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

19 files changed, 125 insertions, 82 deletions

diff --git a/doc/interop-test-descriptions.md b/doc/interop-test-descriptions.md
index 666af185b9..7c153fa3fa 100644
--- a/doc/interop-test-descriptions.md
+++ b/doc/interop-test-descriptions.md
@@ -779,25 +779,38 @@ Client asserts:
 
 ### unimplemented_method
 
-Status: Ready for implementation. Blocking beta.
-
-This test verifies calling unimplemented RPC method returns the UNIMPLEMENTED status code.
+This test verifies that calling an unimplemented RPC method returns the 
+UNIMPLEMENTED status code.
 
 Server features:
 N/A
 
 Procedure:
-* Client calls `grpc.testing.UnimplementedService/UnimplementedCall` with an
-  empty request (defined as `grpc.testing.Empty`):
+* Client calls `grpc.testing.TestService/UnimplementedMethod` with an empty
+  request (defined as `grpc.testing.Empty`):
 
     ```
     {
     }
     ```
+   
+Client asserts:
+* received status code is 12 (UNIMPLEMENTED)
+
+### unimplemented_service
+
+This test verifies calling an unimplemented server returns the UNIMPLEMENTED
+status code.
+
+Server features:
+N/A
+
+Procedure:
+* Client calls `grpc.testing.UnimplementedService/UnimplementedCall` with an
+  empty request (defined as `grpc.testing.Empty`)
 
 Client asserts:
 * received status code is 12 (UNIMPLEMENTED)
-* received status message is empty or null/unset
 
 ### cancel_after_begin
 
diff --git a/src/core/ext/client_config/client_channel.c b/src/core/ext/client_config/client_channel.c
index a6056c3e8d..cbf79afa17 100644
--- a/src/core/ext/client_config/client_channel.c
+++ b/src/core/ext/client_config/client_channel.c
@@ -513,10 +513,14 @@ static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
 
 static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *arg,
                              grpc_error *error) {
-  call_data *calld = arg;
+  grpc_call_element *elem = arg;
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
   gpr_mu_lock(&calld->mu);
   GPR_ASSERT(calld->creation_phase ==
              GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL);
+  grpc_polling_entity_del_from_pollset_set(exec_ctx, calld->pollent,
+                                           chand->interested_parties);
   calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
   if (calld->connected_subchannel == NULL) {
     gpr_atm_no_barrier_store(&calld->subchannel_call, 1);
@@ -564,6 +568,9 @@ typedef struct {
   grpc_closure closure;
 } continue_picking_args;
 
+/** Return true if subchannel is available immediately (in which case on_ready
+    should not be called), or false otherwise (in which case on_ready should be
+    called when the subchannel is available). */
 static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                             grpc_metadata_batch *initial_metadata,
                             uint32_t initial_metadata_flags,
@@ -629,8 +636,8 @@ static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
     gpr_mu_unlock(&chand->mu);
     // TODO(dgq): make this deadline configurable somehow.
     const grpc_lb_policy_pick_args inputs = {
-        calld->pollent, initial_metadata, initial_metadata_flags,
-        &calld->lb_token_mdelem, gpr_inf_future(GPR_CLOCK_MONOTONIC)};
+        initial_metadata, initial_metadata_flags, &calld->lb_token_mdelem,
+        gpr_inf_future(GPR_CLOCK_MONOTONIC)};
     r = grpc_lb_policy_pick(exec_ctx, lb_policy, &inputs, connected_subchannel,
                             NULL, on_ready);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "pick_subchannel");
@@ -672,6 +679,7 @@ static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                          grpc_call_element *elem,
                                          grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   grpc_deadline_state_client_start_transport_stream_op(exec_ctx, elem, op);
   /* try to (atomically) get the call */
@@ -739,14 +747,20 @@ retry:
       calld->connected_subchannel == NULL &&
       op->send_initial_metadata != NULL) {
     calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL;
-    grpc_closure_init(&calld->next_step, subchannel_ready, calld);
+    grpc_closure_init(&calld->next_step, subchannel_ready, elem);
     GRPC_CALL_STACK_REF(calld->owning_call, "pick_subchannel");
+    /* If a subchannel is not available immediately, the polling entity from
+       call_data should be provided to channel_data's interested_parties, so
+       that IO of the lb_policy and resolver could be done under it. */
     if (pick_subchannel(exec_ctx, elem, op->send_initial_metadata,
                         op->send_initial_metadata_flags,
                         &calld->connected_subchannel, &calld->next_step,
                         GRPC_ERROR_NONE)) {
       calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
       GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_subchannel");
+    } else {
+      grpc_polling_entity_add_to_pollset_set(exec_ctx, calld->pollent,
+                                             chand->interested_parties);
     }
   }
   /* if we've got a subchannel, then let's ask it to create a call */
diff --git a/src/core/ext/client_config/lb_policy.h b/src/core/ext/client_config/lb_policy.h
index 110d08fcac..de424cd105 100644
--- a/src/core/ext/client_config/lb_policy.h
+++ b/src/core/ext/client_config/lb_policy.h
@@ -35,7 +35,6 @@
 #define GRPC_CORE_EXT_CLIENT_CONFIG_LB_POLICY_H
 
 #include "src/core/ext/client_config/subchannel.h"
-#include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
 /** A load balancing policy: specified by a vtable and a struct (which
@@ -55,8 +54,6 @@ struct grpc_lb_policy {
 
 /** Extra arguments for an LB pick */
 typedef struct grpc_lb_policy_pick_args {
-  /** Parties interested in the pick's progress */
-  grpc_polling_entity *pollent;
   /** Initial metadata associated with the picking call. */
   grpc_metadata_batch *initial_metadata;
   /** Bitmask used for selective cancelling. See \a
@@ -153,7 +150,8 @@ void grpc_lb_policy_init(grpc_lb_policy *policy,
     once the pick is complete with its error argument set to indicate
     success or failure.
 
-    Any I/O should be done under \a pick_args->pollent. */
+    Any IO should be done under the \a interested_parties \a grpc_pollset_set
+    in the \a grpc_lb_policy struct. */
 int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
                         const grpc_lb_policy_pick_args *pick_args,
                         grpc_connected_subchannel **target, void **user_data,
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index c18cc0eb9e..140dc9b782 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -388,14 +388,14 @@ static grpc_lb_addresses *process_serverlist(
           GPR_ARRAY_SIZE(server->load_balance_token) - 1;
       grpc_mdstr *lb_token_mdstr = grpc_mdstr_from_buffer(
           (uint8_t *)server->load_balance_token, lb_token_size);
-      user_data = grpc_mdelem_from_metadata_strings(
-          GRPC_MDSTR_LOAD_REPORTING_INITIAL, lb_token_mdstr);
+      user_data = grpc_mdelem_from_metadata_strings(GRPC_MDSTR_LB_TOKEN,
+                                                    lb_token_mdstr);
     } else {
       gpr_log(GPR_ERROR,
               "Missing LB token for backend address '%s'. The empty token will "
               "be used instead",
               grpc_sockaddr_to_uri((struct sockaddr *)&addr.addr));
-      user_data = GRPC_MDELEM_LOAD_REPORTING_INITIAL_EMPTY;
+      user_data = GRPC_MDELEM_LB_TOKEN_EMPTY;
     }
 
     grpc_lb_addresses_set_address(lb_addresses, addr_idx, &addr.addr, addr.len,
@@ -447,6 +447,9 @@ static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
             (intptr_t)glb_policy->rr_policy);
   }
   GPR_ASSERT(glb_policy->rr_policy != NULL);
+  grpc_pollset_set_add_pollset_set(exec_ctx,
+                                   glb_policy->rr_policy->interested_parties,
+                                   glb_policy->base.interested_parties);
   glb_policy->rr_connectivity->state = grpc_lb_policy_check_connectivity(
       exec_ctx, glb_policy->rr_policy, &error);
   grpc_lb_policy_notify_on_state_change(
@@ -677,8 +680,6 @@ static void glb_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   while (pp != NULL) {
     pending_pick *next = pp->next;
     if (pp->target == target) {
-      grpc_polling_entity_del_from_pollset_set(
-          exec_ctx, pp->pick_args.pollent, glb_policy->base.interested_parties);
       *target = NULL;
       grpc_exec_ctx_sched(
           exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
@@ -710,8 +711,6 @@ static void glb_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->pick_args.initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_polling_entity_del_from_pollset_set(
-          exec_ctx, pp->pick_args.pollent, glb_policy->base.interested_parties);
       grpc_exec_ctx_sched(
           exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure,
           GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
@@ -801,8 +800,6 @@ static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
      * Eventually, wrapped_on_complete will be called, which will -among other
      * things- add the LB token to the call's initial metadata */
   } else {
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
-                                           glb_policy->base.interested_parties);
     add_pending_pick(&glb_policy->pending_picks, pick_args, target,
                      on_complete);
 
@@ -926,7 +923,7 @@ static lb_client_data *lb_client_data_create(glb_lb_policy *glb_policy) {
 
   /* Note the following LB call progresses every time there's activity in \a
    * glb_policy->base.interested_parties, which is comprised of the polling
-   * entities passed to glb_pick(). */
+   * entities from \a client_channel. */
   lb_client->lb_call = grpc_channel_create_pollset_set_call(
       glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS,
       glb_policy->base.interested_parties,
diff --git a/src/core/ext/lb_policy/pick_first/pick_first.c b/src/core/ext/lb_policy/pick_first/pick_first.c
index 961a0c9b19..6533327343 100644
--- a/src/core/ext/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/lb_policy/pick_first/pick_first.c
@@ -39,7 +39,6 @@
 
 typedef struct pending_pick {
   struct pending_pick *next;
-  grpc_polling_entity *pollent;
   uint32_t initial_metadata_flags;
   grpc_connected_subchannel **target;
   grpc_closure *on_complete;
@@ -119,8 +118,6 @@ static void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   while (pp != NULL) {
     pending_pick *next = pp->next;
     *pp->target = NULL;
-    grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                             p->base.interested_parties);
     grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
     gpr_free(pp);
     pp = next;
@@ -138,8 +135,6 @@ static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   while (pp != NULL) {
     pending_pick *next = pp->next;
     if (pp->target == target) {
-      grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                               p->base.interested_parties);
       *target = NULL;
       grpc_exec_ctx_sched(
           exec_ctx, pp->on_complete,
@@ -168,8 +163,6 @@ static void pf_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                               p->base.interested_parties);
       grpc_exec_ctx_sched(
           exec_ctx, pp->on_complete,
           GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
@@ -229,11 +222,8 @@ static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
-                                           p->base.interested_parties);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollent = pick_args->pollent;
     pp->target = target;
     pp->initial_metadata_flags = pick_args->initial_metadata_flags;
     pp->on_complete = on_complete;
@@ -319,8 +309,6 @@ static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
           *pp->target = selected;
-          grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                                   p->base.interested_parties);
           grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
           gpr_free(pp);
         }
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index 325202fc6d..9bd3f9da24 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -78,9 +78,6 @@ int grpc_lb_round_robin_trace = 0;
 typedef struct pending_pick {
   struct pending_pick *next;
 
-  /* polling entity for the pick()'s async notification */
-  grpc_polling_entity *pollent;
-
   /* output argument where to store the pick()ed user_data. It'll be NULL if no
    * such data is present or there's an error (the definite test for errors is
    * \a target being NULL). */
@@ -318,8 +315,6 @@ static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   while (pp != NULL) {
     pending_pick *next = pp->next;
     if (pp->target == target) {
-      grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                               p->base.interested_parties);
       *target = NULL;
       grpc_exec_ctx_sched(
           exec_ctx, pp->on_complete,
@@ -348,8 +343,6 @@ static void rr_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                               p->base.interested_parties);
       *pp->target = NULL;
       grpc_exec_ctx_sched(
           exec_ctx, pp->on_complete,
@@ -422,11 +415,8 @@ static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_polling_entity_add_to_pollset_set(exec_ctx, pick_args->pollent,
-                                           p->base.interested_parties);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollent = pick_args->pollent;
     pp->target = target;
     pp->on_complete = on_complete;
     pp->initial_metadata_flags = pick_args->initial_metadata_flags;
@@ -482,8 +472,6 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
                     "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
                     (void *)selected->subchannel, (void *)selected);
           }
-          grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
-                                                   p->base.interested_parties);
           grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
           gpr_free(pp);
         }
diff --git a/src/core/ext/load_reporting/load_reporting.h b/src/core/ext/load_reporting/load_reporting.h
index e37817d8c2..e13097654d 100644
--- a/src/core/ext/load_reporting/load_reporting.h
+++ b/src/core/ext/load_reporting/load_reporting.h
@@ -37,13 +37,21 @@
 #include <grpc/impl/codegen/grpc_types.h>
 #include "src/core/lib/channel/channel_stack.h"
 
-/** Metadata key for initial metadata coming from clients */
-/* TODO(dgq): change to the final value TBD */
-#define GRPC_LOAD_REPORTING_INITIAL_MD_KEY "load-reporting-initial"
+/** Metadata key for the gRPC LB load balancer token.
+ *
+ * The value corresponding to this key is an opaque token that is given to the
+ * frontend as part of each pick; the frontend sends this token to the backend
+ * in each request it sends when using that pick. The token is used by the
+ * backend to verify the request and to allow the backend to report load to the
+ * gRPC LB system. */
+#define GRPC_LB_TOKEN_MD_KEY "lb-token"
 
-/** Metadata key for trailing metadata from servers */
-/* TODO(dgq): change to the final value TBD */
-#define GRPC_LOAD_REPORTING_TRAILING_MD_KEY "load-reporting-trailing"
+/** Metadata key for gRPC LB cost reporting.
+ *
+ * The value corresponding to this key is an opaque binary blob reported by the
+ * backend as part of its trailing metadata containing cost information for the
+ * call. */
+#define GRPC_LB_COST_MD_KEY "lb-cost"
 
 /** Identifiers for the invocation point of the users LR callback */
 typedef enum grpc_load_reporting_source {
diff --git a/src/core/ext/load_reporting/load_reporting_filter.c b/src/core/ext/load_reporting/load_reporting_filter.c
index 394f0cb832..22bf36367f 100644
--- a/src/core/ext/load_reporting/load_reporting_filter.c
+++ b/src/core/ext/load_reporting/load_reporting_filter.c
@@ -75,7 +75,7 @@ static grpc_mdelem *recv_md_filter(void *user_data, grpc_mdelem *md) {
 
   if (md->key == GRPC_MDSTR_PATH) {
     calld->service_method = grpc_mdstr_as_c_string(md->value);
-  } else if (md->key == GRPC_MDSTR_LOAD_REPORTING_INITIAL) {
+  } else if (md->key == GRPC_MDSTR_LB_TOKEN) {
     calld->initial_md_string = gpr_strdup(grpc_mdstr_as_c_string(md->value));
     return NULL;
   }
@@ -193,7 +193,7 @@ static grpc_mdelem *lr_trailing_md_filter(void *user_data, grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   call_data *calld = elem->call_data;
 
-  if (md->key == GRPC_MDSTR_LOAD_REPORTING_TRAILING) {
+  if (md->key == GRPC_MDSTR_LB_COST) {
     calld->trailing_md_string = gpr_strdup(grpc_mdstr_as_c_string(md->value));
     return NULL;
   }
diff --git a/src/core/lib/transport/static_metadata.c b/src/core/lib/transport/static_metadata.c
index 5e0352a467..f019ef156a 100644
--- a/src/core/lib/transport/static_metadata.c
+++ b/src/core/lib/transport/static_metadata.c
@@ -126,9 +126,9 @@ const char *const grpc_static_metadata_strings[GRPC_STATIC_MDSTR_COUNT] = {
     "if-range",
     "if-unmodified-since",
     "last-modified",
+    "lb-cost",
+    "lb-token",
     "link",
-    "load-reporting-initial",
-    "load-reporting-trailing",
     "location",
     "max-forwards",
     ":method",
diff --git a/src/core/lib/transport/static_metadata.h b/src/core/lib/transport/static_metadata.h
index 5b9ee1a60a..e0a8196419 100644
--- a/src/core/lib/transport/static_metadata.h
+++ b/src/core/lib/transport/static_metadata.h
@@ -175,12 +175,12 @@ extern grpc_mdstr grpc_static_mdstr_table[GRPC_STATIC_MDSTR_COUNT];
 #define GRPC_MDSTR_IF_UNMODIFIED_SINCE (&grpc_static_mdstr_table[62])
 /* "last-modified" */
 #define GRPC_MDSTR_LAST_MODIFIED (&grpc_static_mdstr_table[63])
+/* "lb-cost" */
+#define GRPC_MDSTR_LB_COST (&grpc_static_mdstr_table[64])
+/* "lb-token" */
+#define GRPC_MDSTR_LB_TOKEN (&grpc_static_mdstr_table[65])
 /* "link" */
-#define GRPC_MDSTR_LINK (&grpc_static_mdstr_table[64])
-/* "load-reporting-initial" */
-#define GRPC_MDSTR_LOAD_REPORTING_INITIAL (&grpc_static_mdstr_table[65])
-/* "load-reporting-trailing" */
-#define GRPC_MDSTR_LOAD_REPORTING_TRAILING (&grpc_static_mdstr_table[66])
+#define GRPC_MDSTR_LINK (&grpc_static_mdstr_table[66])
 /* "location" */
 #define GRPC_MDSTR_LOCATION (&grpc_static_mdstr_table[67])
 /* "max-forwards" */
@@ -337,13 +337,12 @@ extern uintptr_t grpc_static_mdelem_user_data[GRPC_STATIC_MDELEM_COUNT];
 #define GRPC_MDELEM_IF_UNMODIFIED_SINCE_EMPTY (&grpc_static_mdelem_table[44])
 /* "last-modified": "" */
 #define GRPC_MDELEM_LAST_MODIFIED_EMPTY (&grpc_static_mdelem_table[45])
+/* "lb-cost": "" */
+#define GRPC_MDELEM_LB_COST_EMPTY (&grpc_static_mdelem_table[46])
+/* "lb-token": "" */
+#define GRPC_MDELEM_LB_TOKEN_EMPTY (&grpc_static_mdelem_table[47])
 /* "link": "" */
-#define GRPC_MDELEM_LINK_EMPTY (&grpc_static_mdelem_table[46])
-/* "load-reporting-initial": "" */
-#define GRPC_MDELEM_LOAD_REPORTING_INITIAL_EMPTY (&grpc_static_mdelem_table[47])
-/* "load-reporting-trailing": "" */
-#define GRPC_MDELEM_LOAD_REPORTING_TRAILING_EMPTY \
-  (&grpc_static_mdelem_table[48])
+#define GRPC_MDELEM_LINK_EMPTY (&grpc_static_mdelem_table[48])
 /* "location": "" */
 #define GRPC_MDELEM_LOCATION_EMPTY (&grpc_static_mdelem_table[49])
 /* "max-forwards": "" */
diff --git a/src/proto/grpc/testing/test.proto b/src/proto/grpc/testing/test.proto
index b52c4cbad6..d6ef58ab12 100644
--- a/src/proto/grpc/testing/test.proto
+++ b/src/proto/grpc/testing/test.proto
@@ -74,6 +74,10 @@ service TestService {
   // first request.
   rpc HalfDuplexCall(stream StreamingOutputCallRequest)
       returns (stream StreamingOutputCallResponse);
+
+  // The test server will not implement this method. It will be used
+  // to test the behavior when clients call unimplemented methods.
+  rpc UnimplementedMethod(grpc.testing.Empty) returns (grpc.testing.Empty);
 }
 
 // A simple service NOT implemented at servers so clients can test for
diff --git a/test/core/end2end/fuzzers/hpack.dictionary b/test/core/end2end/fuzzers/hpack.dictionary
index a93bccfa0d..181bbe845e 100644
--- a/test/core/end2end/fuzzers/hpack.dictionary
+++ b/test/core/end2end/fuzzers/hpack.dictionary
@@ -63,9 +63,9 @@
 "\x08if-range"
 "\x13if-unmodified-since"
 "\x0Dlast-modified"
+"\x07lb-cost"
+"\x08lb-token"
 "\x04link"
-"\x16load-reporting-initial"
-"\x17load-reporting-trailing"
 "\x08location"
 "\x0Cmax-forwards"
 "\x07:method"
@@ -138,9 +138,9 @@
 "\x00\x08if-range\x00"
 "\x00\x13if-unmodified-since\x00"
 "\x00\x0Dlast-modified\x00"
+"\x00\x07lb-cost\x00"
+"\x00\x08lb-token\x00"
 "\x00\x04link\x00"
-"\x00\x16load-reporting-initial\x00"
-"\x00\x17load-reporting-trailing\x00"
 "\x00\x08location\x00"
 "\x00\x0Cmax-forwards\x00"
 "\x00\x07:method\x03GET"
diff --git a/test/core/end2end/tests/load_reporting_hook.c b/test/core/end2end/tests/load_reporting_hook.c
index 59d054cf87..7f95dfd949 100644
--- a/test/core/end2end/tests/load_reporting_hook.c
+++ b/test/core/end2end/tests/load_reporting_hook.c
@@ -295,13 +295,13 @@ static void test_load_reporting_hook(grpc_end2end_test_config config) {
   grpc_metadata initial_lr_metadata;
   grpc_metadata trailing_lr_metadata;
 
-  initial_lr_metadata.key = GRPC_LOAD_REPORTING_INITIAL_MD_KEY;
+  initial_lr_metadata.key = GRPC_LB_TOKEN_MD_KEY;
   initial_lr_metadata.value = "client-token";
   initial_lr_metadata.value_length = strlen(initial_lr_metadata.value);
   memset(&initial_lr_metadata.internal_data, 0,
          sizeof(initial_lr_metadata.internal_data));
 
-  trailing_lr_metadata.key = GRPC_LOAD_REPORTING_TRAILING_MD_KEY;
+  trailing_lr_metadata.key = GRPC_LB_COST_MD_KEY;
   trailing_lr_metadata.value = "server-token";
   trailing_lr_metadata.value_length = strlen(trailing_lr_metadata.value);
   memset(&trailing_lr_metadata.internal_data, 0,
diff --git a/test/cpp/grpclb/grpclb_test.cc b/test/cpp/grpclb/grpclb_test.cc
index 7666c4e60b..80f2fa4f4d 100644
--- a/test/cpp/grpclb/grpclb_test.cc
+++ b/test/cpp/grpclb/grpclb_test.cc
@@ -334,8 +334,7 @@ static void start_backend_server(server_fixture *sf) {
     // have a version for int but does have one for long long int.
     string expected_token = "token" + std::to_string((long long int)sf->port);
     expected_token.resize(64, '-');
-    GPR_ASSERT(contains_metadata(&request_metadata_recv,
-                                 "load-reporting-initial",
+    GPR_ASSERT(contains_metadata(&request_metadata_recv, "lb-token",
                                  expected_token.c_str()));
 
     gpr_log(GPR_INFO, "Server[%s] after tag 100", sf->servers_hostport);
diff --git a/test/cpp/interop/client.cc b/test/cpp/interop/client.cc
index 999be9d8a3..245e27b2bb 100644
--- a/test/cpp/interop/client.cc
+++ b/test/cpp/interop/client.cc
@@ -79,7 +79,8 @@ DEFINE_string(test_case, "large_unary",
               "slow_consumer : single request with response streaming with "
               "slow client consumer;\n"
               "status_code_and_message: verify status code & message;\n"
-              "timeout_on_sleeping_server: deadline exceeds on stream;\n");
+              "timeout_on_sleeping_server: deadline exceeds on stream;\n"
+              "unimplemented_method: client calls an unimplemented_method;\n");
 DEFINE_string(default_service_account, "",
               "Email of GCE default service account");
 DEFINE_string(service_account_key_file, "",
@@ -149,6 +150,8 @@ int main(int argc, char** argv) {
     client.DoStatusWithMessage();
   } else if (FLAGS_test_case == "custom_metadata") {
     client.DoCustomMetadata();
+  } else if (FLAGS_test_case == "unimplemented_method") {
+    client.DoUnimplementedMethod();
   } else if (FLAGS_test_case == "cacheable_unary") {
     client.DoCacheableUnary();
   } else if (FLAGS_test_case == "all") {
@@ -168,6 +171,7 @@ int main(int argc, char** argv) {
     client.DoEmptyStream();
     client.DoStatusWithMessage();
     client.DoCustomMetadata();
+    client.DoUnimplementedMethod();
     client.DoCacheableUnary();
     // service_account_creds and jwt_token_creds can only run with ssl.
     if (FLAGS_use_tls) {
@@ -202,7 +206,8 @@ int main(int argc, char** argv) {
                                "server_compressed_unary",
                                "server_streaming",
                                "status_code_and_message",
-                               "timeout_on_sleeping_server"};
+                               "timeout_on_sleeping_server",
+                               "unimplemented_method"};
     char* joined_testcases =
         gpr_strjoin_sep(testcases, GPR_ARRAY_SIZE(testcases), "\n", NULL);
 
diff --git a/test/cpp/interop/interop_client.cc b/test/cpp/interop/interop_client.cc
index e9a804ccae..effbb8a42e 100644
--- a/test/cpp/interop/interop_client.cc
+++ b/test/cpp/interop/interop_client.cc
@@ -981,5 +981,23 @@ bool InteropClient::DoCustomMetadata() {
   return true;
 }
 
+bool InteropClient::DoUnimplementedMethod() {
+  gpr_log(GPR_DEBUG, "Sending a request for an unimplemented rpc...");
+
+  Empty request = Empty::default_instance();
+  Empty response = Empty::default_instance();
+  ClientContext context;
+
+  Status s = serviceStub_.Get()->UnimplementedMethod(
+    &context, request, &response);
+
+  if (!AssertStatusCode(s, StatusCode::UNIMPLEMENTED)) {
+    return false;
+  }
+
+  gpr_log(GPR_DEBUG, "unimplemented rpc done.");
+  return true;
+}
+
 }  // namespace testing
 }  // namespace grpc
diff --git a/test/cpp/interop/interop_client.h b/test/cpp/interop/interop_client.h
index 1e89f0987d..0a96e7734d 100644
--- a/test/cpp/interop/interop_client.h
+++ b/test/cpp/interop/interop_client.h
@@ -79,6 +79,7 @@ class InteropClient {
   bool DoEmptyStream();
   bool DoStatusWithMessage();
   bool DoCustomMetadata();
+  bool DoUnimplementedMethod();
   bool DoCacheableUnary();
   // Auth tests.
   // username is a string containing the user email
diff --git a/tools/codegen/core/gen_static_metadata.py b/tools/codegen/core/gen_static_metadata.py
index 6f400102e4..6f8cad279c 100755
--- a/tools/codegen/core/gen_static_metadata.py
+++ b/tools/codegen/core/gen_static_metadata.py
@@ -109,8 +109,8 @@ CONFIG = [
     ('if-range', ''),
     ('if-unmodified-since', ''),
     ('last-modified', ''),
-    ('load-reporting-initial', ''),
-    ('load-reporting-trailing', ''),
+    ('lb-token', ''),
+    ('lb-cost', ''),
     ('link', ''),
     ('location', ''),
     ('max-forwards', ''),
diff --git a/tools/gce/linux_performance_worker_init.sh b/tools/gce/linux_performance_worker_init.sh
index ea80d74bdf..487672549f 100755
--- a/tools/gce/linux_performance_worker_init.sh
+++ b/tools/gce/linux_performance_worker_init.sh
@@ -128,4 +128,15 @@ gem install bundler
 # Java dependencies - nothing as we already have Java JDK 8
 
 # Go dependencies
-sudo apt-get install -y golang-go
+# Currently, the golang package available via apt-get doesn't have the latest go.
+# Significant performance improvements with grpc-go have been observed after
+# upgrading from go 1.5 to a later version, so a later go version is preferred.
+# Following go install instructions from https://golang.org/doc/install
+GO_VERSION=1.7.1
+OS=linux
+ARCH=amd64
+curl -O https://storage.googleapis.com/golang/go${GO_VERSION}.${OS}-${ARCH}.tar.gz
+sudo tar -C /usr/local -xzf go$GO_VERSION.$OS-$ARCH.tar.gz
+# Put go on the PATH, keep the usual installation dir
+sudo ln -s /usr/local/go/bin/go /usr/bin/go
+rm go$GO_VERSION.$OS-$ARCH.tar.gz