add ostream exporter and example

Author: ethandmd

examples/metrics_simple/metrics_ostream.cc

@@ -17,6 +17,7 @@
 #include "opentelemetry/sdk/metrics/instruments.h"
 #include "opentelemetry/sdk/metrics/meter_provider.h"
 #include "opentelemetry/sdk/metrics/meter_provider_factory.h"
+#include "opentelemetry/sdk/metrics/meter_context_factory.h"
 #include "opentelemetry/sdk/metrics/metric_reader.h"
 #include "opentelemetry/sdk/metrics/provider.h"
 #include "opentelemetry/sdk/metrics/push_metric_exporter.h"
@@ -56,9 +57,9 @@ void InitMetrics(const std::string &name)
   auto reader =
       metrics_sdk::PeriodicExportingMetricReaderFactory::Create(std::move(exporter), options);
 
-  auto provider = opentelemetry::sdk::metrics::MeterProviderFactory::Create();
-
-  provider->AddMetricReader(std::move(reader));
+  auto context = metrics_sdk::MeterContextFactory::Create();
+  context->AddMetricReader(std::move(reader));
+  auto provider = opentelemetry::sdk::metrics::MeterProviderFactory::Create(std::move(context));
 
   // counter view
   std::string counter_name = name + "_counter";
@@ -112,6 +113,28 @@ void InitMetrics(const std::string &name)
   provider->AddView(std::move(histogram_instrument_selector), std::move(histogram_meter_selector),
                     std::move(histogram_view));
 
+  // hisogram view with base2 exponential aggregation
+  std::string histogram_base2_name = name + "_exponential_histogram";
+  unit                            = "histogram-unit";
+  auto histogram_base2_instrument_selector = metrics_sdk::InstrumentSelectorFactory::Create(
+      metrics_sdk::InstrumentType::kHistogram, histogram_base2_name, unit);
+  auto histogram_base2_meter_selector = metrics_sdk::MeterSelectorFactory::Create(name, version,
+                                                                                   schema);
+  auto histogram_base2_aggregation_config = std::unique_ptr<metrics_sdk::Base2ExponentialHistogramAggregationConfig>(
+      new metrics_sdk::Base2ExponentialHistogramAggregationConfig);
+  histogram_base2_aggregation_config->max_scale_ = 3;
+  histogram_base2_aggregation_config->record_min_max_ = true;
+  histogram_base2_aggregation_config->max_buckets_ = 100;
+
+  std::shared_ptr<metrics_sdk::AggregationConfig> base2_aggregation_config(
+      std::move(histogram_base2_aggregation_config));
+
+  auto histogram_base2_view = metrics_sdk::ViewFactory::Create(
+      name, "description", unit, metrics_sdk::AggregationType::kBase2ExponentialHistogram,
+      base2_aggregation_config);
+
+  provider->AddView(std::move(histogram_base2_instrument_selector), std::move(histogram_base2_meter_selector), std::move(histogram_base2_view));
+
   std::shared_ptr<opentelemetry::metrics::MeterProvider> api_provider(std::move(provider));
 
   metrics_sdk::Provider::SetMeterProvider(api_provider);
@@ -147,6 +170,10 @@ int main(int argc, char **argv)
   {
     foo_library::histogram_example(name);
   }
+  else if (example_type == "exponential_histogram")
+  {
+    foo_library::histogram_exp_example(name);
+  }
 #if OPENTELEMETRY_ABI_VERSION_NO >= 2
   else if (example_type == "gauge")
   {
@@ -170,6 +197,7 @@ int main(int argc, char **argv)
     std::thread counter_example{&foo_library::counter_example, name};
     std::thread observable_counter_example{&foo_library::observable_counter_example, name};
     std::thread histogram_example{&foo_library::histogram_example, name};
+    std::thread histogram_exp_example{&foo_library::histogram_exp_example, name};
 #if OPENTELEMETRY_ABI_VERSION_NO >= 2
     std::thread gauge_example{&foo_library::gauge_example, name};
 #endif
@@ -181,6 +209,7 @@ int main(int argc, char **argv)
     counter_example.join();
     observable_counter_example.join();
     histogram_example.join();
+    histogram_exp_example.join();
 #if OPENTELEMETRY_ABI_VERSION_NO >= 2
     gauge_example.join();
 #endif

exporters/ostream/src/metric_exporter.cc

@@ -247,6 +247,37 @@ void OStreamMetricExporter::printPointData(const opentelemetry::sdk::metrics::Po
       sout_ << nostd::get<int64_t>(last_point_data.value_);
     }
   }
+  else if (nostd::holds_alternative<sdk::metrics::Base2ExponentialHistogramPointData>(point_data))
+  {
+    auto histogram_point_data =
+        nostd::get<sdk::metrics::Base2ExponentialHistogramPointData>(point_data);
+    sout_ << "\n  type: Base2ExponentialHistogramPointData";
+    sout_ << "\n  count: " << histogram_point_data.count_;
+    sout_ << "\n  sum: " << histogram_point_data.sum_;
+    sout_ << "\n  zero_count: " << histogram_point_data.zero_count_;
+    if (histogram_point_data.record_min_max_)
+    {
+        sout_ << "\n  min: " << histogram_point_data.min_;
+        sout_ << "\n  max: " << histogram_point_data.max_;
+    }
+    sout_ << "\n  scale: " << histogram_point_data.scale_;
+    sout_ << "\n  positive buckets: ";
+    if (!histogram_point_data.positive_buckets_.Empty())
+    {
+      for (auto i = histogram_point_data.positive_buckets_.StartIndex(); i <= histogram_point_data.positive_buckets_.EndIndex(); ++i)
+      {
+        sout_ << "\n\t" << i << ": " << histogram_point_data.positive_buckets_.Get(i);
+      }
+    }
+    sout_ << "\n  negative buckets: ";
+    if (!histogram_point_data.negative_buckets_.Empty())
+    {
+      for (auto i = histogram_point_data.negative_buckets_.StartIndex(); i <= histogram_point_data.negative_buckets_.EndIndex(); ++i)
+      {
+        sout_ << "\n\t" << i << ": " << histogram_point_data.negative_buckets_.Get(i);
+      }
+    }
+  }
 }
 
 void OStreamMetricExporter::printPointAttributes(