Merge branch 'master' of https://github.com/grpc/grpc into credentials_refactoring

21 files changed, 430 insertions, 300 deletions

diff --git a/src/core/ext/client_config/resolver_registry.c b/src/core/ext/client_config/resolver_registry.c
index 07f29bcb27..e7a4abd568 100644
--- a/src/core/ext/client_config/resolver_registry.c
+++ b/src/core/ext/client_config/resolver_registry.c
@@ -47,7 +47,6 @@ static int g_number_of_resolvers = 0;
 static char *g_default_resolver_prefix;
 
 void grpc_resolver_registry_init(const char *default_resolver_prefix) {
-  g_number_of_resolvers = 0;
   g_default_resolver_prefix = gpr_strdup(default_resolver_prefix);
 }
 
@@ -57,6 +56,13 @@ void grpc_resolver_registry_shutdown(void) {
     grpc_resolver_factory_unref(g_all_of_the_resolvers[i]);
   }
   gpr_free(g_default_resolver_prefix);
+  // FIXME(ctiller): this should live in grpc_resolver_registry_init,
+  // however that would have the client_config plugin call this AFTER we start
+  // registering resolvers from third party plugins, and so they'd never show
+  // up.
+  // We likely need some kind of dependency system for plugins.... what form
+  // that takes is TBD.
+  g_number_of_resolvers = 0;
 }
 
 void grpc_register_resolver_type(grpc_resolver_factory *factory) {
diff --git a/src/core/ext/lb_policy/grpclb/load_balancer_api.c b/src/core/ext/lb_policy/grpclb/load_balancer_api.c
index 459d6d9954..59b89997dd 100644
--- a/src/core/ext/lb_policy/grpclb/load_balancer_api.c
+++ b/src/core/ext/lb_policy/grpclb/load_balancer_api.c
@@ -50,7 +50,7 @@ static bool decode_serverlist(pb_istream_t *stream, const pb_field_t *field,
   decode_serverlist_arg *dec_arg = *arg;
   if (dec_arg->first_pass != 0) { /* first pass */
     grpc_grpclb_server server;
-    if (!pb_decode(stream, grpc_lb_v0_Server_fields, &server)) {
+    if (!pb_decode(stream, grpc_lb_v1_Server_fields, &server)) {
       return false;
     }
     dec_arg->num_servers++;
@@ -61,7 +61,7 @@ static bool decode_serverlist(pb_istream_t *stream, const pb_field_t *field,
       dec_arg->servers =
           gpr_malloc(sizeof(grpc_grpclb_server *) * dec_arg->num_servers);
     }
-    if (!pb_decode(stream, grpc_lb_v0_Server_fields, server)) {
+    if (!pb_decode(stream, grpc_lb_v1_Server_fields, server)) {
       return false;
     }
     dec_arg->servers[dec_arg->i++] = server;
@@ -87,13 +87,13 @@ gpr_slice grpc_grpclb_request_encode(const grpc_grpclb_request *request) {
   pb_ostream_t outputstream;
   gpr_slice slice;
   memset(&sizestream, 0, sizeof(pb_ostream_t));
-  pb_encode(&sizestream, grpc_lb_v0_LoadBalanceRequest_fields, request);
+  pb_encode(&sizestream, grpc_lb_v1_LoadBalanceRequest_fields, request);
   encoded_length = sizestream.bytes_written;
 
   slice = gpr_slice_malloc(encoded_length);
   outputstream =
       pb_ostream_from_buffer(GPR_SLICE_START_PTR(slice), encoded_length);
-  GPR_ASSERT(pb_encode(&outputstream, grpc_lb_v0_LoadBalanceRequest_fields,
+  GPR_ASSERT(pb_encode(&outputstream, grpc_lb_v1_LoadBalanceRequest_fields,
                        request) != 0);
   return slice;
 }
@@ -109,7 +109,7 @@ grpc_grpclb_response *grpc_grpclb_response_parse(gpr_slice encoded_response) {
                              GPR_SLICE_LENGTH(encoded_response));
   grpc_grpclb_response *res = gpr_malloc(sizeof(grpc_grpclb_response));
   memset(res, 0, sizeof(*res));
-  status = pb_decode(&stream, grpc_lb_v0_LoadBalanceResponse_fields, res);
+  status = pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, res);
   if (!status) {
     grpc_grpclb_response_destroy(res);
     return NULL;
@@ -132,7 +132,7 @@ grpc_grpclb_serverlist *grpc_grpclb_response_parse_serverlist(
   res->server_list.servers.funcs.decode = decode_serverlist;
   res->server_list.servers.arg = &arg;
   arg.first_pass = 1;
-  status = pb_decode(&stream, grpc_lb_v0_LoadBalanceResponse_fields, res);
+  status = pb_decode(&stream, grpc_lb_v1_LoadBalanceResponse_fields, res);
   if (!status) {
     grpc_grpclb_response_destroy(res);
     return NULL;
@@ -140,7 +140,7 @@ grpc_grpclb_serverlist *grpc_grpclb_response_parse_serverlist(
 
   arg.first_pass = 0;
   status =
-      pb_decode(&stream_at_start, grpc_lb_v0_LoadBalanceResponse_fields, res);
+      pb_decode(&stream_at_start, grpc_lb_v1_LoadBalanceResponse_fields, res);
   if (!status) {
     grpc_grpclb_response_destroy(res);
     return NULL;
diff --git a/src/core/ext/lb_policy/grpclb/load_balancer_api.h b/src/core/ext/lb_policy/grpclb/load_balancer_api.h
index 968f7d278a..71b5616d0c 100644
--- a/src/core/ext/lb_policy/grpclb/load_balancer_api.h
+++ b/src/core/ext/lb_policy/grpclb/load_balancer_api.h
@@ -37,7 +37,7 @@
 #include <grpc/support/slice_buffer.h>
 
 #include "src/core/ext/client_config/lb_policy_factory.h"
-#include "src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h"
+#include "src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -45,10 +45,10 @@ extern "C" {
 
 #define GRPC_GRPCLB_SERVICE_NAME_MAX_LENGTH 128
 
-typedef grpc_lb_v0_LoadBalanceRequest grpc_grpclb_request;
-typedef grpc_lb_v0_LoadBalanceResponse grpc_grpclb_response;
-typedef grpc_lb_v0_Server grpc_grpclb_server;
-typedef grpc_lb_v0_Duration grpc_grpclb_duration;
+typedef grpc_lb_v1_LoadBalanceRequest grpc_grpclb_request;
+typedef grpc_lb_v1_LoadBalanceResponse grpc_grpclb_response;
+typedef grpc_lb_v1_Server grpc_grpclb_server;
+typedef grpc_lb_v1_Duration grpc_grpclb_duration;
 typedef struct grpc_grpclb_serverlist {
   grpc_grpclb_server **servers;
   size_t num_servers;
diff --git a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h
deleted file mode 100644
index 3599f881bb..0000000000
--- a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h
+++ /dev/null
@@ -1,182 +0,0 @@
-/*
- *
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-/* Automatically generated nanopb header */
-/* Generated by nanopb-0.3.5-dev */
-
-#ifndef PB_LOAD_BALANCER_PB_H_INCLUDED
-#define PB_LOAD_BALANCER_PB_H_INCLUDED
-#include "third_party/nanopb/pb.h"
-#if PB_PROTO_HEADER_VERSION != 30
-#error Regenerate this file with the current version of nanopb generator.
-#endif
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* Struct definitions */
-typedef struct _grpc_lb_v0_ClientStats {
-    bool has_total_requests;
-    int64_t total_requests;
-    bool has_client_rpc_errors;
-    int64_t client_rpc_errors;
-    bool has_dropped_requests;
-    int64_t dropped_requests;
-} grpc_lb_v0_ClientStats;
-
-typedef struct _grpc_lb_v0_Duration {
-    bool has_seconds;
-    int64_t seconds;
-    bool has_nanos;
-    int32_t nanos;
-} grpc_lb_v0_Duration;
-
-typedef struct _grpc_lb_v0_InitialLoadBalanceRequest {
-    bool has_name;
-    char name[128];
-} grpc_lb_v0_InitialLoadBalanceRequest;
-
-typedef PB_BYTES_ARRAY_T(64) grpc_lb_v0_Server_load_balance_token_t;
-typedef struct _grpc_lb_v0_Server {
-    bool has_ip_address;
-    char ip_address[46];
-    bool has_port;
-    int32_t port;
-    bool has_load_balance_token;
-    grpc_lb_v0_Server_load_balance_token_t load_balance_token;
-    bool has_drop_request;
-    bool drop_request;
-} grpc_lb_v0_Server;
-
-typedef struct _grpc_lb_v0_InitialLoadBalanceResponse {
-    bool has_client_config;
-    char client_config[64];
-    bool has_load_balancer_delegate;
-    char load_balancer_delegate[64];
-    bool has_client_stats_report_interval;
-    grpc_lb_v0_Duration client_stats_report_interval;
-} grpc_lb_v0_InitialLoadBalanceResponse;
-
-typedef struct _grpc_lb_v0_LoadBalanceRequest {
-    bool has_initial_request;
-    grpc_lb_v0_InitialLoadBalanceRequest initial_request;
-    bool has_client_stats;
-    grpc_lb_v0_ClientStats client_stats;
-} grpc_lb_v0_LoadBalanceRequest;
-
-typedef struct _grpc_lb_v0_ServerList {
-    pb_callback_t servers;
-    bool has_expiration_interval;
-    grpc_lb_v0_Duration expiration_interval;
-} grpc_lb_v0_ServerList;
-
-typedef struct _grpc_lb_v0_LoadBalanceResponse {
-    bool has_initial_response;
-    grpc_lb_v0_InitialLoadBalanceResponse initial_response;
-    bool has_server_list;
-    grpc_lb_v0_ServerList server_list;
-} grpc_lb_v0_LoadBalanceResponse;
-
-/* Default values for struct fields */
-
-/* Initializer values for message structs */
-#define grpc_lb_v0_Duration_init_default         {false, 0, false, 0}
-#define grpc_lb_v0_LoadBalanceRequest_init_default {false, grpc_lb_v0_InitialLoadBalanceRequest_init_default, false, grpc_lb_v0_ClientStats_init_default}
-#define grpc_lb_v0_InitialLoadBalanceRequest_init_default {false, ""}
-#define grpc_lb_v0_ClientStats_init_default      {false, 0, false, 0, false, 0}
-#define grpc_lb_v0_LoadBalanceResponse_init_default {false, grpc_lb_v0_InitialLoadBalanceResponse_init_default, false, grpc_lb_v0_ServerList_init_default}
-#define grpc_lb_v0_InitialLoadBalanceResponse_init_default {false, "", false, "", false, grpc_lb_v0_Duration_init_default}
-#define grpc_lb_v0_ServerList_init_default       {{{NULL}, NULL}, false, grpc_lb_v0_Duration_init_default}
-#define grpc_lb_v0_Server_init_default           {false, "", false, 0, false, {0, {0}}, false, 0}
-#define grpc_lb_v0_Duration_init_zero            {false, 0, false, 0}
-#define grpc_lb_v0_LoadBalanceRequest_init_zero  {false, grpc_lb_v0_InitialLoadBalanceRequest_init_zero, false, grpc_lb_v0_ClientStats_init_zero}
-#define grpc_lb_v0_InitialLoadBalanceRequest_init_zero {false, ""}
-#define grpc_lb_v0_ClientStats_init_zero         {false, 0, false, 0, false, 0}
-#define grpc_lb_v0_LoadBalanceResponse_init_zero {false, grpc_lb_v0_InitialLoadBalanceResponse_init_zero, false, grpc_lb_v0_ServerList_init_zero}
-#define grpc_lb_v0_InitialLoadBalanceResponse_init_zero {false, "", false, "", false, grpc_lb_v0_Duration_init_zero}
-#define grpc_lb_v0_ServerList_init_zero          {{{NULL}, NULL}, false, grpc_lb_v0_Duration_init_zero}
-#define grpc_lb_v0_Server_init_zero              {false, "", false, 0, false, {0, {0}}, false, 0}
-
-/* Field tags (for use in manual encoding/decoding) */
-#define grpc_lb_v0_ClientStats_total_requests_tag 1
-#define grpc_lb_v0_ClientStats_client_rpc_errors_tag 2
-#define grpc_lb_v0_ClientStats_dropped_requests_tag 3
-#define grpc_lb_v0_Duration_seconds_tag          1
-#define grpc_lb_v0_Duration_nanos_tag            2
-#define grpc_lb_v0_InitialLoadBalanceRequest_name_tag 1
-#define grpc_lb_v0_Server_ip_address_tag         1
-#define grpc_lb_v0_Server_port_tag               2
-#define grpc_lb_v0_Server_load_balance_token_tag 3
-#define grpc_lb_v0_Server_drop_request_tag       4
-#define grpc_lb_v0_InitialLoadBalanceResponse_client_config_tag 1
-#define grpc_lb_v0_InitialLoadBalanceResponse_load_balancer_delegate_tag 2
-#define grpc_lb_v0_InitialLoadBalanceResponse_client_stats_report_interval_tag 3
-#define grpc_lb_v0_LoadBalanceRequest_initial_request_tag 1
-#define grpc_lb_v0_LoadBalanceRequest_client_stats_tag 2
-#define grpc_lb_v0_ServerList_servers_tag        1
-#define grpc_lb_v0_ServerList_expiration_interval_tag 3
-#define grpc_lb_v0_LoadBalanceResponse_initial_response_tag 1
-#define grpc_lb_v0_LoadBalanceResponse_server_list_tag 2
-
-/* Struct field encoding specification for nanopb */
-extern const pb_field_t grpc_lb_v0_Duration_fields[3];
-extern const pb_field_t grpc_lb_v0_LoadBalanceRequest_fields[3];
-extern const pb_field_t grpc_lb_v0_InitialLoadBalanceRequest_fields[2];
-extern const pb_field_t grpc_lb_v0_ClientStats_fields[4];
-extern const pb_field_t grpc_lb_v0_LoadBalanceResponse_fields[3];
-extern const pb_field_t grpc_lb_v0_InitialLoadBalanceResponse_fields[4];
-extern const pb_field_t grpc_lb_v0_ServerList_fields[3];
-extern const pb_field_t grpc_lb_v0_Server_fields[5];
-
-/* Maximum encoded size of messages (where known) */
-#define grpc_lb_v0_Duration_size                 22
-#define grpc_lb_v0_LoadBalanceRequest_size       169
-#define grpc_lb_v0_InitialLoadBalanceRequest_size 131
-#define grpc_lb_v0_ClientStats_size              33
-#define grpc_lb_v0_LoadBalanceResponse_size      (165 + grpc_lb_v0_ServerList_size)
-#define grpc_lb_v0_InitialLoadBalanceResponse_size 156
-#define grpc_lb_v0_Server_size                   127
-
-/* Message IDs (where set with "msgid" option) */
-#ifdef PB_MSGID
-
-#define LOAD_BALANCER_MESSAGES \
-
-
-#endif
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-#endif
diff --git a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.c b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
index 9719673181..52e11c40bb 100644
--- a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.c
+++ b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c
@@ -33,7 +33,7 @@
 /* Automatically generated nanopb constant definitions */
 /* Generated by nanopb-0.3.5-dev */
 
-#include "src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h"
+#include "src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h"
 
 #if PB_PROTO_HEADER_VERSION != 30
 #error Regenerate this file with the current version of nanopb generator.
@@ -41,54 +41,53 @@
 
 
 
-const pb_field_t grpc_lb_v0_Duration_fields[3] = {
-    PB_FIELD(  1, INT64   , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_Duration, seconds, seconds, 0),
-    PB_FIELD(  2, INT32   , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_Duration, nanos, seconds, 0),
+const pb_field_t grpc_lb_v1_Duration_fields[3] = {
+    PB_FIELD(  1, INT64   , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_Duration, seconds, seconds, 0),
+    PB_FIELD(  2, INT32   , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Duration, nanos, seconds, 0),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_LoadBalanceRequest_fields[3] = {
-    PB_FIELD(  1, MESSAGE , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_LoadBalanceRequest, initial_request, initial_request, &grpc_lb_v0_InitialLoadBalanceRequest_fields),
-    PB_FIELD(  2, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_LoadBalanceRequest, client_stats, initial_request, &grpc_lb_v0_ClientStats_fields),
+const pb_field_t grpc_lb_v1_LoadBalanceRequest_fields[3] = {
+    PB_FIELD(  1, MESSAGE , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_LoadBalanceRequest, initial_request, initial_request, &grpc_lb_v1_InitialLoadBalanceRequest_fields),
+    PB_FIELD(  2, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_LoadBalanceRequest, client_stats, initial_request, &grpc_lb_v1_ClientStats_fields),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_InitialLoadBalanceRequest_fields[2] = {
-    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_InitialLoadBalanceRequest, name, name, 0),
+const pb_field_t grpc_lb_v1_InitialLoadBalanceRequest_fields[2] = {
+    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_InitialLoadBalanceRequest, name, name, 0),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_ClientStats_fields[4] = {
-    PB_FIELD(  1, INT64   , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_ClientStats, total_requests, total_requests, 0),
-    PB_FIELD(  2, INT64   , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_ClientStats, client_rpc_errors, total_requests, 0),
-    PB_FIELD(  3, INT64   , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_ClientStats, dropped_requests, client_rpc_errors, 0),
+const pb_field_t grpc_lb_v1_ClientStats_fields[4] = {
+    PB_FIELD(  1, INT64   , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_ClientStats, total_requests, total_requests, 0),
+    PB_FIELD(  2, INT64   , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_ClientStats, client_rpc_errors, total_requests, 0),
+    PB_FIELD(  3, INT64   , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_ClientStats, dropped_requests, client_rpc_errors, 0),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_LoadBalanceResponse_fields[3] = {
-    PB_FIELD(  1, MESSAGE , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_LoadBalanceResponse, initial_response, initial_response, &grpc_lb_v0_InitialLoadBalanceResponse_fields),
-    PB_FIELD(  2, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_LoadBalanceResponse, server_list, initial_response, &grpc_lb_v0_ServerList_fields),
+const pb_field_t grpc_lb_v1_LoadBalanceResponse_fields[3] = {
+    PB_FIELD(  1, MESSAGE , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_LoadBalanceResponse, initial_response, initial_response, &grpc_lb_v1_InitialLoadBalanceResponse_fields),
+    PB_FIELD(  2, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_LoadBalanceResponse, server_list, initial_response, &grpc_lb_v1_ServerList_fields),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_InitialLoadBalanceResponse_fields[4] = {
-    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_InitialLoadBalanceResponse, client_config, client_config, 0),
-    PB_FIELD(  2, STRING  , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_InitialLoadBalanceResponse, load_balancer_delegate, client_config, 0),
-    PB_FIELD(  3, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_InitialLoadBalanceResponse, client_stats_report_interval, load_balancer_delegate, &grpc_lb_v0_Duration_fields),
+const pb_field_t grpc_lb_v1_InitialLoadBalanceResponse_fields[3] = {
+    PB_FIELD(  2, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_InitialLoadBalanceResponse, load_balancer_delegate, load_balancer_delegate, 0),
+    PB_FIELD(  3, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_InitialLoadBalanceResponse, client_stats_report_interval, load_balancer_delegate, &grpc_lb_v1_Duration_fields),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_ServerList_fields[3] = {
-    PB_FIELD(  1, MESSAGE , REPEATED, CALLBACK, FIRST, grpc_lb_v0_ServerList, servers, servers, &grpc_lb_v0_Server_fields),
-    PB_FIELD(  3, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_ServerList, expiration_interval, servers, &grpc_lb_v0_Duration_fields),
+const pb_field_t grpc_lb_v1_ServerList_fields[3] = {
+    PB_FIELD(  1, MESSAGE , REPEATED, CALLBACK, FIRST, grpc_lb_v1_ServerList, servers, servers, &grpc_lb_v1_Server_fields),
+    PB_FIELD(  3, MESSAGE , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_ServerList, expiration_interval, servers, &grpc_lb_v1_Duration_fields),
     PB_LAST_FIELD
 };
 
-const pb_field_t grpc_lb_v0_Server_fields[5] = {
-    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v0_Server, ip_address, ip_address, 0),
-    PB_FIELD(  2, INT32   , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_Server, port, ip_address, 0),
-    PB_FIELD(  3, BYTES   , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_Server, load_balance_token, port, 0),
-    PB_FIELD(  4, BOOL    , OPTIONAL, STATIC  , OTHER, grpc_lb_v0_Server, drop_request, load_balance_token, 0),
+const pb_field_t grpc_lb_v1_Server_fields[5] = {
+    PB_FIELD(  1, STRING  , OPTIONAL, STATIC  , FIRST, grpc_lb_v1_Server, ip_address, ip_address, 0),
+    PB_FIELD(  2, INT32   , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, port, ip_address, 0),
+    PB_FIELD(  3, STRING  , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, load_balance_token, port, 0),
+    PB_FIELD(  4, BOOL    , OPTIONAL, STATIC  , OTHER, grpc_lb_v1_Server, drop_request, load_balance_token, 0),
     PB_LAST_FIELD
 };
 
@@ -102,7 +101,7 @@ const pb_field_t grpc_lb_v0_Server_fields[5] = {
  * numbers or field sizes that are larger than what can fit in 8 or 16 bit
  * field descriptors.
  */
-PB_STATIC_ASSERT((pb_membersize(grpc_lb_v0_LoadBalanceRequest, initial_request) < 65536 && pb_membersize(grpc_lb_v0_LoadBalanceRequest, client_stats) < 65536 && pb_membersize(grpc_lb_v0_LoadBalanceResponse, initial_response) < 65536 && pb_membersize(grpc_lb_v0_LoadBalanceResponse, server_list) < 65536 && pb_membersize(grpc_lb_v0_InitialLoadBalanceResponse, client_stats_report_interval) < 65536 && pb_membersize(grpc_lb_v0_ServerList, servers) < 65536 && pb_membersize(grpc_lb_v0_ServerList, expiration_interval) < 65536), YOU_MUST_DEFINE_PB_FIELD_32BIT_FOR_MESSAGES_grpc_lb_v0_Duration_grpc_lb_v0_LoadBalanceRequest_grpc_lb_v0_InitialLoadBalanceRequest_grpc_lb_v0_ClientStats_grpc_lb_v0_LoadBalanceResponse_grpc_lb_v0_InitialLoadBalanceResponse_grpc_lb_v0_ServerList_grpc_lb_v0_Server)
+PB_STATIC_ASSERT((pb_membersize(grpc_lb_v1_LoadBalanceRequest, initial_request) < 65536 && pb_membersize(grpc_lb_v1_LoadBalanceRequest, client_stats) < 65536 && pb_membersize(grpc_lb_v1_LoadBalanceResponse, initial_response) < 65536 && pb_membersize(grpc_lb_v1_LoadBalanceResponse, server_list) < 65536 && pb_membersize(grpc_lb_v1_InitialLoadBalanceResponse, client_stats_report_interval) < 65536 && pb_membersize(grpc_lb_v1_ServerList, servers) < 65536 && pb_membersize(grpc_lb_v1_ServerList, expiration_interval) < 65536), YOU_MUST_DEFINE_PB_FIELD_32BIT_FOR_MESSAGES_grpc_lb_v1_Duration_grpc_lb_v1_LoadBalanceRequest_grpc_lb_v1_InitialLoadBalanceRequest_grpc_lb_v1_ClientStats_grpc_lb_v1_LoadBalanceResponse_grpc_lb_v1_InitialLoadBalanceResponse_grpc_lb_v1_ServerList_grpc_lb_v1_Server)
 #endif
 
 #if !defined(PB_FIELD_16BIT) && !defined(PB_FIELD_32BIT)
@@ -113,7 +112,7 @@ PB_STATIC_ASSERT((pb_membersize(grpc_lb_v0_LoadBalanceRequest, initial_request)
  * numbers or field sizes that are larger than what can fit in the default
  * 8 bit descriptors.
  */
-PB_STATIC_ASSERT((pb_membersize(grpc_lb_v0_LoadBalanceRequest, initial_request) < 256 && pb_membersize(grpc_lb_v0_LoadBalanceRequest, client_stats) < 256 && pb_membersize(grpc_lb_v0_LoadBalanceResponse, initial_response) < 256 && pb_membersize(grpc_lb_v0_LoadBalanceResponse, server_list) < 256 && pb_membersize(grpc_lb_v0_InitialLoadBalanceResponse, client_stats_report_interval) < 256 && pb_membersize(grpc_lb_v0_ServerList, servers) < 256 && pb_membersize(grpc_lb_v0_ServerList, expiration_interval) < 256), YOU_MUST_DEFINE_PB_FIELD_16BIT_FOR_MESSAGES_grpc_lb_v0_Duration_grpc_lb_v0_LoadBalanceRequest_grpc_lb_v0_InitialLoadBalanceRequest_grpc_lb_v0_ClientStats_grpc_lb_v0_LoadBalanceResponse_grpc_lb_v0_InitialLoadBalanceResponse_grpc_lb_v0_ServerList_grpc_lb_v0_Server)
+PB_STATIC_ASSERT((pb_membersize(grpc_lb_v1_LoadBalanceRequest, initial_request) < 256 && pb_membersize(grpc_lb_v1_LoadBalanceRequest, client_stats) < 256 && pb_membersize(grpc_lb_v1_LoadBalanceResponse, initial_response) < 256 && pb_membersize(grpc_lb_v1_LoadBalanceResponse, server_list) < 256 && pb_membersize(grpc_lb_v1_InitialLoadBalanceResponse, client_stats_report_interval) < 256 && pb_membersize(grpc_lb_v1_ServerList, servers) < 256 && pb_membersize(grpc_lb_v1_ServerList, expiration_interval) < 256), YOU_MUST_DEFINE_PB_FIELD_16BIT_FOR_MESSAGES_grpc_lb_v1_Duration_grpc_lb_v1_LoadBalanceRequest_grpc_lb_v1_InitialLoadBalanceRequest_grpc_lb_v1_ClientStats_grpc_lb_v1_LoadBalanceResponse_grpc_lb_v1_InitialLoadBalanceResponse_grpc_lb_v1_ServerList_grpc_lb_v1_Server)
 #endif
 
 
diff --git a/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
new file mode 100644
index 0000000000..d5dc39ab94
--- /dev/null
+++ b/src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h
@@ -0,0 +1,178 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+/* Automatically generated nanopb header */
+/* Generated by nanopb-0.3.5-dev */
+
+#ifndef PB_LOAD_BALANCER_PB_H_INCLUDED
+#define PB_LOAD_BALANCER_PB_H_INCLUDED
+#include "third_party/nanopb/pb.h"
+#if PB_PROTO_HEADER_VERSION != 30
+#error Regenerate this file with the current version of nanopb generator.
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Struct definitions */
+typedef struct _grpc_lb_v1_ClientStats {
+    bool has_total_requests;
+    int64_t total_requests;
+    bool has_client_rpc_errors;
+    int64_t client_rpc_errors;
+    bool has_dropped_requests;
+    int64_t dropped_requests;
+} grpc_lb_v1_ClientStats;
+
+typedef struct _grpc_lb_v1_Duration {
+    bool has_seconds;
+    int64_t seconds;
+    bool has_nanos;
+    int32_t nanos;
+} grpc_lb_v1_Duration;
+
+typedef struct _grpc_lb_v1_InitialLoadBalanceRequest {
+    bool has_name;
+    char name[128];
+} grpc_lb_v1_InitialLoadBalanceRequest;
+
+typedef struct _grpc_lb_v1_Server {
+    bool has_ip_address;
+    char ip_address[46];
+    bool has_port;
+    int32_t port;
+    bool has_load_balance_token;
+    char load_balance_token[64];
+    bool has_drop_request;
+    bool drop_request;
+} grpc_lb_v1_Server;
+
+typedef struct _grpc_lb_v1_InitialLoadBalanceResponse {
+    bool has_load_balancer_delegate;
+    char load_balancer_delegate[64];
+    bool has_client_stats_report_interval;
+    grpc_lb_v1_Duration client_stats_report_interval;
+} grpc_lb_v1_InitialLoadBalanceResponse;
+
+typedef struct _grpc_lb_v1_LoadBalanceRequest {
+    bool has_initial_request;
+    grpc_lb_v1_InitialLoadBalanceRequest initial_request;
+    bool has_client_stats;
+    grpc_lb_v1_ClientStats client_stats;
+} grpc_lb_v1_LoadBalanceRequest;
+
+typedef struct _grpc_lb_v1_ServerList {
+    pb_callback_t servers;
+    bool has_expiration_interval;
+    grpc_lb_v1_Duration expiration_interval;
+} grpc_lb_v1_ServerList;
+
+typedef struct _grpc_lb_v1_LoadBalanceResponse {
+    bool has_initial_response;
+    grpc_lb_v1_InitialLoadBalanceResponse initial_response;
+    bool has_server_list;
+    grpc_lb_v1_ServerList server_list;
+} grpc_lb_v1_LoadBalanceResponse;
+
+/* Default values for struct fields */
+
+/* Initializer values for message structs */
+#define grpc_lb_v1_Duration_init_default         {false, 0, false, 0}
+#define grpc_lb_v1_LoadBalanceRequest_init_default {false, grpc_lb_v1_InitialLoadBalanceRequest_init_default, false, grpc_lb_v1_ClientStats_init_default}
+#define grpc_lb_v1_InitialLoadBalanceRequest_init_default {false, ""}
+#define grpc_lb_v1_ClientStats_init_default      {false, 0, false, 0, false, 0}
+#define grpc_lb_v1_LoadBalanceResponse_init_default {false, grpc_lb_v1_InitialLoadBalanceResponse_init_default, false, grpc_lb_v1_ServerList_init_default}
+#define grpc_lb_v1_InitialLoadBalanceResponse_init_default {false, "", false, grpc_lb_v1_Duration_init_default}
+#define grpc_lb_v1_ServerList_init_default       {{{NULL}, NULL}, false, grpc_lb_v1_Duration_init_default}
+#define grpc_lb_v1_Server_init_default           {false, "", false, 0, false, "", false, 0}
+#define grpc_lb_v1_Duration_init_zero            {false, 0, false, 0}
+#define grpc_lb_v1_LoadBalanceRequest_init_zero  {false, grpc_lb_v1_InitialLoadBalanceRequest_init_zero, false, grpc_lb_v1_ClientStats_init_zero}
+#define grpc_lb_v1_InitialLoadBalanceRequest_init_zero {false, ""}
+#define grpc_lb_v1_ClientStats_init_zero         {false, 0, false, 0, false, 0}
+#define grpc_lb_v1_LoadBalanceResponse_init_zero {false, grpc_lb_v1_InitialLoadBalanceResponse_init_zero, false, grpc_lb_v1_ServerList_init_zero}
+#define grpc_lb_v1_InitialLoadBalanceResponse_init_zero {false, "", false, grpc_lb_v1_Duration_init_zero}
+#define grpc_lb_v1_ServerList_init_zero          {{{NULL}, NULL}, false, grpc_lb_v1_Duration_init_zero}
+#define grpc_lb_v1_Server_init_zero              {false, "", false, 0, false, "", false, 0}
+
+/* Field tags (for use in manual encoding/decoding) */
+#define grpc_lb_v1_ClientStats_total_requests_tag 1
+#define grpc_lb_v1_ClientStats_client_rpc_errors_tag 2
+#define grpc_lb_v1_ClientStats_dropped_requests_tag 3
+#define grpc_lb_v1_Duration_seconds_tag          1
+#define grpc_lb_v1_Duration_nanos_tag            2
+#define grpc_lb_v1_InitialLoadBalanceRequest_name_tag 1
+#define grpc_lb_v1_Server_ip_address_tag         1
+#define grpc_lb_v1_Server_port_tag               2
+#define grpc_lb_v1_Server_load_balance_token_tag 3
+#define grpc_lb_v1_Server_drop_request_tag       4
+#define grpc_lb_v1_InitialLoadBalanceResponse_load_balancer_delegate_tag 2
+#define grpc_lb_v1_InitialLoadBalanceResponse_client_stats_report_interval_tag 3
+#define grpc_lb_v1_LoadBalanceRequest_initial_request_tag 1
+#define grpc_lb_v1_LoadBalanceRequest_client_stats_tag 2
+#define grpc_lb_v1_ServerList_servers_tag        1
+#define grpc_lb_v1_ServerList_expiration_interval_tag 3
+#define grpc_lb_v1_LoadBalanceResponse_initial_response_tag 1
+#define grpc_lb_v1_LoadBalanceResponse_server_list_tag 2
+
+/* Struct field encoding specification for nanopb */
+extern const pb_field_t grpc_lb_v1_Duration_fields[3];
+extern const pb_field_t grpc_lb_v1_LoadBalanceRequest_fields[3];
+extern const pb_field_t grpc_lb_v1_InitialLoadBalanceRequest_fields[2];
+extern const pb_field_t grpc_lb_v1_ClientStats_fields[4];
+extern const pb_field_t grpc_lb_v1_LoadBalanceResponse_fields[3];
+extern const pb_field_t grpc_lb_v1_InitialLoadBalanceResponse_fields[3];
+extern const pb_field_t grpc_lb_v1_ServerList_fields[3];
+extern const pb_field_t grpc_lb_v1_Server_fields[5];
+
+/* Maximum encoded size of messages (where known) */
+#define grpc_lb_v1_Duration_size                 22
+#define grpc_lb_v1_LoadBalanceRequest_size       169
+#define grpc_lb_v1_InitialLoadBalanceRequest_size 131
+#define grpc_lb_v1_ClientStats_size              33
+#define grpc_lb_v1_LoadBalanceResponse_size      (98 + grpc_lb_v1_ServerList_size)
+#define grpc_lb_v1_InitialLoadBalanceResponse_size 90
+#define grpc_lb_v1_Server_size                   127
+
+/* Message IDs (where set with "msgid" option) */
+#ifdef PB_MSGID
+
+#define LOAD_BALANCER_MESSAGES \
+
+
+#endif
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index 3f6051b892..dcdc0c6285 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -306,8 +306,10 @@ static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) {
   size_t i;
   p->started_picking = 1;
 
-  gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%d", p,
-          p->num_subchannels);
+  if (grpc_lb_round_robin_trace) {
+    gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%d", p,
+            p->num_subchannels);
+  }
 
   for (i = 0; i < p->num_subchannels; i++) {
     subchannel_data *sd = p->subchannels[i];
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 8c8593748d..b6886a2201 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -56,6 +56,8 @@
 #define DEFAULT_CONNECTION_WINDOW_TARGET (1024 * 1024)
 #define MAX_WINDOW 0x7fffffffu
 
+#define DEFAULT_MAX_HEADER_LIST_SIZE (16 * 1024)
+
 #define MAX_CLIENT_STREAM_ID 0x7fffffffu
 
 int grpc_http_trace = 0;
@@ -65,8 +67,8 @@ int grpc_flowctl_trace = 0;
   ((grpc_chttp2_transport *)((char *)(tw)-offsetof(grpc_chttp2_transport, \
                                                    writing)))
 
-#define TRANSPORT_FROM_PARSING(tw)                                        \
-  ((grpc_chttp2_transport *)((char *)(tw)-offsetof(grpc_chttp2_transport, \
+#define TRANSPORT_FROM_PARSING(tp)                                        \
+  ((grpc_chttp2_transport *)((char *)(tp)-offsetof(grpc_chttp2_transport, \
                                                    parsing)))
 
 #define TRANSPORT_FROM_GLOBAL(tg)                                         \
@@ -311,6 +313,8 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     push_setting(t, GRPC_CHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 0);
   }
   push_setting(t, GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE, DEFAULT_WINDOW);
+  push_setting(t, GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE,
+               DEFAULT_MAX_HEADER_LIST_SIZE);
 
   if (channel_args) {
     for (i = 0; i < channel_args->num_args; i++) {
@@ -378,6 +382,18 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
               &t->writing.hpack_compressor,
               (uint32_t)channel_args->args[i].value.integer);
         }
+      } else if (0 == strcmp(channel_args->args[i].key,
+                             GRPC_ARG_MAX_METADATA_SIZE)) {
+        if (channel_args->args[i].type != GRPC_ARG_INTEGER) {
+          gpr_log(GPR_ERROR, "%s: must be an integer",
+                  GRPC_ARG_MAX_METADATA_SIZE);
+        } else if (channel_args->args[i].value.integer < 0) {
+          gpr_log(GPR_ERROR, "%s: must be non-negative",
+                  GRPC_ARG_MAX_METADATA_SIZE);
+        } else {
+          push_setting(t, GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE,
+                       (uint32_t)channel_args->args[i].value.integer);
+        }
       }
     }
   }
@@ -510,7 +526,7 @@ static int init_stream(grpc_exec_ctx *exec_ctx, grpc_transport *gt,
                           [GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE];
     *t->accepting_stream = s;
     grpc_chttp2_stream_map_add(&t->parsing_stream_map, s->global.id, s);
-    s->global.in_stream_map = 1;
+    s->global.in_stream_map = true;
   }
 
   grpc_chttp2_run_with_global_lock(exec_ctx, t, s, finish_init_stream_locked,
@@ -783,7 +799,8 @@ void grpc_chttp2_add_incoming_goaway(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
     uint32_t goaway_error, gpr_slice goaway_text) {
   char *msg = gpr_dump_slice(goaway_text, GPR_DUMP_HEX | GPR_DUMP_ASCII);
-  gpr_log(GPR_DEBUG, "got goaway [%d]: %s", goaway_error, msg);
+  GRPC_CHTTP2_IF_TRACING(
+      gpr_log(GPR_DEBUG, "got goaway [%d]: %s", goaway_error, msg));
   gpr_free(msg);
   gpr_slice_unref(goaway_text);
   transport_global->seen_goaway = 1;
@@ -833,7 +850,7 @@ static void maybe_start_some_streams(
     grpc_chttp2_stream_map_add(
         &TRANSPORT_FROM_GLOBAL(transport_global)->new_stream_map,
         stream_global->id, STREAM_FROM_GLOBAL(stream_global));
-    stream_global->in_stream_map = 1;
+    stream_global->in_stream_map = true;
     transport_global->concurrent_stream_count++;
     grpc_chttp2_become_writable(transport_global, stream_global);
   }
@@ -932,24 +949,38 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx,
     stream_global->send_initial_metadata_finished =
         add_closure_barrier(on_complete);
     stream_global->send_initial_metadata = op->send_initial_metadata;
-    if (contains_non_ok_status(transport_global, op->send_initial_metadata)) {
-      stream_global->seen_error = 1;
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-    if (!stream_global->write_closed) {
-      if (transport_global->is_client) {
-        GPR_ASSERT(stream_global->id == 0);
-        grpc_chttp2_list_add_waiting_for_concurrency(transport_global,
-                                                     stream_global);
-        maybe_start_some_streams(exec_ctx, transport_global);
+    const size_t metadata_size =
+        grpc_metadata_batch_size(op->send_initial_metadata);
+    const size_t metadata_peer_limit =
+        transport_global->settings[GRPC_PEER_SETTINGS]
+                                  [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+    if (metadata_size > metadata_peer_limit) {
+      gpr_log(GPR_DEBUG,
+              "to-be-sent initial metadata size exceeds peer limit "
+              "(%lu vs. %lu)",
+              metadata_size, metadata_peer_limit);
+      cancel_from_api(exec_ctx, transport_global, stream_global,
+                      GRPC_STATUS_RESOURCE_EXHAUSTED);
+    } else {
+      if (contains_non_ok_status(transport_global, op->send_initial_metadata)) {
+        stream_global->seen_error = true;
+        grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
+      }
+      if (!stream_global->write_closed) {
+        if (transport_global->is_client) {
+          GPR_ASSERT(stream_global->id == 0);
+          grpc_chttp2_list_add_waiting_for_concurrency(transport_global,
+                                                       stream_global);
+          maybe_start_some_streams(exec_ctx, transport_global);
+        } else {
+          GPR_ASSERT(stream_global->id != 0);
+          grpc_chttp2_become_writable(transport_global, stream_global);
+        }
       } else {
-        GPR_ASSERT(stream_global->id != 0);
-        grpc_chttp2_become_writable(transport_global, stream_global);
+        grpc_chttp2_complete_closure_step(
+            exec_ctx, stream_global,
+            &stream_global->send_initial_metadata_finished, 0);
       }
-    } else {
-      grpc_chttp2_complete_closure_step(
-          exec_ctx, stream_global,
-          &stream_global->send_initial_metadata_finished, 0);
     }
   }
 
@@ -973,19 +1004,34 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx,
     stream_global->send_trailing_metadata_finished =
         add_closure_barrier(on_complete);
     stream_global->send_trailing_metadata = op->send_trailing_metadata;
-    if (contains_non_ok_status(transport_global, op->send_trailing_metadata)) {
-      stream_global->seen_error = 1;
-      grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
-    }
-    if (stream_global->write_closed) {
-      grpc_chttp2_complete_closure_step(
-          exec_ctx, stream_global,
-          &stream_global->send_trailing_metadata_finished,
-          grpc_metadata_batch_is_empty(op->send_trailing_metadata));
-    } else if (stream_global->id != 0) {
-      /* TODO(ctiller): check if there's flow control for any outstanding
-         bytes before going writable */
-      grpc_chttp2_become_writable(transport_global, stream_global);
+    const size_t metadata_size =
+        grpc_metadata_batch_size(op->send_trailing_metadata);
+    const size_t metadata_peer_limit =
+        transport_global->settings[GRPC_PEER_SETTINGS]
+                                  [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+    if (metadata_size > metadata_peer_limit) {
+      gpr_log(GPR_DEBUG,
+              "to-be-sent trailing metadata size exceeds peer limit "
+              "(%lu vs. %lu)",
+              metadata_size, metadata_peer_limit);
+      cancel_from_api(exec_ctx, transport_global, stream_global,
+                      GRPC_STATUS_RESOURCE_EXHAUSTED);
+    } else {
+      if (contains_non_ok_status(transport_global,
+                                 op->send_trailing_metadata)) {
+        stream_global->seen_error = true;
+        grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
+      }
+      if (stream_global->write_closed) {
+        grpc_chttp2_complete_closure_step(
+            exec_ctx, stream_global,
+            &stream_global->send_trailing_metadata_finished,
+            grpc_metadata_batch_is_empty(op->send_trailing_metadata));
+      } else if (stream_global->id != 0) {
+        /* TODO(ctiller): check if there's flow control for any outstanding
+           bytes before going writable */
+        grpc_chttp2_become_writable(transport_global, stream_global);
+      }
     }
   }
 
@@ -1148,6 +1194,16 @@ static void check_read_ops(grpc_exec_ctx *exec_ctx,
       grpc_chttp2_list_pop_check_read_ops(transport_global, &stream_global)) {
     if (stream_global->recv_initial_metadata_ready != NULL &&
         stream_global->published_initial_metadata) {
+      if (stream_global->seen_error) {
+        while ((bs = grpc_chttp2_incoming_frame_queue_pop(
+                    &stream_global->incoming_frames)) != NULL) {
+          incoming_byte_stream_destroy_locked(exec_ctx, NULL, NULL, bs);
+        }
+        if (stream_global->exceeded_metadata_size) {
+          cancel_from_api(exec_ctx, transport_global, stream_global,
+                          GRPC_STATUS_RESOURCE_EXHAUSTED);
+        }
+      }
       grpc_chttp2_incoming_metadata_buffer_publish(
           &stream_global->received_initial_metadata,
           stream_global->recv_initial_metadata);
@@ -1177,10 +1233,15 @@ static void check_read_ops(grpc_exec_ctx *exec_ctx,
     }
     if (stream_global->recv_trailing_metadata_finished != NULL &&
         stream_global->read_closed && stream_global->write_closed) {
-      while (stream_global->seen_error &&
-             (bs = grpc_chttp2_incoming_frame_queue_pop(
-                  &stream_global->incoming_frames)) != NULL) {
-        incoming_byte_stream_destroy_locked(exec_ctx, NULL, NULL, bs);
+      if (stream_global->seen_error) {
+        while ((bs = grpc_chttp2_incoming_frame_queue_pop(
+                    &stream_global->incoming_frames)) != NULL) {
+          incoming_byte_stream_destroy_locked(exec_ctx, NULL, NULL, bs);
+        }
+        if (stream_global->exceeded_metadata_size) {
+          cancel_from_api(exec_ctx, transport_global, stream_global,
+                          GRPC_STATUS_RESOURCE_EXHAUSTED);
+        }
       }
       if (stream_global->all_incoming_byte_streams_finished) {
         grpc_chttp2_incoming_metadata_buffer_publish(
@@ -1212,7 +1273,7 @@ static void remove_stream(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     s = grpc_chttp2_stream_map_delete(&t->new_stream_map, id);
   }
   GPR_ASSERT(s);
-  s->global.in_stream_map = 0;
+  s->global.in_stream_map = false;
   if (t->parsing.incoming_stream == &s->parsing) {
     t->parsing.incoming_stream = NULL;
     grpc_chttp2_parsing_become_skip_parser(exec_ctx, &t->parsing);
@@ -1256,7 +1317,7 @@ static void cancel_from_api(grpc_exec_ctx *exec_ctx,
                             NULL);
   }
   if (status != GRPC_STATUS_OK && !stream_global->seen_error) {
-    stream_global->seen_error = 1;
+    stream_global->seen_error = true;
     grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
   }
   grpc_chttp2_mark_stream_closed(exec_ctx, transport_global, stream_global, 1,
@@ -1268,7 +1329,7 @@ void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx,
                              grpc_chttp2_stream_global *stream_global,
                              grpc_status_code status, gpr_slice *slice) {
   if (status != GRPC_STATUS_OK) {
-    stream_global->seen_error = 1;
+    stream_global->seen_error = true;
     grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
   }
   /* stream_global->recv_trailing_metadata_finished gives us a
@@ -1292,7 +1353,7 @@ void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx,
               GRPC_MDSTR_GRPC_MESSAGE,
               grpc_mdstr_from_slice(gpr_slice_ref(*slice))));
     }
-    stream_global->published_trailing_metadata = 1;
+    stream_global->published_trailing_metadata = true;
     grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
   }
   if (slice) {
@@ -1322,13 +1383,13 @@ void grpc_chttp2_mark_stream_closed(
   }
   grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
   if (close_reads && !stream_global->read_closed) {
-    stream_global->read_closed = 1;
-    stream_global->published_initial_metadata = 1;
-    stream_global->published_trailing_metadata = 1;
+    stream_global->read_closed = true;
+    stream_global->published_initial_metadata = true;
+    stream_global->published_trailing_metadata = true;
     decrement_active_streams_locked(exec_ctx, transport_global, stream_global);
   }
   if (close_writes && !stream_global->write_closed) {
-    stream_global->write_closed = 1;
+    stream_global->write_closed = true;
     if (TRANSPORT_FROM_GLOBAL(transport_global)->executor.writing_active) {
       GRPC_CHTTP2_STREAM_REF(stream_global, "finish_writes");
       grpc_chttp2_list_add_closed_waiting_for_writing(transport_global,
diff --git a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
index 22467e9ddd..7f01105e3e 100644
--- a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
+++ b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
@@ -45,15 +45,20 @@ gpr_slice grpc_chttp2_rst_stream_create(uint32_t id, uint32_t code,
   stats->framing_bytes += frame_size;
   uint8_t *p = GPR_SLICE_START_PTR(slice);
 
+  // Frame size.
   *p++ = 0;
   *p++ = 0;
   *p++ = 4;
+  // Frame type.
   *p++ = GRPC_CHTTP2_FRAME_RST_STREAM;
+  // Flags.
   *p++ = 0;
+  // Stream ID.
   *p++ = (uint8_t)(id >> 24);
   *p++ = (uint8_t)(id >> 16);
   *p++ = (uint8_t)(id >> 8);
   *p++ = (uint8_t)(id);
+  // Error code.
   *p++ = (uint8_t)(code >> 24);
   *p++ = (uint8_t)(code >> 16);
   *p++ = (uint8_t)(code >> 8);
diff --git a/src/core/ext/transport/chttp2/transport/hpack_encoder.c b/src/core/ext/transport/chttp2/transport/hpack_encoder.c
index 555027c866..ebeee37f0d 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_encoder.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_encoder.c
@@ -63,6 +63,8 @@
 /* don't consider adding anything bigger than this to the hpack table */
 #define MAX_DECODER_SPACE_USAGE 512
 
+extern int grpc_http_trace;
+
 typedef struct {
   int is_first_frame;
   /* number of bytes in 'output' when we started the frame - used to calculate
@@ -532,7 +534,9 @@ void grpc_chttp2_hpack_compressor_set_max_table_size(
     }
   }
   c->advertise_table_size_change = 1;
-  gpr_log(GPR_DEBUG, "set max table size from encoder to %d", max_table_size);
+  if (grpc_http_trace) {
+    gpr_log(GPR_DEBUG, "set max table size from encoder to %d", max_table_size);
+  }
 }
 
 void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
diff --git a/src/core/ext/transport/chttp2/transport/hpack_table.c b/src/core/ext/transport/chttp2/transport/hpack_table.c
index 4d64506de2..295f31c44f 100644
--- a/src/core/ext/transport/chttp2/transport/hpack_table.c
+++ b/src/core/ext/transport/chttp2/transport/hpack_table.c
@@ -253,7 +253,9 @@ void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
   if (tbl->max_bytes == max_bytes) {
     return;
   }
-  gpr_log(GPR_DEBUG, "Update hpack parser max size to %d", max_bytes);
+  if (grpc_http_trace) {
+    gpr_log(GPR_DEBUG, "Update hpack parser max size to %d", max_bytes);
+  }
   while (tbl->mem_used > max_bytes) {
     evict1(tbl);
   }
diff --git a/src/core/ext/transport/chttp2/transport/incoming_metadata.c b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
index db21744f0c..3e463a7995 100644
--- a/src/core/ext/transport/chttp2/transport/incoming_metadata.c
+++ b/src/core/ext/transport/chttp2/transport/incoming_metadata.c
@@ -65,6 +65,7 @@ void grpc_chttp2_incoming_metadata_buffer_add(
         gpr_realloc(buffer->elems, sizeof(*buffer->elems) * buffer->capacity);
   }
   buffer->elems[buffer->count++].md = elem;
+  buffer->size += GRPC_MDELEM_LENGTH(elem);
 }
 
 void grpc_chttp2_incoming_metadata_buffer_set_deadline(
diff --git a/src/core/ext/transport/chttp2/transport/incoming_metadata.h b/src/core/ext/transport/chttp2/transport/incoming_metadata.h
index 17ecf8e181..df4343b93e 100644
--- a/src/core/ext/transport/chttp2/transport/incoming_metadata.h
+++ b/src/core/ext/transport/chttp2/transport/incoming_metadata.h
@@ -42,6 +42,7 @@ typedef struct {
   size_t capacity;
   gpr_timespec deadline;
   int published;
+  size_t size;  // total size of metadata
 } grpc_chttp2_incoming_metadata_buffer;
 
 /** assumes everything initially zeroed */
diff --git a/src/core/ext/transport/chttp2/transport/internal.h b/src/core/ext/transport/chttp2/transport/internal.h
index 8c4fa2d34a..5872fd8e0a 100644
--- a/src/core/ext/transport/chttp2/transport/internal.h
+++ b/src/core/ext/transport/chttp2/transport/internal.h
@@ -422,23 +422,21 @@ typedef struct {
   /** number of streams that are currently being read */
   gpr_refcount active_streams;
 
-  /** when the application requests writes be closed, the write_closed is
-      'queued'; when the close is flow controlled into the send path, we are
-      'sending' it; when the write has been performed it is 'sent' */
+  /** Is this stream closed for writing. */
   bool write_closed;
-  /** is this stream reading half-closed (boolean) */
+  /** Is this stream reading half-closed. */
   bool read_closed;
-  /** are all published incoming byte streams closed */
+  /** Are all published incoming byte streams closed. */
   bool all_incoming_byte_streams_finished;
-  /** is this stream in the stream map? (boolean) */
+  /** Is this stream in the stream map. */
   bool in_stream_map;
-  /** has this stream seen an error? if 1, then pending incoming frames
-      can be thrown away */
+  /** Has this stream seen an error.
+      If true, then pending incoming frames can be thrown away. */
   bool seen_error;
+  bool exceeded_metadata_size;
 
   bool published_initial_metadata;
   bool published_trailing_metadata;
-  bool faked_trailing_metadata;
 
   grpc_chttp2_incoming_metadata_buffer received_initial_metadata;
   grpc_chttp2_incoming_metadata_buffer received_trailing_metadata;
@@ -481,7 +479,8 @@ struct grpc_chttp2_stream_parsing {
   /** which metadata did we get (on this parse) */
   uint8_t got_metadata_on_parse[2];
   /** should we raise the seen_error flag in transport_global */
-  uint8_t seen_error;
+  bool seen_error;
+  bool exceeded_metadata_size;
   /** window available for peer to send to us */
   int64_t incoming_window;
   /** parsing state for data frames */
diff --git a/src/core/ext/transport/chttp2/transport/parsing.c b/src/core/ext/transport/chttp2/transport/parsing.c
index 2995066e51..4bd374b7fa 100644
--- a/src/core/ext/transport/chttp2/transport/parsing.c
+++ b/src/core/ext/transport/chttp2/transport/parsing.c
@@ -45,6 +45,10 @@
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/transport/static_metadata.h"
 
+#define TRANSPORT_FROM_PARSING(tp)                                        \
+  ((grpc_chttp2_transport *)((char *)(tp)-offsetof(grpc_chttp2_transport, \
+                                                   parsing)))
+
 static int init_frame_parser(grpc_exec_ctx *exec_ctx,
                              grpc_chttp2_transport_parsing *transport_parsing);
 static int init_header_frame_parser(
@@ -170,7 +174,9 @@ void grpc_chttp2_publish_reads(
   while (grpc_chttp2_list_pop_parsing_seen_stream(
       transport_global, transport_parsing, &stream_global, &stream_parsing)) {
     if (stream_parsing->seen_error) {
-      stream_global->seen_error = 1;
+      stream_global->seen_error = true;
+      stream_global->exceeded_metadata_size =
+          stream_parsing->exceeded_metadata_size;
       grpc_chttp2_list_add_check_read_ops(transport_global, stream_global);
     }
 
@@ -612,7 +618,7 @@ static void on_initial_header(void *tp, grpc_mdelem *md) {
 
   if (md->key == GRPC_MDSTR_GRPC_STATUS && md != GRPC_MDELEM_GRPC_STATUS_0) {
     /* TODO(ctiller): check for a status like " 0" */
-    stream_parsing->seen_error = 1;
+    stream_parsing->seen_error = true;
   }
 
   if (md->key == GRPC_MDSTR_GRPC_TIMEOUT) {
@@ -633,8 +639,26 @@ static void on_initial_header(void *tp, grpc_mdelem *md) {
         gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), *cached_timeout));
     GRPC_MDELEM_UNREF(md);
   } else {
-    grpc_chttp2_incoming_metadata_buffer_add(
-        &stream_parsing->metadata_buffer[0], md);
+    const size_t new_size =
+        stream_parsing->metadata_buffer[0].size + GRPC_MDELEM_LENGTH(md);
+    grpc_chttp2_transport_global *transport_global =
+        &TRANSPORT_FROM_PARSING(transport_parsing)->global;
+    const size_t metadata_size_limit =
+        transport_global->settings[GRPC_LOCAL_SETTINGS]
+                                  [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+    if (new_size > metadata_size_limit) {
+      if (!stream_parsing->exceeded_metadata_size) {
+        gpr_log(GPR_DEBUG,
+                "received initial metadata size exceeds limit (%lu vs. %lu)",
+                new_size, metadata_size_limit);
+        stream_parsing->seen_error = true;
+        stream_parsing->exceeded_metadata_size = true;
+      }
+      GRPC_MDELEM_UNREF(md);
+    } else {
+      grpc_chttp2_incoming_metadata_buffer_add(
+          &stream_parsing->metadata_buffer[0], md);
+    }
   }
 
   grpc_chttp2_list_add_parsing_seen_stream(transport_parsing, stream_parsing);
@@ -658,12 +682,30 @@ static void on_trailing_header(void *tp, grpc_mdelem *md) {
 
   if (md->key == GRPC_MDSTR_GRPC_STATUS && md != GRPC_MDELEM_GRPC_STATUS_0) {
     /* TODO(ctiller): check for a status like " 0" */
-    stream_parsing->seen_error = 1;
+    stream_parsing->seen_error = true;
+  }
+
+  const size_t new_size =
+      stream_parsing->metadata_buffer[1].size + GRPC_MDELEM_LENGTH(md);
+  grpc_chttp2_transport_global *transport_global =
+      &TRANSPORT_FROM_PARSING(transport_parsing)->global;
+  const size_t metadata_size_limit =
+      transport_global->settings[GRPC_LOCAL_SETTINGS]
+                                [GRPC_CHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE];
+  if (new_size > metadata_size_limit) {
+    if (!stream_parsing->exceeded_metadata_size) {
+      gpr_log(GPR_DEBUG,
+              "received trailing metadata size exceeds limit (%lu vs. %lu)",
+              new_size, metadata_size_limit);
+      stream_parsing->seen_error = true;
+      stream_parsing->exceeded_metadata_size = true;
+    }
+    GRPC_MDELEM_UNREF(md);
+  } else {
+    grpc_chttp2_incoming_metadata_buffer_add(
+        &stream_parsing->metadata_buffer[1], md);
   }
 
-  grpc_chttp2_incoming_metadata_buffer_add(&stream_parsing->metadata_buffer[1],
-                                           md);
-
   grpc_chttp2_list_add_parsing_seen_stream(transport_parsing, stream_parsing);
 
   GPR_TIMER_END("on_trailing_header", 0);
diff --git a/src/core/lib/channel/channel_args.h b/src/core/lib/channel/channel_args.h
index 0a51780a14..23c7b7b897 100644
--- a/src/core/lib/channel/channel_args.h
+++ b/src/core/lib/channel/channel_args.h
@@ -56,10 +56,6 @@ grpc_channel_args *grpc_channel_args_merge(const grpc_channel_args *a,
 /** Destroy arguments created by \a grpc_channel_args_copy */
 void grpc_channel_args_destroy(grpc_channel_args *a);
 
-/** Reads census_enabled settings from channel args. Returns 1 if census_enabled
- * is specified in channel args, otherwise returns 0. */
-int grpc_channel_args_is_census_enabled(const grpc_channel_args *a);
-
 /** Returns the compression algorithm set in \a a. */
 grpc_compression_algorithm grpc_channel_args_get_compression_algorithm(
     const grpc_channel_args *a);
diff --git a/src/core/lib/iomgr/tcp_posix.c b/src/core/lib/iomgr/tcp_posix.c
index 7210aef5d5..e2869224f1 100644
--- a/src/core/lib/iomgr/tcp_posix.c
+++ b/src/core/lib/iomgr/tcp_posix.c
@@ -164,7 +164,7 @@ static void call_read_cb(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp, int success) {
     for (i = 0; i < tcp->incoming_buffer->count; i++) {
       char *dump = gpr_dump_slice(tcp->incoming_buffer->slices[i],
                                   GPR_DUMP_HEX | GPR_DUMP_ASCII);
-      gpr_log(GPR_DEBUG, "READ %p: %s", tcp, dump);
+      gpr_log(GPR_DEBUG, "READ %p (peer=%s): %s", tcp, tcp->peer_string, dump);
       gpr_free(dump);
     }
   }
@@ -398,7 +398,7 @@ static void tcp_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
     for (i = 0; i < buf->count; i++) {
       char *data =
           gpr_dump_slice(buf->slices[i], GPR_DUMP_HEX | GPR_DUMP_ASCII);
-      gpr_log(GPR_DEBUG, "WRITE %p: %s", tcp, data);
+      gpr_log(GPR_DEBUG, "WRITE %p (peer=%s): %s", tcp, tcp->peer_string, data);
       gpr_free(data);
     }
   }
diff --git a/src/core/lib/surface/version.c b/src/core/lib/surface/version.c
index fe954cbefb..aca76d2bb7 100644
--- a/src/core/lib/surface/version.c
+++ b/src/core/lib/surface/version.c
@@ -36,4 +36,4 @@
 
 #include <grpc/grpc.h>
 
-const char *grpc_version_string(void) { return "0.14.0-dev"; }
+const char *grpc_version_string(void) { return "0.15.0-dev"; }
diff --git a/src/core/lib/transport/metadata.h b/src/core/lib/transport/metadata.h
index 713d9e6782..6d82f4d681 100644
--- a/src/core/lib/transport/metadata.h
+++ b/src/core/lib/transport/metadata.h
@@ -147,6 +147,10 @@ const char *grpc_mdstr_as_c_string(grpc_mdstr *s);
 
 #define GRPC_MDSTR_LENGTH(s) (GPR_SLICE_LENGTH(s->slice))
 
+/* We add 32 bytes of padding as per RFC-7540 section 6.5.2. */
+#define GRPC_MDELEM_LENGTH(e) \
+  (GRPC_MDSTR_LENGTH((e)->key) + GRPC_MDSTR_LENGTH((e)->value) + 32)
+
 int grpc_mdstr_is_legal_header(grpc_mdstr *s);
 int grpc_mdstr_is_legal_nonbin_header(grpc_mdstr *s);
 int grpc_mdstr_is_bin_suffixed(grpc_mdstr *s);
diff --git a/src/core/lib/transport/metadata_batch.c b/src/core/lib/transport/metadata_batch.c
index 4567221a48..e4398abeb7 100644
--- a/src/core/lib/transport/metadata_batch.c
+++ b/src/core/lib/transport/metadata_batch.c
@@ -192,3 +192,12 @@ int grpc_metadata_batch_is_empty(grpc_metadata_batch *batch) {
          gpr_time_cmp(gpr_inf_future(batch->deadline.clock_type),
                       batch->deadline) == 0;
 }
+
+size_t grpc_metadata_batch_size(grpc_metadata_batch *batch) {
+  size_t size = 0;
+  for (grpc_linked_mdelem *elem = batch->list.head; elem != NULL;
+       elem = elem->next) {
+    size += GRPC_MDELEM_LENGTH(elem->md);
+  }
+  return size;
+}
diff --git a/src/core/lib/transport/metadata_batch.h b/src/core/lib/transport/metadata_batch.h
index b62668876e..7af823f7ca 100644
--- a/src/core/lib/transport/metadata_batch.h
+++ b/src/core/lib/transport/metadata_batch.h
@@ -66,6 +66,9 @@ void grpc_metadata_batch_destroy(grpc_metadata_batch *batch);
 void grpc_metadata_batch_clear(grpc_metadata_batch *batch);
 int grpc_metadata_batch_is_empty(grpc_metadata_batch *batch);
 
+/* Returns the transport size of the batch. */
+size_t grpc_metadata_batch_size(grpc_metadata_batch *batch);
+
 /** Moves the metadata information from \a src to \a dst. Upon return, \a src is
  * zeroed. */
 void grpc_metadata_batch_move(grpc_metadata_batch *dst,