[call-v3] Remove `v3_backend_metric_filter` experiment (#36227)

We're all rolled out.

Closes #36227

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36227 from ctiller:v3bmf 08392ddd36
PiperOrigin-RevId: 621263847

bazel/experiments.bzl

@@ -43,7 +43,6 @@ EXPERIMENT_ENABLES = {
     "tcp_rcv_lowat": "tcp_rcv_lowat",
     "trace_record_callops": "trace_record_callops",
     "unconstrained_max_quota_buffer_size": "unconstrained_max_quota_buffer_size",
-    "v3_backend_metric_filter": "v3_backend_metric_filter",
     "work_serializer_clears_time_cache": "work_serializer_clears_time_cache",
     "work_serializer_dispatch": "event_engine_client,work_serializer_dispatch",
 }

src/core/ext/filters/backend_metrics/backend_metric_filter.cc

@@ -117,55 +117,15 @@ absl::optional<std::string> MaybeSerializeBackendMetrics(
 }
 }  // namespace
 
-const grpc_channel_filter LegacyBackendMetricFilter::kFilter =
-    MakePromiseBasedFilter<LegacyBackendMetricFilter, FilterEndpoint::kServer>(
-        "backend_metric");
-
 const grpc_channel_filter BackendMetricFilter::kFilter =
     MakePromiseBasedFilter<BackendMetricFilter, FilterEndpoint::kServer>(
         "backend_metric");
 
-absl::StatusOr<LegacyBackendMetricFilter> LegacyBackendMetricFilter::Create(
-    const ChannelArgs&, ChannelFilter::Args) {
-  return LegacyBackendMetricFilter();
-}
-
 absl::StatusOr<BackendMetricFilter> BackendMetricFilter::Create(
     const ChannelArgs&, ChannelFilter::Args) {
   return BackendMetricFilter();
 }
 
-ArenaPromise<ServerMetadataHandle> LegacyBackendMetricFilter::MakeCallPromise(
-    CallArgs call_args, NextPromiseFactory next_promise_factory) {
-  return ArenaPromise<ServerMetadataHandle>(Map(
-      next_promise_factory(std::move(call_args)),
-      [this](ServerMetadataHandle trailing_metadata) {
-        auto* ctx = &GetContext<
-            grpc_call_context_element>()[GRPC_CONTEXT_BACKEND_METRIC_PROVIDER];
-        if (ctx == nullptr) {
-          if (GRPC_TRACE_FLAG_ENABLED(grpc_backend_metric_filter_trace)) {
-            gpr_log(GPR_INFO, "[%p] No BackendMetricProvider.", this);
-          }
-          return trailing_metadata;
-        }
-        absl::optional<std::string> serialized = MaybeSerializeBackendMetrics(
-            reinterpret_cast<BackendMetricProvider*>(ctx->value));
-        if (serialized.has_value() && !serialized->empty()) {
-          if (GRPC_TRACE_FLAG_ENABLED(grpc_backend_metric_filter_trace)) {
-            gpr_log(GPR_INFO,
-                    "[%p] Backend metrics serialized. size: %" PRIuPTR, this,
-                    serialized->size());
-          }
-          trailing_metadata->Set(
-              EndpointLoadMetricsBinMetadata(),
-              Slice::FromCopiedString(std::move(*serialized)));
-        } else if (GRPC_TRACE_FLAG_ENABLED(grpc_backend_metric_filter_trace)) {
-          gpr_log(GPR_INFO, "[%p] No backend metrics.", this);
-        }
-        return trailing_metadata;
-      }));
-}
-
 void BackendMetricFilter::Call::OnServerTrailingMetadata(ServerMetadata& md) {
   auto* ctx = &GetContext<
       grpc_call_context_element>()[GRPC_CONTEXT_BACKEND_METRIC_PROVIDER];
@@ -190,15 +150,9 @@ void BackendMetricFilter::Call::OnServerTrailingMetadata(ServerMetadata& md) {
 }
 
 void RegisterBackendMetricFilter(CoreConfiguration::Builder* builder) {
-  if (IsV3BackendMetricFilterEnabled()) {
   builder->channel_init()
       ->RegisterFilter<BackendMetricFilter>(GRPC_SERVER_CHANNEL)
       .IfHasChannelArg(GRPC_ARG_SERVER_CALL_METRIC_RECORDING);
-  } else {
-    builder->channel_init()
-        ->RegisterFilter<LegacyBackendMetricFilter>(GRPC_SERVER_CHANNEL)
-        .IfHasChannelArg(GRPC_ARG_SERVER_CALL_METRIC_RECORDING);
-  }
 }
 
 }  // namespace grpc_core

src/core/ext/filters/backend_metrics/backend_metric_filter.h

@@ -31,18 +31,6 @@
 
 namespace grpc_core {
 
-class LegacyBackendMetricFilter : public ChannelFilter {
- public:
-  static const grpc_channel_filter kFilter;
-
-  static absl::StatusOr<LegacyBackendMetricFilter> Create(
-      const ChannelArgs& args, ChannelFilter::Args);
-
-  // Construct a promise for one call.
-  ArenaPromise<ServerMetadataHandle> MakeCallPromise(
-      CallArgs call_args, NextPromiseFactory next_promise_factory) override;
-};
-
 class BackendMetricFilter : public ImplementChannelFilter<BackendMetricFilter> {
  public:
   static const grpc_channel_filter kFilter;

src/core/lib/experiments/experiments.cc

@@ -128,9 +128,6 @@ const char* const description_unconstrained_max_quota_buffer_size =
     "Discard the cap on the max free pool size for one memory allocator";
 const char* const additional_constraints_unconstrained_max_quota_buffer_size =
     "{}";
-const char* const description_v3_backend_metric_filter =
-    "Use the backend metric filter utilizing the v3 filter api";
-const char* const additional_constraints_v3_backend_metric_filter = "{}";
 const char* const description_work_serializer_clears_time_cache =
     "Have the work serializer clear the time cache when it dispatches work.";
 const char* const additional_constraints_work_serializer_clears_time_cache =
@@ -214,8 +211,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      description_unconstrained_max_quota_buffer_size,
      additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
      false, true},
-    {"v3_backend_metric_filter", description_v3_backend_metric_filter,
-     additional_constraints_v3_backend_metric_filter, nullptr, 0, false, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
      additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,
@@ -333,9 +328,6 @@ const char* const description_unconstrained_max_quota_buffer_size =
     "Discard the cap on the max free pool size for one memory allocator";
 const char* const additional_constraints_unconstrained_max_quota_buffer_size =
     "{}";
-const char* const description_v3_backend_metric_filter =
-    "Use the backend metric filter utilizing the v3 filter api";
-const char* const additional_constraints_v3_backend_metric_filter = "{}";
 const char* const description_work_serializer_clears_time_cache =
     "Have the work serializer clear the time cache when it dispatches work.";
 const char* const additional_constraints_work_serializer_clears_time_cache =
@@ -419,8 +411,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      description_unconstrained_max_quota_buffer_size,
      additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
      false, true},
-    {"v3_backend_metric_filter", description_v3_backend_metric_filter,
-     additional_constraints_v3_backend_metric_filter, nullptr, 0, false, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
      additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,
@@ -538,9 +528,6 @@ const char* const description_unconstrained_max_quota_buffer_size =
     "Discard the cap on the max free pool size for one memory allocator";
 const char* const additional_constraints_unconstrained_max_quota_buffer_size =
     "{}";
-const char* const description_v3_backend_metric_filter =
-    "Use the backend metric filter utilizing the v3 filter api";
-const char* const additional_constraints_v3_backend_metric_filter = "{}";
 const char* const description_work_serializer_clears_time_cache =
     "Have the work serializer clear the time cache when it dispatches work.";
 const char* const additional_constraints_work_serializer_clears_time_cache =
@@ -624,8 +611,6 @@ const ExperimentMetadata g_experiment_metadata[] = {
      description_unconstrained_max_quota_buffer_size,
      additional_constraints_unconstrained_max_quota_buffer_size, nullptr, 0,
      false, true},
-    {"v3_backend_metric_filter", description_v3_backend_metric_filter,
-     additional_constraints_v3_backend_metric_filter, nullptr, 0, false, true},
     {"work_serializer_clears_time_cache",
      description_work_serializer_clears_time_cache,
      additional_constraints_work_serializer_clears_time_cache, nullptr, 0, true,

src/core/lib/experiments/experiments.h

@@ -95,7 +95,6 @@ inline bool IsTcpFrameSizeTuningEnabled() { return false; }
 inline bool IsTcpRcvLowatEnabled() { return false; }
 inline bool IsTraceRecordCallopsEnabled() { return false; }
 inline bool IsUnconstrainedMaxQuotaBufferSizeEnabled() { return false; }
-inline bool IsV3BackendMetricFilterEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 inline bool IsWorkSerializerDispatchEnabled() { return false; }
@@ -140,7 +139,6 @@ inline bool IsTcpFrameSizeTuningEnabled() { return false; }
 inline bool IsTcpRcvLowatEnabled() { return false; }
 inline bool IsTraceRecordCallopsEnabled() { return false; }
 inline bool IsUnconstrainedMaxQuotaBufferSizeEnabled() { return false; }
-inline bool IsV3BackendMetricFilterEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 inline bool IsWorkSerializerDispatchEnabled() { return false; }
@@ -186,7 +184,6 @@ inline bool IsTcpFrameSizeTuningEnabled() { return false; }
 inline bool IsTcpRcvLowatEnabled() { return false; }
 inline bool IsTraceRecordCallopsEnabled() { return false; }
 inline bool IsUnconstrainedMaxQuotaBufferSizeEnabled() { return false; }
-inline bool IsV3BackendMetricFilterEnabled() { return false; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() { return true; }
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_DISPATCH
@@ -221,7 +218,6 @@ enum ExperimentIds {
   kExperimentIdTcpRcvLowat,
   kExperimentIdTraceRecordCallops,
   kExperimentIdUnconstrainedMaxQuotaBufferSize,
-  kExperimentIdV3BackendMetricFilter,
   kExperimentIdWorkSerializerClearsTimeCache,
   kExperimentIdWorkSerializerDispatch,
   kNumExperiments
@@ -330,10 +326,6 @@ inline bool IsTraceRecordCallopsEnabled() {
 inline bool IsUnconstrainedMaxQuotaBufferSizeEnabled() {
   return IsExperimentEnabled(kExperimentIdUnconstrainedMaxQuotaBufferSize);
 }
-#define GRPC_EXPERIMENT_IS_INCLUDED_V3_BACKEND_METRIC_FILTER
-inline bool IsV3BackendMetricFilterEnabled() {
-  return IsExperimentEnabled(kExperimentIdV3BackendMetricFilter);
-}
 #define GRPC_EXPERIMENT_IS_INCLUDED_WORK_SERIALIZER_CLEARS_TIME_CACHE
 inline bool IsWorkSerializerClearsTimeCacheEnabled() {
   return IsExperimentEnabled(kExperimentIdWorkSerializerClearsTimeCache);

src/core/lib/experiments/experiments.yaml

@@ -215,12 +215,6 @@
   expiry: 2024/09/01
   owner: ctiller@google.com
   test_tags: [resource_quota_test]
-- name: v3_backend_metric_filter
-  description:
-    Use the backend metric filter utilizing the v3 filter api
-  expiry: 2024/05/05
-  owner: ctiller@google.com
-  test_tags: []
 - name: work_serializer_clears_time_cache
   description:
     Have the work serializer clear the time cache when it dispatches work.