Merge branch 'master' of https://github.com/grpc/grpc into channelz-uuid-fix

14 files changed, 80 insertions, 244 deletions

diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc b/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc
deleted file mode 100644
index d79453d008..0000000000
--- a/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc
+++ /dev/null
@@ -1,140 +0,0 @@
-/*
- *
- * Copyright 2018 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h"
-
-#include <grpc/support/atm.h>
-#include <grpc/support/log.h>
-
-#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
-#include "src/core/lib/iomgr/error.h"
-#include "src/core/lib/profiling/timers.h"
-
-static grpc_error* init_channel_elem(grpc_channel_element* elem,
-                                     grpc_channel_element_args* args) {
-  return GRPC_ERROR_NONE;
-}
-
-static void destroy_channel_elem(grpc_channel_element* elem) {}
-
-namespace {
-
-struct call_data {
-  // Stats object to update.
-  grpc_core::RefCountedPtr<grpc_core::XdsLbClientStats> client_stats;
-  // State for intercepting send_initial_metadata.
-  grpc_closure on_complete_for_send;
-  grpc_closure* original_on_complete_for_send;
-  bool send_initial_metadata_succeeded;
-  // State for intercepting recv_initial_metadata.
-  grpc_closure recv_initial_metadata_ready;
-  grpc_closure* original_recv_initial_metadata_ready;
-  bool recv_initial_metadata_succeeded;
-};
-
-}  // namespace
-
-static void on_complete_for_send(void* arg, grpc_error* error) {
-  call_data* calld = static_cast<call_data*>(arg);
-  if (error == GRPC_ERROR_NONE) {
-    calld->send_initial_metadata_succeeded = true;
-  }
-  GRPC_CLOSURE_RUN(calld->original_on_complete_for_send, GRPC_ERROR_REF(error));
-}
-
-static void recv_initial_metadata_ready(void* arg, grpc_error* error) {
-  call_data* calld = static_cast<call_data*>(arg);
-  if (error == GRPC_ERROR_NONE) {
-    calld->recv_initial_metadata_succeeded = true;
-  }
-  GRPC_CLOSURE_RUN(calld->original_recv_initial_metadata_ready,
-                   GRPC_ERROR_REF(error));
-}
-
-static grpc_error* init_call_elem(grpc_call_element* elem,
-                                  const grpc_call_element_args* args) {
-  call_data* calld = static_cast<call_data*>(elem->call_data);
-  // Get stats object from context and take a ref.
-  GPR_ASSERT(args->context != nullptr);
-  if (args->context[GRPC_GRPCLB_CLIENT_STATS].value != nullptr) {
-    calld->client_stats = static_cast<grpc_core::XdsLbClientStats*>(
-                              args->context[GRPC_GRPCLB_CLIENT_STATS].value)
-                              ->Ref();
-    // Record call started.
-    calld->client_stats->AddCallStarted();
-  }
-  return GRPC_ERROR_NONE;
-}
-
-static void destroy_call_elem(grpc_call_element* elem,
-                              const grpc_call_final_info* final_info,
-                              grpc_closure* ignored) {
-  call_data* calld = static_cast<call_data*>(elem->call_data);
-  if (calld->client_stats != nullptr) {
-    // Record call finished, optionally setting client_failed_to_send and
-    // received.
-    calld->client_stats->AddCallFinished(
-        !calld->send_initial_metadata_succeeded /* client_failed_to_send */,
-        calld->recv_initial_metadata_succeeded /* known_received */);
-    // All done, so unref the stats object.
-    // TODO(roth): Eliminate this once filter stack is converted to C++.
-    calld->client_stats.reset();
-  }
-}
-
-static void start_transport_stream_op_batch(
-    grpc_call_element* elem, grpc_transport_stream_op_batch* batch) {
-  call_data* calld = static_cast<call_data*>(elem->call_data);
-  GPR_TIMER_SCOPE("clr_start_transport_stream_op_batch", 0);
-  if (calld->client_stats != nullptr) {
-    // Intercept send_initial_metadata.
-    if (batch->send_initial_metadata) {
-      calld->original_on_complete_for_send = batch->on_complete;
-      GRPC_CLOSURE_INIT(&calld->on_complete_for_send, on_complete_for_send,
-                        calld, grpc_schedule_on_exec_ctx);
-      batch->on_complete = &calld->on_complete_for_send;
-    }
-    // Intercept recv_initial_metadata.
-    if (batch->recv_initial_metadata) {
-      calld->original_recv_initial_metadata_ready =
-          batch->payload->recv_initial_metadata.recv_initial_metadata_ready;
-      GRPC_CLOSURE_INIT(&calld->recv_initial_metadata_ready,
-                        recv_initial_metadata_ready, calld,
-                        grpc_schedule_on_exec_ctx);
-      batch->payload->recv_initial_metadata.recv_initial_metadata_ready =
-          &calld->recv_initial_metadata_ready;
-    }
-  }
-  // Chain to next filter.
-  grpc_call_next_op(elem, batch);
-}
-
-const grpc_channel_filter xds_client_load_reporting_filter = {
-    start_transport_stream_op_batch,
-    grpc_channel_next_op,
-    sizeof(call_data),
-    init_call_elem,
-    grpc_call_stack_ignore_set_pollset_or_pollset_set,
-    destroy_call_elem,
-    0,  // sizeof(channel_data)
-    init_channel_elem,
-    destroy_channel_elem,
-    grpc_channel_next_get_info,
-    "client_load_reporting"};
diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h b/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h
deleted file mode 100644
index 31a799154c..0000000000
--- a/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- *
- * Copyright 2018 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_CLIENT_LOAD_REPORTING_FILTER_H
-#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_CLIENT_LOAD_REPORTING_FILTER_H
-
-#include <grpc/support/port_platform.h>
-
-#include "src/core/lib/channel/channel_stack.h"
-
-extern const grpc_channel_filter xds_client_load_reporting_filter;
-
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_CLIENT_LOAD_REPORTING_FILTER_H \
-        */
diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/xds.cc b/src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
index e6c94167f6..7fb4cbdcd2 100644
--- a/src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/xds/xds.cc
@@ -75,11 +75,10 @@
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
 #include "src/core/ext/filters/client_channel/client_channel_factory.h"
-#include "src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h"
-#include "src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.h"
 #include "src/core/ext/filters/client_channel/lb_policy/xds/xds.h"
 #include "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h"
 #include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h"
 #include "src/core/ext/filters/client_channel/lb_policy_factory.h"
 #include "src/core/ext/filters/client_channel/lb_policy_registry.h"
 #include "src/core/ext/filters/client_channel/parse_address.h"
@@ -673,7 +672,7 @@ bool XdsLb::BalancerCallState::LoadReportCountersAreZero(
          request->client_stats.num_calls_finished_with_client_failed_to_send ==
              0 &&
          request->client_stats.num_calls_finished_known_received == 0 &&
-         (drop_entries == nullptr || drop_entries->size() == 0);
+         (drop_entries == nullptr || drop_entries->empty());
 }
 
 void XdsLb::BalancerCallState::SendClientLoadReportLocked() {
@@ -1275,9 +1274,9 @@ grpc_connectivity_state XdsLb::CheckConnectivityLocked(
 }
 
 void XdsLb::NotifyOnStateChangeLocked(grpc_connectivity_state* current,
-                                      grpc_closure* notify) {
+                                      grpc_closure* closure) {
   grpc_connectivity_state_notify_on_state_change(&state_tracker_, current,
-                                                 notify);
+                                                 closure);
 }
 
 void XdsLb::ProcessChannelArgsLocked(const grpc_channel_args& args) {
@@ -1483,7 +1482,6 @@ void XdsLb::OnBalancerChannelConnectivityChangedLocked(void* arg,
         xdslb_policy->lb_call_backoff_.Reset();
         xdslb_policy->StartBalancerCallLocked();
       }
-      [[fallthrough]];
       // Fall through.
     case GRPC_CHANNEL_SHUTDOWN:
     done:
@@ -1861,34 +1859,11 @@ class XdsFactory : public LoadBalancingPolicyFactory {
 // Plugin registration
 //
 
-namespace {
-
-// Only add client_load_reporting filter if the grpclb LB policy is used.
-bool maybe_add_client_load_reporting_filter(grpc_channel_stack_builder* builder,
-                                            void* arg) {
-  const grpc_channel_args* args =
-      grpc_channel_stack_builder_get_channel_arguments(builder);
-  const grpc_arg* channel_arg =
-      grpc_channel_args_find(args, GRPC_ARG_LB_POLICY_NAME);
-  if (channel_arg != nullptr && channel_arg->type == GRPC_ARG_STRING &&
-      strcmp(channel_arg->value.string, "grpclb") == 0) {
-    return grpc_channel_stack_builder_append_filter(
-        builder, (const grpc_channel_filter*)arg, nullptr, nullptr);
-  }
-  return true;
-}
-
-}  // namespace
-
 void grpc_lb_policy_xds_init() {
   grpc_core::LoadBalancingPolicyRegistry::Builder::
       RegisterLoadBalancingPolicyFactory(
           grpc_core::UniquePtr<grpc_core::LoadBalancingPolicyFactory>(
               grpc_core::New<grpc_core::XdsFactory>()));
-  grpc_channel_init_register_stage(GRPC_CLIENT_SUBCHANNEL,
-                                   GRPC_CHANNEL_INIT_BUILTIN_PRIORITY,
-                                   maybe_add_client_load_reporting_filter,
-                                   (void*)&xds_client_load_reporting_filter);
 }
 
 void grpc_lb_policy_xds_shutdown() {}
diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.cc b/src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
index 3bd2653635..79b7bdbe33 100644
--- a/src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.cc
+++ b/src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.cc
@@ -20,7 +20,7 @@
 
 #include "pb_decode.h"
 #include "pb_encode.h"
-#include "src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h"
 
 #include <grpc/support/alloc.h>
 
diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.h b/src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h
index 3f096af6d6..9d08defa7e 100644
--- a/src/core/ext/filters/client_channel/lb_policy/xds/load_balancer_api.h
+++ b/src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h
@@ -16,8 +16,8 @@
  *
  */
 
-#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_LOAD_BALANCER_API_H
-#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_LOAD_BALANCER_API_H
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H
 
 #include <grpc/support/port_platform.h>
 
@@ -85,5 +85,5 @@ grpc_millis xds_grpclb_duration_to_millis(xds_grpclb_duration* duration_pb);
 /** Destroy \a initial_response */
 void xds_grpclb_initial_response_destroy(xds_grpclb_initial_response* response);
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_LOAD_BALANCER_API_H \
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_XDS_XDS_LOAD_BALANCER_API_H \
         */
diff --git a/src/core/ext/transport/chttp2/transport/parsing.cc b/src/core/ext/transport/chttp2/transport/parsing.cc
index f532b084c9..1ff96d3cd3 100644
--- a/src/core/ext/transport/chttp2/transport/parsing.cc
+++ b/src/core/ext/transport/chttp2/transport/parsing.cc
@@ -368,6 +368,7 @@ static grpc_error* init_data_frame_parser(grpc_chttp2_transport* t) {
         &s->data_parser, t->incoming_frame_flags, s->id, s);
   }
 error_handler:
+  intptr_t unused;
   if (err == GRPC_ERROR_NONE) {
     t->incoming_stream = s;
     /* t->parser = grpc_chttp2_data_parser_parse;*/
@@ -375,7 +376,7 @@ error_handler:
     t->parser_data = &s->data_parser;
     t->ping_state.last_ping_sent_time = GRPC_MILLIS_INF_PAST;
     return GRPC_ERROR_NONE;
-  } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, nullptr)) {
+  } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, &unused)) {
     /* handle stream errors by closing the stream */
     if (s != nullptr) {
       grpc_chttp2_mark_stream_closed(t, s, true, false, err);
@@ -756,9 +757,10 @@ static grpc_error* parse_frame_slice(grpc_chttp2_transport* t, grpc_slice slice,
                                      int is_last) {
   grpc_chttp2_stream* s = t->incoming_stream;
   grpc_error* err = t->parser(t->parser_data, t, s, slice, is_last);
+  intptr_t unused;
   if (GPR_LIKELY(err == GRPC_ERROR_NONE)) {
     return err;
-  } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, nullptr)) {
+  } else if (grpc_error_get_int(err, GRPC_ERROR_INT_STREAM_ID, &unused)) {
     if (grpc_http_trace.enabled()) {
       const char* msg = grpc_error_string(err);
       gpr_log(GPR_ERROR, "%s", msg);
diff --git a/src/core/lib/iomgr/error.cc b/src/core/lib/iomgr/error.cc
index 146a539027..6ae077fd54 100644
--- a/src/core/lib/iomgr/error.cc
+++ b/src/core/lib/iomgr/error.cc
@@ -121,14 +121,8 @@ static const char* error_time_name(grpc_error_times key) {
   GPR_UNREACHABLE_CODE(return "unknown");
 }
 
-bool grpc_error_is_special(grpc_error* err) {
-  return err == GRPC_ERROR_NONE || err == GRPC_ERROR_OOM ||
-         err == GRPC_ERROR_CANCELLED;
-}
-
 #ifndef NDEBUG
-grpc_error* grpc_error_ref(grpc_error* err, const char* file, int line) {
-  if (grpc_error_is_special(err)) return err;
+grpc_error* grpc_error_do_ref(grpc_error* err, const char* file, int line) {
   if (grpc_trace_error_refcount.enabled()) {
     gpr_log(GPR_DEBUG, "%p: %" PRIdPTR " -> %" PRIdPTR " [%s:%d]", err,
             gpr_atm_no_barrier_load(&err->atomics.refs.count),
@@ -138,8 +132,7 @@ grpc_error* grpc_error_ref(grpc_error* err, const char* file, int line) {
   return err;
 }
 #else
-grpc_error* grpc_error_ref(grpc_error* err) {
-  if (grpc_error_is_special(err)) return err;
+grpc_error* grpc_error_do_ref(grpc_error* err) {
   gpr_ref(&err->atomics.refs);
   return err;
 }
@@ -177,8 +170,7 @@ static void error_destroy(grpc_error* err) {
 }
 
 #ifndef NDEBUG
-void grpc_error_unref(grpc_error* err, const char* file, int line) {
-  if (grpc_error_is_special(err)) return;
+void grpc_error_do_unref(grpc_error* err, const char* file, int line) {
   if (grpc_trace_error_refcount.enabled()) {
     gpr_log(GPR_DEBUG, "%p: %" PRIdPTR " -> %" PRIdPTR " [%s:%d]", err,
             gpr_atm_no_barrier_load(&err->atomics.refs.count),
@@ -189,8 +181,7 @@ void grpc_error_unref(grpc_error* err, const char* file, int line) {
   }
 }
 #else
-void grpc_error_unref(grpc_error* err) {
-  if (grpc_error_is_special(err)) return;
+void grpc_error_do_unref(grpc_error* err) {
   if (gpr_unref(&err->atomics.refs)) {
     error_destroy(err);
   }
@@ -450,26 +441,23 @@ grpc_error* grpc_error_set_int(grpc_error* src, grpc_error_ints which,
 }
 
 typedef struct {
-  grpc_error* error;
   grpc_status_code code;
   const char* msg;
 } special_error_status_map;
 static const special_error_status_map error_status_map[] = {
-    {GRPC_ERROR_NONE, GRPC_STATUS_OK, ""},
-    {GRPC_ERROR_CANCELLED, GRPC_STATUS_CANCELLED, "Cancelled"},
-    {GRPC_ERROR_OOM, GRPC_STATUS_RESOURCE_EXHAUSTED, "Out of memory"},
+    {GRPC_STATUS_OK, ""},                               // GRPC_ERROR_NONE
+    {GRPC_STATUS_INVALID_ARGUMENT, ""},                 // GRPC_ERROR_RESERVED_1
+    {GRPC_STATUS_RESOURCE_EXHAUSTED, "Out of memory"},  // GRPC_ERROR_OOM
+    {GRPC_STATUS_INVALID_ARGUMENT, ""},                 // GRPC_ERROR_RESERVED_2
+    {GRPC_STATUS_CANCELLED, "Cancelled"},               // GRPC_ERROR_CANCELLED
 };
 
 bool grpc_error_get_int(grpc_error* err, grpc_error_ints which, intptr_t* p) {
   GPR_TIMER_SCOPE("grpc_error_get_int", 0);
   if (grpc_error_is_special(err)) {
-    for (size_t i = 0; i < GPR_ARRAY_SIZE(error_status_map); i++) {
-      if (error_status_map[i].error == err) {
-        if (which != GRPC_ERROR_INT_GRPC_STATUS) return false;
-        if (p != nullptr) *p = error_status_map[i].code;
-        return true;
-      }
-    }
+    if (which != GRPC_ERROR_INT_GRPC_STATUS) return false;
+    *p = error_status_map[reinterpret_cast<size_t>(err)].code;
+    return true;
   }
   uint8_t slot = err->ints[which];
   if (slot != UINT8_MAX) {
@@ -490,13 +478,10 @@ grpc_error* grpc_error_set_str(grpc_error* src, grpc_error_strs which,
 bool grpc_error_get_str(grpc_error* err, grpc_error_strs which,
                         grpc_slice* str) {
   if (grpc_error_is_special(err)) {
-    for (size_t i = 0; i < GPR_ARRAY_SIZE(error_status_map); i++) {
-      if (error_status_map[i].error == err) {
-        if (which != GRPC_ERROR_STR_GRPC_MESSAGE) return false;
-        *str = grpc_slice_from_static_string(error_status_map[i].msg);
-        return true;
-      }
-    }
+    if (which != GRPC_ERROR_STR_GRPC_MESSAGE) return false;
+    *str = grpc_slice_from_static_string(
+        error_status_map[reinterpret_cast<size_t>(err)].msg);
+    return true;
   }
   uint8_t slot = err->strs[which];
   if (slot != UINT8_MAX) {
diff --git a/src/core/lib/iomgr/error.h b/src/core/lib/iomgr/error.h
index 49f4029bc2..cb740d5b01 100644
--- a/src/core/lib/iomgr/error.h
+++ b/src/core/lib/iomgr/error.h
@@ -120,8 +120,15 @@ typedef enum {
 /// polling engines) can safely use the lower bit for themselves.
 
 #define GRPC_ERROR_NONE ((grpc_error*)NULL)
+#define GRPC_ERROR_RESERVED_1 ((grpc_error*)1)
 #define GRPC_ERROR_OOM ((grpc_error*)2)
+#define GRPC_ERROR_RESERVED_2 ((grpc_error*)3)
 #define GRPC_ERROR_CANCELLED ((grpc_error*)4)
+#define GRPC_ERROR_SPECIAL_MAX GRPC_ERROR_CANCELLED
+
+inline bool grpc_error_is_special(struct grpc_error* err) {
+  return err <= GRPC_ERROR_SPECIAL_MAX;
+}
 
 // debug only toggles that allow for a sanity to check that ensures we will
 // never create any errors in the per-RPC hotpath.
@@ -158,19 +165,37 @@ grpc_error* grpc_error_create(const char* file, int line, grpc_slice desc,
                     errs, count)
 
 #ifndef NDEBUG
-grpc_error* grpc_error_ref(grpc_error* err, const char* file, int line);
-void grpc_error_unref(grpc_error* err, const char* file, int line);
+grpc_error* grpc_error_do_ref(grpc_error* err, const char* file, int line);
+void grpc_error_do_unref(grpc_error* err, const char* file, int line);
+inline grpc_error* grpc_error_ref(grpc_error* err, const char* file, int line) {
+  if (grpc_error_is_special(err)) return err;
+  return grpc_error_do_ref(err, file, line);
+}
+inline void grpc_error_unref(grpc_error* err, const char* file, int line) {
+  if (grpc_error_is_special(err)) return;
+  grpc_error_do_unref(err, file, line);
+}
 #define GRPC_ERROR_REF(err) grpc_error_ref(err, __FILE__, __LINE__)
 #define GRPC_ERROR_UNREF(err) grpc_error_unref(err, __FILE__, __LINE__)
 #else
-grpc_error* grpc_error_ref(grpc_error* err);
-void grpc_error_unref(grpc_error* err);
+grpc_error* grpc_error_do_ref(grpc_error* err);
+void grpc_error_do_unref(grpc_error* err);
+inline grpc_error* grpc_error_ref(grpc_error* err) {
+  if (grpc_error_is_special(err)) return err;
+  return grpc_error_do_ref(err);
+}
+inline void grpc_error_unref(grpc_error* err) {
+  if (grpc_error_is_special(err)) return;
+  grpc_error_do_unref(err);
+}
 #define GRPC_ERROR_REF(err) grpc_error_ref(err)
 #define GRPC_ERROR_UNREF(err) grpc_error_unref(err)
 #endif
 
 grpc_error* grpc_error_set_int(grpc_error* src, grpc_error_ints which,
                                intptr_t value) GRPC_MUST_USE_RESULT;
+/// It is an error to pass nullptr as `p`. Caller should allocate a dummy
+/// intptr_t for `p`, even if the value of `p` is not used.
 bool grpc_error_get_int(grpc_error* error, grpc_error_ints which, intptr_t* p);
 /// This call takes ownership of the slice; the error is responsible for
 /// eventually unref-ing it.
diff --git a/src/core/lib/iomgr/error_internal.h b/src/core/lib/iomgr/error_internal.h
index 7fde347abd..8027396019 100644
--- a/src/core/lib/iomgr/error_internal.h
+++ b/src/core/lib/iomgr/error_internal.h
@@ -58,6 +58,4 @@ struct grpc_error {
   intptr_t arena[0];
 };
 
-bool grpc_error_is_special(struct grpc_error* err);
-
 #endif /* GRPC_CORE_LIB_IOMGR_ERROR_INTERNAL_H */
diff --git a/src/core/lib/iomgr/socket_utils_common_posix.cc b/src/core/lib/iomgr/socket_utils_common_posix.cc
index 50674b0845..bdfc1d70c3 100644
--- a/src/core/lib/iomgr/socket_utils_common_posix.cc
+++ b/src/core/lib/iomgr/socket_utils_common_posix.cc
@@ -307,7 +307,10 @@ grpc_error* grpc_set_socket_tcp_user_timeout(
     }
   }
 #else
-  gpr_log(GPR_INFO, "TCP_USER_TIMEOUT not supported for this platform");
+  extern grpc_core::TraceFlag grpc_tcp_trace;
+  if (grpc_tcp_trace.enabled()) {
+    gpr_log(GPR_INFO, "TCP_USER_TIMEOUT not supported for this platform");
+  }
 #endif /* GRPC_HAVE_TCP_USER_TIMEOUT */
   return GRPC_ERROR_NONE;
 }
diff --git a/src/core/lib/surface/completion_queue.cc b/src/core/lib/surface/completion_queue.cc
index 5dc9991f70..b81ae73b4d 100644
--- a/src/core/lib/surface/completion_queue.cc
+++ b/src/core/lib/surface/completion_queue.cc
@@ -79,6 +79,7 @@ typedef struct non_polling_worker {
 
 typedef struct {
   gpr_mu mu;
+  bool kicked_without_poller;
   non_polling_worker* root;
   grpc_closure* shutdown;
 } non_polling_poller;
@@ -103,6 +104,10 @@ static grpc_error* non_polling_poller_work(grpc_pollset* pollset,
                                            grpc_millis deadline) {
   non_polling_poller* npp = reinterpret_cast<non_polling_poller*>(pollset);
   if (npp->shutdown) return GRPC_ERROR_NONE;
+  if (npp->kicked_without_poller) {
+    npp->kicked_without_poller = false;
+    return GRPC_ERROR_NONE;
+  }
   non_polling_worker w;
   gpr_cv_init(&w.cv);
   if (worker != nullptr) *worker = reinterpret_cast<grpc_pollset_worker*>(&w);
@@ -148,6 +153,8 @@ static grpc_error* non_polling_poller_kick(
       w->kicked = true;
       gpr_cv_signal(&w->cv);
     }
+  } else {
+    p->kicked_without_poller = true;
   }
   return GRPC_ERROR_NONE;
 }
diff --git a/src/core/lib/transport/error_utils.cc b/src/core/lib/transport/error_utils.cc
index 2eff8b2916..558f1d494c 100644
--- a/src/core/lib/transport/error_utils.cc
+++ b/src/core/lib/transport/error_utils.cc
@@ -26,8 +26,9 @@
 
 static grpc_error* recursively_find_error_with_field(grpc_error* error,
                                                      grpc_error_ints which) {
+  intptr_t unused;
   // If the error itself has a status code, return it.
-  if (grpc_error_get_int(error, which, nullptr)) {
+  if (grpc_error_get_int(error, which, &unused)) {
     return error;
   }
   if (grpc_error_is_special(error)) return nullptr;
@@ -102,7 +103,8 @@ void grpc_error_get_status(grpc_error* error, grpc_millis deadline,
 }
 
 bool grpc_error_has_clear_grpc_status(grpc_error* error) {
-  if (grpc_error_get_int(error, GRPC_ERROR_INT_GRPC_STATUS, nullptr)) {
+  intptr_t unused;
+  if (grpc_error_get_int(error, GRPC_ERROR_INT_GRPC_STATUS, &unused)) {
     return true;
   }
   uint8_t slot = error->first_err;
diff --git a/src/core/plugin_registry/grpc_plugin_registry.cc b/src/core/plugin_registry/grpc_plugin_registry.cc
index fb523a173d..94c2493d5e 100644
--- a/src/core/plugin_registry/grpc_plugin_registry.cc
+++ b/src/core/plugin_registry/grpc_plugin_registry.cc
@@ -36,6 +36,8 @@ void grpc_resolver_fake_init(void);
 void grpc_resolver_fake_shutdown(void);
 void grpc_lb_policy_grpclb_init(void);
 void grpc_lb_policy_grpclb_shutdown(void);
+void grpc_lb_policy_xds_init(void);
+void grpc_lb_policy_xds_shutdown(void);
 void grpc_lb_policy_pick_first_init(void);
 void grpc_lb_policy_pick_first_shutdown(void);
 void grpc_lb_policy_round_robin_init(void);
@@ -72,6 +74,8 @@ void grpc_register_built_in_plugins(void) {
                        grpc_resolver_fake_shutdown);
   grpc_register_plugin(grpc_lb_policy_grpclb_init,
                        grpc_lb_policy_grpclb_shutdown);
+  grpc_register_plugin(grpc_lb_policy_xds_init,
+                       grpc_lb_policy_xds_shutdown);
   grpc_register_plugin(grpc_lb_policy_pick_first_init,
                        grpc_lb_policy_pick_first_shutdown);
   grpc_register_plugin(grpc_lb_policy_round_robin_init,
diff --git a/src/core/plugin_registry/grpc_unsecure_plugin_registry.cc b/src/core/plugin_registry/grpc_unsecure_plugin_registry.cc
index 80214aebe2..5749ab6b95 100644
--- a/src/core/plugin_registry/grpc_unsecure_plugin_registry.cc
+++ b/src/core/plugin_registry/grpc_unsecure_plugin_registry.cc
@@ -40,6 +40,8 @@ void grpc_resolver_fake_init(void);
 void grpc_resolver_fake_shutdown(void);
 void grpc_lb_policy_grpclb_init(void);
 void grpc_lb_policy_grpclb_shutdown(void);
+void grpc_lb_policy_xds_init(void);
+void grpc_lb_policy_xds_shutdown(void);
 void grpc_lb_policy_pick_first_init(void);
 void grpc_lb_policy_pick_first_shutdown(void);
 void grpc_lb_policy_round_robin_init(void);
@@ -74,6 +76,8 @@ void grpc_register_built_in_plugins(void) {
                        grpc_resolver_fake_shutdown);
   grpc_register_plugin(grpc_lb_policy_grpclb_init,
                        grpc_lb_policy_grpclb_shutdown);
+  grpc_register_plugin(grpc_lb_policy_xds_init,
+                       grpc_lb_policy_xds_shutdown);
   grpc_register_plugin(grpc_lb_policy_pick_first_init,
                        grpc_lb_policy_pick_first_shutdown);
   grpc_register_plugin(grpc_lb_policy_round_robin_init,