grpc · markdroth · Jan 16, 2020 · Jan 16, 2020
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -388,6 +388,9 @@ protobuf_generate_grpc_cpp(
 protobuf_generate_grpc_cpp(
   src/proto/grpc/testing/xds/ads_for_test.proto
 )
+protobuf_generate_grpc_cpp(
+  src/proto/grpc/testing/xds/cds_for_test.proto
+)
 protobuf_generate_grpc_cpp(
   src/proto/grpc/testing/xds/eds_for_test.proto
 )
@@ -16032,6 +16035,10 @@ add_executable(xds_end2end_test
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.cc
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/ads_for_test.pb.h
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.h
+  ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/cds_for_test.pb.cc
+  ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.cc
+  ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/cds_for_test.pb.h
+  ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.h
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/eds_for_test.pb.cc
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/eds_for_test.grpc.pb.cc
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/xds/eds_for_test.pb.h

diff --git a/Makefile b/Makefile
@@ -3029,6 +3029,22 @@ $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.cc: src/proto/grpc/tes
 	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
 endif
 
+ifeq ($(NO_PROTOC),true)
+$(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.pb.cc: protoc_dep_error
+$(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.cc: protoc_dep_error
+else
+
+$(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.pb.cc: src/proto/grpc/testing/xds/cds_for_test.proto $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
+	$(E) "[PROTOC]  Generating protobuf CC file from $<"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --cpp_out=$(GENDIR) $<
+
+$(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.cc: src/proto/grpc/testing/xds/cds_for_test.proto $(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.pb.cc $(PROTOBUF_DEP) $(PROTOC_PLUGINS) 
+	$(E) "[GRPC]    Generating gRPC's protobuf service CC file from $<"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(PROTOC) -Ithird_party/protobuf/src -I. --grpc_out=$(GENDIR) --plugin=protoc-gen-grpc=$(PROTOC_PLUGINS_DIR)/grpc_cpp_plugin$(EXECUTABLE_SUFFIX) $<
+endif
+
 ifeq ($(NO_PROTOC),true)
 $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.pb.cc: protoc_dep_error
 $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.grpc.pb.cc: protoc_dep_error
@@ -20614,6 +20630,7 @@ endif
 
 XDS_END2END_TEST_SRC = \
     $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.cc \
+    $(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.cc \
     $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.grpc.pb.cc \
     $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.grpc.pb.cc \
     test/cpp/end2end/xds_end2end_test.cc \
@@ -20649,6 +20666,8 @@ endif
 
 $(OBJDIR)/$(CONFIG)/src/proto/grpc/testing/xds/ads_for_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
+$(OBJDIR)/$(CONFIG)/src/proto/grpc/testing/xds/cds_for_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
 $(OBJDIR)/$(CONFIG)/src/proto/grpc/testing/xds/eds_for_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
 $(OBJDIR)/$(CONFIG)/src/proto/grpc/testing/xds/lrs_for_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
@@ -20662,7 +20681,7 @@ ifneq ($(NO_DEPS),true)
 -include $(XDS_END2END_TEST_OBJS:.o=.dep)
 endif
 endif
-$(OBJDIR)/$(CONFIG)/test/cpp/end2end/xds_end2end_test.o: $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.grpc.pb.cc
+$(OBJDIR)/$(CONFIG)/test/cpp/end2end/xds_end2end_test.o: $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/ads_for_test.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/cds_for_test.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/eds_for_test.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.pb.cc $(GENDIR)/src/proto/grpc/testing/xds/lrs_for_test.grpc.pb.cc
 
 
 PUBLIC_HEADERS_MUST_BE_C89_SRC = \

diff --git a/build.yaml b/build.yaml
@@ -6091,6 +6091,7 @@ targets:
   language: c++
   src:
   - src/proto/grpc/testing/xds/ads_for_test.proto
+  - src/proto/grpc/testing/xds/cds_for_test.proto
   - src/proto/grpc/testing/xds/eds_for_test.proto
   - src/proto/grpc/testing/xds/lrs_for_test.proto
   - test/cpp/end2end/xds_end2end_test.cc

diff --git a/src/core/ext/filters/client_channel/lb_policy.cc b/src/core/ext/filters/client_channel/lb_policy.cc
@@ -44,7 +44,7 @@ LoadBalancingPolicy::~LoadBalancingPolicy() {
 
 void LoadBalancingPolicy::Orphan() {
   ShutdownLocked();
-  Unref();
+  Unref(DEBUG_LOCATION, "Orphan");
 }
 
 //
@@ -104,7 +104,8 @@ LoadBalancingPolicy::PickResult LoadBalancingPolicy::QueuePicker::Pick(
   //    ExitIdleLocked().
   if (!exit_idle_called_) {
     exit_idle_called_ = true;
-    parent_->Ref().release();  // ref held by closure.
+    // Ref held by closure.
+    parent_->Ref(DEBUG_LOCATION, "QueuePicker::CallExitIdle").release();
     parent_->combiner()->Run(
         GRPC_CLOSURE_CREATE(&CallExitIdle, parent_.get(), nullptr),
         GRPC_ERROR_NONE);
@@ -118,7 +119,7 @@ void LoadBalancingPolicy::QueuePicker::CallExitIdle(void* arg,
                                                     grpc_error* /*error*/) {
   LoadBalancingPolicy* parent = static_cast<LoadBalancingPolicy*>(arg);
   parent->ExitIdleLocked();
-  parent->Unref();
+  parent->Unref(DEBUG_LOCATION, "QueuePicker::CallExitIdle");
 }
 
 //

diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/cds.cc b/src/core/ext/filters/client_channel/lb_policy/xds/cds.cc
@@ -39,13 +39,13 @@ constexpr char kCds[] = "cds_experimental";
 // Parsed config for this LB policy.
 class ParsedCdsConfig : public LoadBalancingPolicy::Config {
  public:
-  explicit ParsedCdsConfig(grpc_core::UniquePtr<char> cluster)
+  explicit ParsedCdsConfig(std::string cluster)
       : cluster_(std::move(cluster)) {}
-  const char* cluster() const { return cluster_.get(); }
+  const char* cluster() const { return cluster_.c_str(); }
   const char* name() const override { return kCds; }
 
  private:
-  grpc_core::UniquePtr<char> cluster_;
+  std::string cluster_;
 };
 
 // CDS LB policy.
@@ -119,9 +119,9 @@ void CdsLb::ClusterWatcher::OnClusterChanged(CdsUpdate cluster_data) {
   }
   // Construct config for child policy.
   char* lrs_str = nullptr;
-  if (cluster_data.lrs_load_reporting_server_name != nullptr) {
+  if (cluster_data.lrs_load_reporting_server_name.has_value()) {
     gpr_asprintf(&lrs_str, "    \"lrsLoadReportingServerName\": \"%s\",\n",
-                 cluster_data.lrs_load_reporting_server_name.get());
+                 cluster_data.lrs_load_reporting_server_name.value().c_str());
   }
   char* json_str;
   gpr_asprintf(&json_str,
@@ -132,9 +132,9 @@ void CdsLb::ClusterWatcher::OnClusterChanged(CdsUpdate cluster_data) {
                "  }\n"
                "}]",
                (lrs_str == nullptr ? "" : lrs_str),
-               (cluster_data.eds_service_name == nullptr
+               (cluster_data.eds_service_name.empty()
                     ? parent_->config_->cluster()
-                    : cluster_data.eds_service_name.get()));
+                    : cluster_data.eds_service_name.c_str()));
   gpr_free(lrs_str);
   grpc_core::UniquePtr<char> json_str_deleter(json_str);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_cds_lb_trace)) {
@@ -342,8 +342,7 @@ class CdsFactory : public LoadBalancingPolicyFactory {
           "required field 'cluster' not present"));
     }
     if (error_list.empty()) {
-      return MakeRefCounted<ParsedCdsConfig>(
-          grpc_core::UniquePtr<char>(gpr_strdup(cluster)));
+      return MakeRefCounted<ParsedCdsConfig>(cluster);
     } else {
       *error = GRPC_ERROR_CREATE_FROM_VECTOR("Cds Parser", &error_list);
       return nullptr;

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
@@ -78,8 +78,8 @@ class ParsedXdsConfig : public LoadBalancingPolicy::Config {
  public:
   ParsedXdsConfig(RefCountedPtr<LoadBalancingPolicy::Config> child_policy,
                   RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy,
-                  grpc_core::UniquePtr<char> eds_service_name,
-                  grpc_core::UniquePtr<char> lrs_load_reporting_server_name)
+                  std::string eds_service_name,
+                  Optional<std::string> lrs_load_reporting_server_name)
       : child_policy_(std::move(child_policy)),
         fallback_policy_(std::move(fallback_policy)),
         eds_service_name_(std::move(eds_service_name)),
@@ -96,17 +96,19 @@ class ParsedXdsConfig : public LoadBalancingPolicy::Config {
     return fallback_policy_;
   }
 
-  const char* eds_service_name() const { return eds_service_name_.get(); };
+  const char* eds_service_name() const {
+    return eds_service_name_.empty() ? nullptr : eds_service_name_.c_str();
+  };
 
-  const char* lrs_load_reporting_server_name() const {
-    return lrs_load_reporting_server_name_.get();
+  const Optional<std::string>& lrs_load_reporting_server_name() const {
+    return lrs_load_reporting_server_name_;
   };
 
  private:
   RefCountedPtr<LoadBalancingPolicy::Config> child_policy_;
   RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy_;
-  grpc_core::UniquePtr<char> eds_service_name_;
-  grpc_core::UniquePtr<char> lrs_load_reporting_server_name_;
+  std::string eds_service_name_;
+  Optional<std::string> lrs_load_reporting_server_name_;
 };
 
 class XdsLb : public LoadBalancingPolicy {
@@ -160,6 +162,8 @@ class XdsLb : public LoadBalancingPolicy {
           pickers_(std::move(pickers)),
           drop_config_(xds_policy_->drop_config_) {}
 
+    ~LocalityPicker() { xds_policy_.reset(DEBUG_LOCATION, "LocalityPicker"); }
+
     PickResult Pick(PickArgs args) override;
 
    private:
@@ -285,6 +289,8 @@ class XdsLb : public LoadBalancingPolicy {
 
       LocalityMap(RefCountedPtr<XdsLb> xds_policy, uint32_t priority);
 
+      ~LocalityMap() { xds_policy_.reset(DEBUG_LOCATION, "LocalityMap"); }
+
       void UpdateLocked(
           const XdsPriorityListUpdate::LocalityMap& locality_map_update);
       void ResetBackoffLocked();
@@ -397,7 +403,7 @@ class XdsLb : public LoadBalancingPolicy {
     if (config_ != nullptr && config_->eds_service_name() != nullptr) {
       return config_->eds_service_name();
     }
-    return server_name_.get();
+    return server_name_.c_str();
   }
 
   XdsClient* xds_client() const {
@@ -406,7 +412,7 @@ class XdsLb : public LoadBalancingPolicy {
   }
 
   // Server name from target URI.
-  grpc_core::UniquePtr<char> server_name_;
+  std::string server_name_;
 
   // Current channel args and config from the resolver.
   const grpc_channel_args* args_ = nullptr;
@@ -495,7 +501,7 @@ LoadBalancingPolicy::PickResult XdsLb::EndpointPickerWrapper::Pick(
 
 XdsLb::PickResult XdsLb::LocalityPicker::Pick(PickArgs args) {
   // Handle drop.
-  const grpc_core::UniquePtr<char>* drop_category;
+  const std::string* drop_category;
   if (drop_config_->ShouldDrop(&drop_category)) {
     xds_policy_->client_stats_.AddCallDropped(*drop_category);
     PickResult result;
@@ -612,6 +618,8 @@ class XdsLb::EndpointWatcher : public XdsClient::EndpointWatcherInterface {
   explicit EndpointWatcher(RefCountedPtr<XdsLb> xds_policy)
       : xds_policy_(std::move(xds_policy)) {}
 
+  ~EndpointWatcher() { xds_policy_.reset(DEBUG_LOCATION, "EndpointWatcher"); }
+
   void OnEndpointChanged(EdsUpdate update) override {
     if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
       gpr_log(GPR_INFO, "[xdslb %p] Received EDS update from xds client",
@@ -706,11 +714,10 @@ XdsLb::XdsLb(Args args)
   GPR_ASSERT(server_uri != nullptr);
   grpc_uri* uri = grpc_uri_parse(server_uri, true);
   GPR_ASSERT(uri->path[0] != '\0');
-  server_name_.reset(
-      gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path));
+  server_name_ = uri->path[0] == '/' ? uri->path + 1 : uri->path;
   if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
     gpr_log(GPR_INFO, "[xdslb %p] server name from channel: %s", this,
-            server_name_.get());
+            server_name_.c_str());
   }
   grpc_uri_destroy(uri);
 }
@@ -743,9 +750,12 @@ void XdsLb::ShutdownLocked() {
   // watcher holds a ref to us.
   xds_client()->CancelEndpointDataWatch(StringView(eds_service_name()),
                                         endpoint_watcher_);
-  if (config_->lrs_load_reporting_server_name() != nullptr) {
+  if (config_->lrs_load_reporting_server_name().has_value()) {
+    // TODO(roth): We should pass the cluster name (in addition to the
+    // eds_service_name) when adding the client stats. To do so, we need to
+    // first find a way to plumb the cluster name down into this LB policy.
     xds_client()->RemoveClientStats(
-        StringView(config_->lrs_load_reporting_server_name()),
+        StringView(config_->lrs_load_reporting_server_name().value().c_str()),
         StringView(eds_service_name()), &client_stats_);
   }
   xds_client_from_channel_.reset();
@@ -820,7 +830,8 @@ void XdsLb::UpdateLocked(UpdateArgs args) {
       xds_client()->CancelEndpointDataWatch(StringView(old_eds_service_name),
                                             endpoint_watcher_);
     }
-    auto watcher = MakeUnique<EndpointWatcher>(Ref());
+    auto watcher =
+        MakeUnique<EndpointWatcher>(Ref(DEBUG_LOCATION, "EndpointWatcher"));
     endpoint_watcher_ = watcher.get();
     xds_client()->WatchEndpointData(StringView(eds_service_name()),
                                     std::move(watcher));
@@ -831,21 +842,25 @@ void XdsLb::UpdateLocked(UpdateArgs args) {
   // all of the pickers whenever load reporting is enabled or disabled
   // here.
   if (is_initial_update ||
-      (config_->lrs_load_reporting_server_name() == nullptr) !=
-          (old_config->lrs_load_reporting_server_name() == nullptr) ||
-      (config_->lrs_load_reporting_server_name() != nullptr &&
-       old_config->lrs_load_reporting_server_name() != nullptr &&
-       strcmp(config_->lrs_load_reporting_server_name(),
-              old_config->lrs_load_reporting_server_name()) != 0)) {
+      (config_->lrs_load_reporting_server_name().has_value()) !=
+          (old_config->lrs_load_reporting_server_name().has_value()) ||
+      (config_->lrs_load_reporting_server_name().has_value() &&
+       old_config->lrs_load_reporting_server_name().has_value() &&
+       config_->lrs_load_reporting_server_name().value() !=
+           old_config->lrs_load_reporting_server_name().value())) {
     if (old_config != nullptr &&
-        old_config->lrs_load_reporting_server_name() != nullptr) {
+        old_config->lrs_load_reporting_server_name().has_value()) {
       xds_client()->RemoveClientStats(
-          StringView(old_config->lrs_load_reporting_server_name()),
+          StringView(
+              old_config->lrs_load_reporting_server_name().value().c_str()),
           StringView(old_eds_service_name), &client_stats_);
     }
-    if (config_->lrs_load_reporting_server_name() != nullptr) {
+    if (config_->lrs_load_reporting_server_name().has_value()) {
+      // TODO(roth): We should pass the cluster name (in addition to the
+      // eds_service_name) when adding the client stats. To do so, we need to
+      // first find a way to plumb the cluster name down into this LB policy.
       xds_client()->AddClientStats(
-          StringView(config_->lrs_load_reporting_server_name()),
+          StringView(config_->lrs_load_reporting_server_name().value().c_str()),
           StringView(eds_service_name()), &client_stats_);
     }
   }
@@ -1083,7 +1098,7 @@ void XdsLb::PriorityList::MaybeCreateLocalityMapLocked(uint32_t priority) {
   // Exhausted priorities in the update.
   if (!priority_list_update().Contains(priority)) return;
   auto new_locality_map = new LocalityMap(
-      xds_policy_->Ref(DEBUG_LOCATION, "XdsLb+LocalityMap"), priority);
+      xds_policy_->Ref(DEBUG_LOCATION, "LocalityMap"), priority);
   priorities_.emplace_back(OrphanablePtr<LocalityMap>(new_locality_map));
   new_locality_map->UpdateLocked(*priority_list_update().Find(priority));
 }
@@ -1152,7 +1167,6 @@ XdsLb::PriorityList::LocalityMap::LocalityMap(RefCountedPtr<XdsLb> xds_policy,
     gpr_log(GPR_INFO, "[xdslb %p] Creating priority %" PRIu32,
             xds_policy_.get(), priority_);
   }
-
   GRPC_CLOSURE_INIT(&on_failover_timer_, OnFailoverTimer, this,
                     grpc_schedule_on_exec_ctx);
   // Start the failover timer.
@@ -1239,9 +1253,10 @@ void XdsLb::PriorityList::LocalityMap::UpdateXdsPickerLocked() {
     picker_list.push_back(std::make_pair(end, locality->picker_wrapper()));
   }
   xds_policy()->channel_control_helper()->UpdateState(
-      GRPC_CHANNEL_READY, grpc_core::MakeUnique<LocalityPicker>(
-                              xds_policy_->Ref(DEBUG_LOCATION, "XdsLb+Picker"),
-                              std::move(picker_list)));
+      GRPC_CHANNEL_READY,
+      grpc_core::MakeUnique<LocalityPicker>(
+          xds_policy_->Ref(DEBUG_LOCATION, "LocalityPicker"),
+          std::move(picker_list)));
 }
 
 OrphanablePtr<XdsLb::PriorityList::LocalityMap::Locality>
@@ -1869,11 +1884,15 @@ class XdsFactory : public LoadBalancingPolicyFactory {
       }
     }
     if (error_list.empty()) {
+      Optional<std::string> optional_lrs_load_reporting_server_name;
+      if (lrs_load_reporting_server_name != nullptr) {
+        optional_lrs_load_reporting_server_name.set(
+            std::string(lrs_load_reporting_server_name));
+      }
       return MakeRefCounted<ParsedXdsConfig>(
           std::move(child_policy), std::move(fallback_policy),
-          grpc_core::UniquePtr<char>(gpr_strdup(eds_service_name)),
-          grpc_core::UniquePtr<char>(
-              gpr_strdup(lrs_load_reporting_server_name)));
+          eds_service_name == nullptr ? "" : eds_service_name,
+          std::move(optional_lrs_load_reporting_server_name));
     } else {
       *error = GRPC_ERROR_CREATE_FROM_VECTOR("Xds Parser", &error_list);
       return nullptr;