[OTel C++] Add APIs to enable/disable metrics (#36183)

Closes #36183

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36183 from yashykt:OTelEnableDisableMetrics 948abe7235
PiperOrigin-RevId: 619696880

include/grpcpp/ext/otel_plugin.h

@@ -100,6 +100,13 @@ class OpenTelemetryPluginBuilder {
   OpenTelemetryPluginBuilder& SetGenericMethodAttributeFilter(
       absl::AnyInvocable<bool(absl::string_view /*generic_method*/) const>
           generic_method_attribute_filter);
+  // Methods to manipulate which instruments are enabled in the OpenTelemetry
+  // Stats Plugin.
+  OpenTelemetryPluginBuilder& EnableMetrics(
+      absl::Span<const absl::string_view> metric_names);
+  OpenTelemetryPluginBuilder& DisableMetrics(
+      absl::Span<const absl::string_view> metric_names);
+  OpenTelemetryPluginBuilder& DisableAllMetrics();
   /// Add a plugin option to add to the opentelemetry plugin being built. At
   /// present, this type is an opaque type. Ownership of \a option is
   /// transferred when `AddPluginOption` is invoked. A maximum of 64 plugin

src/cpp/ext/otel/otel_plugin.cc

@@ -150,15 +150,19 @@ OpenTelemetryPluginBuilderImpl::SetMeterProvider(
   return *this;
 }
 
-OpenTelemetryPluginBuilderImpl& OpenTelemetryPluginBuilderImpl::EnableMetric(
-    absl::string_view metric_name) {
-  metrics_.emplace(metric_name);
+OpenTelemetryPluginBuilderImpl& OpenTelemetryPluginBuilderImpl::EnableMetrics(
+    absl::Span<const absl::string_view> metric_names) {
+  for (const auto& metric_name : metric_names) {
+    metrics_.emplace(metric_name);
+  }
   return *this;
 }
 
-OpenTelemetryPluginBuilderImpl& OpenTelemetryPluginBuilderImpl::DisableMetric(
-    absl::string_view metric_name) {
-  metrics_.erase(metric_name);
+OpenTelemetryPluginBuilderImpl& OpenTelemetryPluginBuilderImpl::DisableMetrics(
+    absl::Span<const absl::string_view> metric_names) {
+  for (const auto& metric_name : metric_names) {
+    metrics_.erase(metric_name);
+  }
   return *this;
 }
 
@@ -607,6 +611,23 @@ OpenTelemetryPluginBuilder::SetGenericMethodAttributeFilter(
   return *this;
 }
 
+OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::EnableMetrics(
+    absl::Span<const absl::string_view> metric_names) {
+  impl_->EnableMetrics(metric_names);
+  return *this;
+}
+
+OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::DisableMetrics(
+    absl::Span<const absl::string_view> metric_names) {
+  impl_->DisableMetrics(metric_names);
+  return *this;
+}
+
+OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::DisableAllMetrics() {
+  impl_->DisableAllMetrics();
+  return *this;
+}
+
 OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::AddPluginOption(
     std::unique_ptr<OpenTelemetryPluginOption> option) {
   impl_->AddPluginOption(

src/cpp/ext/otel/otel_plugin.h

@@ -135,8 +135,10 @@ class OpenTelemetryPluginBuilderImpl {
   // grpc.server.call.duration
   // grpc.server.call.sent_total_compressed_message_size
   // grpc.server.call.rcvd_total_compressed_message_size
-  OpenTelemetryPluginBuilderImpl& EnableMetric(absl::string_view metric_name);
-  OpenTelemetryPluginBuilderImpl& DisableMetric(absl::string_view metric_name);
+  OpenTelemetryPluginBuilderImpl& EnableMetrics(
+      absl::Span<const absl::string_view> metric_names);
+  OpenTelemetryPluginBuilderImpl& DisableMetrics(
+      absl::Span<const absl::string_view> metric_names);
   OpenTelemetryPluginBuilderImpl& DisableAllMetrics();
   // If set, \a target_selector is called per channel to decide whether to
   // collect metrics on that target or not.
@@ -173,6 +175,10 @@ class OpenTelemetryPluginBuilderImpl {
       absl::string_view optional_label_key);
   absl::Status BuildAndRegisterGlobal();
 
+  const absl::flat_hash_set<std::string>& TestOnlyEnabledMetrics() {
+    return metrics_;
+  }
+
  private:
   std::shared_ptr<opentelemetry::metrics::MeterProvider> meter_provider_;
   std::unique_ptr<LabelsInjector> labels_injector_;

test/cpp/ext/csm/metadata_exchange_test.cc

@@ -155,7 +155,7 @@ class MetadataExchangeTest
     : public OpenTelemetryPluginEnd2EndTest,
       public ::testing::WithParamInterface<TestScenario> {
  protected:
-  void Init(absl::flat_hash_set<absl::string_view> metric_names,
+  void Init(const std::vector<absl::string_view>& metric_names,
             bool enable_client_side_injector = true,
             std::map<std::string, std::string> labels_to_inject = {}) {
     const char* kBootstrap =
@@ -178,7 +178,7 @@ class MetadataExchangeTest
     }
     OpenTelemetryPluginEnd2EndTest::Init(std::move(
         Options()
-            .set_metric_names(std::move(metric_names))
+            .set_metric_names(metric_names)
             .add_plugin_option(std::make_unique<MeshLabelsPluginOption>(
                 GetParam().GetTestResource().GetAttributes()))
             .set_labels_to_inject(std::move(labels_to_inject))

test/cpp/ext/otel/otel_plugin_test.cc

@@ -1353,6 +1353,24 @@ TEST_F(OpenTelemetryPluginNPCMetricsTest,
               HistogramResultEq(kSum, kMin, kMax, kCount))))));
 }
 
+TEST(OpenTelemetryPluginMetricsEnablingDisablingTest, TestEnableDisableAPIs) {
+  grpc::internal::OpenTelemetryPluginBuilderImpl builder;
+  // First disable all metrics
+  builder.DisableAllMetrics();
+  EXPECT_TRUE(builder.TestOnlyEnabledMetrics().empty());
+  // Add in a few metrics
+  builder.EnableMetrics(
+      {"grpc.test.metric_1", "grpc.test.metric_2", "grpc.test.metric_3"});
+  EXPECT_THAT(
+      builder.TestOnlyEnabledMetrics(),
+      ::testing::UnorderedElementsAre(
+          "grpc.test.metric_1", "grpc.test.metric_2", "grpc.test.metric_3"));
+  // Now remove a few metrics
+  builder.DisableMetrics({"grpc.test.metric_1", "grpc.test.metric_2"});
+  EXPECT_THAT(builder.TestOnlyEnabledMetrics(),
+              ::testing::UnorderedElementsAre("grpc.test.metric_3"));
+}
+
 }  // namespace
 }  // namespace testing
 }  // namespace grpc

test/cpp/ext/otel/otel_test_library.cc

@@ -199,9 +199,7 @@ OpenTelemetryPluginEnd2EndTest::BuildAndRegisterOpenTelemetryPlugin(
       std::make_shared<grpc::testing::MockMetricReader>();
   meter_provider->AddMetricReader(reader);
   ot_builder.DisableAllMetrics();
-  for (const auto& metric_name : options.metric_names) {
-    ot_builder.EnableMetric(metric_name);
-  }
+  ot_builder.EnableMetrics(options.metric_names);
   if (options.use_meter_provider) {
     auto meter_provider =
         std::make_shared<opentelemetry::sdk::metrics::MeterProvider>();

test/cpp/ext/otel/otel_test_library.h

@@ -60,7 +60,7 @@ class OpenTelemetryPluginEnd2EndTest : public ::testing::Test {
  protected:
   struct Options {
    public:
-    Options& set_metric_names(absl::flat_hash_set<absl::string_view> names) {
+    Options& set_metric_names(std::vector<absl::string_view> names) {
       metric_names = std::move(names);
       return *this;
     }
@@ -119,7 +119,7 @@ class OpenTelemetryPluginEnd2EndTest : public ::testing::Test {
       return *this;
     }
 
-    absl::flat_hash_set<absl::string_view> metric_names;
+    std::vector<absl::string_view> metric_names;
     // TODO(yashykt): opentelemetry::sdk::resource::Resource doesn't have a copy
     // assignment operator so wrapping it in a unique_ptr till it is fixed.
     std::unique_ptr<opentelemetry::sdk::resource::Resource> resource =