Merge remote-tracking branch 'upstream/master' into fix-stream-compression-config-interface

61 files changed, 644 insertions, 344 deletions

diff --git a/src/core/ext/filters/client_channel/channel_connectivity.c b/src/core/ext/filters/client_channel/channel_connectivity.cc
index 3844b98021..31a8fc39ce 100644
--- a/src/core/ext/filters/client_channel/channel_connectivity.c
+++ b/src/core/ext/filters/client_channel/channel_connectivity.cc
@@ -18,6 +18,8 @@
 
 #include "src/core/lib/surface/channel.h"
 
+#include <inttypes.h>
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
@@ -186,8 +188,8 @@ static void watcher_timer_init(grpc_exec_ctx *exec_ctx, void *arg,
   watcher_timer_init_arg *wa = (watcher_timer_init_arg *)arg;
 
   grpc_timer_init(exec_ctx, &wa->w->alarm,
-                  gpr_convert_clock_type(wa->deadline, GPR_CLOCK_MONOTONIC),
-                  &wa->w->on_timeout, gpr_now(GPR_CLOCK_MONOTONIC));
+                  grpc_timespec_to_millis_round_up(wa->deadline),
+                  &wa->w->on_timeout);
   gpr_free(wa);
 }
 
diff --git a/src/core/ext/filters/client_channel/client_channel.c b/src/core/ext/filters/client_channel/client_channel.cc
index 016199b1f4..22c2bc8880 100644
--- a/src/core/ext/filters/client_channel/client_channel.c
+++ b/src/core/ext/filters/client_channel/client_channel.cc
@@ -16,8 +16,11 @@
  *
  */
 
+#include <grpc/support/port_platform.h>
+
 #include "src/core/ext/filters/client_channel/client_channel.h"
 
+#include <inttypes.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
@@ -68,7 +71,7 @@ typedef enum {
 
 typedef struct {
   gpr_refcount refs;
-  gpr_timespec timeout;
+  grpc_millis timeout;
   wait_for_ready_value wait_for_ready;
 } method_parameters;
 
@@ -98,17 +101,18 @@ static bool parse_wait_for_ready(grpc_json *field,
   return true;
 }
 
-static bool parse_timeout(grpc_json *field, gpr_timespec *timeout) {
+static bool parse_timeout(grpc_json *field, grpc_millis *timeout) {
   if (field->type != GRPC_JSON_STRING) return false;
   size_t len = strlen(field->value);
   if (field->value[len - 1] != 's') return false;
   char *buf = gpr_strdup(field->value);
   buf[len - 1] = '\0';  // Remove trailing 's'.
   char *decimal_point = strchr(buf, '.');
+  int nanos = 0;
   if (decimal_point != NULL) {
     *decimal_point = '\0';
-    timeout->tv_nsec = gpr_parse_nonnegative_int(decimal_point + 1);
-    if (timeout->tv_nsec == -1) {
+    nanos = gpr_parse_nonnegative_int(decimal_point + 1);
+    if (nanos == -1) {
       gpr_free(buf);
       return false;
     }
@@ -127,24 +131,25 @@ static bool parse_timeout(grpc_json *field, gpr_timespec *timeout) {
         gpr_free(buf);
         return false;
     }
-    timeout->tv_nsec *= multiplier;
+    nanos *= multiplier;
   }
-  timeout->tv_sec = gpr_parse_nonnegative_int(buf);
+  int seconds = gpr_parse_nonnegative_int(buf);
   gpr_free(buf);
-  if (timeout->tv_sec == -1) return false;
+  if (seconds == -1) return false;
+  *timeout = seconds * GPR_MS_PER_SEC + nanos / GPR_NS_PER_MS;
   return true;
 }
 
 static void *method_parameters_create_from_json(const grpc_json *json) {
   wait_for_ready_value wait_for_ready = WAIT_FOR_READY_UNSET;
-  gpr_timespec timeout = {0, 0, GPR_TIMESPAN};
+  grpc_millis timeout = 0;
   for (grpc_json *field = json->child; field != NULL; field = field->next) {
     if (field->key == NULL) continue;
     if (strcmp(field->key, "waitForReady") == 0) {
       if (wait_for_ready != WAIT_FOR_READY_UNSET) return NULL;  // Duplicate.
       if (!parse_wait_for_ready(field, &wait_for_ready)) return NULL;
     } else if (strcmp(field->key, "timeout") == 0) {
-      if (timeout.tv_sec > 0 || timeout.tv_nsec > 0) return NULL;  // Duplicate.
+      if (timeout > 0) return NULL;  // Duplicate.
       if (!parse_timeout(field, &timeout)) return NULL;
     }
   }
@@ -823,7 +828,7 @@ typedef struct client_channel_call_data {
 
   grpc_slice path;  // Request path.
   gpr_timespec call_start_time;
-  gpr_timespec deadline;
+  grpc_millis deadline;
   gpr_arena *arena;
   grpc_call_stack *owning_call;
   grpc_call_combiner *call_combiner;
@@ -976,11 +981,11 @@ static void apply_service_config_to_call_locked(grpc_exec_ctx *exec_ctx,
       // If the deadline from the service config is shorter than the one
       // from the client API, reset the deadline timer.
       if (chand->deadline_checking_enabled &&
-          gpr_time_cmp(calld->method_params->timeout,
-                       gpr_time_0(GPR_TIMESPAN)) != 0) {
-        const gpr_timespec per_method_deadline =
-            gpr_time_add(calld->call_start_time, calld->method_params->timeout);
-        if (gpr_time_cmp(per_method_deadline, calld->deadline) < 0) {
+          calld->method_params->timeout != 0) {
+        const grpc_millis per_method_deadline =
+            grpc_timespec_to_millis_round_up(calld->call_start_time) +
+            calld->method_params->timeout;
+        if (per_method_deadline < calld->deadline) {
           calld->deadline = per_method_deadline;
           grpc_deadline_state_reset(exec_ctx, elem, calld->deadline);
         }
@@ -995,13 +1000,14 @@ static void create_subchannel_call_locked(grpc_exec_ctx *exec_ctx,
   channel_data *chand = (channel_data *)elem->channel_data;
   call_data *calld = (call_data *)elem->call_data;
   const grpc_connected_subchannel_call_args call_args = {
-      .pollent = calld->pollent,
-      .path = calld->path,
-      .start_time = calld->call_start_time,
-      .deadline = calld->deadline,
-      .arena = calld->arena,
-      .context = calld->subchannel_call_context,
-      .call_combiner = calld->call_combiner};
+      calld->pollent,                  // pollent
+      calld->path,                     // path
+      calld->call_start_time,          // start_time
+      calld->deadline,                 // deadline
+      calld->arena,                    // arena
+      calld->subchannel_call_context,  // context
+      calld->call_combiner             // call_combiner
+  };
   grpc_error *new_error = grpc_connected_subchannel_create_call(
       exec_ctx, calld->connected_subchannel, &call_args,
       &calld->subchannel_call);
@@ -1418,7 +1424,7 @@ static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
   // Initialize data members.
   calld->path = grpc_slice_ref_internal(args->path);
   calld->call_start_time = args->start_time;
-  calld->deadline = gpr_convert_clock_type(args->deadline, GPR_CLOCK_MONOTONIC);
+  calld->deadline = args->deadline;
   calld->arena = args->arena;
   calld->owning_call = args->call_stack;
   calld->call_combiner = args->call_combiner;
diff --git a/src/core/ext/filters/client_channel/client_channel.h b/src/core/ext/filters/client_channel/client_channel.h
index c99f0092e9..b32f378c6c 100644
--- a/src/core/ext/filters/client_channel/client_channel.h
+++ b/src/core/ext/filters/client_channel/client_channel.h
@@ -28,6 +28,10 @@ extern grpc_tracer_flag grpc_client_channel_trace;
 // Channel arg key for server URI string.
 #define GRPC_ARG_SERVER_URI "grpc.server_uri"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* A client channel is a channel that begins disconnected, and can connect
    to some endpoint on demand. If that endpoint disconnects, it will be
    connected to again later.
@@ -52,4 +56,8 @@ void grpc_client_channel_watch_connectivity_state(
 grpc_subchannel_call *grpc_client_channel_get_subchannel_call(
     grpc_call_element *elem);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/client_channel_factory.c b/src/core/ext/filters/client_channel/client_channel_factory.cc
index 57eac8f875..57eac8f875 100644
--- a/src/core/ext/filters/client_channel/client_channel_factory.c
+++ b/src/core/ext/filters/client_channel/client_channel_factory.cc
diff --git a/src/core/ext/filters/client_channel/client_channel_factory.h b/src/core/ext/filters/client_channel/client_channel_factory.h
index ce6266c769..bad8b97042 100644
--- a/src/core/ext/filters/client_channel/client_channel_factory.h
+++ b/src/core/ext/filters/client_channel/client_channel_factory.h
@@ -27,6 +27,10 @@
 // Channel arg key for client channel factory.
 #define GRPC_ARG_CLIENT_CHANNEL_FACTORY "grpc.client_channel_factory"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_client_channel_factory grpc_client_channel_factory;
 typedef struct grpc_client_channel_factory_vtable
     grpc_client_channel_factory_vtable;
@@ -74,4 +78,8 @@ grpc_channel *grpc_client_channel_factory_create_channel(
 grpc_arg grpc_client_channel_factory_create_channel_arg(
     grpc_client_channel_factory *factory);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_FACTORY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_FACTORY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/client_channel_plugin.c b/src/core/ext/filters/client_channel/client_channel_plugin.cc
index 1f71c5a7f9..4431d11519 100644
--- a/src/core/ext/filters/client_channel/client_channel_plugin.c
+++ b/src/core/ext/filters/client_channel/client_channel_plugin.cc
@@ -65,7 +65,7 @@ static bool set_default_host_if_unset(grpc_exec_ctx *exec_ctx,
   return true;
 }
 
-void grpc_client_channel_init(void) {
+extern "C" void grpc_client_channel_init(void) {
   grpc_lb_policy_registry_init();
   grpc_resolver_registry_init();
   grpc_retry_throttle_map_init();
@@ -84,7 +84,7 @@ void grpc_client_channel_init(void) {
 #endif
 }
 
-void grpc_client_channel_shutdown(void) {
+extern "C" void grpc_client_channel_shutdown(void) {
   grpc_subchannel_index_shutdown();
   grpc_channel_init_shutdown();
   grpc_proxy_mapper_registry_shutdown();
diff --git a/src/core/ext/filters/client_channel/connector.c b/src/core/ext/filters/client_channel/connector.cc
index c258468e58..c258468e58 100644
--- a/src/core/ext/filters/client_channel/connector.c
+++ b/src/core/ext/filters/client_channel/connector.cc
diff --git a/src/core/ext/filters/client_channel/connector.h b/src/core/ext/filters/client_channel/connector.h
index 7f3d4a1cc0..b91c93e446 100644
--- a/src/core/ext/filters/client_channel/connector.h
+++ b/src/core/ext/filters/client_channel/connector.h
@@ -23,6 +23,10 @@
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/transport/transport.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_connector grpc_connector;
 typedef struct grpc_connector_vtable grpc_connector_vtable;
 
@@ -34,7 +38,7 @@ typedef struct {
   /** set of pollsets interested in this connection */
   grpc_pollset_set *interested_parties;
   /** deadline for connection */
-  gpr_timespec deadline;
+  grpc_millis deadline;
   /** channel arguments (to be passed to transport) */
   const grpc_channel_args *channel_args;
 } grpc_connect_in_args;
@@ -70,4 +74,8 @@ void grpc_connector_connect(grpc_exec_ctx *exec_ctx, grpc_connector *connector,
 void grpc_connector_shutdown(grpc_exec_ctx *exec_ctx, grpc_connector *connector,
                              grpc_error *why);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CONNECTOR_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CONNECTOR_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/http_connect_handshaker.c b/src/core/ext/filters/client_channel/http_connect_handshaker.cc
index 418bb41ef6..418bb41ef6 100644
--- a/src/core/ext/filters/client_channel/http_connect_handshaker.c
+++ b/src/core/ext/filters/client_channel/http_connect_handshaker.cc
diff --git a/src/core/ext/filters/client_channel/http_connect_handshaker.h b/src/core/ext/filters/client_channel/http_connect_handshaker.h
index 928a23dc93..5042c61bec 100644
--- a/src/core/ext/filters/client_channel/http_connect_handshaker.h
+++ b/src/core/ext/filters/client_channel/http_connect_handshaker.h
@@ -28,7 +28,15 @@
 /// seperated by colons.
 #define GRPC_ARG_HTTP_CONNECT_HEADERS "grpc.http_connect_headers"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /// Registers handshaker factory.
 void grpc_http_connect_register_handshaker_factory();
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/http_proxy.c b/src/core/ext/filters/client_channel/http_proxy.cc
index c507a2750e..a16b44d3dc 100644
--- a/src/core/ext/filters/client_channel/http_proxy.c
+++ b/src/core/ext/filters/client_channel/http_proxy.cc
@@ -91,6 +91,7 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
   char* user_cred = NULL;
   *name_to_resolve = get_http_proxy_server(exec_ctx, &user_cred);
   if (*name_to_resolve == NULL) return false;
+  char* no_proxy_str = NULL;
   grpc_uri* uri =
       grpc_uri_parse(exec_ctx, server_uri, false /* suppress_errors */);
   if (uri == NULL || uri->path[0] == '\0') {
@@ -98,20 +99,14 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
             "'http_proxy' environment variable set, but cannot "
             "parse server URI '%s' -- not using proxy",
             server_uri);
-    if (uri != NULL) {
-      gpr_free(user_cred);
-      grpc_uri_destroy(uri);
-    }
-    return false;
+    goto no_use_proxy;
   }
   if (strcmp(uri->scheme, "unix") == 0) {
     gpr_log(GPR_INFO, "not using proxy for Unix domain socket '%s'",
             server_uri);
-    gpr_free(user_cred);
-    grpc_uri_destroy(uri);
-    return false;
+    goto no_use_proxy;
   }
-  char* no_proxy_str = gpr_getenv("no_proxy");
+  no_proxy_str = gpr_getenv("no_proxy");
   if (no_proxy_str != NULL) {
     static const char* NO_PROXY_SEPARATOR = ",";
     bool use_proxy = true;
@@ -147,12 +142,7 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
       gpr_free(no_proxy_hosts);
       gpr_free(server_host);
       gpr_free(server_port);
-      if (!use_proxy) {
-        grpc_uri_destroy(uri);
-        gpr_free(*name_to_resolve);
-        *name_to_resolve = NULL;
-        return false;
-      }
+      if (!use_proxy) goto no_use_proxy;
     }
   }
   grpc_arg args_to_add[2];
@@ -173,9 +163,15 @@ static bool proxy_mapper_map_name(grpc_exec_ctx* exec_ctx,
   } else {
     *new_args = grpc_channel_args_copy_and_add(args, args_to_add, 1);
   }
-  gpr_free(user_cred);
   grpc_uri_destroy(uri);
+  gpr_free(user_cred);
   return true;
+no_use_proxy:
+  if (uri != NULL) grpc_uri_destroy(uri);
+  gpr_free(*name_to_resolve);
+  *name_to_resolve = NULL;
+  gpr_free(user_cred);
+  return false;
 }
 
 static bool proxy_mapper_map_address(grpc_exec_ctx* exec_ctx,
diff --git a/src/core/ext/filters/client_channel/http_proxy.h b/src/core/ext/filters/client_channel/http_proxy.h
index 34694931d0..65d52334af 100644
--- a/src/core/ext/filters/client_channel/http_proxy.h
+++ b/src/core/ext/filters/client_channel/http_proxy.h
@@ -19,6 +19,14 @@
 #ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_PROXY_H
 #define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_PROXY_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void grpc_register_http_proxy_mapper();
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_PROXY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_HTTP_PROXY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/lb_policy.c b/src/core/ext/filters/client_channel/lb_policy.cc
index 8e6673d737..8e6673d737 100644
--- a/src/core/ext/filters/client_channel/lb_policy.c
+++ b/src/core/ext/filters/client_channel/lb_policy.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy.h b/src/core/ext/filters/client_channel/lb_policy.h
index 645d51e138..010299c2f4 100644
--- a/src/core/ext/filters/client_channel/lb_policy.h
+++ b/src/core/ext/filters/client_channel/lb_policy.h
@@ -23,6 +23,10 @@
 #include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** A load balancing policy: specified by a vtable and a struct (which
     is expected to be extended to contain some parameters) */
 typedef struct grpc_lb_policy grpc_lb_policy;
@@ -204,4 +208,8 @@ void grpc_lb_policy_update_locked(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy *policy,
                                   const grpc_lb_policy_args *lb_policy_args);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_H */
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
index 7ad322902b..7ad322902b 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
index 51e30b20b8..c6a0d69c3f 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h
@@ -21,7 +21,15 @@
 
 #include "src/core/lib/channel/channel_stack.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 extern const grpc_channel_filter grpc_client_load_reporting_filter;
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_GRPCLB_CLIENT_LOAD_REPORTING_FILTER_H \
           */
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
index 85ef7894ea..53fa0fff04 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc
@@ -80,6 +80,7 @@
    headers. Therefore, sockaddr.h must always be included first */
 #include "src/core/lib/iomgr/sockaddr.h"
 
+#include <inttypes.h>
 #include <limits.h>
 #include <string.h>
 
@@ -102,6 +103,7 @@
 #include "src/core/ext/filters/client_channel/parse_address.h"
 #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
 #include "src/core/ext/filters/client_channel/subchannel_index.h"
+#include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/iomgr/combiner.h"
@@ -111,7 +113,6 @@
 #include "src/core/lib/slice/slice_hash_table.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
-#include "src/core/lib/support/backoff.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/call.h"
 #include "src/core/lib/surface/channel.h"
@@ -123,6 +124,7 @@
 #define GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER 1.6
 #define GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS 120
 #define GRPC_GRPCLB_RECONNECT_JITTER 0.2
+#define GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS 10000
 
 grpc_tracer_flag grpc_lb_glb_trace = GRPC_TRACER_INITIALIZER(false, "glb");
 
@@ -299,6 +301,10 @@ typedef struct glb_lb_policy {
   /** timeout in milliseconds for the LB call. 0 means no deadline. */
   int lb_call_timeout_ms;
 
+  /** timeout in milliseconds for before using fallback backend addresses.
+   * 0 means not using fallback. */
+  int lb_fallback_timeout_ms;
+
   /** for communicating with the LB server */
   grpc_channel *lb_channel;
 
@@ -325,6 +331,9 @@ typedef struct glb_lb_policy {
    * Otherwise, we delegate to the RR policy. */
   size_t serverlist_index;
 
+  /** stores the backend addresses from the resolver */
+  grpc_lb_addresses *fallback_backend_addresses;
+
   /** list of picks that are waiting on RR's policy connectivity */
   pending_pick *pending_picks;
 
@@ -345,6 +354,9 @@ typedef struct glb_lb_policy {
   /** is \a lb_call_retry_timer active? */
   bool retry_timer_active;
 
+  /** is \a lb_fallback_timer active? */
+  bool fallback_timer_active;
+
   /** called upon changes to the LB channel's connectivity. */
   grpc_closure lb_channel_on_connectivity_changed;
 
@@ -354,9 +366,6 @@ typedef struct glb_lb_policy {
   /************************************************************/
   /*  client data associated with the LB server communication */
   /************************************************************/
-  /* Finished sending initial request. */
-  grpc_closure lb_on_sent_initial_request;
-
   /* Status from the LB server has been received. This signals the end of the LB
    * call. */
   grpc_closure lb_on_server_status_received;
@@ -367,6 +376,9 @@ typedef struct glb_lb_policy {
   /* LB call retry timer callback. */
   grpc_closure lb_on_call_retry;
 
+  /* LB fallback timer callback. */
+  grpc_closure lb_on_fallback;
+
   grpc_call *lb_call; /* streaming call to the LB server, */
 
   grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */
@@ -385,19 +397,21 @@ typedef struct glb_lb_policy {
   grpc_slice lb_call_status_details;
 
   /** LB call retry backoff state */
-  gpr_backoff lb_call_backoff_state;
+  grpc_backoff lb_call_backoff_state;
 
   /** LB call retry timer */
   grpc_timer lb_call_retry_timer;
 
-  bool initial_request_sent;
+  /** LB fallback timer */
+  grpc_timer lb_fallback_timer;
+
   bool seen_initial_response;
 
   /* Stats for client-side load reporting. Should be unreffed and
    * recreated whenever lb_call is replaced. */
   grpc_grpclb_client_stats *client_stats;
   /* Interval and timer for next client load report. */
-  gpr_timespec client_stats_report_interval;
+  grpc_millis client_stats_report_interval;
   grpc_timer client_load_report_timer;
   bool client_load_report_timer_pending;
   bool last_client_load_report_counters_were_zero;
@@ -443,11 +457,11 @@ static bool is_server_valid(const grpc_grpclb_server *server, size_t idx,
 static void *lb_token_copy(void *token) {
   return token == NULL
              ? NULL
-             : (void *)GRPC_MDELEM_REF((grpc_mdelem){(uintptr_t)token}).payload;
+             : (void *)GRPC_MDELEM_REF(grpc_mdelem{(uintptr_t)token}).payload;
 }
 static void lb_token_destroy(grpc_exec_ctx *exec_ctx, void *token) {
   if (token != NULL) {
-    GRPC_MDELEM_UNREF(exec_ctx, (grpc_mdelem){(uintptr_t)token});
+    GRPC_MDELEM_UNREF(exec_ctx, grpc_mdelem{(uintptr_t)token});
   }
 }
 static int lb_token_cmp(void *token1, void *token2) {
@@ -536,6 +550,32 @@ static grpc_lb_addresses *process_serverlist_locked(
   return lb_addresses;
 }
 
+/* Returns the backend addresses extracted from the given addresses */
+static grpc_lb_addresses *extract_backend_addresses_locked(
+    grpc_exec_ctx *exec_ctx, const grpc_lb_addresses *addresses) {
+  /* first pass: count the number of backend addresses */
+  size_t num_backends = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (!addresses->addresses[i].is_balancer) {
+      ++num_backends;
+    }
+  }
+  /* second pass: actually populate the addresses and (empty) LB tokens */
+  grpc_lb_addresses *backend_addresses =
+      grpc_lb_addresses_create(num_backends, &lb_token_vtable);
+  size_t num_copied = 0;
+  for (size_t i = 0; i < addresses->num_addresses; ++i) {
+    if (addresses->addresses[i].is_balancer) continue;
+    const grpc_resolved_address *addr = &addresses->addresses[i].address;
+    grpc_lb_addresses_set_address(backend_addresses, num_copied, &addr->addr,
+                                  addr->len, false /* is_balancer */,
+                                  NULL /* balancer_name */,
+                                  (void *)GRPC_MDELEM_LB_TOKEN_EMPTY.payload);
+    ++num_copied;
+  }
+  return backend_addresses;
+}
+
 static void update_lb_connectivity_status_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     grpc_connectivity_state rr_state, grpc_error *rr_state_error) {
@@ -603,35 +643,38 @@ static bool pick_from_internal_rr_locked(
     grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
     const grpc_lb_policy_pick_args *pick_args, bool force_async,
     grpc_connected_subchannel **target, wrapped_rr_closure_arg *wc_arg) {
-  // Look at the index into the serverlist to see if we should drop this call.
-  grpc_grpclb_server *server =
-      glb_policy->serverlist->servers[glb_policy->serverlist_index++];
-  if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
-    glb_policy->serverlist_index = 0;  // Wrap-around.
-  }
-  if (server->drop) {
-    // Not using the RR policy, so unref it.
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
-              (intptr_t)wc_arg->rr_policy);
+  // Check for drops if we are not using fallback backend addresses.
+  if (glb_policy->serverlist != NULL) {
+    // Look at the index into the serverlist to see if we should drop this call.
+    grpc_grpclb_server *server =
+        glb_policy->serverlist->servers[glb_policy->serverlist_index++];
+    if (glb_policy->serverlist_index == glb_policy->serverlist->num_servers) {
+      glb_policy->serverlist_index = 0;  // Wrap-around.
     }
-    GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
-    // Update client load reporting stats to indicate the number of
-    // dropped calls.  Note that we have to do this here instead of in
-    // the client_load_reporting filter, because we do not create a
-    // subchannel call (and therefore no client_load_reporting filter)
-    // for dropped calls.
-    grpc_grpclb_client_stats_add_call_dropped_locked(server->load_balance_token,
-                                                     wc_arg->client_stats);
-    grpc_grpclb_client_stats_unref(wc_arg->client_stats);
-    if (force_async) {
-      GPR_ASSERT(wc_arg->wrapped_closure != NULL);
-      GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
+    if (server->drop) {
+      // Not using the RR policy, so unref it.
+      if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+        gpr_log(GPR_INFO, "Unreffing RR for drop (0x%" PRIxPTR ")",
+                (intptr_t)wc_arg->rr_policy);
+      }
+      GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "glb_pick_sync");
+      // Update client load reporting stats to indicate the number of
+      // dropped calls.  Note that we have to do this here instead of in
+      // the client_load_reporting filter, because we do not create a
+      // subchannel call (and therefore no client_load_reporting filter)
+      // for dropped calls.
+      grpc_grpclb_client_stats_add_call_dropped_locked(
+          server->load_balance_token, wc_arg->client_stats);
+      grpc_grpclb_client_stats_unref(wc_arg->client_stats);
+      if (force_async) {
+        GPR_ASSERT(wc_arg->wrapped_closure != NULL);
+        GRPC_CLOSURE_SCHED(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_NONE);
+        gpr_free(wc_arg->free_when_done);
+        return false;
+      }
       gpr_free(wc_arg->free_when_done);
-      return false;
+      return true;
     }
-    gpr_free(wc_arg->free_when_done);
-    return true;
   }
   // Pick via the RR policy.
   const bool pick_done = grpc_lb_policy_pick_locked(
@@ -669,8 +712,18 @@ static bool pick_from_internal_rr_locked(
 
 static grpc_lb_policy_args *lb_policy_args_create(grpc_exec_ctx *exec_ctx,
                                                   glb_lb_policy *glb_policy) {
-  grpc_lb_addresses *addresses =
-      process_serverlist_locked(exec_ctx, glb_policy->serverlist);
+  grpc_lb_addresses *addresses;
+  if (glb_policy->serverlist != NULL) {
+    GPR_ASSERT(glb_policy->serverlist->num_servers > 0);
+    addresses = process_serverlist_locked(exec_ctx, glb_policy->serverlist);
+  } else {
+    // If rr_handover_locked() is invoked when we haven't received any
+    // serverlist from the balancer, we use the fallback backends returned by
+    // the resolver. Note that the fallback backend list may be empty, in which
+    // case the new round_robin policy will keep the requested picks pending.
+    GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+    addresses = grpc_lb_addresses_copy(glb_policy->fallback_backend_addresses);
+  }
   GPR_ASSERT(addresses != NULL);
   grpc_lb_policy_args *args = (grpc_lb_policy_args *)gpr_zalloc(sizeof(*args));
   args->client_channel_factory = glb_policy->cc_factory;
@@ -776,8 +829,6 @@ static void create_rr_locked(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy,
 /* glb_policy->rr_policy may be NULL (initial handover) */
 static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
                                glb_lb_policy *glb_policy) {
-  GPR_ASSERT(glb_policy->serverlist != NULL &&
-             glb_policy->serverlist->num_servers > 0);
   if (glb_policy->shutting_down) return;
   grpc_lb_policy_args *args = lb_policy_args_create(exec_ctx, glb_policy);
   GPR_ASSERT(args != NULL);
@@ -926,6 +977,9 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   if (glb_policy->serverlist != NULL) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
+  if (glb_policy->fallback_backend_addresses != NULL) {
+    grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
+  }
   grpc_fake_resolver_response_generator_unref(glb_policy->response_generator);
   grpc_subchannel_index_unref();
   if (glb_policy->pending_update_args != NULL) {
@@ -956,6 +1010,10 @@ static void glb_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
     grpc_timer_cancel(exec_ctx, &glb_policy->lb_call_retry_timer);
     glb_policy->retry_timer_active = false;
   }
+  if (glb_policy->fallback_timer_active) {
+    grpc_timer_cancel(exec_ctx, &glb_policy->lb_fallback_timer);
+    glb_policy->fallback_timer_active = false;
+  }
 
   pending_pick *pp = glb_policy->pending_picks;
   glb_policy->pending_picks = NULL;
@@ -1067,12 +1125,28 @@ static void glb_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
   GRPC_ERROR_UNREF(error);
 }
 
+static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                        grpc_error *error);
 static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
                                       glb_lb_policy *glb_policy);
 static void start_picking_locked(grpc_exec_ctx *exec_ctx,
                                  glb_lb_policy *glb_policy) {
+  /* start a timer to fall back */
+  if (glb_policy->lb_fallback_timeout_ms > 0 &&
+      glb_policy->serverlist == NULL && !glb_policy->fallback_timer_active) {
+    grpc_millis deadline =
+        grpc_exec_ctx_now(exec_ctx) + glb_policy->lb_fallback_timeout_ms;
+    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_fallback_timer");
+    GRPC_CLOSURE_INIT(&glb_policy->lb_on_fallback, lb_on_fallback_timer_locked,
+                      glb_policy,
+                      grpc_combiner_scheduler(glb_policy->base.combiner));
+    glb_policy->fallback_timer_active = true;
+    grpc_timer_init(exec_ctx, &glb_policy->lb_fallback_timer, deadline,
+                    &glb_policy->lb_on_fallback);
+  }
+
   glb_policy->started_picking = true;
-  gpr_backoff_reset(&glb_policy->lb_call_backoff_state);
+  grpc_backoff_reset(&glb_policy->lb_call_backoff_state);
   query_for_backends_locked(exec_ctx, glb_policy);
 }
 
@@ -1173,20 +1247,69 @@ static void glb_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
       exec_ctx, &glb_policy->state_tracker, current, notify);
 }
 
+static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                          grpc_error *error) {
+  glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
+  glb_policy->retry_timer_active = false;
+  if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_INFO, "Restaring call to LB server (grpclb %p)",
+              (void *)glb_policy);
+    }
+    GPR_ASSERT(glb_policy->lb_call == NULL);
+    query_for_backends_locked(exec_ctx, glb_policy);
+  }
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, "grpclb_retry_timer");
+}
+
+static void maybe_restart_lb_call(grpc_exec_ctx *exec_ctx,
+                                  glb_lb_policy *glb_policy) {
+  if (glb_policy->started_picking && glb_policy->updating_lb_call) {
+    if (glb_policy->retry_timer_active) {
+      grpc_timer_cancel(exec_ctx, &glb_policy->lb_call_retry_timer);
+    }
+    if (!glb_policy->shutting_down) start_picking_locked(exec_ctx, glb_policy);
+    glb_policy->updating_lb_call = false;
+  } else if (!glb_policy->shutting_down) {
+    /* if we aren't shutting down, restart the LB client call after some time */
+    grpc_millis next_try =
+        grpc_backoff_step(exec_ctx, &glb_policy->lb_call_backoff_state);
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_DEBUG, "Connection to LB server lost (grpclb: %p)...",
+              (void *)glb_policy);
+      grpc_millis timeout = next_try - grpc_exec_ctx_now(exec_ctx);
+      if (timeout > 0) {
+        gpr_log(GPR_DEBUG, "... retry_timer_active in %" PRIdPTR "ms.",
+                timeout);
+      } else {
+        gpr_log(GPR_DEBUG, "... retry_timer_active immediately.");
+      }
+    }
+    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
+    GRPC_CLOSURE_INIT(&glb_policy->lb_on_call_retry,
+                      lb_call_on_retry_timer_locked, glb_policy,
+                      grpc_combiner_scheduler(glb_policy->base.combiner));
+    glb_policy->retry_timer_active = true;
+    grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
+                    &glb_policy->lb_on_call_retry);
+  }
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
+                            "lb_on_server_status_received_locked");
+}
+
 static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                            grpc_error *error);
 
 static void schedule_next_client_load_report(grpc_exec_ctx *exec_ctx,
                                              glb_lb_policy *glb_policy) {
-  const gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-  const gpr_timespec next_client_load_report_time =
-      gpr_time_add(now, glb_policy->client_stats_report_interval);
+  const grpc_millis next_client_load_report_time =
+      grpc_exec_ctx_now(exec_ctx) + glb_policy->client_stats_report_interval;
   GRPC_CLOSURE_INIT(&glb_policy->client_load_report_closure,
                     send_client_load_report_locked, glb_policy,
                     grpc_combiner_scheduler(glb_policy->base.combiner));
   grpc_timer_init(exec_ctx, &glb_policy->client_load_report_timer,
                   next_client_load_report_time,
-                  &glb_policy->client_load_report_closure, now);
+                  &glb_policy->client_load_report_closure);
 }
 
 static void client_load_report_done_locked(grpc_exec_ctx *exec_ctx, void *arg,
@@ -1203,21 +1326,6 @@ static void client_load_report_done_locked(grpc_exec_ctx *exec_ctx, void *arg,
   schedule_next_client_load_report(exec_ctx, glb_policy);
 }
 
-static void do_send_client_load_report_locked(grpc_exec_ctx *exec_ctx,
-                                              glb_lb_policy *glb_policy) {
-  grpc_op op;
-  memset(&op, 0, sizeof(op));
-  op.op = GRPC_OP_SEND_MESSAGE;
-  op.data.send_message.send_message = glb_policy->client_load_report_payload;
-  GRPC_CLOSURE_INIT(&glb_policy->client_load_report_closure,
-                    client_load_report_done_locked, glb_policy,
-                    grpc_combiner_scheduler(glb_policy->base.combiner));
-  grpc_call_error call_error = grpc_call_start_batch_and_execute(
-      exec_ctx, glb_policy->lb_call, &op, 1,
-      &glb_policy->client_load_report_closure);
-  GPR_ASSERT(GRPC_CALL_OK == call_error);
-}
-
 static bool load_report_counters_are_zero(grpc_grpclb_request *request) {
   grpc_grpclb_dropped_call_counts *drop_entries =
       (grpc_grpclb_dropped_call_counts *)
@@ -1237,6 +1345,9 @@ static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
     glb_policy->client_load_report_timer_pending = false;
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                               "client_load_report");
+    if (glb_policy->lb_call == NULL) {
+      maybe_restart_lb_call(exec_ctx, glb_policy);
+    }
     return;
   }
   // Construct message payload.
@@ -1260,17 +1371,23 @@ static void send_client_load_report_locked(grpc_exec_ctx *exec_ctx, void *arg,
       grpc_raw_byte_buffer_create(&request_payload_slice, 1);
   grpc_slice_unref_internal(exec_ctx, request_payload_slice);
   grpc_grpclb_request_destroy(request);
-  // If we've already sent the initial request, then we can go ahead and
-  // sent the load report.  Otherwise, we need to wait until the initial
-  // request has been sent to send this
-  // (see lb_on_sent_initial_request_locked() below).
-  if (glb_policy->initial_request_sent) {
-    do_send_client_load_report_locked(exec_ctx, glb_policy);
+  // Send load report message.
+  grpc_op op;
+  memset(&op, 0, sizeof(op));
+  op.op = GRPC_OP_SEND_MESSAGE;
+  op.data.send_message.send_message = glb_policy->client_load_report_payload;
+  GRPC_CLOSURE_INIT(&glb_policy->client_load_report_closure,
+                    client_load_report_done_locked, glb_policy,
+                    grpc_combiner_scheduler(glb_policy->base.combiner));
+  grpc_call_error call_error = grpc_call_start_batch_and_execute(
+      exec_ctx, glb_policy->lb_call, &op, 1,
+      &glb_policy->client_load_report_closure);
+  if (call_error != GRPC_CALL_OK) {
+    gpr_log(GPR_ERROR, "call_error=%d", call_error);
+    GPR_ASSERT(GRPC_CALL_OK == call_error);
   }
 }
 
-static void lb_on_sent_initial_request_locked(grpc_exec_ctx *exec_ctx,
-                                              void *arg, grpc_error *error);
 static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
                                                 void *arg, grpc_error *error);
 static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
@@ -1286,12 +1403,10 @@ static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
    * glb_policy->base.interested_parties, which is comprised of the polling
    * entities from \a client_channel. */
   grpc_slice host = grpc_slice_from_copied_string(glb_policy->server_name);
-  gpr_timespec deadline =
+  grpc_millis deadline =
       glb_policy->lb_call_timeout_ms == 0
-          ? gpr_inf_future(GPR_CLOCK_MONOTONIC)
-          : gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC),
-                         gpr_time_from_millis(glb_policy->lb_call_timeout_ms,
-                                              GPR_TIMESPAN));
+          ? GRPC_MILLIS_INF_FUTURE
+          : grpc_exec_ctx_now(exec_ctx) + glb_policy->lb_call_timeout_ms;
   glb_policy->lb_call = grpc_channel_create_pollset_set_call(
       exec_ctx, glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
       glb_policy->base.interested_parties,
@@ -1315,9 +1430,6 @@ static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
   grpc_slice_unref_internal(exec_ctx, request_payload_slice);
   grpc_grpclb_request_destroy(request);
 
-  GRPC_CLOSURE_INIT(&glb_policy->lb_on_sent_initial_request,
-                    lb_on_sent_initial_request_locked, glb_policy,
-                    grpc_combiner_scheduler(glb_policy->base.combiner));
   GRPC_CLOSURE_INIT(&glb_policy->lb_on_server_status_received,
                     lb_on_server_status_received_locked, glb_policy,
                     grpc_combiner_scheduler(glb_policy->base.combiner));
@@ -1325,14 +1437,13 @@ static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
                     lb_on_response_received_locked, glb_policy,
                     grpc_combiner_scheduler(glb_policy->base.combiner));
 
-  gpr_backoff_init(&glb_policy->lb_call_backoff_state,
-                   GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS,
-                   GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER,
-                   GRPC_GRPCLB_RECONNECT_JITTER,
-                   GRPC_GRPCLB_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
-                   GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
+  grpc_backoff_init(&glb_policy->lb_call_backoff_state,
+                    GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS,
+                    GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER,
+                    GRPC_GRPCLB_RECONNECT_JITTER,
+                    GRPC_GRPCLB_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
+                    GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
 
-  glb_policy->initial_request_sent = false;
   glb_policy->seen_initial_response = false;
   glb_policy->last_client_load_report_counters_were_zero = false;
 }
@@ -1349,7 +1460,7 @@ static void lb_call_destroy_locked(grpc_exec_ctx *exec_ctx,
   grpc_byte_buffer_destroy(glb_policy->lb_request_payload);
   grpc_slice_unref_internal(exec_ctx, glb_policy->lb_call_status_details);
 
-  if (!glb_policy->client_load_report_timer_pending) {
+  if (glb_policy->client_load_report_timer_pending) {
     grpc_timer_cancel(exec_ctx, &glb_policy->client_load_report_timer);
   }
 }
@@ -1373,7 +1484,7 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(glb_policy->lb_call != NULL);
 
   grpc_call_error call_error;
-  grpc_op ops[4];
+  grpc_op ops[3];
   memset(ops, 0, sizeof(ops));
 
   grpc_op *op = ops;
@@ -1394,13 +1505,8 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   op->flags = 0;
   op->reserved = NULL;
   op++;
-  /* take a weak ref (won't prevent calling of \a glb_shutdown if the strong ref
-   * count goes to zero) to be unref'd in lb_on_sent_initial_request_locked() */
-  GRPC_LB_POLICY_WEAK_REF(&glb_policy->base,
-                          "lb_on_sent_initial_request_locked");
-  call_error = grpc_call_start_batch_and_execute(
-      exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops),
-      &glb_policy->lb_on_sent_initial_request);
+  call_error = grpc_call_start_batch_and_execute(exec_ctx, glb_policy->lb_call,
+                                                 ops, (size_t)(op - ops), NULL);
   GPR_ASSERT(GRPC_CALL_OK == call_error);
 
   op = ops;
@@ -1437,19 +1543,6 @@ static void query_for_backends_locked(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(GRPC_CALL_OK == call_error);
 }
 
-static void lb_on_sent_initial_request_locked(grpc_exec_ctx *exec_ctx,
-                                              void *arg, grpc_error *error) {
-  glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
-  glb_policy->initial_request_sent = true;
-  // If we attempted to send a client load report before the initial
-  // request was sent, send the load report now.
-  if (glb_policy->client_load_report_payload != NULL) {
-    do_send_client_load_report_locked(exec_ctx, glb_policy);
-  }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
-                            "lb_on_sent_initial_request_locked");
-}
-
 static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                            grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
@@ -1457,7 +1550,7 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
   memset(ops, 0, sizeof(ops));
   grpc_op *op = ops;
   if (glb_policy->lb_response_payload != NULL) {
-    gpr_backoff_reset(&glb_policy->lb_call_backoff_state);
+    grpc_backoff_reset(&glb_policy->lb_call_backoff_state);
     /* Received data from the LB server. Look inside
      * glb_policy->lb_response_payload, for a serverlist. */
     grpc_byte_buffer_reader bbr;
@@ -1471,16 +1564,14 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
         (response = grpc_grpclb_initial_response_parse(response_slice)) !=
             NULL) {
       if (response->has_client_stats_report_interval) {
-        glb_policy->client_stats_report_interval =
-            gpr_time_max(gpr_time_from_seconds(1, GPR_TIMESPAN),
-                         grpc_grpclb_duration_to_timespec(
-                             &response->client_stats_report_interval));
+        glb_policy->client_stats_report_interval = GPR_MAX(
+            GPR_MS_PER_SEC, grpc_grpclb_duration_to_millis(
+                                &response->client_stats_report_interval));
         if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
           gpr_log(GPR_INFO,
                   "received initial LB response message; "
-                  "client load reporting interval = %" PRId64 ".%09d sec",
-                  glb_policy->client_stats_report_interval.tv_sec,
-                  glb_policy->client_stats_report_interval.tv_nsec);
+                  "client load reporting interval = %" PRIdPTR " milliseconds",
+                  glb_policy->client_stats_report_interval);
         }
         /* take a weak ref (won't prevent calling of \a glb_shutdown() if the
          * strong ref count goes to zero) to be unref'd in
@@ -1525,6 +1616,15 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
             if (glb_policy->serverlist != NULL) {
               /* dispose of the old serverlist */
               grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
+            } else {
+              /* or dispose of the fallback */
+              grpc_lb_addresses_destroy(exec_ctx,
+                                        glb_policy->fallback_backend_addresses);
+              glb_policy->fallback_backend_addresses = NULL;
+              if (glb_policy->fallback_timer_active) {
+                grpc_timer_cancel(exec_ctx, &glb_policy->lb_fallback_timer);
+                glb_policy->fallback_timer_active = false;
+              }
             }
             /* and update the copy in the glb_lb_policy instance. This
              * serverlist instance will be destroyed either upon the next
@@ -1535,9 +1635,7 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
           }
         } else {
           if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-            gpr_log(GPR_INFO,
-                    "Received empty server list. Picks will stay pending until "
-                    "a response with > 0 servers is received");
+            gpr_log(GPR_INFO, "Received empty server list, ignoring.");
           }
           grpc_grpclb_destroy_serverlist(serverlist);
         }
@@ -1572,19 +1670,25 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
   }
 }
 
-static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
-                                          grpc_error *error) {
+static void lb_on_fallback_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                        grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)arg;
-  glb_policy->retry_timer_active = false;
-  if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO, "Restaring call to LB server (grpclb %p)",
-              (void *)glb_policy);
+  glb_policy->fallback_timer_active = false;
+  /* If we receive a serverlist after the timer fires but before this callback
+   * actually runs, don't fall back. */
+  if (glb_policy->serverlist == NULL) {
+    if (!glb_policy->shutting_down && error == GRPC_ERROR_NONE) {
+      if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+        gpr_log(GPR_INFO,
+                "Falling back to use backends from resolver (grpclb %p)",
+                (void *)glb_policy);
+      }
+      GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+      rr_handover_locked(exec_ctx, glb_policy);
     }
-    GPR_ASSERT(glb_policy->lb_call == NULL);
-    query_for_backends_locked(exec_ctx, glb_policy);
   }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, "grpclb_retry_timer");
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
+                            "grpclb_fallback_timer");
 }
 
 static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
@@ -1603,66 +1707,30 @@ static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
   }
   /* We need to perform cleanups no matter what. */
   lb_call_destroy_locked(exec_ctx, glb_policy);
-  if (glb_policy->started_picking && glb_policy->updating_lb_call) {
-    if (glb_policy->retry_timer_active) {
-      grpc_timer_cancel(exec_ctx, &glb_policy->lb_call_retry_timer);
-    }
-    if (!glb_policy->shutting_down) start_picking_locked(exec_ctx, glb_policy);
-    glb_policy->updating_lb_call = false;
-  } else if (!glb_policy->shutting_down) {
-    /* if we aren't shutting down, restart the LB client call after some time */
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec next_try =
-        gpr_backoff_step(&glb_policy->lb_call_backoff_state, now);
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_DEBUG, "Connection to LB server lost (grpclb: %p)...",
-              (void *)glb_policy);
-      gpr_timespec timeout = gpr_time_sub(next_try, now);
-      if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) {
-        gpr_log(GPR_DEBUG,
-                "... retry_timer_active in %" PRId64 ".%09d seconds.",
-                timeout.tv_sec, timeout.tv_nsec);
-      } else {
-        gpr_log(GPR_DEBUG, "... retry_timer_active immediately.");
-      }
-    }
-    GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
-    GRPC_CLOSURE_INIT(&glb_policy->lb_on_call_retry,
-                      lb_call_on_retry_timer_locked, glb_policy,
-                      grpc_combiner_scheduler(glb_policy->base.combiner));
-    glb_policy->retry_timer_active = true;
-    grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
-                    &glb_policy->lb_on_call_retry, now);
+  // If the load report timer is still pending, we wait for it to be
+  // called before restarting the call.  Otherwise, we restart the call
+  // here.
+  if (!glb_policy->client_load_report_timer_pending) {
+    maybe_restart_lb_call(exec_ctx, glb_policy);
+  }
+}
+
+static void fallback_update_locked(grpc_exec_ctx *exec_ctx,
+                                   glb_lb_policy *glb_policy,
+                                   const grpc_lb_addresses *addresses) {
+  GPR_ASSERT(glb_policy->fallback_backend_addresses != NULL);
+  grpc_lb_addresses_destroy(exec_ctx, glb_policy->fallback_backend_addresses);
+  glb_policy->fallback_backend_addresses =
+      extract_backend_addresses_locked(exec_ctx, addresses);
+  if (glb_policy->lb_fallback_timeout_ms > 0 &&
+      !glb_policy->fallback_timer_active) {
+    rr_handover_locked(exec_ctx, glb_policy);
   }
-  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
-                            "lb_on_server_status_received_locked");
 }
 
 static void glb_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                               const grpc_lb_policy_args *args) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)policy;
-  if (glb_policy->updating_lb_channel) {
-    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
-      gpr_log(GPR_INFO,
-              "Update already in progress for grpclb %p. Deferring update.",
-              (void *)glb_policy);
-    }
-    if (glb_policy->pending_update_args != NULL) {
-      grpc_channel_args_destroy(exec_ctx,
-                                glb_policy->pending_update_args->args);
-      gpr_free(glb_policy->pending_update_args);
-    }
-    glb_policy->pending_update_args = (grpc_lb_policy_args *)gpr_zalloc(
-        sizeof(*glb_policy->pending_update_args));
-    glb_policy->pending_update_args->client_channel_factory =
-        args->client_channel_factory;
-    glb_policy->pending_update_args->args = grpc_channel_args_copy(args->args);
-    glb_policy->pending_update_args->combiner = args->combiner;
-    return;
-  }
-
-  glb_policy->updating_lb_channel = true;
-  // Propagate update to lb_channel (pick first).
   const grpc_arg *arg =
       grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
@@ -1680,13 +1748,43 @@ static void glb_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
               "ignoring.",
               (void *)glb_policy);
     }
+    return;
   }
   const grpc_lb_addresses *addresses =
       (const grpc_lb_addresses *)arg->value.pointer.p;
+
+  if (glb_policy->serverlist == NULL) {
+    // If a non-empty serverlist hasn't been received from the balancer,
+    // propagate the update to fallback_backend_addresses.
+    fallback_update_locked(exec_ctx, glb_policy, addresses);
+  } else if (glb_policy->updating_lb_channel) {
+    // If we have recieved serverlist from the balancer, we need to defer update
+    // when there is an in-progress one.
+    if (GRPC_TRACER_ON(grpc_lb_glb_trace)) {
+      gpr_log(GPR_INFO,
+              "Update already in progress for grpclb %p. Deferring update.",
+              (void *)glb_policy);
+    }
+    if (glb_policy->pending_update_args != NULL) {
+      grpc_channel_args_destroy(exec_ctx,
+                                glb_policy->pending_update_args->args);
+      gpr_free(glb_policy->pending_update_args);
+    }
+    glb_policy->pending_update_args = (grpc_lb_policy_args *)gpr_zalloc(
+        sizeof(*glb_policy->pending_update_args));
+    glb_policy->pending_update_args->client_channel_factory =
+        args->client_channel_factory;
+    glb_policy->pending_update_args->args = grpc_channel_args_copy(args->args);
+    glb_policy->pending_update_args->combiner = args->combiner;
+    return;
+  }
+
+  glb_policy->updating_lb_channel = true;
   GPR_ASSERT(glb_policy->lb_channel != NULL);
   grpc_channel_args *lb_channel_args = build_lb_channel_args(
       exec_ctx, addresses, glb_policy->response_generator, args->args);
-  /* Propagate updates to the LB channel through the fake resolver */
+  /* Propagate updates to the LB channel (pick first) through the fake resolver
+   */
   grpc_fake_resolver_response_generator_set_response(
       exec_ctx, glb_policy->response_generator, lb_channel_args);
   grpc_channel_args_destroy(exec_ctx, lb_channel_args);
@@ -1789,13 +1887,7 @@ static const grpc_lb_policy_vtable glb_lb_policy_vtable = {
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
-  /* Count the number of gRPC-LB addresses. There must be at least one.
-   * TODO(roth): For now, we ignore non-balancer addresses, but in the
-   * future, we may change the behavior such that we fall back to using
-   * the non-balancer addresses if we cannot reach any balancers. In the
-   * fallback case, we should use the LB policy indicated by
-   * GRPC_ARG_LB_POLICY_NAME (although if that specifies grpclb or is
-   * unset, we should default to pick_first). */
+  /* Count the number of gRPC-LB addresses. There must be at least one. */
   const grpc_arg *arg =
       grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
@@ -1829,7 +1921,11 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
 
   arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS);
   glb_policy->lb_call_timeout_ms =
-      grpc_channel_arg_get_integer(arg, (grpc_integer_options){0, 0, INT_MAX});
+      grpc_channel_arg_get_integer(arg, {0, 0, INT_MAX});
+
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS);
+  glb_policy->lb_fallback_timeout_ms = grpc_channel_arg_get_integer(
+      arg, {GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS, 0, INT_MAX});
 
   // Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
   // since we use this to trigger the client_load_reporting filter.
@@ -1839,6 +1935,11 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_policy->args = grpc_channel_args_copy_and_add_and_remove(
       args->args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
 
+  /* Extract the backend addresses (may be empty) from the resolver for
+   * fallback. */
+  glb_policy->fallback_backend_addresses =
+      extract_backend_addresses_locked(exec_ctx, addresses);
+
   /* Create a client channel over them to communicate with a LB service */
   glb_policy->response_generator =
       grpc_fake_resolver_response_generator_create();
@@ -1900,7 +2001,7 @@ static bool maybe_add_client_load_reporting_filter(
   return true;
 }
 
-void grpc_lb_policy_grpclb_init() {
+extern "C" void grpc_lb_policy_grpclb_init() {
   grpc_register_lb_policy(grpc_glb_lb_factory_create());
   grpc_register_tracer(&grpc_lb_glb_trace);
 #ifndef NDEBUG
@@ -1912,4 +2013,4 @@ void grpc_lb_policy_grpclb_init() {
                                    (void *)&grpc_client_load_reporting_filter);
 }
 
-void grpc_lb_policy_grpclb_shutdown() {}
+extern "C" void grpc_lb_policy_grpclb_shutdown() {}
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
index 63ad66c5e9..c67df609fc 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h
@@ -21,9 +21,17 @@
 
 #include "src/core/ext/filters/client_channel/lb_policy_factory.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Returns a load balancing factory for the glb policy, which tries to connect
  * to a load balancing server to decide the next successfully connected
  * subchannel to pick. */
 grpc_lb_policy_factory *grpc_glb_lb_factory_create();
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_GRPCLB_GRPCLB_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_GRPCLB_GRPCLB_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
index f2967182e2..f2967182e2 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h
index 6120bf53f7..e8599d1f51 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h
@@ -23,6 +23,10 @@
 #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
 #include "src/core/lib/slice/slice_hash_table.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Create the channel used for communicating with an LB service.
  * Note that an LB *service* may be comprised of several LB *servers*.
  *
@@ -40,5 +44,9 @@ grpc_channel_args *grpc_lb_policy_grpclb_build_lb_channel_args(
     grpc_fake_resolver_response_generator *response_generator,
     const grpc_channel_args *args);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_GRPCLB_GRPCLB_CHANNEL_H \
           */
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
index 2681b2a079..2681b2a079 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
index 903120ca7d..903120ca7d 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h
index c51e2a431a..b38c076f38 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h
@@ -23,6 +23,10 @@
 
 #include <grpc/impl/codegen/grpc_types.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_grpclb_client_stats grpc_grpclb_client_stats;
 
 typedef struct {
@@ -61,5 +65,9 @@ void grpc_grpclb_client_stats_get_locked(
 void grpc_grpclb_dropped_call_counts_destroy(
     grpc_grpclb_dropped_call_counts* drop_entries);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_GRPCLB_GRPCLB_CLIENT_STATS_H \
           */
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
index 8ef6dfc6f4..4d5fb2081c 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.cc
@@ -299,13 +299,10 @@ int grpc_grpclb_duration_compare(const grpc_grpclb_duration *lhs,
   return 0;
 }
 
-gpr_timespec grpc_grpclb_duration_to_timespec(
-    grpc_grpclb_duration *duration_pb) {
-  gpr_timespec duration;
-  duration.tv_sec = duration_pb->has_seconds ? duration_pb->seconds : 0;
-  duration.tv_nsec = duration_pb->has_nanos ? duration_pb->nanos : 0;
-  duration.clock_type = GPR_TIMESPAN;
-  return duration;
+grpc_millis grpc_grpclb_duration_to_millis(grpc_grpclb_duration *duration_pb) {
+  return (grpc_millis)(
+      (duration_pb->has_seconds ? duration_pb->seconds : 0) * GPR_MS_PER_SEC +
+      (duration_pb->has_nanos ? duration_pb->nanos : 0) / GPR_NS_PER_MS);
 }
 
 void grpc_grpclb_initial_response_destroy(
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
index c4a98492c9..56b9c096d0 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h
@@ -81,8 +81,7 @@ void grpc_grpclb_destroy_serverlist(grpc_grpclb_serverlist *serverlist);
 int grpc_grpclb_duration_compare(const grpc_grpclb_duration *lhs,
                                  const grpc_grpclb_duration *rhs);
 
-gpr_timespec grpc_grpclb_duration_to_timespec(
-    grpc_grpclb_duration *duration_pb);
+grpc_millis grpc_grpclb_duration_to_millis(grpc_grpclb_duration *duration_pb);
 
 /** Destroy \a initial_response */
 void grpc_grpclb_initial_response_destroy(
diff --git a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
index d20cbb8388..b07fc3b720 100644
--- a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc
@@ -706,9 +706,9 @@ static grpc_lb_policy_factory *pick_first_lb_factory_create() {
 
 /* Plugin registration */
 
-void grpc_lb_policy_pick_first_init() {
+extern "C" void grpc_lb_policy_pick_first_init() {
   grpc_register_lb_policy(pick_first_lb_factory_create());
   grpc_register_tracer(&grpc_lb_pick_first_trace);
 }
 
-void grpc_lb_policy_pick_first_shutdown() {}
+extern "C" void grpc_lb_policy_pick_first_shutdown() {}
diff --git a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
index a3a62e9f3c..6812bb50cd 100644
--- a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.cc
@@ -916,9 +916,9 @@ static grpc_lb_policy_factory *round_robin_lb_factory_create() {
 
 /* Plugin registration */
 
-void grpc_lb_policy_round_robin_init() {
+extern "C" void grpc_lb_policy_round_robin_init() {
   grpc_register_lb_policy(round_robin_lb_factory_create());
   grpc_register_tracer(&grpc_lb_round_robin_trace);
 }
 
-void grpc_lb_policy_round_robin_shutdown() {}
+extern "C" void grpc_lb_policy_round_robin_shutdown() {}
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.c b/src/core/ext/filters/client_channel/lb_policy_factory.cc
index 4d1405454c..05ab43d0b6 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.c
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.cc
@@ -56,7 +56,7 @@ grpc_lb_addresses* grpc_lb_addresses_copy(const grpc_lb_addresses* addresses) {
 }
 
 void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
-                                   void* address, size_t address_len,
+                                   const void* address, size_t address_len,
                                    bool is_balancer, const char* balancer_name,
                                    void* user_data) {
   GPR_ASSERT(index < addresses->num_addresses);
diff --git a/src/core/ext/filters/client_channel/lb_policy_factory.h b/src/core/ext/filters/client_channel/lb_policy_factory.h
index 9d9fb143df..69bcba4232 100644
--- a/src/core/ext/filters/client_channel/lb_policy_factory.h
+++ b/src/core/ext/filters/client_channel/lb_policy_factory.h
@@ -29,6 +29,10 @@
 // Channel arg key for grpc_lb_addresses.
 #define GRPC_ARG_LB_ADDRESSES "grpc.lb_addresses"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_lb_policy_factory grpc_lb_policy_factory;
 typedef struct grpc_lb_policy_factory_vtable grpc_lb_policy_factory_vtable;
 
@@ -73,7 +77,7 @@ grpc_lb_addresses *grpc_lb_addresses_copy(const grpc_lb_addresses *addresses);
  * \a address is a socket address of length \a address_len.
  * Takes ownership of \a balancer_name. */
 void grpc_lb_addresses_set_address(grpc_lb_addresses *addresses, size_t index,
-                                   void *address, size_t address_len,
+                                   const void *address, size_t address_len,
                                    bool is_balancer, const char *balancer_name,
                                    void *user_data);
 
@@ -130,4 +134,8 @@ grpc_lb_policy *grpc_lb_policy_factory_create_lb_policy(
     grpc_exec_ctx *exec_ctx, grpc_lb_policy_factory *factory,
     grpc_lb_policy_args *args);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_FACTORY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_FACTORY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/lb_policy_registry.c b/src/core/ext/filters/client_channel/lb_policy_registry.cc
index f2460f8304..f2460f8304 100644
--- a/src/core/ext/filters/client_channel/lb_policy_registry.c
+++ b/src/core/ext/filters/client_channel/lb_policy_registry.cc
diff --git a/src/core/ext/filters/client_channel/lb_policy_registry.h b/src/core/ext/filters/client_channel/lb_policy_registry.h
index f5995687cf..0867844c37 100644
--- a/src/core/ext/filters/client_channel/lb_policy_registry.h
+++ b/src/core/ext/filters/client_channel/lb_policy_registry.h
@@ -22,6 +22,10 @@
 #include "src/core/ext/filters/client_channel/lb_policy_factory.h"
 #include "src/core/lib/iomgr/exec_ctx.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Initialize the registry and set \a default_factory as the factory to be
  * returned when no name is provided in a lookup */
 void grpc_lb_policy_registry_init(void);
@@ -37,4 +41,8 @@ void grpc_register_lb_policy(grpc_lb_policy_factory *factory);
 grpc_lb_policy *grpc_lb_policy_create(grpc_exec_ctx *exec_ctx, const char *name,
                                       grpc_lb_policy_args *args);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_REGISTRY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_REGISTRY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/parse_address.c b/src/core/ext/filters/client_channel/parse_address.cc
index 2152b5a1e9..2152b5a1e9 100644
--- a/src/core/ext/filters/client_channel/parse_address.c
+++ b/src/core/ext/filters/client_channel/parse_address.cc
diff --git a/src/core/ext/filters/client_channel/parse_address.h b/src/core/ext/filters/client_channel/parse_address.h
index c90a827da5..742df380b7 100644
--- a/src/core/ext/filters/client_channel/parse_address.h
+++ b/src/core/ext/filters/client_channel/parse_address.h
@@ -24,6 +24,10 @@
 #include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Populate \a resolved_addr from \a uri, whose path is expected to contain a
  * unix socket path. Returns true upon success. */
 bool grpc_parse_unix(const grpc_uri *uri, grpc_resolved_address *resolved_addr);
@@ -45,4 +49,8 @@ bool grpc_parse_ipv4_hostport(const char *hostport, grpc_resolved_address *addr,
 bool grpc_parse_ipv6_hostport(const char *hostport, grpc_resolved_address *addr,
                               bool log_errors);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PARSE_ADDRESS_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PARSE_ADDRESS_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/proxy_mapper.c b/src/core/ext/filters/client_channel/proxy_mapper.cc
index c6ea5fc680..c6ea5fc680 100644
--- a/src/core/ext/filters/client_channel/proxy_mapper.c
+++ b/src/core/ext/filters/client_channel/proxy_mapper.cc
diff --git a/src/core/ext/filters/client_channel/proxy_mapper.h b/src/core/ext/filters/client_channel/proxy_mapper.h
index a13861ccaf..1325a9f1f6 100644
--- a/src/core/ext/filters/client_channel/proxy_mapper.h
+++ b/src/core/ext/filters/client_channel/proxy_mapper.h
@@ -25,6 +25,10 @@
 
 #include "src/core/lib/iomgr/resolve_address.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_proxy_mapper grpc_proxy_mapper;
 
 typedef struct {
@@ -71,4 +75,8 @@ bool grpc_proxy_mapper_map_address(grpc_exec_ctx* exec_ctx,
 
 void grpc_proxy_mapper_destroy(grpc_proxy_mapper* mapper);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PROXY_MAPPER_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PROXY_MAPPER_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/proxy_mapper_registry.c b/src/core/ext/filters/client_channel/proxy_mapper_registry.cc
index 09967eea3c..09967eea3c 100644
--- a/src/core/ext/filters/client_channel/proxy_mapper_registry.c
+++ b/src/core/ext/filters/client_channel/proxy_mapper_registry.cc
diff --git a/src/core/ext/filters/client_channel/proxy_mapper_registry.h b/src/core/ext/filters/client_channel/proxy_mapper_registry.h
index 99e54d1a78..2d389f1c21 100644
--- a/src/core/ext/filters/client_channel/proxy_mapper_registry.h
+++ b/src/core/ext/filters/client_channel/proxy_mapper_registry.h
@@ -21,6 +21,10 @@
 
 #include "src/core/ext/filters/client_channel/proxy_mapper.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void grpc_proxy_mapper_registry_init();
 void grpc_proxy_mapper_registry_shutdown();
 
@@ -41,4 +45,8 @@ bool grpc_proxy_mappers_map_address(grpc_exec_ctx* exec_ctx,
                                     grpc_resolved_address** new_address,
                                     grpc_channel_args** new_args);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PROXY_MAPPER_REGISTRY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_PROXY_MAPPER_REGISTRY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/resolver.c b/src/core/ext/filters/client_channel/resolver.cc
index 8401504fcf..8401504fcf 100644
--- a/src/core/ext/filters/client_channel/resolver.c
+++ b/src/core/ext/filters/client_channel/resolver.cc
diff --git a/src/core/ext/filters/client_channel/resolver.h b/src/core/ext/filters/client_channel/resolver.h
index ae9c8f66fe..73fbbbbc3b 100644
--- a/src/core/ext/filters/client_channel/resolver.h
+++ b/src/core/ext/filters/client_channel/resolver.h
@@ -22,6 +22,10 @@
 #include "src/core/ext/filters/client_channel/subchannel.h"
 #include "src/core/lib/iomgr/iomgr.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_resolver grpc_resolver;
 typedef struct grpc_resolver_vtable grpc_resolver_vtable;
 
@@ -87,4 +91,8 @@ void grpc_resolver_next_locked(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
                                grpc_channel_args **result,
                                grpc_closure *on_complete);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_H */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
index 9bb229ad95..5f7ab987cb 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc
@@ -32,13 +32,13 @@
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
+#include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/gethostname.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/json/json.h"
-#include "src/core/lib/support/backoff.h"
 #include "src/core/lib/support/env.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/service_config.h"
@@ -89,7 +89,7 @@ typedef struct {
   bool have_retry_timer;
   grpc_timer retry_timer;
   /** retry backoff state */
-  gpr_backoff backoff_state;
+  grpc_backoff backoff_state;
 
   /** currently resolving addresses */
   grpc_lb_addresses *lb_addresses;
@@ -137,7 +137,7 @@ static void dns_ares_channel_saw_error_locked(grpc_exec_ctx *exec_ctx,
                                               grpc_resolver *resolver) {
   ares_dns_resolver *r = (ares_dns_resolver *)resolver;
   if (!r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
+    grpc_backoff_reset(&r->backoff_state);
     dns_ares_start_resolving_locked(exec_ctx, r);
   }
 }
@@ -271,22 +271,20 @@ static void dns_ares_on_resolved_locked(grpc_exec_ctx *exec_ctx, void *arg,
   } else {
     const char *msg = grpc_error_string(error);
     gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg);
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
-    gpr_timespec timeout = gpr_time_sub(next_try, now);
+    grpc_millis next_try = grpc_backoff_step(exec_ctx, &r->backoff_state);
+    grpc_millis timeout = next_try - grpc_exec_ctx_now(exec_ctx);
     gpr_log(GPR_INFO, "dns resolution failed (will retry): %s",
             grpc_error_string(error));
     GPR_ASSERT(!r->have_retry_timer);
     r->have_retry_timer = true;
     GRPC_RESOLVER_REF(&r->base, "retry-timer");
-    if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) {
-      gpr_log(GPR_DEBUG, "retrying in %" PRId64 ".%09d seconds", timeout.tv_sec,
-              timeout.tv_nsec);
+    if (timeout > 0) {
+      gpr_log(GPR_DEBUG, "retrying in %" PRIdPTR " milliseconds", timeout);
     } else {
       gpr_log(GPR_DEBUG, "retrying immediately");
     }
     grpc_timer_init(exec_ctx, &r->retry_timer, next_try,
-                    &r->dns_ares_on_retry_timer_locked, now);
+                    &r->dns_ares_on_retry_timer_locked);
   }
   if (r->resolved_result != NULL) {
     grpc_channel_args_destroy(exec_ctx, r->resolved_result);
@@ -307,7 +305,7 @@ static void dns_ares_next_locked(grpc_exec_ctx *exec_ctx,
   r->next_completion = on_complete;
   r->target_result = target_result;
   if (r->resolved_version == 0 && !r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
+    grpc_backoff_reset(&r->backoff_state);
     dns_ares_start_resolving_locked(exec_ctx, r);
   } else {
     dns_ares_maybe_finish_next_locked(exec_ctx, r);
@@ -381,11 +379,11 @@ static grpc_resolver *dns_ares_create(grpc_exec_ctx *exec_ctx,
     grpc_pollset_set_add_pollset_set(exec_ctx, r->interested_parties,
                                      args->pollset_set);
   }
-  gpr_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS,
-                   GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER,
-                   GRPC_DNS_RECONNECT_JITTER,
-                   GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
-                   GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
+  grpc_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS,
+                    GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER,
+                    GRPC_DNS_RECONNECT_JITTER,
+                    GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
+                    GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
   GRPC_CLOSURE_INIT(&r->dns_ares_on_retry_timer_locked,
                     dns_ares_on_retry_timer_locked, r,
                     grpc_combiner_scheduler(r->base.combiner));
@@ -425,7 +423,7 @@ static grpc_resolver_factory *dns_ares_resolver_factory_create() {
   return &dns_resolver_factory;
 }
 
-void grpc_resolver_dns_ares_init(void) {
+extern "C" void grpc_resolver_dns_ares_init(void) {
   char *resolver = gpr_getenv("GRPC_DNS_RESOLVER");
   /* TODO(zyc): Turn on c-ares based resolver by default after the address
      sorter and the CNAME support are added. */
@@ -441,7 +439,7 @@ void grpc_resolver_dns_ares_init(void) {
   gpr_free(resolver);
 }
 
-void grpc_resolver_dns_ares_shutdown(void) {
+extern "C" void grpc_resolver_dns_ares_shutdown(void) {
   char *resolver = gpr_getenv("GRPC_DNS_RESOLVER");
   if (resolver != NULL && gpr_stricmp(resolver, "ares") == 0) {
     grpc_ares_cleanup();
@@ -451,8 +449,8 @@ void grpc_resolver_dns_ares_shutdown(void) {
 
 #else /* GRPC_ARES == 1 && !defined(GRPC_UV) */
 
-void grpc_resolver_dns_ares_init(void) {}
+extern "C" void grpc_resolver_dns_ares_init(void) {}
 
-void grpc_resolver_dns_ares_shutdown(void) {}
+extern "C" void grpc_resolver_dns_ares_shutdown(void) {}
 
 #endif /* GRPC_ARES == 1 && !defined(GRPC_UV) */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
index 386012d2ed..3d4309f2fa 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h
@@ -22,6 +22,10 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/pollset_set.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_ares_ev_driver grpc_ares_ev_driver;
 
 /* Start \a ev_driver. It will keep working until all IO on its ares_channel is
@@ -49,5 +53,9 @@ void grpc_ares_ev_driver_destroy(grpc_ares_ev_driver *ev_driver);
 void grpc_ares_ev_driver_shutdown(grpc_exec_ctx *exec_ctx,
                                   grpc_ares_ev_driver *ev_driver);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H \
           */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
index c30cc93b6f..c30cc93b6f 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
index 04379975e1..04379975e1 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
index 108333047d..38fbea9aac 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h
@@ -25,6 +25,10 @@
 #include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_ares_request grpc_ares_request;
 
 /* Asynchronously resolve \a name. Use \a default_port if a port isn't
@@ -65,5 +69,9 @@ grpc_error *grpc_ares_init(void);
    it has been called the same number of times as grpc_ares_init(). */
 void grpc_ares_cleanup(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_WRAPPER_H \
           */
diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.c b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
index f2587c4520..f2587c4520 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc
diff --git a/src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.c b/src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc
index 5ea75f0554..e669b6dfc7 100644
--- a/src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.c
+++ b/src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc
@@ -16,6 +16,9 @@
  *
  */
 
+#include <grpc/support/port_platform.h>
+
+#include <inttypes.h>
 #include <string.h>
 
 #include <grpc/support/alloc.h>
@@ -24,11 +27,11 @@
 
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
+#include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/timer.h"
-#include "src/core/lib/support/backoff.h"
 #include "src/core/lib/support/env.h"
 #include "src/core/lib/support/string.h"
 
@@ -67,7 +70,7 @@ typedef struct {
   grpc_timer retry_timer;
   grpc_closure on_retry;
   /** retry backoff state */
-  gpr_backoff backoff_state;
+  grpc_backoff backoff_state;
 
   /** currently resolving addresses */
   grpc_resolved_addresses *addresses;
@@ -110,7 +113,7 @@ static void dns_channel_saw_error_locked(grpc_exec_ctx *exec_ctx,
                                          grpc_resolver *resolver) {
   dns_resolver *r = (dns_resolver *)resolver;
   if (!r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
+    grpc_backoff_reset(&r->backoff_state);
     dns_start_resolving_locked(exec_ctx, r);
   }
 }
@@ -123,7 +126,7 @@ static void dns_next_locked(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
   r->next_completion = on_complete;
   r->target_result = target_result;
   if (r->resolved_version == 0 && !r->resolving) {
-    gpr_backoff_reset(&r->backoff_state);
+    grpc_backoff_reset(&r->backoff_state);
     dns_start_resolving_locked(exec_ctx, r);
   } else {
     dns_maybe_finish_next_locked(exec_ctx, r);
@@ -150,6 +153,9 @@ static void dns_on_resolved_locked(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_channel_args *result = NULL;
   GPR_ASSERT(r->resolving);
   r->resolving = false;
+  GRPC_ERROR_REF(error);
+  error = grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS,
+                             grpc_slice_from_copied_string(r->name_to_resolve));
   if (r->addresses != NULL) {
     grpc_lb_addresses *addresses = grpc_lb_addresses_create(
         r->addresses->naddrs, NULL /* user_data_vtable */);
@@ -164,23 +170,21 @@ static void dns_on_resolved_locked(grpc_exec_ctx *exec_ctx, void *arg,
     grpc_resolved_addresses_destroy(r->addresses);
     grpc_lb_addresses_destroy(exec_ctx, addresses);
   } else {
-    gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
-    gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
-    gpr_timespec timeout = gpr_time_sub(next_try, now);
+    grpc_millis next_try = grpc_backoff_step(exec_ctx, &r->backoff_state);
+    grpc_millis timeout = next_try - grpc_exec_ctx_now(exec_ctx);
     gpr_log(GPR_INFO, "dns resolution failed (will retry): %s",
             grpc_error_string(error));
     GPR_ASSERT(!r->have_retry_timer);
     r->have_retry_timer = true;
     GRPC_RESOLVER_REF(&r->base, "retry-timer");
-    if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) {
-      gpr_log(GPR_DEBUG, "retrying in %" PRId64 ".%09d seconds", timeout.tv_sec,
-              timeout.tv_nsec);
+    if (timeout > 0) {
+      gpr_log(GPR_DEBUG, "retrying in %" PRIdPTR " milliseconds", timeout);
     } else {
       gpr_log(GPR_DEBUG, "retrying immediately");
     }
     GRPC_CLOSURE_INIT(&r->on_retry, dns_on_retry_timer_locked, r,
                       grpc_combiner_scheduler(r->base.combiner));
-    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry, now);
+    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry);
   }
   if (r->resolved_result != NULL) {
     grpc_channel_args_destroy(exec_ctx, r->resolved_result);
@@ -188,6 +192,7 @@ static void dns_on_resolved_locked(grpc_exec_ctx *exec_ctx, void *arg,
   r->resolved_result = result;
   r->resolved_version++;
   dns_maybe_finish_next_locked(exec_ctx, r);
+  GRPC_ERROR_UNREF(error);
 
   GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "dns-resolving");
 }
@@ -251,11 +256,11 @@ static grpc_resolver *dns_create(grpc_exec_ctx *exec_ctx,
     grpc_pollset_set_add_pollset_set(exec_ctx, r->interested_parties,
                                      args->pollset_set);
   }
-  gpr_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS,
-                   GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER,
-                   GRPC_DNS_RECONNECT_JITTER,
-                   GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
-                   GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
+  grpc_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS,
+                    GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER,
+                    GRPC_DNS_RECONNECT_JITTER,
+                    GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS * 1000,
+                    GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000);
   return &r->base;
 }
 
@@ -289,7 +294,7 @@ static grpc_resolver_factory *dns_resolver_factory_create() {
   return &dns_resolver_factory;
 }
 
-void grpc_resolver_dns_native_init(void) {
+extern "C" void grpc_resolver_dns_native_init(void) {
   char *resolver = gpr_getenv("GRPC_DNS_RESOLVER");
   if (resolver != NULL && gpr_stricmp(resolver, "native") == 0) {
     gpr_log(GPR_DEBUG, "Using native dns resolver");
@@ -307,4 +312,4 @@ void grpc_resolver_dns_native_init(void) {
   gpr_free(resolver);
 }
 
-void grpc_resolver_dns_native_shutdown(void) {}
+extern "C" void grpc_resolver_dns_native_shutdown(void) {}
diff --git a/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.c b/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc
index 69ea440ae6..ed5b1011fb 100644
--- a/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.c
+++ b/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.cc
@@ -258,8 +258,8 @@ static const grpc_resolver_factory_vtable fake_resolver_factory_vtable = {
 static grpc_resolver_factory fake_resolver_factory = {
     &fake_resolver_factory_vtable};
 
-void grpc_resolver_fake_init(void) {
+extern "C" void grpc_resolver_fake_init(void) {
   grpc_register_resolver_type(&fake_resolver_factory);
 }
 
-void grpc_resolver_fake_shutdown(void) {}
+extern "C" void grpc_resolver_fake_shutdown(void) {}
diff --git a/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h b/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h
index c084ef2a58..95c3bafed8 100644
--- a/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h
+++ b/src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h
@@ -21,6 +21,10 @@
 #include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR \
   "grpc.fake_resolver.response_generator"
 
@@ -56,5 +60,9 @@ grpc_fake_resolver_response_generator_ref(
 void grpc_fake_resolver_response_generator_unref(
     grpc_fake_resolver_response_generator* generator);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FAKE_FAKE_RESOLVER_H \
           */
diff --git a/src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.c b/src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.cc
index 7ceb8f40a1..dda9542325 100644
--- a/src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.c
+++ b/src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.cc
@@ -211,7 +211,7 @@ DECL_FACTORY(unix);
 DECL_FACTORY(ipv4);
 DECL_FACTORY(ipv6);
 
-void grpc_resolver_sockaddr_init(void) {
+extern "C" void grpc_resolver_sockaddr_init(void) {
   grpc_register_resolver_type(&ipv4_resolver_factory);
   grpc_register_resolver_type(&ipv6_resolver_factory);
 #ifdef GRPC_HAVE_UNIX_SOCKET
@@ -219,4 +219,4 @@ void grpc_resolver_sockaddr_init(void) {
 #endif
 }
 
-void grpc_resolver_sockaddr_shutdown(void) {}
+extern "C" void grpc_resolver_sockaddr_shutdown(void) {}
diff --git a/src/core/ext/filters/client_channel/resolver_factory.c b/src/core/ext/filters/client_channel/resolver_factory.cc
index 6f0a7c1e36..6f0a7c1e36 100644
--- a/src/core/ext/filters/client_channel/resolver_factory.c
+++ b/src/core/ext/filters/client_channel/resolver_factory.cc
diff --git a/src/core/ext/filters/client_channel/resolver_factory.h b/src/core/ext/filters/client_channel/resolver_factory.h
index 6bd7929d4e..6e533e3248 100644
--- a/src/core/ext/filters/client_channel/resolver_factory.h
+++ b/src/core/ext/filters/client_channel/resolver_factory.h
@@ -24,6 +24,10 @@
 #include "src/core/ext/filters/client_channel/uri_parser.h"
 #include "src/core/lib/iomgr/pollset_set.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct grpc_resolver_factory grpc_resolver_factory;
 typedef struct grpc_resolver_factory_vtable grpc_resolver_factory_vtable;
 
@@ -67,4 +71,8 @@ grpc_resolver *grpc_resolver_factory_create_resolver(
 char *grpc_resolver_factory_get_default_authority(
     grpc_resolver_factory *factory, grpc_uri *uri);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FACTORY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FACTORY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/resolver_registry.c b/src/core/ext/filters/client_channel/resolver_registry.cc
index 1a0fb0bc3c..1a0fb0bc3c 100644
--- a/src/core/ext/filters/client_channel/resolver_registry.c
+++ b/src/core/ext/filters/client_channel/resolver_registry.cc
diff --git a/src/core/ext/filters/client_channel/resolver_registry.h b/src/core/ext/filters/client_channel/resolver_registry.h
index 692490543d..eb08d887b1 100644
--- a/src/core/ext/filters/client_channel/resolver_registry.h
+++ b/src/core/ext/filters/client_channel/resolver_registry.h
@@ -22,6 +22,10 @@
 #include "src/core/ext/filters/client_channel/resolver_factory.h"
 #include "src/core/lib/iomgr/pollset_set.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void grpc_resolver_registry_init();
 void grpc_resolver_registry_shutdown(void);
 
@@ -66,4 +70,8 @@ char *grpc_get_default_authority(grpc_exec_ctx *exec_ctx, const char *target);
 char *grpc_resolver_factory_add_default_prefix_if_needed(
     grpc_exec_ctx *exec_ctx, const char *target);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_REGISTRY_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_REGISTRY_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/retry_throttle.c b/src/core/ext/filters/client_channel/retry_throttle.cc
index 09dcade089..09dcade089 100644
--- a/src/core/ext/filters/client_channel/retry_throttle.c
+++ b/src/core/ext/filters/client_channel/retry_throttle.cc
diff --git a/src/core/ext/filters/client_channel/retry_throttle.h b/src/core/ext/filters/client_channel/retry_throttle.h
index bf99297e98..3b849475b9 100644
--- a/src/core/ext/filters/client_channel/retry_throttle.h
+++ b/src/core/ext/filters/client_channel/retry_throttle.h
@@ -21,6 +21,10 @@
 
 #include <stdbool.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /// Tracks retry throttling data for an individual server name.
 typedef struct grpc_server_retry_throttle_data grpc_server_retry_throttle_data;
 
@@ -47,4 +51,8 @@ void grpc_retry_throttle_map_shutdown();
 grpc_server_retry_throttle_data* grpc_retry_throttle_map_get_data_for_server(
     const char* server_name, int max_milli_tokens, int milli_token_ratio);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RETRY_THROTTLE_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RETRY_THROTTLE_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/subchannel.c b/src/core/ext/filters/client_channel/subchannel.cc
index 40a51c72d6..5710a22178 100644
--- a/src/core/ext/filters/client_channel/subchannel.c
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -18,6 +18,7 @@
 
 #include "src/core/ext/filters/client_channel/subchannel.h"
 
+#include <inttypes.h>
 #include <limits.h>
 #include <string.h>
 
@@ -30,6 +31,7 @@
 #include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/filters/client_channel/subchannel_index.h"
 #include "src/core/ext/filters/client_channel/uri_parser.h"
+#include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/debug/stats.h"
@@ -37,7 +39,6 @@
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/slice_internal.h"
-#include "src/core/lib/support/backoff.h"
 #include "src/core/lib/surface/channel.h"
 #include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/transport/connectivity_state.h"
@@ -117,9 +118,9 @@ struct grpc_subchannel {
   external_state_watcher root_external_state_watcher;
 
   /** next connect attempt time */
-  gpr_timespec next_attempt;
+  grpc_millis next_attempt;
   /** backoff state */
-  gpr_backoff backoff_state;
+  grpc_backoff backoff_state;
   /** do we have an active alarm? */
   bool have_alarm;
   /** have we started the backoff loop */
@@ -343,31 +344,27 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
                       "grpc.testing.fixed_reconnect_backoff_ms")) {
         fixed_reconnect_backoff = true;
         initial_backoff_ms = min_backoff_ms = max_backoff_ms =
-            grpc_channel_arg_get_integer(
-                &c->args->args[i],
-                (grpc_integer_options){initial_backoff_ms, 100, INT_MAX});
+            grpc_channel_arg_get_integer(&c->args->args[i],
+                                         {initial_backoff_ms, 100, INT_MAX});
       } else if (0 == strcmp(c->args->args[i].key,
                              GRPC_ARG_MIN_RECONNECT_BACKOFF_MS)) {
         fixed_reconnect_backoff = false;
         min_backoff_ms = grpc_channel_arg_get_integer(
-            &c->args->args[i],
-            (grpc_integer_options){min_backoff_ms, 100, INT_MAX});
+            &c->args->args[i], {min_backoff_ms, 100, INT_MAX});
       } else if (0 == strcmp(c->args->args[i].key,
                              GRPC_ARG_MAX_RECONNECT_BACKOFF_MS)) {
         fixed_reconnect_backoff = false;
         max_backoff_ms = grpc_channel_arg_get_integer(
-            &c->args->args[i],
-            (grpc_integer_options){max_backoff_ms, 100, INT_MAX});
+            &c->args->args[i], {max_backoff_ms, 100, INT_MAX});
       } else if (0 == strcmp(c->args->args[i].key,
                              GRPC_ARG_INITIAL_RECONNECT_BACKOFF_MS)) {
         fixed_reconnect_backoff = false;
         initial_backoff_ms = grpc_channel_arg_get_integer(
-            &c->args->args[i],
-            (grpc_integer_options){initial_backoff_ms, 100, INT_MAX});
+            &c->args->args[i], {initial_backoff_ms, 100, INT_MAX});
       }
     }
   }
-  gpr_backoff_init(
+  grpc_backoff_init(
       &c->backoff_state, initial_backoff_ms,
       fixed_reconnect_backoff ? 1.0
                               : GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER,
@@ -431,8 +428,7 @@ static void on_alarm(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   }
   if (error == GRPC_ERROR_NONE) {
     gpr_log(GPR_INFO, "Failed to connect to channel, retrying");
-    c->next_attempt =
-        gpr_backoff_step(&c->backoff_state, gpr_now(GPR_CLOCK_MONOTONIC));
+    c->next_attempt = grpc_backoff_step(exec_ctx, &c->backoff_state);
     continue_connect_locked(exec_ctx, c);
     gpr_mu_unlock(&c->mu);
   } else {
@@ -467,24 +463,22 @@ static void maybe_start_connecting_locked(grpc_exec_ctx *exec_ctx,
   c->connecting = true;
   GRPC_SUBCHANNEL_WEAK_REF(c, "connecting");
 
-  gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
   if (!c->backoff_begun) {
     c->backoff_begun = true;
-    c->next_attempt = gpr_backoff_begin(&c->backoff_state, now);
+    c->next_attempt = grpc_backoff_begin(exec_ctx, &c->backoff_state);
     continue_connect_locked(exec_ctx, c);
   } else {
     GPR_ASSERT(!c->have_alarm);
     c->have_alarm = true;
-    gpr_timespec time_til_next = gpr_time_sub(c->next_attempt, now);
-    if (gpr_time_cmp(time_til_next, gpr_time_0(time_til_next.clock_type)) <=
-        0) {
+    const grpc_millis time_til_next =
+        c->next_attempt - grpc_exec_ctx_now(exec_ctx);
+    if (time_til_next <= 0) {
       gpr_log(GPR_INFO, "Retry immediately");
     } else {
-      gpr_log(GPR_INFO, "Retry in %" PRId64 ".%09d seconds",
-              time_til_next.tv_sec, time_til_next.tv_nsec);
+      gpr_log(GPR_INFO, "Retry in %" PRIdPTR " milliseconds", time_til_next);
     }
     GRPC_CLOSURE_INIT(&c->on_alarm, on_alarm, c, grpc_schedule_on_exec_ctx);
-    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, &c->on_alarm, now);
+    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, &c->on_alarm);
   }
 }
 
@@ -759,14 +753,15 @@ grpc_error *grpc_connected_subchannel_create_call(
   grpc_call_stack *callstk = SUBCHANNEL_CALL_TO_CALL_STACK(*call);
   (*call)->connection = GRPC_CONNECTED_SUBCHANNEL_REF(con, "subchannel_call");
   const grpc_call_element_args call_args = {
-      .call_stack = callstk,
-      .server_transport_data = NULL,
-      .context = args->context,
-      .path = args->path,
-      .start_time = args->start_time,
-      .deadline = args->deadline,
-      .arena = args->arena,
-      .call_combiner = args->call_combiner};
+      callstk,            /* call_stack */
+      NULL,               /* server_transport_data */
+      args->context,      /* context */
+      args->path,         /* path */
+      args->start_time,   /* start_time */
+      args->deadline,     /* deadline */
+      args->arena,        /* arena */
+      args->call_combiner /* call_combiner */
+  };
   grpc_error *error = grpc_call_stack_init(
       exec_ctx, chanstk, 1, subchannel_call_destroy, *call, &call_args);
   if (error != GRPC_ERROR_NONE) {
diff --git a/src/core/ext/filters/client_channel/subchannel.h b/src/core/ext/filters/client_channel/subchannel.h
index 51d712f6a7..46b29f1fe0 100644
--- a/src/core/ext/filters/client_channel/subchannel.h
+++ b/src/core/ext/filters/client_channel/subchannel.h
@@ -26,6 +26,10 @@
 #include "src/core/lib/transport/connectivity_state.h"
 #include "src/core/lib/transport/metadata.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 // Channel arg containing a grpc_resolved_address to connect to.
 #define GRPC_ARG_SUBCHANNEL_ADDRESS "grpc.subchannel_address"
 
@@ -103,7 +107,7 @@ typedef struct {
   grpc_polling_entity *pollent;
   grpc_slice path;
   gpr_timespec start_time;
-  gpr_timespec deadline;
+  grpc_millis deadline;
   gpr_arena *arena;
   grpc_call_context_element *context;
   grpc_call_combiner *call_combiner;
@@ -188,4 +192,8 @@ const char *grpc_get_subchannel_address_uri_arg(const grpc_channel_args *args);
 /// Caller is responsible for freeing the string.
 grpc_arg grpc_create_subchannel_address_arg(const grpc_resolved_address *addr);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_SUBCHANNEL_H */
diff --git a/src/core/ext/filters/client_channel/subchannel_index.c b/src/core/ext/filters/client_channel/subchannel_index.cc
index d7a51f3899..1f466ec0b8 100644
--- a/src/core/ext/filters/client_channel/subchannel_index.c
+++ b/src/core/ext/filters/client_channel/subchannel_index.cc
@@ -114,11 +114,12 @@ static void *scv_avl_copy(void *p, void *unused) {
 }
 
 static const gpr_avl_vtable subchannel_avl_vtable = {
-    .destroy_key = sck_avl_destroy,
-    .copy_key = sck_avl_copy,
-    .compare_keys = sck_avl_compare,
-    .destroy_value = scv_avl_destroy,
-    .copy_value = scv_avl_copy};
+    sck_avl_destroy,  // destroy_key
+    sck_avl_copy,     // copy_key
+    sck_avl_compare,  // compare_keys
+    scv_avl_destroy,  // destroy_value
+    scv_avl_copy      // copy_value
+};
 
 void grpc_subchannel_index_init(void) {
   g_subchannel_index = gpr_avl_create(&subchannel_avl_vtable);
diff --git a/src/core/ext/filters/client_channel/subchannel_index.h b/src/core/ext/filters/client_channel/subchannel_index.h
index 92e36d5283..09bac3592c 100644
--- a/src/core/ext/filters/client_channel/subchannel_index.h
+++ b/src/core/ext/filters/client_channel/subchannel_index.h
@@ -21,6 +21,10 @@
 
 #include "src/core/ext/filters/client_channel/subchannel.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** \file Provides an index of active subchannels so that they can be
     shared amongst channels */
 
@@ -78,4 +82,8 @@ void grpc_subchannel_index_unref(void);
  * force_creation set. */
 void grpc_subchannel_index_test_only_set_force_creation(bool force_creation);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_SUBCHANNEL_INDEX_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_SUBCHANNEL_INDEX_H */
\ No newline at end of file
diff --git a/src/core/ext/filters/client_channel/uri_parser.c b/src/core/ext/filters/client_channel/uri_parser.cc
index fb4fb8e694..fb4fb8e694 100644
--- a/src/core/ext/filters/client_channel/uri_parser.c
+++ b/src/core/ext/filters/client_channel/uri_parser.cc
diff --git a/src/core/ext/filters/client_channel/uri_parser.h b/src/core/ext/filters/client_channel/uri_parser.h
index 05ca2e00e4..43e8ae64e0 100644
--- a/src/core/ext/filters/client_channel/uri_parser.h
+++ b/src/core/ext/filters/client_channel/uri_parser.h
@@ -22,6 +22,10 @@
 #include <stddef.h>
 #include "src/core/lib/iomgr/exec_ctx.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct {
   char *scheme;
   char *authority;
@@ -47,4 +51,8 @@ const char *grpc_uri_get_query_arg(const grpc_uri *uri, const char *key);
 /** destroy a uri */
 void grpc_uri_destroy(grpc_uri *uri);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_URI_PARSER_H */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_URI_PARSER_H */
\ No newline at end of file