[Metrics SDK] Add support for Pull Metric Reader

CHANGELOG.md

@@ -15,6 +15,8 @@ Increment the:
 
 ## [Unreleased]
 
+* [Metrics SDK] Add support for Pull Metric Exporter [#1701](https://github.com/open-telemetry/opentelemetry-cpp/pull/1701)
+  which includes breaking change in the Metrics api.
 * [BUILD] Add CMake OTELCPP_MAINTAINER_MODE [#1650](https://github.com/open-telemetry/opentelemetry-cpp/pull/1650)
 * [SEMANTIC CONVENTIONS] Upgrade to version 1.14.0 [#1697](https://github.com/open-telemetry/opentelemetry-cpp/pull/1697)
 

examples/metrics_simple/README.md

@@ -24,7 +24,7 @@ Exporter which will print to stdout by default.
 The reader periodically collects metrics from the Aggregation Store and exports them.
 
     ```cpp
-    std::unique_ptr<metric_sdk::MetricExporter> exporter{new exportermetrics::OStreamMetricExporter};
+    std::unique_ptr<metric_sdk::PushMetricExporter> exporter{new exportermetrics::OStreamMetricExporter};
     std::unique_ptr<metric_sdk::MetricReader> reader{
         new metric_sdk::PeriodicExportingMetricReader(std::move(exporter), options)};
     ```

examples/metrics_simple/metrics_ostream.cc

@@ -29,7 +29,8 @@ namespace
 
 void initMetrics(const std::string &name)
 {
-  std::unique_ptr<metric_sdk::MetricExporter> exporter{new exportermetrics::OStreamMetricExporter};
+  std::unique_ptr<metric_sdk::PushMetricExporter> exporter{
+      new exportermetrics::OStreamMetricExporter};
 
   std::string version{"1.2.0"};
   std::string schema{"https://opentelemetry.io/schemas/1.2.0"};

examples/prometheus/README.md

@@ -24,15 +24,15 @@ The main difference between the [ostream-metrics](../metrics_simple/README.md)
 example with this one is that the line below is replaced:
 
 ```cpp
-std::unique_ptr<metric_sdk::MetricExporter> exporter{
+std::unique_ptr<metric_sdk::PushMetricExporter> exporter{
     new exportermetrics::OStreamMetricExporter};
 
 ```
 
 with
 
 ```cpp
-std::unique_ptr<metrics_sdk::MetricExporter> exporter{
+std::unique_ptr<metrics_sdk::PushMetricExporter> exporter{
     new metrics_exporter::PrometheusExporter(opts)};
 ```
 

examples/prometheus/main.cc

@@ -36,7 +36,7 @@ void initMetrics(const std::string &name, const std::string &addr)
   }
   std::puts("PrometheusExporter example program running ...");
 
-  std::unique_ptr<metrics_sdk::MetricExporter> exporter{
+  std::unique_ptr<metrics_sdk::PushMetricExporter> exporter{
       new metrics_exporter::PrometheusExporter(opts)};
 
   std::string version{"1.2.0"};

exporters/ostream/include/opentelemetry/exporters/ostream/metric_exporter.h

@@ -9,7 +9,7 @@
 #  include "opentelemetry/common/spin_lock_mutex.h"
 #  include "opentelemetry/sdk/metrics/data/metric_data.h"
 #  include "opentelemetry/sdk/metrics/instruments.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 #  include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -21,7 +21,7 @@ namespace metrics
 /**
  * The OStreamMetricExporter exports record data through an ostream
  */
-class OStreamMetricExporter final : public opentelemetry::sdk::metrics::MetricExporter
+class OStreamMetricExporter final : public opentelemetry::sdk::metrics::PushMetricExporter
 {
 public:
   /**

exporters/ostream/test/ostream_metric_test.cc

@@ -23,7 +23,7 @@ namespace exportermetrics = opentelemetry::exporter::metrics;
 TEST(OStreamMetricsExporter, Shutdown)
 {
   auto exporter =
-      std::unique_ptr<metric_sdk::MetricExporter>(new exportermetrics::OStreamMetricExporter);
+      std::unique_ptr<metric_sdk::PushMetricExporter>(new exportermetrics::OStreamMetricExporter);
   ASSERT_TRUE(exporter->Shutdown());
   auto result = exporter->Export(metric_sdk::ResourceMetrics{});
   EXPECT_EQ(result, opentelemetry::sdk::common::ExportResult::kFailure);
@@ -32,7 +32,7 @@ TEST(OStreamMetricsExporter, Shutdown)
 TEST(OStreamMetricsExporter, ExportSumPointData)
 {
   auto exporter =
-      std::unique_ptr<metric_sdk::MetricExporter>(new exportermetrics::OStreamMetricExporter);
+      std::unique_ptr<metric_sdk::PushMetricExporter>(new exportermetrics::OStreamMetricExporter);
 
   metric_sdk::SumPointData sum_point_data{};
   sum_point_data.value_ = 10.0;
@@ -95,7 +95,7 @@ TEST(OStreamMetricsExporter, ExportSumPointData)
 TEST(OStreamMetricsExporter, ExportHistogramPointData)
 {
   auto exporter =
-      std::unique_ptr<metric_sdk::MetricExporter>(new exportermetrics::OStreamMetricExporter);
+      std::unique_ptr<metric_sdk::PushMetricExporter>(new exportermetrics::OStreamMetricExporter);
 
   metric_sdk::HistogramPointData histogram_point_data{};
   histogram_point_data.boundaries_ = std::list<double>{10.1, 20.2, 30.2};
@@ -177,7 +177,7 @@ TEST(OStreamMetricsExporter, ExportHistogramPointData)
 TEST(OStreamMetricsExporter, ExportLastValuePointData)
 {
   auto exporter =
-      std::unique_ptr<metric_sdk::MetricExporter>(new exportermetrics::OStreamMetricExporter);
+      std::unique_ptr<metric_sdk::PushMetricExporter>(new exportermetrics::OStreamMetricExporter);
 
   metric_sdk::ResourceMetrics data;
   auto resource = opentelemetry::sdk::resource::Resource::Create(
@@ -246,7 +246,7 @@ TEST(OStreamMetricsExporter, ExportLastValuePointData)
 TEST(OStreamMetricsExporter, ExportDropPointData)
 {
   auto exporter =
-      std::unique_ptr<metric_sdk::MetricExporter>(new exportermetrics::OStreamMetricExporter);
+      std::unique_ptr<metric_sdk::PushMetricExporter>(new exportermetrics::OStreamMetricExporter);
 
   metric_sdk::ResourceMetrics data;
   auto resource = opentelemetry::sdk::resource::Resource::Create(

exporters/otlp/include/opentelemetry/exporters/otlp/otlp_grpc_metric_exporter.h

@@ -15,7 +15,7 @@
 
 #  include "opentelemetry/exporters/otlp/otlp_environment.h"
 #  include "opentelemetry/exporters/otlp/otlp_grpc_metric_exporter_options.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace exporter
@@ -26,7 +26,7 @@ namespace otlp
 /**
  * The OTLP exporter exports metrics data in OpenTelemetry Protocol (OTLP) format in gRPC.
  */
-class OtlpGrpcMetricExporter : public opentelemetry::sdk::metrics::MetricExporter
+class OtlpGrpcMetricExporter : public opentelemetry::sdk::metrics::PushMetricExporter
 {
 public:
   /**

exporters/otlp/include/opentelemetry/exporters/otlp/otlp_grpc_metric_exporter_factory.h

@@ -6,7 +6,7 @@
 #ifndef ENABLE_METRICS_PREVIEW
 
 #  include "opentelemetry/exporters/otlp/otlp_grpc_metric_exporter_options.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace exporter
@@ -23,12 +23,12 @@ class OtlpGrpcMetricExporterFactory
   /**
    * Create a OtlpGrpcMetricExporter.
    */
-  static std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> Create();
+  static std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> Create();
 
   /**
    * Create a OtlpGrpcMetricExporter.
    */
-  static std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> Create(
+  static std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> Create(
       const OtlpGrpcMetricExporterOptions &options);
 };
 

exporters/otlp/include/opentelemetry/exporters/otlp/otlp_http_metric_exporter.h

@@ -4,7 +4,7 @@
 #pragma once
 #ifndef ENABLE_METRICS_PREVIEW
 
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
 #  include "opentelemetry/exporters/otlp/otlp_environment.h"
 #  include "opentelemetry/exporters/otlp/otlp_http_client.h"
@@ -24,7 +24,7 @@ namespace otlp
 /**
  * The OTLP exporter exports metrics data in OpenTelemetry Protocol (OTLP) format in HTTP.
  */
-class OtlpHttpMetricExporter final : public opentelemetry::sdk::metrics::MetricExporter
+class OtlpHttpMetricExporter final : public opentelemetry::sdk::metrics::PushMetricExporter
 {
 public:
   /**

exporters/otlp/include/opentelemetry/exporters/otlp/otlp_http_metric_exporter_factory.h

@@ -5,7 +5,7 @@
 #ifndef ENABLE_METRICS_PREVIEW
 
 #  include "opentelemetry/exporters/otlp/otlp_http_metric_exporter_options.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
 #  include <memory>
 
@@ -24,12 +24,12 @@ class OtlpHttpMetricExporterFactory
   /**
    * Create a OtlpHttpMetricExporter.
    */
-  static std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> Create();
+  static std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> Create();
 
   /**
    * Create a OtlpHttpMetricExporter.
    */
-  static std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> Create(
+  static std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> Create(
       const OtlpHttpMetricExporterOptions &options);
 };
 

exporters/otlp/src/otlp_grpc_metric_exporter_factory.cc

@@ -15,16 +15,17 @@ namespace exporter
 namespace otlp
 {
 
-std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> OtlpGrpcMetricExporterFactory::Create()
+std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>
+OtlpGrpcMetricExporterFactory::Create()
 {
   OtlpGrpcMetricExporterOptions options;
   return Create(options);
 }
 
-std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> OtlpGrpcMetricExporterFactory::Create(
-    const OtlpGrpcMetricExporterOptions &options)
+std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>
+OtlpGrpcMetricExporterFactory::Create(const OtlpGrpcMetricExporterOptions &options)
 {
-  std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> exporter(
+  std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> exporter(
       new OtlpGrpcMetricExporter(options));
   return exporter;
 }

exporters/otlp/src/otlp_http_metric_exporter_factory.cc

@@ -13,16 +13,17 @@ namespace exporter
 namespace otlp
 {
 
-std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> OtlpHttpMetricExporterFactory::Create()
+std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>
+OtlpHttpMetricExporterFactory::Create()
 {
   OtlpHttpMetricExporterOptions options;
   return Create(options);
 }
 
-std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> OtlpHttpMetricExporterFactory::Create(
-    const OtlpHttpMetricExporterOptions &options)
+std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>
+OtlpHttpMetricExporterFactory::Create(const OtlpHttpMetricExporterOptions &options)
 {
-  std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> exporter(
+  std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> exporter(
       new OtlpHttpMetricExporter(options));
   return exporter;
 }

exporters/otlp/test/otlp_grpc_metric_exporter_factory_test.cc

@@ -27,7 +27,7 @@ TEST(OtlpGrpcMetricExporterFactory, BuildTest)
   OtlpGrpcMetricExporterOptions opts;
   opts.endpoint = "localhost:45454";
 
-  std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> exporter =
+  std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> exporter =
       OtlpGrpcMetricExporterFactory::Create(opts);
 
   EXPECT_TRUE(exporter != nullptr);

exporters/otlp/test/otlp_http_metric_exporter_factory_test.cc

@@ -35,7 +35,7 @@ TEST(OtlpHttpMetricExporterFactory, BuildTest)
   OtlpHttpMetricExporterOptions opts;
   opts.url = "localhost:45454";
 
-  std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> exporter =
+  std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> exporter =
       OtlpHttpMetricExporterFactory::Create(opts);
 
   EXPECT_TRUE(exporter != nullptr);

exporters/otlp/test/otlp_http_metric_exporter_test.cc

@@ -78,10 +78,10 @@ namespace http_client = opentelemetry::ext::http::client;
 class OtlpHttpMetricExporterTestPeer : public ::testing::Test
 {
 public:
-  std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter> GetExporter(
+  std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter> GetExporter(
       std::unique_ptr<OtlpHttpClient> http_client)
   {
-    return std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter>(
+    return std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>(
         new OtlpHttpMetricExporter(std::move(http_client)));
   }
 
@@ -734,8 +734,8 @@ class OtlpHttpMetricExporterTestPeer : public ::testing::Test
 
 TEST(OtlpHttpMetricExporterTest, Shutdown)
 {
-  auto exporter =
-      std::unique_ptr<opentelemetry::sdk::metrics::MetricExporter>(new OtlpHttpMetricExporter());
+  auto exporter = std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>(
+      new OtlpHttpMetricExporter());
   ASSERT_TRUE(exporter->Shutdown());
   auto result = exporter->Export(opentelemetry::sdk::metrics::ResourceMetrics{});
   EXPECT_EQ(result, opentelemetry::sdk::common::ExportResult::kFailure);

exporters/prometheus/include/opentelemetry/exporters/prometheus/exporter.h

@@ -12,7 +12,7 @@
 #  include "opentelemetry/exporters/prometheus/collector.h"
 #  include "opentelemetry/nostd/span.h"
 #  include "opentelemetry/sdk/common/env_variables.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 #  include "opentelemetry/version.h"
 
 /**
@@ -46,7 +46,7 @@ struct PrometheusExporterOptions
   std::string url = GetPrometheusDefaultHttpEndpoint();
 };
 
-class PrometheusExporter : public sdk::metrics::MetricExporter
+class PrometheusExporter : public sdk::metrics::PushMetricExporter
 {
 public:
   /**

sdk/include/opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader.h

@@ -18,7 +18,7 @@ namespace sdk
 namespace metrics
 {
 
-class MetricExporter;
+class PushMetricExporter;
 /**
  * Struct to hold PeriodicExortingMetricReader options.
  */
@@ -40,7 +40,7 @@ class PeriodicExportingMetricReader : public MetricReader
 {
 
 public:
-  PeriodicExportingMetricReader(std::unique_ptr<MetricExporter> exporter,
+  PeriodicExportingMetricReader(std::unique_ptr<PushMetricExporter> exporter,
                                 const PeriodicExportingMetricReaderOptions &option);
 
   AggregationTemporality GetAggregationTemporality(
@@ -53,7 +53,7 @@ class PeriodicExportingMetricReader : public MetricReader
 
   void OnInitialized() noexcept override;
 
-  std::unique_ptr<MetricExporter> exporter_;
+  std::unique_ptr<PushMetricExporter> exporter_;
   std::chrono::milliseconds export_interval_millis_;
   std::chrono::milliseconds export_timeout_millis_;
 

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

@@ -82,7 +82,7 @@ class MeterContext : public std::enable_shared_from_this<MeterContext>
    * Note: This reader may not receive any in-flight meter data, but will get newly created meter
    * data. Note: This method is not thread safe, and should ideally be called from main thread.
    */
-  void AddMetricReader(std::unique_ptr<MetricReader> reader) noexcept;
+  void AddMetricReader(std::shared_ptr<MetricReader> reader) noexcept;
 
   /**
    * Attaches a View to list of configured Views for this Meter context.

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

@@ -61,7 +61,7 @@ class MeterProvider final : public opentelemetry::metrics::MeterProvider
    * Note: This reader may not receive any in-flight meter data, but will get newly created meter
    * data. Note: This method is not thread safe, and should ideally be called from main thread.
    */
-  void AddMetricReader(std::unique_ptr<MetricReader> reader) noexcept;
+  void AddMetricReader(std::shared_ptr<MetricReader> reader) noexcept;
 
   /**
    * Attaches a View to list of configured Views for this Meter provider.

sdk/include/opentelemetry/sdk/metrics/metric_exporter.h → sdk/include/opentelemetry/sdk/metrics/push_metric_exporter.h

@@ -20,13 +20,13 @@ namespace metrics
 
 class MetricData;
 /**
- * MetricExporter defines the interface to be used by metrics libraries to
+ * PushMetricExporter defines the interface to be used by metrics libraries to
  *  push metrics data to the OpenTelemetry exporters.
  */
-class MetricExporter
+class PushMetricExporter
 {
 public:
-  virtual ~MetricExporter() = default;
+  virtual ~PushMetricExporter() = default;
 
   /**
    * Exports a batch of metrics data. This method must not be called

sdk/include/opentelemetry/sdk/metrics/state/metric_collector.h

@@ -34,7 +34,7 @@ class CollectorHandle
 class MetricCollector : public MetricProducer, public CollectorHandle
 {
 public:
-  MetricCollector(MeterContext *context, std::unique_ptr<MetricReader> metric_reader);
+  MetricCollector(MeterContext *context, std::shared_ptr<MetricReader> metric_reader);
 
   ~MetricCollector() override = default;
 

sdk/src/metrics/export/periodic_exporting_metric_reader.cc

@@ -4,7 +4,7 @@
 #ifndef ENABLE_METRICS_PREVIEW
 #  include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader.h"
 #  include "opentelemetry/sdk/common/global_log_handler.h"
-#  include "opentelemetry/sdk/metrics/metric_exporter.h"
+#  include "opentelemetry/sdk/metrics/push_metric_exporter.h"
 
 #  include <chrono>
 #  include <future>
@@ -16,7 +16,7 @@ namespace metrics
 {
 
 PeriodicExportingMetricReader::PeriodicExportingMetricReader(
-    std::unique_ptr<MetricExporter> exporter,
+    std::unique_ptr<PushMetricExporter> exporter,
     const PeriodicExportingMetricReaderOptions &option)
     : exporter_{std::move(exporter)},
       export_interval_millis_{option.export_interval_millis},