[CONFIGURATION] File configuration - exemplar filter

CHANGELOG.md

@@ -48,6 +48,9 @@ Increment the:
 * [CONFIGURATION] File configuration - implement distribution
   [#3833](https://github.com/open-telemetry/opentelemetry-cpp/pull/3833)
 
+* [CONFIGURATION] File configuration - exemplar filter
+  [#3837](https://github.com/open-telemetry/opentelemetry-cpp/pull/3837)
+
 Breaking changes:
 
 * [CONFIGURATION] File configuration - remove zipkin

sdk/include/opentelemetry/sdk/configuration/configuration_parser.h

@@ -29,6 +29,7 @@
 #include "opentelemetry/sdk/configuration/double_array_attribute_value_configuration.h"
 #include "opentelemetry/sdk/configuration/double_attribute_value_configuration.h"
 #include "opentelemetry/sdk/configuration/drop_aggregation_configuration.h"
+#include "opentelemetry/sdk/configuration/exemplar_filter.h"
 #include "opentelemetry/sdk/configuration/explicit_bucket_histogram_aggregation_configuration.h"
 #include "opentelemetry/sdk/configuration/extension_log_record_exporter_configuration.h"
 #include "opentelemetry/sdk/configuration/extension_log_record_processor_configuration.h"
@@ -227,6 +228,9 @@ class ConfigurationParser
   InstrumentType ParseInstrumentType(const std::unique_ptr<DocumentNode> &node,
                                      const std::string &name) const;
 
+  ExemplarFilter ParseExemplarFilter(const std::unique_ptr<DocumentNode> &node,
+                                     const std::string &name) const;
+
   std::unique_ptr<ViewSelectorConfiguration> ParseViewSelectorConfiguration(
       const std::unique_ptr<DocumentNode> &node) const;
 

sdk/include/opentelemetry/sdk/configuration/exemplar_filter.h

@@ -0,0 +1,27 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <cstdint>
+
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace configuration
+{
+
+// YAML-SCHEMA: schema/meter_provider.yaml
+// YAML-NODE: ExemplarFilter
+enum class ExemplarFilter : std::uint8_t
+{
+  always_on,
+  always_off,
+  trace_based
+};
+
+}  // namespace configuration
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/configuration/meter_provider_configuration.h

@@ -6,6 +6,7 @@
 #include <memory>
 #include <vector>
 
+#include "opentelemetry/sdk/configuration/exemplar_filter.h"
 #include "opentelemetry/sdk/configuration/metric_reader_configuration.h"
 #include "opentelemetry/sdk/configuration/view_configuration.h"
 #include "opentelemetry/version.h"
@@ -16,14 +17,14 @@ namespace sdk
 namespace configuration
 {
 
-// YAML-SCHEMA: schema/meter_provider.json
+// YAML-SCHEMA: schema/meter_provider.yaml
 // YAML-NODE: MeterProvider
 class MeterProviderConfiguration
 {
 public:
   std::vector<std::unique_ptr<MetricReaderConfiguration>> readers;
   std::vector<std::unique_ptr<ViewConfiguration>> views;
-  // FIXME: exemplar_filter
+  ExemplarFilter exemplar_filter = ExemplarFilter::trace_based;
   // FIXME: meter_configurator
 };
 

sdk/src/configuration/configuration_parser.cc

@@ -38,6 +38,7 @@
 #include "opentelemetry/sdk/configuration/double_array_attribute_value_configuration.h"
 #include "opentelemetry/sdk/configuration/double_attribute_value_configuration.h"
 #include "opentelemetry/sdk/configuration/drop_aggregation_configuration.h"
+#include "opentelemetry/sdk/configuration/exemplar_filter.h"
 #include "opentelemetry/sdk/configuration/explicit_bucket_histogram_aggregation_configuration.h"
 #include "opentelemetry/sdk/configuration/extension_log_record_exporter_configuration.h"
 #include "opentelemetry/sdk/configuration/extension_log_record_processor_configuration.h"
@@ -1171,6 +1172,34 @@ InstrumentType ConfigurationParser::ParseInstrumentType(const std::unique_ptr<Do
   throw InvalidSchemaException(node->Location(), message);
 }
 
+ExemplarFilter ConfigurationParser::ParseExemplarFilter(const std::unique_ptr<DocumentNode> &node,
+                                                        const std::string &name) const
+{
+  if (name == "")
+  {
+    return ExemplarFilter::trace_based;
+  }
+
+  if (name == "always_on")
+  {
+    return ExemplarFilter::always_on;
+  }
+
+  if (name == "always_off")
+  {
+    return ExemplarFilter::always_off;
+  }
+
+  if (name == "trace_based")
+  {
+    return ExemplarFilter::trace_based;
+  }
+
+  std::string message("Illegal exemplar filter: ");
+  message.append(name);
+  throw InvalidSchemaException(node->Location(), message);
+}
+
 std::unique_ptr<ViewSelectorConfiguration> ConfigurationParser::ParseViewSelectorConfiguration(
     const std::unique_ptr<DocumentNode> &node) const
 {
@@ -1384,7 +1413,8 @@ std::unique_ptr<MeterProviderConfiguration> ConfigurationParser::ParseMeterProvi
     }
   }
 
-  // FIXME: exemplar_filter
+  std::string exemplar_filter = node->GetString("exemplar_filter", "trace_based");
+  model->exemplar_filter      = ParseExemplarFilter(node, exemplar_filter);
 
   // FIXME: meter_configurator/development
 

sdk/src/configuration/sdk_builder.cc

@@ -125,6 +125,7 @@
 #include "opentelemetry/sdk/logs/processor.h"
 #include "opentelemetry/sdk/logs/simple_log_record_processor_factory.h"
 #include "opentelemetry/sdk/metrics/aggregation/aggregation_config.h"
+#include "opentelemetry/sdk/metrics/exemplar/filter_type.h"
 #include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader_factory.h"
 #include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader_options.h"
 #include "opentelemetry/sdk/metrics/instruments.h"
@@ -155,6 +156,10 @@
 #include "opentelemetry/sdk/trace/tracer_provider_factory.h"
 #include "opentelemetry/version.h"
 
+#ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
+#  include "opentelemetry/sdk/configuration/exemplar_filter.h"
+#endif
+
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk
 {
@@ -1149,6 +1154,33 @@ static opentelemetry::sdk::metrics::InstrumentType ConvertInstrumentType(
   return sdk;
 }
 
+#ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
+
+static opentelemetry::sdk::metrics::ExemplarFilterType ConvertExemplarFilter(
+    enum opentelemetry::sdk::configuration::ExemplarFilter config)
+{
+  opentelemetry::sdk::metrics::ExemplarFilterType sdk{
+      opentelemetry::sdk::metrics::ExemplarFilterType::kTraceBased};
+
+  switch (config)
+  {
+    case opentelemetry::sdk::configuration::ExemplarFilter::always_on:
+      sdk = opentelemetry::sdk::metrics::ExemplarFilterType::kAlwaysOn;
+      break;
+    case opentelemetry::sdk::configuration::ExemplarFilter::always_off:
+      sdk = opentelemetry::sdk::metrics::ExemplarFilterType::kAlwaysOff;
+      break;
+    case opentelemetry::sdk::configuration::ExemplarFilter::trace_based:
+      sdk = opentelemetry::sdk::metrics::ExemplarFilterType::kTraceBased;
+      break;
+    default:
+      break;
+  }
+
+  return sdk;
+}
+#endif /* ENABLE_METRICS_EXEMPLAR_PREVIEW */
+
 std::unique_ptr<opentelemetry::sdk::metrics::PushMetricExporter>
 SdkBuilder::CreateOtlpHttpPushMetricExporter(
     const opentelemetry::sdk::configuration::OtlpHttpPushMetricExporterConfiguration *model) const
@@ -1500,6 +1532,17 @@ std::unique_ptr<opentelemetry::sdk::metrics::MeterProvider> SdkBuilder::CreateMe
     meter_context->AddMetricReader(metric_reader);
   }
 
+#ifdef ENABLE_METRICS_EXEMPLAR_PREVIEW
+  auto sdk_exemplar_filter = ConvertExemplarFilter(model->exemplar_filter);
+  meter_context->SetExemplarFilter(sdk_exemplar_filter);
+#else
+  /* Do not spam with warnings if disabled anyway. */
+  if (model->exemplar_filter != ExemplarFilter::always_off)
+  {
+    OTEL_INTERNAL_LOG_WARN("ENABLE_METRICS_EXEMPLAR_PREVIEW not set, ignoring exemplar filter");
+  }
+#endif /* ENABLE_METRICS_EXEMPLAR_PREVIEW */
+
   sdk = opentelemetry::sdk::metrics::MeterProviderFactory::Create(std::move(meter_context));
 
   return sdk;

sdk/test/configuration/yaml_metrics_test.cc

@@ -11,6 +11,7 @@
 #include "opentelemetry/sdk/configuration/cardinality_limits_configuration.h"
 #include "opentelemetry/sdk/configuration/configuration.h"
 #include "opentelemetry/sdk/configuration/default_histogram_aggregation.h"
+#include "opentelemetry/sdk/configuration/exemplar_filter.h"
 #include "opentelemetry/sdk/configuration/explicit_bucket_histogram_aggregation_configuration.h"
 #include "opentelemetry/sdk/configuration/grpc_tls_configuration.h"
 #include "opentelemetry/sdk/configuration/headers_configuration.h"
@@ -98,6 +99,8 @@ file_format: "1.0-metrics"
   auto config = DoParse(yaml);
   ASSERT_NE(config, nullptr);
   ASSERT_NE(config->meter_provider, nullptr);
+  ASSERT_EQ(config->meter_provider->exemplar_filter,
+            opentelemetry::sdk::configuration::ExemplarFilter::trace_based);
   ASSERT_EQ(config->meter_provider->readers.size(), 1);
   auto *reader = config->meter_provider->readers[0].get();
   ASSERT_NE(reader, nullptr);
@@ -133,11 +136,14 @@ file_format: "1.0-metrics"
           observable_gauge: 600
           observable_up_down_counter: 700
           up_down_counter: 800
+  exemplar_filter: always_on
 )";
 
   auto config = DoParse(yaml);
   ASSERT_NE(config, nullptr);
   ASSERT_NE(config->meter_provider, nullptr);
+  ASSERT_EQ(config->meter_provider->exemplar_filter,
+            opentelemetry::sdk::configuration::ExemplarFilter::always_on);
   ASSERT_EQ(config->meter_provider->readers.size(), 1);
   auto *reader = config->meter_provider->readers[0].get();
   ASSERT_NE(reader, nullptr);
@@ -170,11 +176,14 @@ file_format: "1.0-metrics"
     - pull:
         exporter:
           prometheus/development:
+  exemplar_filter: always_off
 )";
 
   auto config = DoParse(yaml);
   ASSERT_NE(config, nullptr);
   ASSERT_NE(config->meter_provider, nullptr);
+  ASSERT_EQ(config->meter_provider->exemplar_filter,
+            opentelemetry::sdk::configuration::ExemplarFilter::always_off);
   ASSERT_EQ(config->meter_provider->readers.size(), 1);
   auto *reader = config->meter_provider->readers[0].get();
   ASSERT_NE(reader, nullptr);
@@ -205,11 +214,14 @@ file_format: "1.0-metrics"
           observable_gauge: 600
           observable_up_down_counter: 700
           up_down_counter: 800
+  exemplar_filter: trace_based
 )";
 
   auto config = DoParse(yaml);
   ASSERT_NE(config, nullptr);
   ASSERT_NE(config->meter_provider, nullptr);
+  ASSERT_EQ(config->meter_provider->exemplar_filter,
+            opentelemetry::sdk::configuration::ExemplarFilter::trace_based);
   ASSERT_EQ(config->meter_provider->readers.size(), 1);
   auto *reader = config->meter_provider->readers[0].get();
   ASSERT_NE(reader, nullptr);