add base2 expo histo aggregation

Author: euroelessar

sdk/include/opentelemetry/sdk/metrics/aggregation/aggregation_config.h

@@ -24,6 +24,15 @@ class HistogramAggregationConfig : public AggregationConfig
   std::vector<double> boundaries_;
   bool record_min_max_ = true;
 };
+
+class Base2ExponentialHistogramAggregationConfig : public AggregationConfig
+{
+public:
+  size_t max_buckets_  = 160;
+  int32_t max_scale_   = 20;
+  bool record_min_max_ = true;
+};
+
 }  // namespace metrics
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/metrics/aggregation/base2_exponential_histogram_aggregation.h

@@ -0,0 +1,56 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "opentelemetry/common/spin_lock_mutex.h"
+#include "opentelemetry/sdk/metrics/aggregation/aggregation.h"
+#include "opentelemetry/sdk/metrics/aggregation/aggregation_config.h"
+#include "opentelemetry/sdk/metrics/aggregation/base2_exponential_histogram_indexer.h"
+
+#include <memory>
+#include <mutex>
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace metrics
+{
+
+class Base2ExponentialHistogramAggregation : public Aggregation
+{
+public:
+  Base2ExponentialHistogramAggregation(const AggregationConfig *aggregation_config = nullptr);
+  Base2ExponentialHistogramAggregation(const Base2ExponentialHistogramPointData &point_data);
+  Base2ExponentialHistogramAggregation(Base2ExponentialHistogramPointData &&point_data);
+
+
+  void Aggregate(int64_t value, const PointAttributes &attributes = {}) noexcept override;
+  void Aggregate(double value, const PointAttributes &attributes = {}) noexcept override;
+
+  /* Returns the result of merge of the existing aggregation with delta
+   * aggregation with same boundaries */
+  std::unique_ptr<Aggregation> Merge(const Aggregation &delta) const noexcept override;
+
+  /* Returns the new delta aggregation by comparing existing aggregation with
+   * next aggregation with same boundaries. Data points for `next` aggregation
+   * (sum , bucket-counts) should be more than the current aggregation - which
+   * is the normal scenario as measurements values are monotonic increasing.
+   */
+  std::unique_ptr<Aggregation> Diff(const Aggregation &next) const noexcept override;
+
+  PointType ToPoint() const noexcept override;
+
+private:
+  void AggregateIntoBuckets(AdaptingCircularBufferCounter *buckets, double value) noexcept;
+  void Downscale(uint32_t by) noexcept;
+
+  mutable opentelemetry::common::SpinLockMutex lock_;
+  Base2ExponentialHistogramPointData point_data_;
+  Base2ExponentialHistogramIndexer indexer_;
+  bool record_min_max_ = true;
+};
+
+}  // namespace metrics
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/metrics/aggregation/default_aggregation.h

@@ -6,6 +6,7 @@
 #include <memory>
 
 #include "opentelemetry/sdk/metrics/aggregation/aggregation.h"
+#include "opentelemetry/sdk/metrics/aggregation/base2_exponential_histogram_aggregation.h"
 #include "opentelemetry/sdk/metrics/aggregation/drop_aggregation.h"
 #include "opentelemetry/sdk/metrics/aggregation/histogram_aggregation.h"
 #include "opentelemetry/sdk/metrics/aggregation/lastvalue_aggregation.h"
@@ -80,6 +81,10 @@ class DefaultAggregation
           return std::unique_ptr<Aggregation>(new DoubleHistogramAggregation(aggregation_config));
         }
         break;
+      case AggregationType::kBase2ExponentialHistogram:
+        return std::unique_ptr<Aggregation>(
+            new Base2ExponentialHistogramAggregation(aggregation_config));
+        break;
       case AggregationType::kLastValue:
         if (instrument_descriptor.value_type_ == InstrumentValueType::kLong)
         {
@@ -139,6 +144,9 @@ class DefaultAggregation
           return std::unique_ptr<Aggregation>(
               new DoubleHistogramAggregation(nostd::get<HistogramPointData>(point_data)));
         }
+      case AggregationType::kBase2ExponentialHistogram:
+        return std::unique_ptr<Aggregation>(new Base2ExponentialHistogramAggregation(
+            nostd::get<Base2ExponentialHistogramPointData>(point_data)));
       case AggregationType::kLastValue:
         if (instrument_descriptor.value_type_ == InstrumentValueType::kLong)
         {

sdk/include/opentelemetry/sdk/metrics/data/metric_data.h

@@ -18,8 +18,11 @@ namespace metrics
 {
 
 using PointAttributes = opentelemetry::sdk::common::OrderedAttributeMap;
-using PointType       = opentelemetry::nostd::
-    variant<SumPointData, HistogramPointData, LastValuePointData, DropPointData>;
+using PointType       = opentelemetry::nostd::variant<SumPointData,
+                                                HistogramPointData,
+                                                Base2ExponentialHistogramPointData,
+                                                LastValuePointData,
+                                                DropPointData>;
 
 struct PointDataAttributes
 {

sdk/include/opentelemetry/sdk/metrics/data/point_data.h

@@ -7,6 +7,7 @@
 
 #include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/nostd/variant.h"
+#include "opentelemetry/sdk/metrics/data/circular_buffer.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -17,7 +18,8 @@ namespace metrics
 
 using ValueType = nostd::variant<int64_t, double>;
 
-// TODO: remove ctors and initializers from below classes when GCC<5 stops shipping on Ubuntu
+// TODO: remove ctors and initializers from below classes when GCC<5 stops
+// shipping on Ubuntu
 
 class SumPointData
 {
@@ -64,6 +66,28 @@ class HistogramPointData
   bool record_min_max_            = true;
 };
 
+class Base2ExponentialHistogramPointData
+{
+public:
+  // TODO: remove ctors and initializers when GCC<5 stops shipping on Ubuntu
+  Base2ExponentialHistogramPointData(Base2ExponentialHistogramPointData &&) = default;
+  Base2ExponentialHistogramPointData &operator=(Base2ExponentialHistogramPointData &&) = default;
+  Base2ExponentialHistogramPointData(const Base2ExponentialHistogramPointData &)       = default;
+  Base2ExponentialHistogramPointData()                                            = default;
+
+  uint64_t count_      = {};
+  double sum_          = {};
+  int32_t scale_       = {};
+  uint64_t zero_count_ = {};
+  AdaptingCircularBufferCounter positive_buckets_{0};
+  AdaptingCircularBufferCounter negative_buckets_{0};
+  double min_            = {};
+  double max_            = {};
+  double zero_threshold_ = {};
+  bool record_min_max_   = true;
+  size_t max_buckets_    = {};
+};
+
 class DropPointData
 {
 public:

sdk/include/opentelemetry/sdk/metrics/instruments.h

@@ -45,7 +45,8 @@ enum class AggregationType
   kHistogram,
   kLastValue,
   kSum,
-  kDefault
+  kDefault,
+  kBase2ExponentialHistogram
 };
 
 enum class AggregationTemporality

sdk/src/metrics/CMakeLists.txt

@@ -20,6 +20,7 @@ add_library(
   state/observable_registry.cc
   state/sync_metric_storage.cc
   state/temporal_metric_storage.cc
+  aggregation/base2_exponential_histogram_aggregation.cc
   aggregation/base2_exponential_histogram_indexer.cc
   aggregation/histogram_aggregation.cc
   aggregation/lastvalue_aggregation.cc