From f13a74312672aaf7c72e984f59dbd351dcda4e8a Mon Sep 17 00:00:00 2001
From: ncteisen <ncteisen@gmail.com>
Date: Wed, 26 Sep 2018 17:19:39 -0700
Subject: [PATCH 1/4] Implement child socket support

---
 .../client_channel/client_channel_channelz.cc | 19 +++++++++++++++++++
 .../client_channel/client_channel_channelz.h  |  8 +++-----
 .../ext/filters/client_channel/subchannel.cc  | 10 ++++++++++
 .../ext/filters/client_channel/subchannel.h   |  3 +++
 .../chttp2/transport/chttp2_transport.cc      | 12 +++++++++++-
 .../cronet/transport/cronet_transport.cc      |  6 +++++-
 .../ext/transport/inproc/inproc_transport.cc  |  5 ++++-
 src/core/lib/transport/transport.cc           |  5 +++++
 src/core/lib/transport/transport.h            | 10 ++++++++++
 src/core/lib/transport/transport_impl.h       |  3 +++
 10 files changed, 73 insertions(+), 8 deletions(-)

diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.cc b/src/core/ext/filters/client_channel/client_channel_channelz.cc
index 7e8f59bcd33..4fedcbcbb6c 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.cc
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.cc
@@ -136,6 +136,23 @@ void SubchannelNode::PopulateConnectivityState(grpc_json* json) {
                          false);
 }
 
+void SubchannelNode::PopulateChildSockets(grpc_json* json) {
+  ChildRefsList child_sockets;
+  grpc_json* json_iterator = nullptr;
+  grpc_subchannel_populate_child_sockets(subchannel_, &child_sockets);
+  if (!child_sockets.empty()) {
+    grpc_json* array_parent = grpc_json_create_child(
+        nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
+    for (size_t i = 0; i < child_sockets.size(); ++i) {
+      json_iterator =
+          grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
+                                 GRPC_JSON_OBJECT, false);
+      grpc_json_add_number_string_child(json_iterator, nullptr, "socketId",
+                                        child_sockets[i]);
+    }
+  }
+}
+
 grpc_json* SubchannelNode::RenderJson() {
   grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
   grpc_json* json = top_level_json;
@@ -166,6 +183,8 @@ grpc_json* SubchannelNode::RenderJson() {
   }
   // ask CallCountingHelper to populate trace and call count data.
   call_counter_.PopulateCallCounts(json);
+  json = top_level_json;
+  PopulateChildSockets(json);
   return top_level_json;
 }
 
diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.h b/src/core/ext/filters/client_channel/client_channel_channelz.h
index 8ce331e529d..a63df00f9f2 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.h
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.h
@@ -31,11 +31,6 @@ typedef struct grpc_subchannel grpc_subchannel;
 
 namespace grpc_core {
 
-// TODO(ncteisen), this only contains the uuids of the children for now,
-// since that is all that is strictly needed. In a future enhancement we will
-// add human readable names as in the channelz.proto
-typedef InlinedVector<intptr_t, 10> ChildRefsList;
-
 namespace channelz {
 
 // Subtype of ChannelNode that overrides and provides client_channel specific
@@ -76,6 +71,9 @@ class SubchannelNode : public BaseNode {
 
   grpc_json* RenderJson() override;
 
+  // helper to populate the socket(s) that this subchannel owns.
+  void PopulateChildSockets(grpc_json* json);
+
   // proxy methods to composed classes.
   void AddTraceEvent(ChannelTrace::Severity severity, grpc_slice data) {
     trace_.AddTraceEvent(severity, data);
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index 57d0b3759f2..29aeb06e7bc 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -97,6 +97,8 @@ struct grpc_subchannel {
   /** set during connection */
   grpc_connect_out_args connecting_result;
 
+  grpc_transport* transport;
+
   /** callback for connection finishing */
   grpc_closure on_connected;
 
@@ -411,6 +413,13 @@ grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
   return subchannel->channelz_subchannel.get();
 }
 
+void grpc_subchannel_populate_child_sockets(
+    grpc_subchannel* subchannel, grpc_core::ChildRefsList* child_sockets) {
+  if (subchannel->transport != nullptr) {
+    grpc_transport_populate_sockets(subchannel->transport, child_sockets);
+  }
+}
+
 static void continue_connect_locked(grpc_subchannel* c) {
   grpc_connect_in_args args;
   args.interested_parties = c->pollset_set;
@@ -621,6 +630,7 @@ static bool publish_transport_locked(grpc_subchannel* c) {
     GRPC_ERROR_UNREF(error);
     return false;
   }
+  c->transport = c->connecting_result.transport;
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 
   /* initialize state watcher */
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 84febb52040..2cf5067fc26 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -126,6 +126,9 @@ void grpc_subchannel_call_unref(
 grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
     grpc_subchannel* subchannel);
 
+void grpc_subchannel_populate_child_sockets(
+    grpc_subchannel* subchannel, grpc_core::ChildRefsList* child_sockets);
+
 /** Returns a pointer to the parent data associated with \a subchannel_call.
     The data will be of the size specified in \a parent_data_size
     field of the args passed to \a grpc_connected_subchannel_create_call(). */
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
index d3232f4d268..202da652de7 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
@@ -3157,6 +3157,15 @@ static grpc_endpoint* chttp2_get_endpoint(grpc_transport* t) {
   return (reinterpret_cast<grpc_chttp2_transport*>(t))->ep;
 }
 
+static void populate_sockets(grpc_transport* transport,
+                             grpc_core::ChildRefsList* child_sockets) {
+  grpc_chttp2_transport* t =
+      reinterpret_cast<grpc_chttp2_transport*>(transport);
+  if (t->channelz_socket != nullptr) {
+    child_sockets->push_back(t->channelz_socket->uuid());
+  }
+}
+
 static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              "chttp2",
                                              init_stream,
@@ -3166,7 +3175,8 @@ static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              perform_transport_op,
                                              destroy_stream,
                                              destroy_transport,
-                                             chttp2_get_endpoint};
+                                             chttp2_get_endpoint,
+                                             populate_sockets};
 
 static const grpc_transport_vtable* get_vtable(void) { return &vtable; }
 
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.cc b/src/core/ext/transport/cronet/transport/cronet_transport.cc
index 81e2634e3a7..f3826a78de0 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.cc
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.cc
@@ -1439,6 +1439,9 @@ static grpc_endpoint* get_endpoint(grpc_transport* gt) { return nullptr; }
 
 static void perform_op(grpc_transport* gt, grpc_transport_op* op) {}
 
+static void populate_sockets(grpc_transport* t,
+                             grpc_core::ChildRefsList* child_sockets) {}
+
 static const grpc_transport_vtable grpc_cronet_vtable = {
     sizeof(stream_obj),
     "cronet_http",
@@ -1449,7 +1452,8 @@ static const grpc_transport_vtable grpc_cronet_vtable = {
     perform_op,
     destroy_stream,
     destroy_transport,
-    get_endpoint};
+    get_endpoint,
+    populate_sockets};
 
 grpc_transport* grpc_create_cronet_transport(void* engine, const char* target,
                                              const grpc_channel_args* args,
diff --git a/src/core/ext/transport/inproc/inproc_transport.cc b/src/core/ext/transport/inproc/inproc_transport.cc
index b0ca7f8207e..2deaacb2e06 100644
--- a/src/core/ext/transport/inproc/inproc_transport.cc
+++ b/src/core/ext/transport/inproc/inproc_transport.cc
@@ -1170,6 +1170,9 @@ static void set_pollset_set(grpc_transport* gt, grpc_stream* gs,
 
 static grpc_endpoint* get_endpoint(grpc_transport* t) { return nullptr; }
 
+static void populate_sockets(grpc_transport* t,
+                             grpc_core::ChildRefsList* child_sockets) {}
+
 /*******************************************************************************
  * GLOBAL INIT AND DESTROY
  */
@@ -1194,7 +1197,7 @@ static const grpc_transport_vtable inproc_vtable = {
     sizeof(inproc_stream), "inproc",        init_stream,
     set_pollset,           set_pollset_set, perform_stream_op,
     perform_transport_op,  destroy_stream,  destroy_transport,
-    get_endpoint};
+    get_endpoint,          populate_sockets};
 
 /*******************************************************************************
  * Main inproc transport functions
diff --git a/src/core/lib/transport/transport.cc b/src/core/lib/transport/transport.cc
index cbdb77c8441..2e7c40dda45 100644
--- a/src/core/lib/transport/transport.cc
+++ b/src/core/lib/transport/transport.cc
@@ -199,6 +199,11 @@ grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport) {
   return transport->vtable->get_endpoint(transport);
 }
 
+void grpc_transport_populate_sockets(grpc_transport* transport,
+                                     grpc_core::ChildRefsList* child_sockets) {
+  return transport->vtable->populate_sockets(transport, child_sockets);
+}
+
 // This comment should be sung to the tune of
 // "Supercalifragilisticexpialidocious":
 //
diff --git a/src/core/lib/transport/transport.h b/src/core/lib/transport/transport.h
index 9e784635c69..93445ebd051 100644
--- a/src/core/lib/transport/transport.h
+++ b/src/core/lib/transport/transport.h
@@ -39,6 +39,13 @@
 #define GRPC_PROTOCOL_VERSION_MIN_MAJOR 2
 #define GRPC_PROTOCOL_VERSION_MIN_MINOR 1
 
+namespace grpc_core {
+// TODO(ncteisen), this only contains the uuids of the children for now,
+// since that is all that is strictly needed. In a future enhancement we will
+// add human readable names as in the channelz.proto
+typedef InlinedVector<intptr_t, 10> ChildRefsList;
+}  // namespace grpc_core
+
 /* forward declarations */
 
 typedef struct grpc_transport grpc_transport;
@@ -366,6 +373,9 @@ void grpc_transport_destroy(grpc_transport* transport);
 /* Get the endpoint used by \a transport */
 grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport);
 
+void grpc_transport_populate_sockets(grpc_transport* transport,
+                                     grpc_core::ChildRefsList* child_sockets);
+
 /* Allocate a grpc_transport_op, and preconfigure the on_consumed closure to
    \a on_consumed and then delete the returned transport op */
 grpc_transport_op* grpc_make_transport_op(grpc_closure* on_consumed);
diff --git a/src/core/lib/transport/transport_impl.h b/src/core/lib/transport/transport_impl.h
index ba5e05df0af..7ae59a1d17f 100644
--- a/src/core/lib/transport/transport_impl.h
+++ b/src/core/lib/transport/transport_impl.h
@@ -60,6 +60,9 @@ typedef struct grpc_transport_vtable {
 
   /* implementation of grpc_transport_get_endpoint */
   grpc_endpoint* (*get_endpoint)(grpc_transport* self);
+
+  void (*populate_sockets)(grpc_transport* self,
+                           grpc_core::ChildRefsList* child_sockets);
 } grpc_transport_vtable;
 
 /* an instance of a grpc transport */

From 4cc16f951c0909196a9ed62774adcbbaf9cc88c1 Mon Sep 17 00:00:00 2001
From: ncteisen <ncteisen@gmail.com>
Date: Thu, 27 Sep 2018 09:45:59 -0500
Subject: [PATCH 2/4] Simplifiy transport querying function

---
 .../client_channel/client_channel_channelz.cc | 29 +++++++------------
 .../client_channel/client_channel_channelz.h  |  5 ++++
 .../ext/filters/client_channel/subchannel.cc  | 16 +++++-----
 .../ext/filters/client_channel/subchannel.h   |  4 +--
 .../chttp2/transport/chttp2_transport.cc      |  9 +++---
 .../cronet/transport/cronet_transport.cc      |  5 ++--
 .../ext/transport/inproc/inproc_transport.cc  |  5 ++--
 src/core/lib/transport/transport.cc           |  5 ++--
 src/core/lib/transport/transport.h            | 10 +------
 src/core/lib/transport/transport_impl.h       |  3 +-
 test/cpp/microbenchmarks/bm_call_create.cc    | 10 ++++---
 11 files changed, 46 insertions(+), 55 deletions(-)

diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.cc b/src/core/ext/filters/client_channel/client_channel_channelz.cc
index 4fedcbcbb6c..8d02304d19f 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.cc
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.cc
@@ -136,23 +136,6 @@ void SubchannelNode::PopulateConnectivityState(grpc_json* json) {
                          false);
 }
 
-void SubchannelNode::PopulateChildSockets(grpc_json* json) {
-  ChildRefsList child_sockets;
-  grpc_json* json_iterator = nullptr;
-  grpc_subchannel_populate_child_sockets(subchannel_, &child_sockets);
-  if (!child_sockets.empty()) {
-    grpc_json* array_parent = grpc_json_create_child(
-        nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
-    for (size_t i = 0; i < child_sockets.size(); ++i) {
-      json_iterator =
-          grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
-                                 GRPC_JSON_OBJECT, false);
-      grpc_json_add_number_string_child(json_iterator, nullptr, "socketId",
-                                        child_sockets[i]);
-    }
-  }
-}
-
 grpc_json* SubchannelNode::RenderJson() {
   grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
   grpc_json* json = top_level_json;
@@ -184,7 +167,17 @@ grpc_json* SubchannelNode::RenderJson() {
   // ask CallCountingHelper to populate trace and call count data.
   call_counter_.PopulateCallCounts(json);
   json = top_level_json;
-  PopulateChildSockets(json);
+  // populate the child socket.
+  intptr_t socket_uuid = grpc_subchannel_get_child_socket_uuid(subchannel_);
+  if (socket_uuid != 0) {
+    grpc_json* array_parent = grpc_json_create_child(
+        nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
+    json_iterator =
+        grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
+                               GRPC_JSON_OBJECT, false);
+    grpc_json_add_number_string_child(json_iterator, nullptr, "socketId",
+                                      socket_uuid);
+  }
   return top_level_json;
 }
 
diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.h b/src/core/ext/filters/client_channel/client_channel_channelz.h
index a63df00f9f2..a6dae165223 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.h
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.h
@@ -31,6 +31,11 @@ typedef struct grpc_subchannel grpc_subchannel;
 
 namespace grpc_core {
 
+// TODO(ncteisen), this only contains the uuids of the children for now,
+// since that is all that is strictly needed. In a future enhancement we will
+// add human readable names as in the channelz.proto
+typedef InlinedVector<intptr_t, 10> ChildRefsList;
+
 namespace channelz {
 
 // Subtype of ChannelNode that overrides and provides client_channel specific
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index 29aeb06e7bc..4c33636646c 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -97,7 +97,9 @@ struct grpc_subchannel {
   /** set during connection */
   grpc_connect_out_args connecting_result;
 
-  grpc_transport* transport;
+  /** uuid of this subchannel's socket. 0 if this subchannel is not
+      connected */
+  intptr_t socket_uuid;
 
   /** callback for connection finishing */
   grpc_closure on_connected;
@@ -256,6 +258,7 @@ static void disconnect(grpc_subchannel* c) {
   c->disconnected = true;
   grpc_connector_shutdown(c->connector, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                             "Subchannel disconnected"));
+  c->socket_uuid = 0;
   c->connected_subchannel.reset();
   gpr_mu_unlock(&c->mu);
 }
@@ -413,11 +416,9 @@ grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
   return subchannel->channelz_subchannel.get();
 }
 
-void grpc_subchannel_populate_child_sockets(
-    grpc_subchannel* subchannel, grpc_core::ChildRefsList* child_sockets) {
-  if (subchannel->transport != nullptr) {
-    grpc_transport_populate_sockets(subchannel->transport, child_sockets);
-  }
+intptr_t grpc_subchannel_get_child_socket_uuid(
+    grpc_subchannel* subchannel) {
+  return subchannel->socket_uuid;
 }
 
 static void continue_connect_locked(grpc_subchannel* c) {
@@ -578,6 +579,7 @@ static void on_connected_subchannel_connectivity_changed(void* p,
                   grpc_connectivity_state_name(
                       connected_subchannel_watcher->connectivity_state));
         }
+        c->socket_uuid = 0;
         c->connected_subchannel.reset();
         grpc_connectivity_state_set(&c->state_tracker,
                                     GRPC_CHANNEL_TRANSIENT_FAILURE,
@@ -630,7 +632,7 @@ static bool publish_transport_locked(grpc_subchannel* c) {
     GRPC_ERROR_UNREF(error);
     return false;
   }
-  c->transport = c->connecting_result.transport;
+  c->socket_uuid = grpc_transport_get_socket_uuid(c->connecting_result.transport);
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 
   /* initialize state watcher */
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 2cf5067fc26..67a2d497111 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -126,8 +126,8 @@ void grpc_subchannel_call_unref(
 grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
     grpc_subchannel* subchannel);
 
-void grpc_subchannel_populate_child_sockets(
-    grpc_subchannel* subchannel, grpc_core::ChildRefsList* child_sockets);
+intptr_t grpc_subchannel_get_child_socket_uuid(
+    grpc_subchannel* subchannel);
 
 /** Returns a pointer to the parent data associated with \a subchannel_call.
     The data will be of the size specified in \a parent_data_size
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
index 202da652de7..45ef4161f78 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
@@ -3157,12 +3157,13 @@ static grpc_endpoint* chttp2_get_endpoint(grpc_transport* t) {
   return (reinterpret_cast<grpc_chttp2_transport*>(t))->ep;
 }
 
-static void populate_sockets(grpc_transport* transport,
-                             grpc_core::ChildRefsList* child_sockets) {
+static intptr_t get_socket_uuid(grpc_transport* transport) {
   grpc_chttp2_transport* t =
       reinterpret_cast<grpc_chttp2_transport*>(transport);
   if (t->channelz_socket != nullptr) {
-    child_sockets->push_back(t->channelz_socket->uuid());
+    return t->channelz_socket->uuid();
+  } else {
+    return 0;
   }
 }
 
@@ -3176,7 +3177,7 @@ static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              destroy_stream,
                                              destroy_transport,
                                              chttp2_get_endpoint,
-                                             populate_sockets};
+                                             get_socket_uuid};
 
 static const grpc_transport_vtable* get_vtable(void) { return &vtable; }
 
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.cc b/src/core/ext/transport/cronet/transport/cronet_transport.cc
index f3826a78de0..bb20d9db084 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.cc
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.cc
@@ -1439,8 +1439,7 @@ static grpc_endpoint* get_endpoint(grpc_transport* gt) { return nullptr; }
 
 static void perform_op(grpc_transport* gt, grpc_transport_op* op) {}
 
-static void populate_sockets(grpc_transport* t,
-                             grpc_core::ChildRefsList* child_sockets) {}
+static intptr_t get_socket_uuid(grpc_transport* t) { return 0; }
 
 static const grpc_transport_vtable grpc_cronet_vtable = {
     sizeof(stream_obj),
@@ -1453,7 +1452,7 @@ static const grpc_transport_vtable grpc_cronet_vtable = {
     destroy_stream,
     destroy_transport,
     get_endpoint,
-    populate_sockets};
+    get_socket_uuid};
 
 grpc_transport* grpc_create_cronet_transport(void* engine, const char* target,
                                              const grpc_channel_args* args,
diff --git a/src/core/ext/transport/inproc/inproc_transport.cc b/src/core/ext/transport/inproc/inproc_transport.cc
index 2deaacb2e06..56951f83386 100644
--- a/src/core/ext/transport/inproc/inproc_transport.cc
+++ b/src/core/ext/transport/inproc/inproc_transport.cc
@@ -1170,8 +1170,7 @@ static void set_pollset_set(grpc_transport* gt, grpc_stream* gs,
 
 static grpc_endpoint* get_endpoint(grpc_transport* t) { return nullptr; }
 
-static void populate_sockets(grpc_transport* t,
-                             grpc_core::ChildRefsList* child_sockets) {}
+static intptr_t get_socket_uuid(grpc_transport* t) { return 0; }
 
 /*******************************************************************************
  * GLOBAL INIT AND DESTROY
@@ -1197,7 +1196,7 @@ static const grpc_transport_vtable inproc_vtable = {
     sizeof(inproc_stream), "inproc",        init_stream,
     set_pollset,           set_pollset_set, perform_stream_op,
     perform_transport_op,  destroy_stream,  destroy_transport,
-    get_endpoint,          populate_sockets};
+    get_endpoint,          get_socket_uuid};
 
 /*******************************************************************************
  * Main inproc transport functions
diff --git a/src/core/lib/transport/transport.cc b/src/core/lib/transport/transport.cc
index 2e7c40dda45..c8fdbb4de26 100644
--- a/src/core/lib/transport/transport.cc
+++ b/src/core/lib/transport/transport.cc
@@ -199,9 +199,8 @@ grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport) {
   return transport->vtable->get_endpoint(transport);
 }
 
-void grpc_transport_populate_sockets(grpc_transport* transport,
-                                     grpc_core::ChildRefsList* child_sockets) {
-  return transport->vtable->populate_sockets(transport, child_sockets);
+intptr_t grpc_transport_get_socket_uuid(grpc_transport* transport) {
+  return transport->vtable->get_socket_uuid(transport);
 }
 
 // This comment should be sung to the tune of
diff --git a/src/core/lib/transport/transport.h b/src/core/lib/transport/transport.h
index 93445ebd051..aad133f6c3d 100644
--- a/src/core/lib/transport/transport.h
+++ b/src/core/lib/transport/transport.h
@@ -39,13 +39,6 @@
 #define GRPC_PROTOCOL_VERSION_MIN_MAJOR 2
 #define GRPC_PROTOCOL_VERSION_MIN_MINOR 1
 
-namespace grpc_core {
-// TODO(ncteisen), this only contains the uuids of the children for now,
-// since that is all that is strictly needed. In a future enhancement we will
-// add human readable names as in the channelz.proto
-typedef InlinedVector<intptr_t, 10> ChildRefsList;
-}  // namespace grpc_core
-
 /* forward declarations */
 
 typedef struct grpc_transport grpc_transport;
@@ -373,8 +366,7 @@ void grpc_transport_destroy(grpc_transport* transport);
 /* Get the endpoint used by \a transport */
 grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport);
 
-void grpc_transport_populate_sockets(grpc_transport* transport,
-                                     grpc_core::ChildRefsList* child_sockets);
+intptr_t grpc_transport_get_socket_uuid(grpc_transport* transport);
 
 /* Allocate a grpc_transport_op, and preconfigure the on_consumed closure to
    \a on_consumed and then delete the returned transport op */
diff --git a/src/core/lib/transport/transport_impl.h b/src/core/lib/transport/transport_impl.h
index 7ae59a1d17f..d609470ef01 100644
--- a/src/core/lib/transport/transport_impl.h
+++ b/src/core/lib/transport/transport_impl.h
@@ -61,8 +61,7 @@ typedef struct grpc_transport_vtable {
   /* implementation of grpc_transport_get_endpoint */
   grpc_endpoint* (*get_endpoint)(grpc_transport* self);
 
-  void (*populate_sockets)(grpc_transport* self,
-                           grpc_core::ChildRefsList* child_sockets);
+  intptr_t (*get_socket_uuid)(grpc_transport* self);
 } grpc_transport_vtable;
 
 /* an instance of a grpc transport */
diff --git a/test/cpp/microbenchmarks/bm_call_create.cc b/test/cpp/microbenchmarks/bm_call_create.cc
index 9516b2e3e25..b0cccafcf82 100644
--- a/test/cpp/microbenchmarks/bm_call_create.cc
+++ b/test/cpp/microbenchmarks/bm_call_create.cc
@@ -446,11 +446,13 @@ void Destroy(grpc_transport* self) {}
 /* implementation of grpc_transport_get_endpoint */
 grpc_endpoint* GetEndpoint(grpc_transport* self) { return nullptr; }
 
+intptr_t GetSocketUuid(grpc_transport* t) { return 0; }
+
 static const grpc_transport_vtable dummy_transport_vtable = {
-    0,          "dummy_http2", InitStream,
-    SetPollset, SetPollsetSet, PerformStreamOp,
-    PerformOp,  DestroyStream, Destroy,
-    GetEndpoint};
+    0,           "dummy_http2",  InitStream,
+    SetPollset,  SetPollsetSet,  PerformStreamOp,
+    PerformOp,   DestroyStream,  Destroy,
+    GetEndpoint, GetSocketUuid};
 
 static grpc_transport dummy_transport = {&dummy_transport_vtable};
 

From f2b493e3697211552a28dba582313174f2a932f2 Mon Sep 17 00:00:00 2001
From: ncteisen <ncteisen@gmail.com>
Date: Thu, 27 Sep 2018 10:38:37 -0500
Subject: [PATCH 3/4] reviewer feedback

---
 .../client_channel/client_channel_channelz.cc |  5 ++--
 .../client_channel/client_channel_channelz.h  |  3 ---
 .../ext/filters/client_channel/subchannel.cc  | 25 +++++++++----------
 .../ext/filters/client_channel/subchannel.h   |  9 ++++---
 test/cpp/microbenchmarks/bm_call_create.cc    |  6 ++---
 5 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.cc b/src/core/ext/filters/client_channel/client_channel_channelz.cc
index 8d02304d19f..b66c920b909 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.cc
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.cc
@@ -172,9 +172,8 @@ grpc_json* SubchannelNode::RenderJson() {
   if (socket_uuid != 0) {
     grpc_json* array_parent = grpc_json_create_child(
         nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
-    json_iterator =
-        grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
-                               GRPC_JSON_OBJECT, false);
+    json_iterator = grpc_json_create_child(json_iterator, array_parent, nullptr,
+                                           nullptr, GRPC_JSON_OBJECT, false);
     grpc_json_add_number_string_child(json_iterator, nullptr, "socketId",
                                       socket_uuid);
   }
diff --git a/src/core/ext/filters/client_channel/client_channel_channelz.h b/src/core/ext/filters/client_channel/client_channel_channelz.h
index a6dae165223..8ce331e529d 100644
--- a/src/core/ext/filters/client_channel/client_channel_channelz.h
+++ b/src/core/ext/filters/client_channel/client_channel_channelz.h
@@ -76,9 +76,6 @@ class SubchannelNode : public BaseNode {
 
   grpc_json* RenderJson() override;
 
-  // helper to populate the socket(s) that this subchannel owns.
-  void PopulateChildSockets(grpc_json* json);
-
   // proxy methods to composed classes.
   void AddTraceEvent(ChannelTrace::Severity severity, grpc_slice data) {
     trace_.AddTraceEvent(severity, data);
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index 4c33636646c..4756733f1f8 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -97,10 +97,6 @@ struct grpc_subchannel {
   /** set during connection */
   grpc_connect_out_args connecting_result;
 
-  /** uuid of this subchannel's socket. 0 if this subchannel is not
-      connected */
-  intptr_t socket_uuid;
-
   /** callback for connection finishing */
   grpc_closure on_connected;
 
@@ -258,7 +254,6 @@ static void disconnect(grpc_subchannel* c) {
   c->disconnected = true;
   grpc_connector_shutdown(c->connector, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                             "Subchannel disconnected"));
-  c->socket_uuid = 0;
   c->connected_subchannel.reset();
   gpr_mu_unlock(&c->mu);
 }
@@ -416,9 +411,12 @@ grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
   return subchannel->channelz_subchannel.get();
 }
 
-intptr_t grpc_subchannel_get_child_socket_uuid(
-    grpc_subchannel* subchannel) {
-  return subchannel->socket_uuid;
+intptr_t grpc_subchannel_get_child_socket_uuid(grpc_subchannel* subchannel) {
+  if (subchannel->connected_subchannel != nullptr) {
+    return subchannel->connected_subchannel->socket_uuid();
+  } else {
+    return 0;
+  }
 }
 
 static void continue_connect_locked(grpc_subchannel* c) {
@@ -579,7 +577,6 @@ static void on_connected_subchannel_connectivity_changed(void* p,
                   grpc_connectivity_state_name(
                       connected_subchannel_watcher->connectivity_state));
         }
-        c->socket_uuid = 0;
         c->connected_subchannel.reset();
         grpc_connectivity_state_set(&c->state_tracker,
                                     GRPC_CHANNEL_TRANSIENT_FAILURE,
@@ -632,7 +629,8 @@ static bool publish_transport_locked(grpc_subchannel* c) {
     GRPC_ERROR_UNREF(error);
     return false;
   }
-  c->socket_uuid = grpc_transport_get_socket_uuid(c->connecting_result.transport);
+  intptr_t socket_uuid =
+      grpc_transport_get_socket_uuid(c->connecting_result.transport);
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 
   /* initialize state watcher */
@@ -653,7 +651,7 @@ static bool publish_transport_locked(grpc_subchannel* c) {
 
   /* publish */
   c->connected_subchannel.reset(grpc_core::New<grpc_core::ConnectedSubchannel>(
-      stk, c->channelz_subchannel.get()));
+      stk, c->channelz_subchannel.get(), socket_uuid));
   gpr_log(GPR_INFO, "New connected subchannel at %p for subchannel %p",
           c->connected_subchannel.get(), c);
 
@@ -823,10 +821,11 @@ namespace grpc_core {
 
 ConnectedSubchannel::ConnectedSubchannel(
     grpc_channel_stack* channel_stack,
-    channelz::SubchannelNode* channelz_subchannel)
+    channelz::SubchannelNode* channelz_subchannel, intptr_t socket_uuid)
     : RefCountedWithTracing<ConnectedSubchannel>(&grpc_trace_stream_refcount),
       channel_stack_(channel_stack),
-      channelz_subchannel_(channelz_subchannel) {}
+      channelz_subchannel_(channelz_subchannel),
+      socket_uuid_(socket_uuid) {}
 
 ConnectedSubchannel::~ConnectedSubchannel() {
   GRPC_CHANNEL_STACK_UNREF(channel_stack_, "connected_subchannel_dtor");
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 67a2d497111..5d95a720853 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -86,7 +86,8 @@ class ConnectedSubchannel : public RefCountedWithTracing<ConnectedSubchannel> {
   };
 
   explicit ConnectedSubchannel(grpc_channel_stack* channel_stack,
-                               channelz::SubchannelNode* channelz_subchannel);
+                               channelz::SubchannelNode* channelz_subchannel,
+                               intptr_t socket_uuid);
   ~ConnectedSubchannel();
 
   grpc_channel_stack* channel_stack() { return channel_stack_; }
@@ -98,12 +99,15 @@ class ConnectedSubchannel : public RefCountedWithTracing<ConnectedSubchannel> {
   channelz::SubchannelNode* channelz_subchannel() {
     return channelz_subchannel_;
   }
+  intptr_t socket_uuid() { return socket_uuid_; }
 
  private:
   grpc_channel_stack* channel_stack_;
   // backpointer to the channelz node in this connected subchannel's
   // owning subchannel.
   channelz::SubchannelNode* channelz_subchannel_;
+  // uuid of this subchannel's socket. 0 if this subchannel is not connected.
+  intptr_t socket_uuid_;
 };
 
 }  // namespace grpc_core
@@ -126,8 +130,7 @@ void grpc_subchannel_call_unref(
 grpc_core::channelz::SubchannelNode* grpc_subchannel_get_channelz_node(
     grpc_subchannel* subchannel);
 
-intptr_t grpc_subchannel_get_child_socket_uuid(
-    grpc_subchannel* subchannel);
+intptr_t grpc_subchannel_get_child_socket_uuid(grpc_subchannel* subchannel);
 
 /** Returns a pointer to the parent data associated with \a subchannel_call.
     The data will be of the size specified in \a parent_data_size
diff --git a/test/cpp/microbenchmarks/bm_call_create.cc b/test/cpp/microbenchmarks/bm_call_create.cc
index b0cccafcf82..45ac782a0e1 100644
--- a/test/cpp/microbenchmarks/bm_call_create.cc
+++ b/test/cpp/microbenchmarks/bm_call_create.cc
@@ -449,9 +449,9 @@ grpc_endpoint* GetEndpoint(grpc_transport* self) { return nullptr; }
 intptr_t GetSocketUuid(grpc_transport* t) { return 0; }
 
 static const grpc_transport_vtable dummy_transport_vtable = {
-    0,           "dummy_http2",  InitStream,
-    SetPollset,  SetPollsetSet,  PerformStreamOp,
-    PerformOp,   DestroyStream,  Destroy,
+    0,           "dummy_http2", InitStream,
+    SetPollset,  SetPollsetSet, PerformStreamOp,
+    PerformOp,   DestroyStream, Destroy,
     GetEndpoint, GetSocketUuid};
 
 static grpc_transport dummy_transport = {&dummy_transport_vtable};

From 404b2515af9c4dcc29440dea8b955ba341521b68 Mon Sep 17 00:00:00 2001
From: ncteisen <ncteisen@gmail.com>
Date: Thu, 27 Sep 2018 11:18:42 -0500
Subject: [PATCH 4/4] reviewer feedback

---
 .../ext/filters/client_channel/connector.h    |  3 +++
 .../ext/filters/client_channel/subchannel.cc  |  3 +--
 .../ext/filters/client_channel/subchannel.h   |  2 +-
 .../chttp2/client/chttp2_connector.cc         |  2 ++
 .../chttp2/transport/chttp2_transport.cc      | 23 +++++++++----------
 .../chttp2/transport/chttp2_transport.h       |  2 ++
 .../cronet/transport/cronet_transport.cc      |  5 +---
 .../ext/transport/inproc/inproc_transport.cc  |  4 +---
 src/core/lib/transport/transport.cc           |  4 ----
 src/core/lib/transport/transport.h            |  2 --
 src/core/lib/transport/transport_impl.h       |  2 --
 test/cpp/microbenchmarks/bm_call_create.cc    | 10 ++++----
 12 files changed, 26 insertions(+), 36 deletions(-)

diff --git a/src/core/ext/filters/client_channel/connector.h b/src/core/ext/filters/client_channel/connector.h
index 556594929c1..ea34dcdab57 100644
--- a/src/core/ext/filters/client_channel/connector.h
+++ b/src/core/ext/filters/client_channel/connector.h
@@ -47,6 +47,9 @@ typedef struct {
 
   /** channel arguments (to be passed to the filters) */
   grpc_channel_args* channel_args;
+
+  /** socket uuid of the connected transport. 0 if not available */
+  intptr_t socket_uuid;
 } grpc_connect_out_args;
 
 struct grpc_connector_vtable {
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index 4756733f1f8..2847f4bdc18 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -629,8 +629,7 @@ static bool publish_transport_locked(grpc_subchannel* c) {
     GRPC_ERROR_UNREF(error);
     return false;
   }
-  intptr_t socket_uuid =
-      grpc_transport_get_socket_uuid(c->connecting_result.transport);
+  intptr_t socket_uuid = c->connecting_result.socket_uuid;
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 
   /* initialize state watcher */
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 5d95a720853..699f93a8e77 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -107,7 +107,7 @@ class ConnectedSubchannel : public RefCountedWithTracing<ConnectedSubchannel> {
   // owning subchannel.
   channelz::SubchannelNode* channelz_subchannel_;
   // uuid of this subchannel's socket. 0 if this subchannel is not connected.
-  intptr_t socket_uuid_;
+  const intptr_t socket_uuid_;
 };
 
 }  // namespace grpc_core
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.cc b/src/core/ext/transport/chttp2/client/chttp2_connector.cc
index e7522ffba87..0ac84032fd4 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.cc
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.cc
@@ -117,6 +117,8 @@ static void on_handshake_done(void* arg, grpc_error* error) {
                                           c->args.interested_parties);
     c->result->transport =
         grpc_create_chttp2_transport(args->args, args->endpoint, true);
+    c->result->socket_uuid =
+        grpc_chttp2_transport_get_socket_uuid(c->result->transport);
     GPR_ASSERT(c->result->transport);
     // TODO(roth): We ideally want to wait until we receive HTTP/2
     // settings from the server before we consider the connection
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
index 45ef4161f78..776c15138b8 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.cc
@@ -3157,16 +3157,6 @@ static grpc_endpoint* chttp2_get_endpoint(grpc_transport* t) {
   return (reinterpret_cast<grpc_chttp2_transport*>(t))->ep;
 }
 
-static intptr_t get_socket_uuid(grpc_transport* transport) {
-  grpc_chttp2_transport* t =
-      reinterpret_cast<grpc_chttp2_transport*>(transport);
-  if (t->channelz_socket != nullptr) {
-    return t->channelz_socket->uuid();
-  } else {
-    return 0;
-  }
-}
-
 static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              "chttp2",
                                              init_stream,
@@ -3176,11 +3166,20 @@ static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              perform_transport_op,
                                              destroy_stream,
                                              destroy_transport,
-                                             chttp2_get_endpoint,
-                                             get_socket_uuid};
+                                             chttp2_get_endpoint};
 
 static const grpc_transport_vtable* get_vtable(void) { return &vtable; }
 
+intptr_t grpc_chttp2_transport_get_socket_uuid(grpc_transport* transport) {
+  grpc_chttp2_transport* t =
+      reinterpret_cast<grpc_chttp2_transport*>(transport);
+  if (t->channelz_socket != nullptr) {
+    return t->channelz_socket->uuid();
+  } else {
+    return 0;
+  }
+}
+
 grpc_transport* grpc_create_chttp2_transport(
     const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client) {
   grpc_chttp2_transport* t = static_cast<grpc_chttp2_transport*>(
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.h b/src/core/ext/transport/chttp2/transport/chttp2_transport.h
index 9d55b3f4b0d..e5872fee436 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.h
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.h
@@ -34,6 +34,8 @@ extern bool g_flow_control_enabled;
 grpc_transport* grpc_create_chttp2_transport(
     const grpc_channel_args* channel_args, grpc_endpoint* ep, bool is_client);
 
+intptr_t grpc_chttp2_transport_get_socket_uuid(grpc_transport* transport);
+
 /// Takes ownership of \a read_buffer, which (if non-NULL) contains
 /// leftover bytes previously read from the endpoint (e.g., by handshakers).
 /// If non-null, \a notify_on_receive_settings will be scheduled when
diff --git a/src/core/ext/transport/cronet/transport/cronet_transport.cc b/src/core/ext/transport/cronet/transport/cronet_transport.cc
index bb20d9db084..81e2634e3a7 100644
--- a/src/core/ext/transport/cronet/transport/cronet_transport.cc
+++ b/src/core/ext/transport/cronet/transport/cronet_transport.cc
@@ -1439,8 +1439,6 @@ static grpc_endpoint* get_endpoint(grpc_transport* gt) { return nullptr; }
 
 static void perform_op(grpc_transport* gt, grpc_transport_op* op) {}
 
-static intptr_t get_socket_uuid(grpc_transport* t) { return 0; }
-
 static const grpc_transport_vtable grpc_cronet_vtable = {
     sizeof(stream_obj),
     "cronet_http",
@@ -1451,8 +1449,7 @@ static const grpc_transport_vtable grpc_cronet_vtable = {
     perform_op,
     destroy_stream,
     destroy_transport,
-    get_endpoint,
-    get_socket_uuid};
+    get_endpoint};
 
 grpc_transport* grpc_create_cronet_transport(void* engine, const char* target,
                                              const grpc_channel_args* args,
diff --git a/src/core/ext/transport/inproc/inproc_transport.cc b/src/core/ext/transport/inproc/inproc_transport.cc
index 56951f83386..b0ca7f8207e 100644
--- a/src/core/ext/transport/inproc/inproc_transport.cc
+++ b/src/core/ext/transport/inproc/inproc_transport.cc
@@ -1170,8 +1170,6 @@ static void set_pollset_set(grpc_transport* gt, grpc_stream* gs,
 
 static grpc_endpoint* get_endpoint(grpc_transport* t) { return nullptr; }
 
-static intptr_t get_socket_uuid(grpc_transport* t) { return 0; }
-
 /*******************************************************************************
  * GLOBAL INIT AND DESTROY
  */
@@ -1196,7 +1194,7 @@ static const grpc_transport_vtable inproc_vtable = {
     sizeof(inproc_stream), "inproc",        init_stream,
     set_pollset,           set_pollset_set, perform_stream_op,
     perform_transport_op,  destroy_stream,  destroy_transport,
-    get_endpoint,          get_socket_uuid};
+    get_endpoint};
 
 /*******************************************************************************
  * Main inproc transport functions
diff --git a/src/core/lib/transport/transport.cc b/src/core/lib/transport/transport.cc
index c8fdbb4de26..cbdb77c8441 100644
--- a/src/core/lib/transport/transport.cc
+++ b/src/core/lib/transport/transport.cc
@@ -199,10 +199,6 @@ grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport) {
   return transport->vtable->get_endpoint(transport);
 }
 
-intptr_t grpc_transport_get_socket_uuid(grpc_transport* transport) {
-  return transport->vtable->get_socket_uuid(transport);
-}
-
 // This comment should be sung to the tune of
 // "Supercalifragilisticexpialidocious":
 //
diff --git a/src/core/lib/transport/transport.h b/src/core/lib/transport/transport.h
index aad133f6c3d..9e784635c69 100644
--- a/src/core/lib/transport/transport.h
+++ b/src/core/lib/transport/transport.h
@@ -366,8 +366,6 @@ void grpc_transport_destroy(grpc_transport* transport);
 /* Get the endpoint used by \a transport */
 grpc_endpoint* grpc_transport_get_endpoint(grpc_transport* transport);
 
-intptr_t grpc_transport_get_socket_uuid(grpc_transport* transport);
-
 /* Allocate a grpc_transport_op, and preconfigure the on_consumed closure to
    \a on_consumed and then delete the returned transport op */
 grpc_transport_op* grpc_make_transport_op(grpc_closure* on_consumed);
diff --git a/src/core/lib/transport/transport_impl.h b/src/core/lib/transport/transport_impl.h
index d609470ef01..ba5e05df0af 100644
--- a/src/core/lib/transport/transport_impl.h
+++ b/src/core/lib/transport/transport_impl.h
@@ -60,8 +60,6 @@ typedef struct grpc_transport_vtable {
 
   /* implementation of grpc_transport_get_endpoint */
   grpc_endpoint* (*get_endpoint)(grpc_transport* self);
-
-  intptr_t (*get_socket_uuid)(grpc_transport* self);
 } grpc_transport_vtable;
 
 /* an instance of a grpc transport */
diff --git a/test/cpp/microbenchmarks/bm_call_create.cc b/test/cpp/microbenchmarks/bm_call_create.cc
index 45ac782a0e1..9516b2e3e25 100644
--- a/test/cpp/microbenchmarks/bm_call_create.cc
+++ b/test/cpp/microbenchmarks/bm_call_create.cc
@@ -446,13 +446,11 @@ void Destroy(grpc_transport* self) {}
 /* implementation of grpc_transport_get_endpoint */
 grpc_endpoint* GetEndpoint(grpc_transport* self) { return nullptr; }
 
-intptr_t GetSocketUuid(grpc_transport* t) { return 0; }
-
 static const grpc_transport_vtable dummy_transport_vtable = {
-    0,           "dummy_http2", InitStream,
-    SetPollset,  SetPollsetSet, PerformStreamOp,
-    PerformOp,   DestroyStream, Destroy,
-    GetEndpoint, GetSocketUuid};
+    0,          "dummy_http2", InitStream,
+    SetPollset, SetPollsetSet, PerformStreamOp,
+    PerformOp,  DestroyStream, Destroy,
+    GetEndpoint};
 
 static grpc_transport dummy_transport = {&dummy_transport_vtable};