[API] Remove Meters (#2205)

CHANGELOG.md

@@ -21,12 +21,23 @@ Increment the:
 * [API] Remove include_trace_context
   [#2194](https://github.com/open-telemetry/opentelemetry-cpp/pull/2194)
 
+* [API] Remove Meters
+  [#2205](https://github.com/open-telemetry/opentelemetry-cpp/pull/2205)
+
 * [SDK] MeterProvider should own MeterContext, not share it
   [#2218](https://github.com/open-telemetry/opentelemetry-cpp/pull/2218)
 
 * [SDK] TracerProvider should own TracerContext, not share it
   [#2221](https://github.com/open-telemetry/opentelemetry-cpp/pull/2221)
 
+Important changes:
+
+* [API] Remove Meters
+  [#2205](https://github.com/open-telemetry/opentelemetry-cpp/pull/2205)
+  * The CMake option `WITH_REMOVE_METER_PREVIEW` was added.
+  * This option is experimental, and may change in the future.
+  * Enabling it is an ABI breaking change.
+
 Breaking changes:
 
 * [REMOVAL] Remove the jaeger exporter

CMakeLists.txt

@@ -197,6 +197,14 @@ option(WITH_OPENTRACING "Whether to include the Opentracing shim" OFF)
 option(OTELCPP_VERSIONED_LIBS "Whether to generate the versioned shared libs"
        OFF)
 
+#
+# This option is experimental, subject to change in the spec:
+#
+# * https://github.com/open-telemetry/opentelemetry-specification/issues/2232
+#
+option(WITH_REMOVE_METER_PREVIEW
+       "EXPERIMENTAL, ABI BREAKING: Allow to remove a meter" OFF)
+
 if(OTELCPP_VERSIONED_LIBS AND NOT BUILD_SHARED_LIBS)
   message(FATAL_ERROR "OTELCPP_VERSIONED_LIBS=ON requires BUILD_SHARED_LIBS=ON")
 endif()

api/CMakeLists.txt

@@ -98,6 +98,11 @@ if(WITH_ASYNC_EXPORT_PREVIEW)
   target_compile_definitions(opentelemetry_api INTERFACE ENABLE_ASYNC_EXPORT)
 endif()
 
+if(WITH_REMOVE_METER_PREVIEW)
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE ENABLE_REMOVE_METER_PREVIEW)
+endif()
+
 # A better place should be in sdk, not api
 if(WITH_OTLP_HTTP_SSL_PREVIEW)
   target_compile_definitions(opentelemetry_api

api/include/opentelemetry/metrics/meter_provider.h

@@ -29,6 +29,11 @@ class MeterProvider
   virtual nostd::shared_ptr<Meter> GetMeter(nostd::string_view library_name,
                                             nostd::string_view library_version = "",
                                             nostd::string_view schema_url      = "") noexcept = 0;
+#ifdef ENABLE_REMOVE_METER_PREVIEW
+  virtual void RemoveMeter(nostd::string_view library_name,
+                           nostd::string_view library_version = "",
+                           nostd::string_view schema_url      = "") noexcept = 0;
+#endif
 };
 }  // namespace metrics
 OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/metrics/noop.h

@@ -203,6 +203,13 @@ class NoopMeterProvider final : public MeterProvider
     return meter_;
   }
 
+#ifdef ENABLE_REMOVE_METER_PREVIEW
+  void RemoveMeter(nostd::string_view /* name */,
+                   nostd::string_view /* version */,
+                   nostd::string_view /* schema_url */) noexcept override
+  {}
+#endif
+
 private:
   nostd::shared_ptr<Meter> meter_;
 };

ci/do_ci.sh

@@ -106,6 +106,7 @@ elif [[ "$1" == "cmake.maintainer.sync.test" ]]; then
         -DWITH_OTLP_HTTP=ON \
         -DWITH_OTLP_HTTP_SSL_PREVIEW=ON \
         -DWITH_OTLP_HTTP_SSL_TLS_PREVIEW=ON \
+        -DWITH_REMOVE_METER_PREVIEW=ON \
         -DWITH_PROMETHEUS=ON \
         -DWITH_EXAMPLES=ON \
         -DWITH_EXAMPLES_HTTP=ON \
@@ -129,6 +130,7 @@ elif [[ "$1" == "cmake.maintainer.async.test" ]]; then
         -DWITH_OTLP_HTTP=ON \
         -DWITH_OTLP_HTTP_SSL_PREVIEW=ON \
         -DWITH_OTLP_HTTP_SSL_TLS_PREVIEW=ON \
+        -DWITH_REMOVE_METER_PREVIEW=ON \
         -DWITH_PROMETHEUS=ON \
         -DWITH_EXAMPLES=ON \
         -DWITH_EXAMPLES_HTTP=ON \
@@ -153,6 +155,7 @@ elif [[ "$1" == "cmake.maintainer.cpp11.async.test" ]]; then
         -DWITH_OTLP_HTTP=ON \
         -DWITH_OTLP_HTTP_SSL_PREVIEW=ON \
         -DWITH_OTLP_HTTP_SSL_TLS_PREVIEW=ON \
+        -DWITH_REMOVE_METER_PREVIEW=ON \
         -DWITH_PROMETHEUS=ON \
         -DWITH_EXAMPLES=ON \
         -DWITH_EXAMPLES_HTTP=ON \

exporters/otlp/test/otlp_grpc_log_record_exporter_test.cc

@@ -154,7 +154,7 @@ TEST_F(OtlpGrpcLogRecordExporterTestPeer, ExportIntegrationTest)
   std::unique_ptr<proto::collector::trace::v1::TraceService::StubInterface> trace_stub_interface(
       trace_mock_stub);
 
-  auto trace_provider = opentelemetry::nostd::shared_ptr<opentelemetry::v1::trace::TracerProvider>(
+  auto trace_provider = opentelemetry::nostd::shared_ptr<opentelemetry::trace::TracerProvider>(
       opentelemetry::sdk::trace::TracerProviderFactory::Create(
           opentelemetry::sdk::trace::SimpleSpanProcessorFactory::Create(
               GetExporter(trace_stub_interface))));
@@ -174,7 +174,7 @@ TEST_F(OtlpGrpcLogRecordExporterTestPeer, ExportIntegrationTest)
 
     auto logger = provider->GetLogger("test", "opentelelemtry_library", "", schema_url,
                                       {{"scope_key1", "scope_value"}, {"scope_key2", 2}});
-    std::unordered_map<std::string, opentelemetry::v1::common::AttributeValue> attributes;
+    std::unordered_map<std::string, opentelemetry::common::AttributeValue> attributes;
     attributes["service.name"]     = "unit_test_service";
     attributes["tenant.id"]        = "test_user";
     attributes["bool_value"]       = true;
@@ -197,7 +197,7 @@ TEST_F(OtlpGrpcLogRecordExporterTestPeer, ExportIntegrationTest)
   opentelemetry::trace::Provider::SetTracerProvider(
       opentelemetry::nostd::shared_ptr<opentelemetry::trace::TracerProvider>(
           new opentelemetry::trace::NoopTracerProvider()));
-  trace_provider = opentelemetry::nostd::shared_ptr<opentelemetry::v1::trace::TracerProvider>();
+  trace_provider = opentelemetry::nostd::shared_ptr<opentelemetry::trace::TracerProvider>();
 }
 
 }  // namespace otlp

sdk/include/opentelemetry/sdk/metrics/meter_context.h

@@ -115,6 +115,10 @@ class MeterContext : public std::enable_shared_from_this<MeterContext>
    */
   void AddMeter(std::shared_ptr<Meter> meter);
 
+  void RemoveMeter(nostd::string_view name,
+                   nostd::string_view version,
+                   nostd::string_view schema_url);
+
   /**
    * Force all active Collectors to flush any buffered meter data
    * within the given timeout.

sdk/include/opentelemetry/sdk/metrics/meter_provider.h

@@ -53,6 +53,12 @@ class MeterProvider final : public opentelemetry::metrics::MeterProvider
       nostd::string_view version    = "",
       nostd::string_view schema_url = "") noexcept override;
 
+#ifdef ENABLE_REMOVE_METER_PREVIEW
+  void RemoveMeter(nostd::string_view name,
+                   nostd::string_view version,
+                   nostd::string_view schema_url) noexcept override;
+#endif
+
   /**
    * Obtain the resource associated with this meter provider.
    * @return The resource for this meter provider.

sdk/src/metrics/meter_context.cc

@@ -3,6 +3,7 @@
 
 #include "opentelemetry/sdk/metrics/meter_context.h"
 #include "opentelemetry/sdk/common/global_log_handler.h"
+#include "opentelemetry/sdk/metrics/meter.h"
 #include "opentelemetry/sdk/metrics/metric_reader.h"
 #include "opentelemetry/sdk/metrics/state/metric_collector.h"
 #include "opentelemetry/sdk_config.h"
@@ -79,6 +80,32 @@ void MeterContext::AddMeter(std::shared_ptr<Meter> meter)
   meters_.push_back(meter);
 }
 
+void MeterContext::RemoveMeter(nostd::string_view name,
+                               nostd::string_view version,
+                               nostd::string_view schema_url)
+{
+  std::lock_guard<opentelemetry::common::SpinLockMutex> guard(meter_lock_);
+
+  std::vector<std::shared_ptr<Meter>> filtered_meters;
+
+  for (auto &meter : meters_)
+  {
+    auto scope = meter->GetInstrumentationScope();
+    if (scope->equal(name, version, schema_url))
+    {
+      OTEL_INTERNAL_LOG_INFO("[MeterContext::RemoveMeter] removing meter name <"
+                             << name << ">, version <" << version << ">, URL <" << schema_url
+                             << ">");
+    }
+    else
+    {
+      filtered_meters.push_back(meter);
+    }
+  }
+
+  meters_.swap(filtered_meters);
+}
+
 bool MeterContext::Shutdown() noexcept
 {
   bool result = true;

sdk/src/metrics/meter_provider.cc

@@ -59,6 +59,23 @@ nostd::shared_ptr<metrics_api::Meter> MeterProvider::GetMeter(
   return nostd::shared_ptr<metrics_api::Meter>{meter};
 }
 
+#ifdef ENABLE_REMOVE_METER_PREVIEW
+void MeterProvider::RemoveMeter(nostd::string_view name,
+                                nostd::string_view version,
+                                nostd::string_view schema_url) noexcept
+{
+  if (name.data() == nullptr || name == "")
+  {
+    OTEL_INTERNAL_LOG_WARN("[MeterProvider::RemoveMeter] Library name is empty.");
+    name = "";
+  }
+
+  const std::lock_guard<std::mutex> guard(lock_);
+
+  context_->RemoveMeter(name, version, schema_url);
+}
+#endif
+
 const resource::Resource &MeterProvider::GetResource() const noexcept
 {
   return context_->GetResource();

sdk/test/logs/log_record_test.cc

@@ -99,13 +99,13 @@ class TestBodyLogger : public opentelemetry::logs::Logger
     }
   }
 
-  const opentelemetry::v1::common::AttributeValue &GetLastLogRecord() const noexcept
+  const opentelemetry::common::AttributeValue &GetLastLogRecord() const noexcept
   {
     return last_body_;
   }
 
 private:
-  opentelemetry::v1::common::AttributeValue last_body_;
+  opentelemetry::common::AttributeValue last_body_;
 };
 
 // Define a basic LoggerProvider class that returns an instance of the logger class defined above

sdk/test/metrics/meter_provider_sdk_test.cc

@@ -16,7 +16,6 @@ using namespace opentelemetry::sdk::metrics;
 
 TEST(MeterProvider, GetMeter)
 {
-
   MeterProvider mp1;
   //   std::unique_ptr<View> view{std::unique_ptr<View>()};
   // MeterProvider mp1(std::move(exporters), std::move(readers), std::move(views);
@@ -59,3 +58,39 @@ TEST(MeterProvider, GetMeter)
   mp1.ForceFlush();
   mp1.Shutdown();
 }
+
+#ifdef ENABLE_REMOVE_METER_PREVIEW
+TEST(MeterProvider, RemoveMeter)
+{
+  MeterProvider mp;
+
+  auto m1 = mp.GetMeter("test", "1", "URL");
+  ASSERT_NE(nullptr, m1);
+
+  // Will return the same meter
+  auto m2 = mp.GetMeter("test", "1", "URL");
+  ASSERT_NE(nullptr, m2);
+  ASSERT_EQ(m1, m2);
+
+  mp.RemoveMeter("unknown", "0", "");
+
+  // Will decrease use_count() on m1 and m2
+  mp.RemoveMeter("test", "1", "URL");
+
+  // Will create a different meter
+  auto m3 = mp.GetMeter("test", "1", "URL");
+  ASSERT_NE(nullptr, m3);
+  ASSERT_NE(m1, m3);
+  ASSERT_NE(m2, m3);
+
+  // Will decrease use_count() on m3
+  mp.RemoveMeter("test", "1", "URL");
+
+  // Will do nothing
+  mp.RemoveMeter("test", "1", "URL");
+
+  // cleanup properly without crash
+  mp.ForceFlush();
+  mp.Shutdown();
+}
+#endif