deps: add support for exporting Summary via OTLP

PR-URL: #180
Reviewed-By: Rafael Gonzaga <[email protected]>
Reviewed-by: Trevor Norris <[email protected]>
PR-URL: #260
Reviewed-By: Juan José Arboleda <[email protected]>
PR-URL: #268

Author: santigimeno

deps/opentelemetry-cpp/exporters/otlp/include/opentelemetry/exporters/otlp/otlp_metric_utils.h

@@ -58,6 +58,9 @@ class OtlpMetricUtils
   static void ConvertGaugeMetric(const opentelemetry::sdk::metrics::MetricData &metric_data,
                                  proto::metrics::v1::Gauge *const gauge) noexcept;
 
+  static void ConvertSummaryMetric(const opentelemetry::sdk::metrics::MetricData &metric_data,
+                                   proto::metrics::v1::Summary *const summary) noexcept;
+
   static void PopulateInstrumentInfoMetrics(
       const opentelemetry::sdk::metrics::MetricData &metric_data,
       proto::metrics::v1::Metric *metric) noexcept;

deps/opentelemetry-cpp/exporters/otlp/src/otlp_metric_utils.cc

@@ -68,6 +68,11 @@ metric_sdk::AggregationType OtlpMetricUtils::GetAggregationType(
   {
     return metric_sdk::AggregationType::kLastValue;
   }
+  else if (nostd::holds_alternative<sdk::metrics::SummaryPointData>(
+               point_data_with_attributes.point_data))
+  {
+    return metric_sdk::AggregationType::kSummary;
+  }
   return metric_sdk::AggregationType::kDrop;
 }
 
@@ -207,6 +212,56 @@ void OtlpMetricUtils::ConvertGaugeMetric(const opentelemetry::sdk::metrics::Metr
   }
 }
 
+void OtlpMetricUtils::ConvertSummaryMetric(const metric_sdk::MetricData &metric_data,
+                                           proto::metrics::v1::Summary *const summary) noexcept
+{
+  auto start_ts = metric_data.start_ts.time_since_epoch().count();
+  auto ts       = metric_data.end_ts.time_since_epoch().count();
+  for (auto &point_data_with_attributes : metric_data.point_data_attr_)
+  {
+    proto::metrics::v1::SummaryDataPoint *proto_summary_point_data = summary->add_data_points();
+    proto_summary_point_data->set_start_time_unix_nano(start_ts);
+    proto_summary_point_data->set_time_unix_nano(ts);
+    auto summary_data = nostd::get<sdk::metrics::SummaryPointData>(point_data_with_attributes.point_data);
+
+    // sum
+    if ((nostd::holds_alternative<int64_t>(summary_data.sum_)))
+    {
+      // Use static_cast to avoid C4244 in MSVC
+      proto_summary_point_data->set_sum(
+          static_cast<double>(nostd::get<int64_t>(summary_data.sum_)));
+    }
+    else
+    {
+      proto_summary_point_data->set_sum(nostd::get<double>(summary_data.sum_));
+    }
+    // count
+    proto_summary_point_data->set_count(summary_data.count_);
+    // quantile values
+    for (auto &kv : summary_data.quantile_values_)
+    {
+      proto::metrics::v1::SummaryDataPoint::ValueAtQuantile *quantile =
+          proto_summary_point_data->add_quantile_values();
+      quantile->set_quantile(kv.first);
+      if ((nostd::holds_alternative<int64_t>(kv.second)))
+      {
+        // Use static_cast to avoid C4244 in MSVC
+        quantile->set_value(static_cast<double>(nostd::get<int64_t>(kv.second)));
+      }
+      else
+      {
+        quantile->set_value(nostd::get<double>(kv.second));
+      }
+    }
+    // set attributes
+    for (auto &kv_attr : point_data_with_attributes.attributes)
+    {
+      OtlpPopulateAttributeUtils::PopulateAttribute(proto_summary_point_data->add_attributes(),
+                                                    kv_attr.first, kv_attr.second);
+    }
+  }
+}
+
 void OtlpMetricUtils::PopulateInstrumentInfoMetrics(
     const opentelemetry::sdk::metrics::MetricData &metric_data,
     proto::metrics::v1::Metric *metric) noexcept
@@ -229,6 +284,10 @@ void OtlpMetricUtils::PopulateInstrumentInfoMetrics(
       ConvertGaugeMetric(metric_data, metric->mutable_gauge());
       break;
     }
+    case metric_sdk::AggregationType::kSummary: {
+      ConvertSummaryMetric(metric_data, metric->mutable_summary());
+      break;
+    }
     default:
       break;
   }
@@ -305,6 +364,8 @@ sdk::metrics::AggregationTemporality OtlpMetricUtils::DeltaTemporalitySelector(
     case sdk::metrics::InstrumentType::kUpDownCounter:
     case sdk::metrics::InstrumentType::kObservableUpDownCounter:
       return sdk::metrics::AggregationTemporality::kCumulative;
+    case sdk::metrics::InstrumentType::kSummary:
+      return sdk::metrics::AggregationTemporality::kUnspecified;
   }
   return sdk::metrics::AggregationTemporality::kUnspecified;
 }
@@ -329,6 +390,8 @@ sdk::metrics::AggregationTemporality OtlpMetricUtils::LowMemoryTemporalitySelect
     case sdk::metrics::InstrumentType::kUpDownCounter:
     case sdk::metrics::InstrumentType::kObservableUpDownCounter:
       return sdk::metrics::AggregationTemporality::kCumulative;
+    case sdk::metrics::InstrumentType::kSummary:
+      return sdk::metrics::AggregationTemporality::kUnspecified;
   }
   return sdk::metrics::AggregationTemporality::kUnspecified;
 }

deps/opentelemetry-cpp/sdk/include/opentelemetry/sdk/metrics/aggregation/default_aggregation.h

@@ -184,6 +184,8 @@ class DefaultAggregation
       case InstrumentType::kGauge:
       case InstrumentType::kObservableGauge:
         return AggregationType::kLastValue;
+      case InstrumentType::kSummary:
+        return AggregationType::kSummary;
       default:
         return AggregationType::kDrop;
     }

deps/opentelemetry-cpp/sdk/include/opentelemetry/sdk/metrics/data/metric_data.h

@@ -19,7 +19,7 @@ namespace metrics
 
 using PointAttributes = opentelemetry::sdk::common::OrderedAttributeMap;
 using PointType       = opentelemetry::nostd::
-    variant<SumPointData, HistogramPointData, LastValuePointData, DropPointData>;
+    variant<SumPointData, HistogramPointData, LastValuePointData, DropPointData, SummaryPointData>;
 
 struct PointDataAttributes
 {

deps/opentelemetry-cpp/sdk/include/opentelemetry/sdk/metrics/data/point_data.h

@@ -74,6 +74,20 @@ class DropPointData
   DropPointData &operator=(DropPointData &&) = default;
 };
 
+class SummaryPointData
+{
+public:
+// TODO: remove ctors and initializers when GCC<5 stops shipping on Ubuntu
+  SummaryPointData(SummaryPointData &&)            = default;
+  SummaryPointData(const SummaryPointData &)       = default;
+  SummaryPointData &operator=(SummaryPointData &&) = default;
+  SummaryPointData()                               = default;
+
+  uint64_t count_                 = {};
+  ValueType sum_                  = {};
+  std::unordered_map<double, ValueType> quantile_values_ = {};
+};
+
 }  // namespace metrics
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE

deps/opentelemetry-cpp/sdk/include/opentelemetry/sdk/metrics/instruments.h

@@ -22,7 +22,8 @@ enum class InstrumentType
   kObservableCounter,
   kObservableGauge,
   kObservableUpDownCounter,
-  kGauge
+  kGauge,
+  kSummary
 };
 
 enum class InstrumentClass
@@ -45,6 +46,7 @@ enum class AggregationType
   kHistogram,
   kLastValue,
   kSum,
+  kSummary,
   kDefault
 };