[OTel C++] Add API to set channel scope filter (#36189)

Also addressing a TODO from previous PRs where `authority` is not being populated in the `ChannelScope`.

Closes #36189

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36189 from yashykt:OTelChannelScope e76f9ce0ca
PiperOrigin-RevId: 621231764

BUILD

@@ -252,6 +252,7 @@ GPR_PUBLIC_HDRS = [
     "include/grpc/support/json.h",
     "include/grpc/support/log.h",
     "include/grpc/support/log_windows.h",
+    "include/grpc/support/metrics.h",
     "include/grpc/support/port_platform.h",
     "include/grpc/support/string_util.h",
     "include/grpc/support/sync.h",

CMakeLists.txt

@@ -1783,6 +1783,7 @@ foreach(_hdr
   include/grpc/support/json.h
   include/grpc/support/log.h
   include/grpc/support/log_windows.h
+  include/grpc/support/metrics.h
   include/grpc/support/port_platform.h
   include/grpc/support/string_util.h
   include/grpc/support/sync.h
@@ -2746,6 +2747,7 @@ foreach(_hdr
   include/grpc/support/json.h
   include/grpc/support/log.h
   include/grpc/support/log_windows.h
+  include/grpc/support/metrics.h
   include/grpc/support/port_platform.h
   include/grpc/support/string_util.h
   include/grpc/support/sync.h
@@ -3446,6 +3448,7 @@ foreach(_hdr
   include/grpc/support/json.h
   include/grpc/support/log.h
   include/grpc/support/log_windows.h
+  include/grpc/support/metrics.h
   include/grpc/support/port_platform.h
   include/grpc/support/string_util.h
   include/grpc/support/sync.h
@@ -5495,6 +5498,7 @@ foreach(_hdr
   include/grpc/support/json.h
   include/grpc/support/log.h
   include/grpc/support/log_windows.h
+  include/grpc/support/metrics.h
   include/grpc/support/port_platform.h
   include/grpc/support/string_util.h
   include/grpc/support/sync.h

Makefile

@@ -1786,6 +1786,7 @@ PUBLIC_HEADERS_C += \
     include/grpc/support/json.h \
     include/grpc/support/log.h \
     include/grpc/support/log_windows.h \
+    include/grpc/support/metrics.h \
     include/grpc/support/port_platform.h \
     include/grpc/support/string_util.h \
     include/grpc/support/sync.h \

Package.swift

@@ -104,6 +104,7 @@ let package = Package(
         "include/grpc/support/json.h",
         "include/grpc/support/log.h",
         "include/grpc/support/log_windows.h",
+        "include/grpc/support/metrics.h",
         "include/grpc/support/port_platform.h",
         "include/grpc/support/string_util.h",
         "include/grpc/support/sync.h",

build_autogenerated.yaml

@@ -40,6 +40,7 @@ libs:
   - include/grpc/support/json.h
   - include/grpc/support/log.h
   - include/grpc/support/log_windows.h
+  - include/grpc/support/metrics.h
   - include/grpc/support/port_platform.h
   - include/grpc/support/string_util.h
   - include/grpc/support/sync.h
@@ -206,6 +207,7 @@ libs:
   - include/grpc/support/json.h
   - include/grpc/support/log.h
   - include/grpc/support/log_windows.h
+  - include/grpc/support/metrics.h
   - include/grpc/support/port_platform.h
   - include/grpc/support/string_util.h
   - include/grpc/support/sync.h
@@ -2192,6 +2194,7 @@ libs:
   - include/grpc/support/json.h
   - include/grpc/support/log.h
   - include/grpc/support/log_windows.h
+  - include/grpc/support/metrics.h
   - include/grpc/support/port_platform.h
   - include/grpc/support/string_util.h
   - include/grpc/support/sync.h
@@ -4369,6 +4372,7 @@ libs:
   - include/grpc/support/json.h
   - include/grpc/support/log.h
   - include/grpc/support/log_windows.h
+  - include/grpc/support/metrics.h
   - include/grpc/support/port_platform.h
   - include/grpc/support/string_util.h
   - include/grpc/support/sync.h

gRPC-Core.podspec

@@ -178,6 +178,7 @@ Pod::Spec.new do |s|
                       'include/grpc/support/json.h',
                       'include/grpc/support/log.h',
                       'include/grpc/support/log_windows.h',
+                      'include/grpc/support/metrics.h',
                       'include/grpc/support/port_platform.h',
                       'include/grpc/support/string_util.h',
                       'include/grpc/support/sync.h',

grpc.gemspec

@@ -110,6 +110,7 @@ Gem::Specification.new do |s|
   s.files += %w( include/grpc/support/json.h )
   s.files += %w( include/grpc/support/log.h )
   s.files += %w( include/grpc/support/log_windows.h )
+  s.files += %w( include/grpc/support/metrics.h )
   s.files += %w( include/grpc/support/port_platform.h )
   s.files += %w( include/grpc/support/string_util.h )
   s.files += %w( include/grpc/support/sync.h )

include/grpc/module.modulemap

@@ -46,6 +46,7 @@ header "byte_buffer.h"
   header "support/json.h"
   header "support/log.h"
   header "support/log_windows.h"
+  header "support/metrics.h"
   header "support/port_platform.h"
   header "support/string_util.h"
   header "support/sync.h"

include/grpc/support/metrics.h

@@ -0,0 +1,51 @@
+// Copyright 2024 The 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_SUPPORT_METRICS_H
+#define GRPC_SUPPORT_METRICS_H
+
+#include <grpc/support/port_platform.h>
+
+#include "absl/strings/string_view.h"
+
+namespace grpc_core {
+namespace experimental {
+
+// Configuration (scope) for a specific client channel to be used for stats
+// plugins.
+class StatsPluginChannelScope {
+ public:
+  StatsPluginChannelScope(absl::string_view target,
+                          absl::string_view default_authority)
+      : target_(target), default_authority_(default_authority) {}
+
+  /// Returns the target used for creating the channel in the canonical form.
+  /// (Canonicalized target definition -
+  /// https://github.com/grpc/proposal/blob/master/A66-otel-stats.md)
+  absl::string_view target() const { return target_; }
+  /// Returns the default authority for the channel.
+  absl::string_view default_authority() const { return default_authority_; }
+
+ private:
+  // Disable copy constructor and copy-assignment operator.
+  StatsPluginChannelScope(const StatsPluginChannelScope&) = delete;
+  StatsPluginChannelScope& operator=(const StatsPluginChannelScope&) = delete;
+  absl::string_view target_;
+  absl::string_view default_authority_;
+};
+
+}  // namespace experimental
+}  // namespace grpc_core
+
+#endif /* GRPC_SUPPORT_METRICS_H */

include/grpcpp/ext/otel_plugin.h

@@ -31,10 +31,13 @@
 #include "absl/strings/string_view.h"
 #include "opentelemetry/metrics/meter_provider.h"
 
+#include <grpc/support/metrics.h>
+
 namespace grpc {
 
 namespace internal {
 class OpenTelemetryPluginBuilderImpl;
+class OpenTelemetryPlugin;
 }  // namespace internal
 
 class OpenTelemetryPluginOption {
@@ -57,6 +60,8 @@ class OpenTelemetryPluginOption {
 /// grpc.server.call.rcvd_total_compressed_message_size
 class OpenTelemetryPluginBuilder {
  public:
+  using ChannelScope = grpc_core::experimental::StatsPluginChannelScope;
+
   /// Metrics
   static constexpr absl::string_view kClientAttemptStartedInstrumentName =
       "grpc.client.attempt.started";
@@ -113,9 +118,14 @@ class OpenTelemetryPluginBuilder {
   /// options can be added.
   OpenTelemetryPluginBuilder& AddPluginOption(
       std::unique_ptr<OpenTelemetryPluginOption> option);
-  // Records \a optional_label_key on all metrics that provide it.
+  /// Records \a optional_label_key on all metrics that provide it.
   OpenTelemetryPluginBuilder& AddOptionalLabel(
       absl::string_view optional_label_key);
+  /// Set scope filter to choose which channels are recorded by this plugin.
+  /// Server-side recording remains unaffected.
+  OpenTelemetryPluginBuilder& SetChannelScopeFilter(
+      absl::AnyInvocable<bool(const ChannelScope& /*scope*/) const>
+          channel_scope_filter);
   /// Registers a global plugin that acts on all channels and servers running on
   /// the process.
   absl::Status BuildAndRegisterGlobal();

package.xml

@@ -92,6 +92,7 @@
     <file baseinstalldir="/" name="include/grpc/support/json.h" role="src" />
     <file baseinstalldir="/" name="include/grpc/support/log.h" role="src" />
     <file baseinstalldir="/" name="include/grpc/support/log_windows.h" role="src" />
+    <file baseinstalldir="/" name="include/grpc/support/metrics.h" role="src" />
     <file baseinstalldir="/" name="include/grpc/support/port_platform.h" role="src" />
     <file baseinstalldir="/" name="include/grpc/support/string_util.h" role="src" />
     <file baseinstalldir="/" name="include/grpc/support/sync.h" role="src" />

src/core/ext/xds/xds_client_grpc.cc

@@ -271,7 +271,7 @@ GlobalStatsPluginRegistry::StatsPluginGroup GetStatsPluginGroupForKey(
     return GlobalStatsPluginRegistry::GetStatsPluginsForServer(ChannelArgs{});
   }
   // TODO(roth): How do we set the authority here?
-  StatsPlugin::ChannelScope scope(key, "");
+  experimental::StatsPluginChannelScope scope(key, "");
   return GlobalStatsPluginRegistry::GetStatsPluginsForChannel(scope);
 }
 

src/core/lib/channel/metrics.cc

@@ -364,7 +364,7 @@ void GlobalStatsPluginRegistry::RegisterStatsPlugin(
 
 GlobalStatsPluginRegistry::StatsPluginGroup
 GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-    const StatsPlugin::ChannelScope& scope) {
+    const experimental::StatsPluginChannelScope& scope) {
   MutexLock lock(&*mutex_);
   StatsPluginGroup group;
   for (const auto& plugin : *plugins_) {

src/core/lib/channel/metrics.h

@@ -28,6 +28,7 @@
 #include "absl/types/span.h"
 
 #include <grpc/support/log.h>
+#include <grpc/support/metrics.h>
 
 #include "src/core/lib/channel/call_tracer.h"
 #include "src/core/lib/channel/channel_args.h"
@@ -167,19 +168,6 @@ class RegisteredMetricCallback;
 // The StatsPlugin interface.
 class StatsPlugin {
  public:
-  // Configuration (scope) for a specific client channel.
-  class ChannelScope {
-   public:
-    ChannelScope(absl::string_view target, absl::string_view authority)
-        : target_(target), authority_(authority) {}
-
-    absl::string_view target() const { return target_; }
-    absl::string_view authority() const { return authority_; }
-
-   private:
-    absl::string_view target_;
-    absl::string_view authority_;
-  };
   // A general-purpose way for stats plugin to store per-channel or per-server
   // state.
   class ScopeConfig {
@@ -193,7 +181,7 @@ class StatsPlugin {
   // Returns true and a channel-specific ScopeConfig which may then be used to
   // configure the ClientCallTracer in GetClientCallTracer().
   virtual std::pair<bool, std::shared_ptr<ScopeConfig>> IsEnabledForChannel(
-      const ChannelScope& scope) const = 0;
+      const experimental::StatsPluginChannelScope& scope) const = 0;
   // Whether this stats plugin is enabled for the server specified by \a args.
   // Returns true and a server-specific ScopeConfig which may then be used to
   // configure the ServerCallTracer in GetServerCallTracer().
@@ -365,7 +353,7 @@ class GlobalStatsPluginRegistry {
   // The following functions can be invoked to get a StatsPluginGroup for
   // a specified scope.
   static StatsPluginGroup GetStatsPluginsForChannel(
-      const StatsPlugin::ChannelScope& scope);
+      const experimental::StatsPluginChannelScope& scope);
   static StatsPluginGroup GetStatsPluginsForServer(const ChannelArgs& args);
 
  private:

src/core/lib/surface/legacy_channel.cc

@@ -93,10 +93,11 @@ absl::StatusOr<OrphanablePtr<Channel>> LegacyChannel::Create(
     *(*r)->stats_plugin_group =
         GlobalStatsPluginRegistry::GetStatsPluginsForServer(args);
   } else {
-    // TODO(roth): Figure out how to populate authority here.
-    // Or maybe just don't worry about this if no one needs it until after
-    // the call v3 stack lands.
-    StatsPlugin::ChannelScope scope(target, "");
+    experimental::StatsPluginChannelScope scope(
+        target, args.GetOwnedString(GRPC_ARG_DEFAULT_AUTHORITY)
+                    .value_or(CoreConfiguration::Get()
+                                  .resolver_registry()
+                                  .GetDefaultAuthority(target)));
     *(*r)->stats_plugin_group =
         GlobalStatsPluginRegistry::GetStatsPluginsForChannel(scope);
   }

src/cpp/ext/otel/otel_plugin.cc

@@ -172,14 +172,6 @@ OpenTelemetryPluginBuilderImpl::DisableAllMetrics() {
   return *this;
 }
 
-OpenTelemetryPluginBuilderImpl&
-OpenTelemetryPluginBuilderImpl::SetTargetSelector(
-    absl::AnyInvocable<bool(absl::string_view /*target*/) const>
-        target_selector) {
-  target_selector_ = std::move(target_selector);
-  return *this;
-}
-
 OpenTelemetryPluginBuilderImpl&
 OpenTelemetryPluginBuilderImpl::SetTargetAttributeFilter(
     absl::AnyInvocable<bool(absl::string_view /*target*/) const>
@@ -222,17 +214,25 @@ OpenTelemetryPluginBuilderImpl::AddOptionalLabel(
   return *this;
 }
 
+OpenTelemetryPluginBuilderImpl&
+OpenTelemetryPluginBuilderImpl::SetChannelScopeFilter(
+    absl::AnyInvocable<
+        bool(const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+        channel_scope_filter) {
+  channel_scope_filter_ = std::move(channel_scope_filter);
+  return *this;
+}
+
 absl::Status OpenTelemetryPluginBuilderImpl::BuildAndRegisterGlobal() {
   if (meter_provider_ == nullptr) {
     return absl::OkStatus();
   }
   grpc_core::GlobalStatsPluginRegistry::RegisterStatsPlugin(
       std::make_shared<OpenTelemetryPlugin>(
-          metrics_, meter_provider_, std::move(target_selector_),
-          std::move(target_attribute_filter_),
+          metrics_, meter_provider_, std::move(target_attribute_filter_),
           std::move(generic_method_attribute_filter_),
           std::move(server_selector_), std::move(plugin_options_),
-          std::move(optional_label_keys_)));
+          std::move(optional_label_keys_), std::move(channel_scope_filter_)));
   return absl::OkStatus();
 }
 
@@ -240,8 +240,6 @@ OpenTelemetryPlugin::OpenTelemetryPlugin(
     const absl::flat_hash_set<std::string>& metrics,
     opentelemetry::nostd::shared_ptr<opentelemetry::metrics::MeterProvider>
         meter_provider,
-    absl::AnyInvocable<bool(absl::string_view /*target*/) const>
-        target_selector,
     absl::AnyInvocable<bool(absl::string_view /*target*/) const>
         target_attribute_filter,
     absl::AnyInvocable<bool(absl::string_view /*generic_method*/) const>
@@ -250,14 +248,17 @@ OpenTelemetryPlugin::OpenTelemetryPlugin(
         server_selector,
     std::vector<std::unique_ptr<InternalOpenTelemetryPluginOption>>
         plugin_options,
-    std::shared_ptr<std::set<absl::string_view>> optional_label_keys)
+    std::shared_ptr<std::set<absl::string_view>> optional_label_keys,
+    absl::AnyInvocable<
+        bool(const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+        channel_scope_filter)
     : meter_provider_(std::move(meter_provider)),
-      target_selector_(std::move(target_selector)),
       server_selector_(std::move(server_selector)),
       target_attribute_filter_(std::move(target_attribute_filter)),
       generic_method_attribute_filter_(
           std::move(generic_method_attribute_filter)),
-      plugin_options_(std::move(plugin_options)) {
+      plugin_options_(std::move(plugin_options)),
+      channel_scope_filter_(std::move(channel_scope_filter)) {
   auto meter = meter_provider_->GetMeter("grpc-c++", GRPC_CPP_VERSION_STRING);
   // Per-call metrics.
   if (metrics.contains(grpc::OpenTelemetryPluginBuilder::
@@ -427,8 +428,9 @@ OpenTelemetryPlugin::OpenTelemetryPlugin(
 }
 
 std::pair<bool, std::shared_ptr<grpc_core::StatsPlugin::ScopeConfig>>
-OpenTelemetryPlugin::IsEnabledForChannel(const ChannelScope& scope) const {
-  if (target_selector_ == nullptr || target_selector_(scope.target())) {
+OpenTelemetryPlugin::IsEnabledForChannel(
+    const OpenTelemetryPluginBuilder::ChannelScope& scope) const {
+  if (channel_scope_filter_ == nullptr || channel_scope_filter_(scope)) {
     return {true, std::make_shared<ClientScopeConfig>(this, scope)};
   }
   return {false, nullptr};
@@ -643,6 +645,13 @@ OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::AddOptionalLabel(
   return *this;
 }
 
+OpenTelemetryPluginBuilder& OpenTelemetryPluginBuilder::SetChannelScopeFilter(
+    absl::AnyInvocable<bool(const ChannelScope& /*scope*/) const>
+        channel_scope_filter) {
+  impl_->SetChannelScopeFilter(std::move(channel_scope_filter));
+  return *this;
+}
+
 absl::Status OpenTelemetryPluginBuilder::BuildAndRegisterGlobal() {
   return impl_->BuildAndRegisterGlobal();
 }

src/cpp/ext/otel/otel_plugin.h

@@ -140,11 +140,6 @@ class OpenTelemetryPluginBuilderImpl {
   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.
-  OpenTelemetryPluginBuilderImpl& SetTargetSelector(
-      absl::AnyInvocable<bool(absl::string_view /*target*/) const>
-          target_selector);
   // If set, \a server_selector is called per incoming call on the server
   // to decide whether to collect metrics on that call or not.
   // TODO(yashkt): We should only need to do this per server connection or even
@@ -173,6 +168,12 @@ class OpenTelemetryPluginBuilderImpl {
   // Records \a optional_label_key on all metrics that provide it.
   OpenTelemetryPluginBuilderImpl& AddOptionalLabel(
       absl::string_view optional_label_key);
+  // Set scope filter to choose which channels are recorded by this plugin.
+  // Server-side recording remains unaffected.
+  OpenTelemetryPluginBuilderImpl& SetChannelScopeFilter(
+      absl::AnyInvocable<
+          bool(const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+          channel_scope_filter);
   absl::Status BuildAndRegisterGlobal();
 
   const absl::flat_hash_set<std::string>& TestOnlyEnabledMetrics() {
@@ -185,7 +186,6 @@ class OpenTelemetryPluginBuilderImpl {
   absl::AnyInvocable<bool(absl::string_view /*target*/) const>
       target_attribute_filter_;
   absl::flat_hash_set<std::string> metrics_;
-  absl::AnyInvocable<bool(absl::string_view /*target*/) const> target_selector_;
   absl::AnyInvocable<bool(absl::string_view /*generic_method*/) const>
       generic_method_attribute_filter_;
   absl::AnyInvocable<bool(const grpc_core::ChannelArgs& /*args*/) const>
@@ -193,6 +193,9 @@ class OpenTelemetryPluginBuilderImpl {
   std::vector<std::unique_ptr<InternalOpenTelemetryPluginOption>>
       plugin_options_;
   std::shared_ptr<std::set<absl::string_view>> optional_label_keys_;
+  absl::AnyInvocable<bool(
+      const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+      channel_scope_filter_;
 };
 
 class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
@@ -201,8 +204,6 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
       const absl::flat_hash_set<std::string>& metrics,
       opentelemetry::nostd::shared_ptr<opentelemetry::metrics::MeterProvider>
           meter_provider,
-      absl::AnyInvocable<bool(absl::string_view /*target*/) const>
-          target_selector,
       absl::AnyInvocable<bool(absl::string_view /*target*/) const>
           target_attribute_filter,
       absl::AnyInvocable<bool(absl::string_view /*generic_method*/) const>
@@ -211,7 +212,10 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
           server_selector,
       std::vector<std::unique_ptr<InternalOpenTelemetryPluginOption>>
           plugin_options,
-      std::shared_ptr<std::set<absl::string_view>> optional_label_keys);
+      std::shared_ptr<std::set<absl::string_view>> optional_label_keys,
+      absl::AnyInvocable<
+          bool(const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+          channel_scope_filter);
 
  private:
   class ClientCallTracer;
@@ -273,7 +277,7 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
   class ClientScopeConfig : public grpc_core::StatsPlugin::ScopeConfig {
    public:
     ClientScopeConfig(const OpenTelemetryPlugin* otel_plugin,
-                      const ChannelScope& scope)
+                      const OpenTelemetryPluginBuilder::ChannelScope& scope)
         : active_plugin_options_view_(ActivePluginOptionsView::MakeForClient(
               scope.target(), otel_plugin)),
           filtered_target_(
@@ -333,7 +337,8 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
 
   // StatsPlugin:
   std::pair<bool, std::shared_ptr<grpc_core::StatsPlugin::ScopeConfig>>
-  IsEnabledForChannel(const ChannelScope& scope) const override;
+  IsEnabledForChannel(
+      const OpenTelemetryPluginBuilder::ChannelScope& scope) const override;
   std::pair<bool, std::shared_ptr<grpc_core::StatsPlugin::ScopeConfig>>
   IsEnabledForServer(const grpc_core::ChannelArgs& args) const override;
   void AddCounter(
@@ -409,7 +414,6 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
   std::vector<InstrumentData> instruments_data_;
   opentelemetry::nostd::shared_ptr<opentelemetry::metrics::MeterProvider>
       meter_provider_;
-  absl::AnyInvocable<bool(absl::string_view /*target*/) const> target_selector_;
   absl::AnyInvocable<bool(const grpc_core::ChannelArgs& /*args*/) const>
       server_selector_;
   absl::AnyInvocable<bool(absl::string_view /*target*/) const>
@@ -418,6 +422,9 @@ class OpenTelemetryPlugin : public grpc_core::StatsPlugin {
       generic_method_attribute_filter_;
   std::vector<std::unique_ptr<InternalOpenTelemetryPluginOption>>
       plugin_options_;
+  absl::AnyInvocable<bool(
+      const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+      channel_scope_filter_;
 };
 
 }  // namespace internal

test/core/channel/metrics_test.cc

@@ -29,6 +29,8 @@
 namespace grpc_core {
 namespace {
 
+using experimental::StatsPluginChannelScope;
+
 class MetricsTest : public ::testing::Test {
  public:
   void TearDown() override {
@@ -55,13 +57,13 @@ TEST_F(MetricsTest, UInt64Counter) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .AddCounter(uint64_counter_handle, 1, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .AddCounter(uint64_counter_handle, 2, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .AddCounter(uint64_counter_handle, 3, kLabelValues, kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetCounterValue(uint64_counter_handle, kLabelValues,
                                        kOptionalLabelValues),
@@ -92,15 +94,15 @@ TEST_F(MetricsTest, DoubleCounter) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .AddCounter(double_counter_handle, 1.23, kLabelValues,
                   kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .AddCounter(double_counter_handle, 2.34, kLabelValues,
                   kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .AddCounter(double_counter_handle, 3.45, kLabelValues,
                   kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetCounterValue(double_counter_handle, kLabelValues,
@@ -133,15 +135,15 @@ TEST_F(MetricsTest, UInt64Histogram) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .RecordHistogram(uint64_histogram_handle, 1, kLabelValues,
                        kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .RecordHistogram(uint64_histogram_handle, 2, kLabelValues,
                        kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .RecordHistogram(uint64_histogram_handle, 3, kLabelValues,
                        kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetHistogramValue(uint64_histogram_handle, kLabelValues,
@@ -174,15 +176,15 @@ TEST_F(MetricsTest, DoubleHistogram) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .RecordHistogram(double_histogram_handle, 1.23, kLabelValues,
                        kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .RecordHistogram(double_histogram_handle, 2.34, kLabelValues,
                        kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .RecordHistogram(double_histogram_handle, 3.45, kLabelValues,
                        kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetHistogramValue(double_histogram_handle, kLabelValues,
@@ -215,13 +217,13 @@ TEST_F(MetricsTest, Int64Gauge) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .SetGauge(int64_gauge_handle, 1, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .SetGauge(int64_gauge_handle, 2, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .SetGauge(int64_gauge_handle, 3, kLabelValues, kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetGaugeValue(int64_gauge_handle, kLabelValues,
                                      kOptionalLabelValues),
@@ -252,13 +254,13 @@ TEST_F(MetricsTest, DoubleGauge) {
   auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
   auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .SetGauge(double_gauge_handle, 1.23, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""))
+      StatsPluginChannelScope(kDomain2To4, ""))
       .SetGauge(double_gauge_handle, 2.34, kLabelValues, kOptionalLabelValues);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""))
+      StatsPluginChannelScope(kDomain3To4, ""))
       .SetGauge(double_gauge_handle, 3.45, kLabelValues, kOptionalLabelValues);
   EXPECT_THAT(plugin1->GetGaugeValue(double_gauge_handle, kLabelValues,
                                      kOptionalLabelValues),
@@ -295,7 +297,7 @@ TEST_F(MetricsTest, Int64CallbackGauge) {
   // label values.  The callbacks get used only by plugin1.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1");
   auto group1 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""));
+      StatsPluginChannelScope(kDomain3To4, ""));
   auto callback1 = group1.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(int64_gauge_handle, 1, kLabelValues,
@@ -356,7 +358,7 @@ TEST_F(MetricsTest, Int64CallbackGauge) {
   // Now register callbacks that hit both plugin1 and plugin2.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2");
   auto group2 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""));
+      StatsPluginChannelScope(kDomain2To4, ""));
   callback1 = group2.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(int64_gauge_handle, 3, kLabelValues,
@@ -417,7 +419,7 @@ TEST_F(MetricsTest, Int64CallbackGauge) {
   // Now register callbacks that hit all three plugins.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2, plugin3");
   auto group3 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""));
+      StatsPluginChannelScope(kDomain1To4, ""));
   callback1 = group3.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(int64_gauge_handle, 5, kLabelValues,
@@ -501,7 +503,7 @@ TEST_F(MetricsTest, DoubleCallbackGauge) {
   // label values.  The callbacks get used only by plugin1.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1");
   auto group1 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain3To4, ""));
+      StatsPluginChannelScope(kDomain3To4, ""));
   auto callback1 = group1.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(double_gauge_handle, 1.23, kLabelValues,
@@ -562,7 +564,7 @@ TEST_F(MetricsTest, DoubleCallbackGauge) {
   // Now register callbacks that hit both plugin1 and plugin2.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2");
   auto group2 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain2To4, ""));
+      StatsPluginChannelScope(kDomain2To4, ""));
   callback1 = group2.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(double_gauge_handle, 3.45, kLabelValues,
@@ -623,7 +625,7 @@ TEST_F(MetricsTest, DoubleCallbackGauge) {
   // Now register callbacks that hit all three plugins.
   gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2, plugin3");
   auto group3 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""));
+      StatsPluginChannelScope(kDomain1To4, ""));
   callback1 = group3.RegisterCallback(
       [&](CallbackMetricReporter& reporter) {
         reporter.Report(double_gauge_handle, 5.67, kLabelValues,
@@ -698,7 +700,7 @@ TEST_F(MetricsTest, DisableByDefaultMetricIsNotRecordedByFakeStatsPlugin) {
   constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
   auto plugin = MakeStatsPluginForTarget(kDomain1To4);
   GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-      StatsPlugin::ChannelScope(kDomain1To4, ""))
+      StatsPluginChannelScope(kDomain1To4, ""))
       .RecordHistogram(double_histogram_handle, 1.23, kLabelValues,
                        kOptionalLabelValues);
   EXPECT_EQ(plugin->GetHistogramValue(double_histogram_handle, kLabelValues,

test/core/util/fake_stats_plugin.cc

@@ -107,7 +107,7 @@ std::shared_ptr<FakeStatsPlugin> MakeStatsPluginForTarget(
     absl::string_view target_suffix) {
   return FakeStatsPluginBuilder()
       .SetChannelFilter(
-          [target_suffix](const StatsPlugin::ChannelScope& scope) {
+          [target_suffix](const experimental::StatsPluginChannelScope& scope) {
             return absl::EndsWith(scope.target(), target_suffix);
           })
       .BuildAndRegister();

test/core/util/fake_stats_plugin.h

@@ -207,7 +207,8 @@ class FakeStatsPlugin : public StatsPlugin {
   class ScopeConfig : public StatsPlugin::ScopeConfig {};
 
   explicit FakeStatsPlugin(
-      absl::AnyInvocable<bool(const ChannelScope& /*scope*/) const>
+      absl::AnyInvocable<
+          bool(const experimental::StatsPluginChannelScope& /*scope*/) const>
           channel_filter = nullptr,
       bool use_disabled_by_default_metrics = false)
       : channel_filter_(std::move(channel_filter)) {
@@ -269,7 +270,8 @@ class FakeStatsPlugin : public StatsPlugin {
   }
 
   std::pair<bool, std::shared_ptr<StatsPlugin::ScopeConfig>>
-  IsEnabledForChannel(const ChannelScope& scope) const override {
+  IsEnabledForChannel(
+      const experimental::StatsPluginChannelScope& scope) const override {
     if (channel_filter_ == nullptr || channel_filter_(scope)) {
       return {true, nullptr};
     }
@@ -658,7 +660,9 @@ class FakeStatsPlugin : public StatsPlugin {
     absl::flat_hash_map<std::string, T> storage_;
   };
 
-  absl::AnyInvocable<bool(const ChannelScope& /*scope*/) const> channel_filter_;
+  absl::AnyInvocable<bool(
+      const experimental::StatsPluginChannelScope& /*scope*/) const>
+      channel_filter_;
   // Instruments.
   Mutex mu_;
   absl::flat_hash_map<uint32_t, Counter<uint64_t>> uint64_counters_
@@ -684,7 +688,8 @@ class FakeStatsPlugin : public StatsPlugin {
 class FakeStatsPluginBuilder {
  public:
   FakeStatsPluginBuilder& SetChannelFilter(
-      absl::AnyInvocable<bool(const StatsPlugin::ChannelScope& /*scope*/) const>
+      absl::AnyInvocable<
+          bool(const experimental::StatsPluginChannelScope& /*scope*/) const>
           channel_filter) {
     channel_filter_ = std::move(channel_filter);
     return *this;
@@ -703,7 +708,8 @@ class FakeStatsPluginBuilder {
   }
 
  private:
-  absl::AnyInvocable<bool(const StatsPlugin::ChannelScope& /*scope*/) const>
+  absl::AnyInvocable<bool(
+      const experimental::StatsPluginChannelScope& /*scope*/) const>
       channel_filter_;
   bool use_disabled_by_default_metrics_ = false;
 };

test/cpp/ext/csm/metadata_exchange_test.cc

@@ -182,8 +182,9 @@ class MetadataExchangeTest
             .add_plugin_option(std::make_unique<MeshLabelsPluginOption>(
                 GetParam().GetTestResource().GetAttributes()))
             .set_labels_to_inject(std::move(labels_to_inject))
-            .set_target_selector(
-                [enable_client_side_injector](absl::string_view /*target*/) {
+            .set_channel_scope_filter(
+                [enable_client_side_injector](
+                    const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) {
                   return enable_client_side_injector;
                 })));
   }

test/cpp/ext/otel/otel_plugin_test.cc

@@ -384,14 +384,17 @@ TEST_F(OpenTelemetryPluginEnd2EndTest, NoMeterProviderRegistered) {
   SendRPC();
 }
 
-// Test that a channel selector returning true records metrics on the channel.
-TEST_F(OpenTelemetryPluginEnd2EndTest, TargetSelectorReturnsTrue) {
-  Init(
-      std::move(Options()
-                    .set_metric_names({grpc::OpenTelemetryPluginBuilder::
-                                           kClientAttemptStartedInstrumentName})
-                    .set_target_selector(
-                        [](absl::string_view /*target*/) { return true; })));
+// Test that a channel scope filter returning true records metrics on the
+// channel.
+TEST_F(OpenTelemetryPluginEnd2EndTest, ChannelScopeFilterReturnsTrue) {
+  Init(std::move(
+      Options()
+          .set_metric_names({grpc::OpenTelemetryPluginBuilder::
+                                 kClientAttemptStartedInstrumentName})
+          .set_channel_scope_filter(
+              [](const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) {
+                return true;
+              })));
   SendRPC();
   const char* kMetricName = "grpc.client.attempt.started";
   auto data = ReadCurrentMetricsData(
@@ -418,15 +421,17 @@ TEST_F(OpenTelemetryPluginEnd2EndTest, TargetSelectorReturnsTrue) {
   EXPECT_EQ(*target_value, canonical_server_address_);
 }
 
-// Test that a target selector returning false does not record metrics on the
-// channel.
-TEST_F(OpenTelemetryPluginEnd2EndTest, TargetSelectorReturnsFalse) {
-  Init(
-      std::move(Options()
-                    .set_metric_names({grpc::OpenTelemetryPluginBuilder::
-                                           kClientAttemptStartedInstrumentName})
-                    .set_target_selector(
-                        [](absl::string_view /*target*/) { return false; })));
+// Test that a channel scope filter returning false does not record metrics on
+// the channel.
+TEST_F(OpenTelemetryPluginEnd2EndTest, ChannelScopeFilterReturnsFalse) {
+  Init(std::move(
+      Options()
+          .set_metric_names({grpc::OpenTelemetryPluginBuilder::
+                                 kClientAttemptStartedInstrumentName})
+          .set_channel_scope_filter(
+              [](const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) {
+                return false;
+              })));
   SendRPC();
   auto data = ReadCurrentMetricsData(
       [&](const absl::flat_hash_map<
@@ -1024,14 +1029,18 @@ TEST_F(OpenTelemetryPluginNPCMetricsTest, RecordUInt64Counter) {
       kOptionalLabelKeys, /*enable_by_default=*/true);
   Init(std::move(Options()
                      .set_metric_names({kMetricName})
-                     .set_target_selector([](absl::string_view target) {
-                       return absl::StartsWith(target, "dns:///");
-                     })
+                     .set_channel_scope_filter(
+                         [](const OpenTelemetryPluginBuilder::ChannelScope&
+                                channel_scope) {
+                           return absl::StartsWith(channel_scope.target(),
+                                                   "dns:///");
+                         })
                      .add_optional_label(kOptionalLabelKeys[0])
                      .add_optional_label(kOptionalLabelKeys[1])));
   auto stats_plugins =
       grpc_core::GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-          grpc_core::StatsPlugin::ChannelScope("dns:///localhost:8080", ""));
+          grpc_core::experimental::StatsPluginChannelScope(
+              "dns:///localhost:8080", ""));
   for (auto v : kCounterValues) {
     stats_plugins.AddCounter(handle, v, kLabelValues, kOptionalLabelValues);
   }
@@ -1065,14 +1074,18 @@ TEST_F(OpenTelemetryPluginNPCMetricsTest, RecordDoubleCounter) {
       kOptionalLabelKeys, /*enable_by_default=*/false);
   Init(std::move(Options()
                      .set_metric_names({kMetricName})
-                     .set_target_selector([](absl::string_view target) {
-                       return absl::StartsWith(target, "dns:///");
-                     })
+                     .set_channel_scope_filter(
+                         [](const OpenTelemetryPluginBuilder::ChannelScope&
+                                channel_scope) {
+                           return absl::StartsWith(channel_scope.target(),
+                                                   "dns:///");
+                         })
                      .add_optional_label(kOptionalLabelKeys[0])
                      .add_optional_label(kOptionalLabelKeys[1])));
   auto stats_plugins =
       grpc_core::GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
-          grpc_core::StatsPlugin::ChannelScope("dns:///localhost:8080", ""));
+          grpc_core::experimental::StatsPluginChannelScope(
+              "dns:///localhost:8080", ""));
   for (auto v : kCounterValues) {
     stats_plugins.AddCounter(handle, v, kLabelValues, kOptionalLabelValues);
   }

test/cpp/ext/otel/otel_test_library.cc

@@ -207,7 +207,7 @@ OpenTelemetryPluginEnd2EndTest::BuildAndRegisterOpenTelemetryPlugin(
     meter_provider->AddMetricReader(reader);
     ot_builder.SetMeterProvider(std::move(meter_provider));
   }
-  ot_builder.SetTargetSelector(std::move(options.target_selector));
+  ot_builder.SetChannelScopeFilter(std::move(options.channel_scope_filter));
   ot_builder.SetServerSelector(std::move(options.server_selector));
   ot_builder.SetTargetAttributeFilter(
       std::move(options.target_attribute_filter));

test/cpp/ext/otel/otel_test_library.h

@@ -80,9 +80,11 @@ class OpenTelemetryPluginEnd2EndTest : public ::testing::Test {
       return *this;
     }
 
-    Options& set_target_selector(
-        absl::AnyInvocable<bool(absl::string_view /*target*/) const> func) {
-      target_selector = std::move(func);
+    Options& set_channel_scope_filter(
+        absl::AnyInvocable<bool(
+            const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+            func) {
+      channel_scope_filter = std::move(func);
       return *this;
     }
 
@@ -128,8 +130,9 @@ class OpenTelemetryPluginEnd2EndTest : public ::testing::Test {
     std::unique_ptr<grpc::internal::LabelsInjector> labels_injector;
     bool use_meter_provider = true;
     std::map<std::string, std::string> labels_to_inject;
-    absl::AnyInvocable<bool(absl::string_view /*target*/) const>
-        target_selector;
+    absl::AnyInvocable<bool(
+        const OpenTelemetryPluginBuilder::ChannelScope& /*scope*/) const>
+        channel_scope_filter;
     absl::AnyInvocable<bool(const grpc_core::ChannelArgs& /*channel_args*/)
                            const>
         server_selector;

tools/doxygen/Doxyfile.c++

@@ -939,6 +939,7 @@ include/grpc/support/cpu.h \
 include/grpc/support/json.h \
 include/grpc/support/log.h \
 include/grpc/support/log_windows.h \
+include/grpc/support/metrics.h \
 include/grpc/support/port_platform.h \
 include/grpc/support/string_util.h \
 include/grpc/support/sync.h \

tools/doxygen/Doxyfile.c++.internal

@@ -939,6 +939,7 @@ include/grpc/support/cpu.h \
 include/grpc/support/json.h \
 include/grpc/support/log.h \
 include/grpc/support/log_windows.h \
+include/grpc/support/metrics.h \
 include/grpc/support/port_platform.h \
 include/grpc/support/string_util.h \
 include/grpc/support/sync.h \

tools/doxygen/Doxyfile.core

@@ -872,6 +872,7 @@ include/grpc/support/cpu.h \
 include/grpc/support/json.h \
 include/grpc/support/log.h \
 include/grpc/support/log_windows.h \
+include/grpc/support/metrics.h \
 include/grpc/support/port_platform.h \
 include/grpc/support/string_util.h \
 include/grpc/support/sync.h \

tools/doxygen/Doxyfile.core.internal

@@ -872,6 +872,7 @@ include/grpc/support/cpu.h \
 include/grpc/support/json.h \
 include/grpc/support/log.h \
 include/grpc/support/log_windows.h \
+include/grpc/support/metrics.h \
 include/grpc/support/port_platform.h \
 include/grpc/support/string_util.h \
 include/grpc/support/sync.h \