/filters/client_channel/method_params.cc
+++ b/src/core/ext/filters/client_channel/method_params.cc
@@ -26,7 +26,7 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/method_params.h"
-#include "src/core/lib/channel/status_util.h"
+#include "src/core/ext/filters/client_channel/status_util.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/memory.h"
 
diff --git a/src/core/ext/filters/client_channel/method_params.h b/src/core/ext/filters/client_channel/method_params.h
index 099924edf3..48ece29867 100644
--- a/src/core/ext/filters/client_channel/method_params.h
+++ b/src/core/ext/filters/client_channel/method_params.h
@@ -21,7 +21,7 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/lib/channel/status_util.h"
+#include "src/core/ext/filters/client_channel/status_util.h"
 #include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/exec_ctx.h"  // for grpc_millis
diff --git a/src/core/lib/channel/status_util.cc b/src/core/ext/filters/client_channel/status_util.cc
index 563db40846..11f732ab44 100644
--- a/src/core/lib/channel/status_util.cc
+++ b/src/core/ext/filters/client_channel/status_util.cc
@@ -18,7 +18,7 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/lib/channel/status_util.h"
+#include "src/core/ext/filters/client_channel/status_util.h"
 
 #include "src/core/lib/gpr/useful.h"
 
diff --git a/src/core/lib/channel/status_util.h b/src/core/ext/filters/client_channel/status_util.h
index 5409de6b3c..e018709730 100644
--- a/src/core/lib/channel/status_util.h
+++ b/src/core/ext/filters/client_channel/status_util.h
@@ -16,8 +16,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H
-#define GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H
 
 #include <grpc/support/port_platform.h>
 
@@ -55,4 +55,4 @@ class StatusCodeSet {
 }  // namespace internal
 }  // namespace grpc_core
 
-#endif /* GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H */
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H */
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index d7815fb7e1..cae7cc35e3 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -40,7 +40,6 @@
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gprpp/debug_location.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
-#include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
diff --git a/src/core/lib/channel/channel_trace.cc b/src/core/lib/channel/channel_trace.cc
deleted file mode 100644
index 67d5fd364b..0000000000
--- a/src/core/lib/channel/channel_trace.cc
+++ /dev/null
@@ -1,238 +0,0 @@
-/*
- *
- * Copyright 2017 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#include <grpc/impl/codegen/port_platform.h>
-
-#include "src/core/lib/channel/channel_trace.h"
-
-#include <grpc/grpc.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "src/core/lib/channel/channel_trace_registry.h"
-#include "src/core/lib/channel/status_util.h"
-#include "src/core/lib/gpr/string.h"
-#include "src/core/lib/gpr/useful.h"
-#include "src/core/lib/gprpp/memory.h"
-#include "src/core/lib/iomgr/error.h"
-#include "src/core/lib/slice/slice_internal.h"
-#include "src/core/lib/surface/channel.h"
-#include "src/core/lib/transport/connectivity_state.h"
-#include "src/core/lib/transport/error_utils.h"
-
-namespace grpc_core {
-
-ChannelTrace::TraceEvent::TraceEvent(
-    Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer, ReferencedType type)
-    : severity_(severity),
-      data_(data),
-      timestamp_(grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
-                                         GPR_CLOCK_REALTIME)),
-      next_(nullptr),
-      referenced_tracer_(std::move(referenced_tracer)),
-      referenced_type_(type) {}
-
-ChannelTrace::TraceEvent::TraceEvent(Severity severity, grpc_slice data)
-    : severity_(severity),
-      data_(data),
-      timestamp_(grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
-                                         GPR_CLOCK_REALTIME)),
-      next_(nullptr) {}
-
-ChannelTrace::TraceEvent::~TraceEvent() { grpc_slice_unref_internal(data_); }
-
-ChannelTrace::ChannelTrace(size_t max_events)
-    : channel_uuid_(-1),
-      num_events_logged_(0),
-      list_size_(0),
-      max_list_size_(max_events),
-      head_trace_(nullptr),
-      tail_trace_(nullptr) {
-  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
-  gpr_mu_init(&tracer_mu_);
-  channel_uuid_ = grpc_channel_trace_registry_register_channel_trace(this);
-  time_created_ = grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
-                                          GPR_CLOCK_REALTIME);
-}
-
-ChannelTrace::~ChannelTrace() {
-  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
-  TraceEvent* it = head_trace_;
-  while (it != nullptr) {
-    TraceEvent* to_free = it;
-    it = it->next();
-    Delete<TraceEvent>(to_free);
-  }
-  grpc_channel_trace_registry_unregister_channel_trace(channel_uuid_);
-  gpr_mu_destroy(&tracer_mu_);
-}
-
-intptr_t ChannelTrace::GetUuid() const { return channel_uuid_; }
-
-void ChannelTrace::AddTraceEventHelper(TraceEvent* new_trace_event) {
-  ++num_events_logged_;
-  // first event case
-  if (head_trace_ == nullptr) {
-    head_trace_ = tail_trace_ = new_trace_event;
-  }
-  // regular event add case
-  else {
-    tail_trace_->set_next(new_trace_event);
-    tail_trace_ = tail_trace_->next();
-  }
-  ++list_size_;
-  // maybe garbage collect the end
-  if (list_size_ > max_list_size_) {
-    TraceEvent* to_free = head_trace_;
-    head_trace_ = head_trace_->next();
-    Delete<TraceEvent>(to_free);
-    --list_size_;
-  }
-}
-
-void ChannelTrace::AddTraceEvent(Severity severity, grpc_slice data) {
-  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
-  AddTraceEventHelper(New<TraceEvent>(severity, data));
-}
-
-void ChannelTrace::AddTraceEventReferencingChannel(
-    Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer) {
-  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
-  // create and fill up the new event
-  AddTraceEventHelper(
-      New<TraceEvent>(severity, data, std::move(referenced_tracer), Channel));
-}
-
-void ChannelTrace::AddTraceEventReferencingSubchannel(
-    Severity severity, grpc_slice data,
-    RefCountedPtr<ChannelTrace> referenced_tracer) {
-  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
-  // create and fill up the new event
-  AddTraceEventHelper(New<TraceEvent>(
-      severity, data, std::move(referenced_tracer), Subchannel));
-}
-
-namespace {
-
-// returns an allocated string that represents tm according to RFC-3339, and,
-// more specifically, follows:
-// https://developers.google.com/protocol-buffers/docs/proto3#json
-//
-// "Uses RFC 3339, where generated output will always be Z-normalized and uses
-// 0, 3, 6 or 9 fractional digits."
-char* fmt_time(gpr_timespec tm) {
-  char time_buffer[35];
-  char ns_buffer[11];  // '.' + 9 digits of precision
-  struct tm* tm_info = localtime((const time_t*)&tm.tv_sec);
-  strftime(time_buffer, sizeof(time_buffer), "%Y-%m-%dT%H:%M:%S", tm_info);
-  snprintf(ns_buffer, 11, ".%09d", tm.tv_nsec);
-  // This loop trims off trailing zeros by inserting a null character that the
-  // right point. We iterate in chunks of three because we want 0, 3, 6, or 9
-  // fractional digits.
-  for (int i = 7; i >= 1; i -= 3) {
-    if (ns_buffer[i] == '0' && ns_buffer[i + 1] == '0' &&
-        ns_buffer[i + 2] == '0') {
-      ns_buffer[i] = '\0';
-      // Edge case in which all fractional digits were 0.
-      if (i == 1) {
-        ns_buffer[0] = '\0';
-      }
-    } else {
-      break;
-    }
-  }
-  char* full_time_str;
-  gpr_asprintf(&full_time_str, "%s%sZ", time_buffer, ns_buffer);
-  return full_time_str;
-}
-
-const char* severity_string(ChannelTrace::Severity severity) {
-  switch (severity) {
-    case ChannelTrace::Severity::Info:
-      return "CT_INFO";
-    case ChannelTrace::Severity::Warning:
-      return "CT_WARNING";
-    case ChannelTrace::Severity::Error:
-      return "CT_ERROR";
-    default:
-      GPR_UNREACHABLE_CODE(return "CT_UNKNOWN");
-  }
-}
-
-}  // anonymous namespace
-
-void ChannelTrace::TraceEvent::RenderTraceEvent(grpc_json* json) const {
-  grpc_json* json_iterator = nullptr;
-  json_iterator = grpc_json_create_child(json_iterator, json, "description",
-                                         grpc_slice_to_c_string(data_),
-                                         GRPC_JSON_STRING, true);
-  json_iterator = grpc_json_create_child(json_iterator, json, "severity",
-                                         severity_string(severity_),
-                                         GRPC_JSON_STRING, false);
-  json_iterator =
-      grpc_json_create_child(json_iterator, json, "timestamp",
-                             fmt_time(timestamp_), GRPC_JSON_STRING, true);
-  if (referenced_tracer_ != nullptr) {
-    char* uuid_str;
-    gpr_asprintf(&uuid_str, "%" PRIdPTR, referenced_tracer_->channel_uuid_);
-    grpc_json* child_ref = grpc_json_create_child(
-        json_iterator, json,
-        (referenced_type_ == Channel) ? "channelRef" : "subchannelRef", nullptr,
-        GRPC_JSON_OBJECT, false);
-    json_iterator = grpc_json_create_child(
-        nullptr, child_ref,
-        (referenced_type_ == Channel) ? "channelId" : "subchannelId", uuid_str,
-        GRPC_JSON_STRING, true);
-    json_iterator = child_ref;
-  }
-}
-
-char* ChannelTrace::RenderTrace() const {
-  if (!max_list_size_)
-    return nullptr;  // tracing is disabled if max_events == 0
-  grpc_json* json = grpc_json_create(GRPC_JSON_OBJECT);
-  char* num_events_logged_str;
-  gpr_asprintf(&num_events_logged_str, "%" PRId64, num_events_logged_);
-  grpc_json* json_iterator = nullptr;
-  json_iterator =
-      grpc_json_create_child(json_iterator, json, "numEventsLogged",
-                             num_events_logged_str, GRPC_JSON_STRING, true);
-  json_iterator =
-      grpc_json_create_child(json_iterator, json, "creationTime",
-                             fmt_time(time_created_), GRPC_JSON_STRING, true);
-  grpc_json* events = grpc_json_create_child(json_iterator, json, "events",
-                                             nullptr, GRPC_JSON_ARRAY, false);
-  json_iterator = nullptr;
-  TraceEvent* it = head_trace_;
-  while (it != nullptr) {
-    json_iterator = grpc_json_create_child(json_iterator, events, nullptr,
-                                           nullptr, GRPC_JSON_OBJECT, false);
-    it->RenderTraceEvent(json_iterator);
-    it = it->next();
-  }
-  char* json_str = grpc_json_dump_to_string(json, 0);
-  grpc_json_destroy(json);
-  return json_str;
-}
-
-}  // namespace grpc_core
diff --git a/src/core/lib/channel/channel_trace.h b/src/core/lib/channel/channel_trace.h
deleted file mode 100644
index 1df1e585f2..0000000000
--- a/src/core/lib/channel/channel_trace.h
+++ /dev/null
@@ -1,133 +0,0 @@
-/*
- *
- * Copyright 2017 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H
-#define GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H
-
-#include <grpc/impl/codegen/port_platform.h>
-
-#include <grpc/grpc.h>
-#include "src/core/lib/gprpp/ref_counted.h"
-#include "src/core/lib/gprpp/ref_counted_ptr.h"
-#include "src/core/lib/iomgr/error.h"
-#include "src/core/lib/json/json.h"
-
-namespace grpc_core {
-
-// Object used to hold live data for a channel. This data is exposed via the
-// channelz service:
-// https://github.com/grpc/proposal/blob/master/A14-channelz.md
-class ChannelTrace : public RefCounted<ChannelTrace> {
- public:
-  ChannelTrace(size_t max_events);
-  ~ChannelTrace();
-
-  // returns the tracer's uuid
-  intptr_t GetUuid() const;
-
-  enum Severity {
-    Unset = 0,  // never to be used
-    Info,       // we start at 1 to avoid using proto default values
-    Warning,
-    Error
-  };
-
-  // Adds a new trace event to the tracing object
-  //
-  // TODO(ncteisen): as this call is used more and more throughout the gRPC
-  // stack, determine if it makes more sense to accept a char* instead of a
-  // slice.
-  void AddTraceEvent(Severity severity, grpc_slice data);
-
-  // Adds a new trace event to the tracing object. This trace event refers to a
-  // an event on a child of the channel. For example, if this channel has
-  // created a new subchannel, then it would record that with a TraceEvent
-  // referencing the new subchannel.
-  //
-  // TODO(ncteisen): Once channelz is implemented, the events should reference
-  // the overall channelz object, not just the ChannelTrace object.
-  // TODO(ncteisen): as this call is used more and more throughout the gRPC
-  // stack, determine if it makes more sense to accept a char* instead of a
-  // slice.
-  void AddTraceEventReferencingChannel(
-      Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelTrace> referenced_tracer);
-  void AddTraceEventReferencingSubchannel(
-      Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelTrace> referenced_tracer);
-
-  // Returns the tracing data rendered as a grpc json string.
-  // The string is owned by the caller and must be freed.
-  char* RenderTrace() const;
-
- private:
-  // Types of objects that can be references by trace events.
-  enum ReferencedType { Channel, Subchannel };
-  // Private class to encapsulate all the data and bookkeeping needed for a
-  // a trace event.
-  class TraceEvent {
-   public:
-    // Constructor for a TraceEvent that references a different channel.
-    // TODO(ncteisen): once channelz is implemented, this should reference the
-    // overall channelz object, not just the ChannelTrace object
-    TraceEvent(Severity severity, grpc_slice data,
-               RefCountedPtr<ChannelTrace> referenced_tracer,
-               ReferencedType type);
-
-    // Constructor for a TraceEvent that does not reverence a different
-    // channel.
-    TraceEvent(Severity severity, grpc_slice data);
-
-    ~TraceEvent();
-
-    // Renders the data inside of this TraceEvent into a json object. This is
-    // used by the ChannelTrace, when it is rendering itself.
-    void RenderTraceEvent(grpc_json* json) const;
-
-    // set and get for the next_ pointer.
-    TraceEvent* next() const { return next_; }
-    void set_next(TraceEvent* next) { next_ = next; }
-
-   private:
-    Severity severity_;
-    grpc_slice data_;
-    gpr_timespec timestamp_;
-    TraceEvent* next_;
-    // the tracer object for the (sub)channel that this trace event refers to.
-    RefCountedPtr<ChannelTrace> referenced_tracer_;
-    // the type that the referenced tracer points to. Unused if this trace
-    // does not point to any channel or subchannel
-    ReferencedType referenced_type_;
-  };  // TraceEvent
-
-  // Internal helper to add and link in a trace event
-  void AddTraceEventHelper(TraceEvent* new_trace_event);
-
-  gpr_mu tracer_mu_;
-  intptr_t channel_uuid_;
-  uint64_t num_events_logged_;
-  size_t list_size_;
-  size_t max_list_size_;
-  TraceEvent* head_trace_;
-  TraceEvent* tail_trace_;
-  gpr_timespec time_created_;
-};
-
-}  // namespace grpc_core
-
-#endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H */
diff --git a/src/core/lib/channel/channel_trace_registry.cc b/src/core/lib/channel/channel_trace_registry.cc
deleted file mode 100644
index 6c82431467..0000000000
--- a/src/core/lib/channel/channel_trace_registry.cc
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- *
- * Copyright 2017 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#include <grpc/impl/codegen/port_platform.h>
-
-#include "src/core/lib/avl/avl.h"
-#include "src/core/lib/channel/channel_trace.h"
-#include "src/core/lib/channel/channel_trace_registry.h"
-#include "src/core/lib/gpr/useful.h"
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-
-// file global lock and avl.
-static gpr_mu g_mu;
-static grpc_avl g_avl;
-static gpr_atm g_uuid = 0;
-
-// avl vtable for uuid (intptr_t) -> ChannelTrace
-// this table is only looking, it does not own anything.
-static void destroy_intptr(void* not_used, void* user_data) {}
-static void* copy_intptr(void* key, void* user_data) { return key; }
-static long compare_intptr(void* key1, void* key2, void* user_data) {
-  return GPR_ICMP(key1, key2);
-}
-
-static void destroy_channel_trace(void* trace, void* user_data) {}
-static void* copy_channel_trace(void* trace, void* user_data) { return trace; }
-static const grpc_avl_vtable avl_vtable = {
-    destroy_intptr, copy_intptr, compare_intptr, destroy_channel_trace,
-    copy_channel_trace};
-
-void grpc_channel_trace_registry_init() {
-  gpr_mu_init(&g_mu);
-  g_avl = grpc_avl_create(&avl_vtable);
-}
-
-void grpc_channel_trace_registry_shutdown() {
-  grpc_avl_unref(g_avl, nullptr);
-  gpr_mu_destroy(&g_mu);
-}
-
-intptr_t grpc_channel_trace_registry_register_channel_trace(
-    grpc_core::ChannelTrace* channel_trace) {
-  intptr_t prior = gpr_atm_no_barrier_fetch_add(&g_uuid, 1);
-  gpr_mu_lock(&g_mu);
-  g_avl = grpc_avl_add(g_avl, (void*)prior, channel_trace, nullptr);
-  gpr_mu_unlock(&g_mu);
-  return prior;
-}
-
-void grpc_channel_trace_registry_unregister_channel_trace(intptr_t uuid) {
-  gpr_mu_lock(&g_mu);
-  g_avl = grpc_avl_remove(g_avl, (void*)uuid, nullptr);
-  gpr_mu_unlock(&g_mu);
-}
-
-grpc_core::ChannelTrace* grpc_channel_trace_registry_get_channel_trace(
-    intptr_t uuid) {
-  gpr_mu_lock(&g_mu);
-  grpc_core::ChannelTrace* ret = static_cast<grpc_core::ChannelTrace*>(
-      grpc_avl_get(g_avl, (void*)uuid, nullptr));
-  gpr_mu_unlock(&g_mu);
-  return ret;
-}
diff --git a/src/core/lib/channel/channel_trace_registry.h b/src/core/lib/channel/channel_trace_registry.h
deleted file mode 100644
index 391ecba7de..0000000000
--- a/src/core/lib/channel/channel_trace_registry.h
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- *
- * Copyright 2017 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H
-#define GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H
-
-#include <grpc/impl/codegen/port_platform.h>
-
-#include "src/core/lib/channel/channel_trace.h"
-
-#include <stdint.h>
-
-// TODO(ncteisen): convert this file to C++
-
-void grpc_channel_trace_registry_init();
-void grpc_channel_trace_registry_shutdown();
-
-// globally registers a ChannelTrace. Returns its unique uuid
-intptr_t grpc_channel_trace_registry_register_channel_trace(
-    grpc_core::ChannelTrace* channel_trace);
-// globally unregisters the ChannelTrace that is associated to uuid.
-void grpc_channel_trace_registry_unregister_channel_trace(intptr_t uuid);
-// if object with uuid has previously been registered, returns the ChannelTrace
-// associated with that uuid. Else returns nullptr.
-grpc_core::ChannelTrace* grpc_channel_trace_registry_get_channel_trace(
-    intptr_t uuid);
-
-#endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H */
diff --git a/src/core/lib/json/json.cc b/src/core/lib/json/json.cc
index 816241bbf0..2141db4c5b 100644
--- a/src/core/lib/json/json.cc
+++ b/src/core/lib/json/json.cc
@@ -21,7 +21,6 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
 
 #include "src/core/lib/json/json.h"
 
@@ -47,40 +46,5 @@ void grpc_json_destroy(grpc_json* json) {
     json->parent->child = json->next;
   }
 
-  if (json->owns_value) {
-    gpr_free((void*)json->value);
-  }
-
   gpr_free(json);
 }
-
-grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
-                                grpc_json* sibling) {
-  // first child case.
-  if (parent->child == nullptr) {
-    GPR_ASSERT(sibling == nullptr);
-    parent->child = child;
-    return child;
-  }
-  if (sibling == nullptr) {
-    sibling = parent->child;
-  }
-  // always find the right most sibling.
-  while (sibling->next != nullptr) {
-    sibling = sibling->next;
-  }
-  sibling->next = child;
-  return child;
-}
-
-grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
-                                  const char* key, const char* value,
-                                  grpc_json_type type, bool owns_value) {
-  grpc_json* child = grpc_json_create(type);
-  grpc_json_link_child(parent, child, sibling);
-  child->owns_value = owns_value;
-  child->parent = parent;
-  child->value = value;
-  child->key = key;
-  return child;
-}
diff --git a/src/core/lib/json/json.h b/src/core/lib/json/json.h
index f93b43048b..3a62ef9cfb 100644
--- a/src/core/lib/json/json.h
+++ b/src/core/lib/json/json.h
@@ -21,7 +21,6 @@
 
 #include <grpc/support/port_platform.h>
 
-#include <stdbool.h>
 #include <stdlib.h>
 
 #include "src/core/lib/json/json_common.h"
@@ -38,9 +37,6 @@ typedef struct grpc_json {
   grpc_json_type type;
   const char* key;
   const char* value;
-
-  /* if set, destructor will free value */
-  bool owns_value;
 } grpc_json;
 
 /* The next two functions are going to parse the input string, and
@@ -71,24 +67,9 @@ char* grpc_json_dump_to_string(grpc_json* json, int indent);
 
 /* Use these to create or delete a grpc_json object.
  * Deletion is recursive. We will not attempt to free any of the strings
- * in any of the objects of that tree, unless the boolean, owns_value,
- * is true.
+ * in any of the objects of that tree.
  */
 grpc_json* grpc_json_create(grpc_json_type type);
 void grpc_json_destroy(grpc_json* json);
 
-/* Links the child json object into the parent's json tree. If the parent
- * already has children, then passing in the most recently added child as the
- * sibling parameter is an optimization. For if sibling is NULL, this function
- * will manually traverse the tree in order to find the right most sibling.
- */
-grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
-                                grpc_json* sibling);
-
-/* Creates a child json object into the parent's json tree then links it in
- * as described above. */
-grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
-                                  const char* key, const char* value,
-                                  grpc_json_type type, bool owns_value);
-
 #endif /* GRPC_CORE_LIB_JSON_JSON_H */
diff --git a/src/core/lib/surface/channel.cc b/src/core/lib/surface/channel.cc
index cecc15b2df..03353d6beb 100644
--- a/src/core/lib/surface/channel.cc
+++ b/src/core/lib/surface/channel.cc
@@ -21,7 +21,6 @@
 #include "src/core/lib/surface/channel.h"
 
 #include <inttypes.h>
-#include <limits.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -31,12 +30,8 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/lib/channel/channel_args.h"
-#include "src/core/lib/channel/channel_trace.h"
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/string.h"
-#include "src/core/lib/gprpp/manual_constructor.h"
-#include "src/core/lib/gprpp/memory.h"
-#include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -67,8 +62,6 @@ struct grpc_channel {
   gpr_mu registered_call_mu;
   registered_call* registered_calls;
 
-  grpc_core::RefCountedPtr<grpc_core::ChannelTrace> tracer;
-
   char* target;
 };
 
@@ -100,14 +93,12 @@ grpc_channel* grpc_channel_create_with_builder(
             grpc_error_string(error));
     GRPC_ERROR_UNREF(error);
     gpr_free(target);
-    grpc_channel_args_destroy(args);
-    return channel;
+    goto done;
   }
 
   memset(channel, 0, sizeof(*channel));
   channel->target = target;
   channel->is_client = grpc_channel_stack_type_is_client(channel_stack_type);
-  size_t channel_tracer_max_nodes = 0;  // default to off
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = nullptr;
 
@@ -170,33 +161,14 @@ grpc_channel* grpc_channel_create_with_builder(
       channel->compression_options.enabled_algorithms_bitset =
           static_cast<uint32_t>(args->args[i].value.integer) |
           0x1; /* always support no compression */
-    } else if (0 == strcmp(args->args[i].key,
-                           GRPC_ARG_MAX_CHANNEL_TRACE_EVENTS_PER_NODE)) {
-      GPR_ASSERT(channel_tracer_max_nodes == 0);
-      // max_nodes defaults to 0 (which is off), clamped between 0 and INT_MAX
-      const grpc_integer_options options = {0, 0, INT_MAX};
-      channel_tracer_max_nodes =
-          (size_t)grpc_channel_arg_get_integer(&args->args[i], options);
     }
   }
 
+done:
   grpc_channel_args_destroy(args);
-  channel->tracer = grpc_core::MakeRefCounted<grpc_core::ChannelTrace>(
-      channel_tracer_max_nodes);
-  channel->tracer->AddTraceEvent(
-      grpc_core::ChannelTrace::Severity::Info,
-      grpc_slice_from_static_string("Channel created"));
   return channel;
 }
 
-char* grpc_channel_get_trace(grpc_channel* channel) {
-  return channel->tracer->RenderTrace();
-}
-
-intptr_t grpc_channel_get_uuid(grpc_channel* channel) {
-  return channel->tracer->GetUuid();
-}
-
 grpc_channel* grpc_channel_create(const char* target,
                                   const grpc_channel_args* input_args,
                                   grpc_channel_stack_type channel_stack_type,
@@ -405,7 +377,6 @@ static void destroy_channel(void* arg, grpc_error* error) {
     GRPC_MDELEM_UNREF(rc->authority);
     gpr_free(rc);
   }
-  channel->tracer.reset();
   GRPC_MDELEM_UNREF(channel->default_authority);
   gpr_mu_destroy(&channel->registered_call_mu);
   gpr_free(channel->target);
diff --git a/src/core/lib/surface/init.cc b/src/core/lib/surface/init.cc
index bd436d6857..ac9f9e6066 100644
--- a/src/core/lib/surface/init.cc
+++ b/src/core/lib/surface/init.cc
@@ -27,7 +27,6 @@
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
 #include "src/core/lib/channel/channel_stack.h"
-#include "src/core/lib/channel/channel_trace_registry.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/debug/stats.h"
@@ -129,7 +128,6 @@ void grpc_init(void) {
     grpc_slice_intern_init();
     grpc_mdctx_global_init();
     grpc_channel_init_init();
-    grpc_channel_trace_registry_init();
     grpc_security_pre_init();
     grpc_core::ExecCtx::GlobalInit();
     grpc_iomgr_init();
@@ -178,7 +176,6 @@ void grpc_shutdown(void) {
       grpc_mdctx_global_shutdown();
       grpc_handshaker_factory_registry_shutdown();
       grpc_slice_intern_shutdown();
-      grpc_channel_trace_registry_shutdown();
       grpc_stats_shutdown();
     }
     grpc_core::ExecCtx::GlobalShutdown();