Metrics SDK: Filtering metrics attributes (#1191)

sdk/include/opentelemetry/sdk/common/attribute_utils.h

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <map>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -143,6 +144,56 @@ class AttributeMap : public std::unordered_map<std::string, OwnedAttributeValue>
 private:
   AttributeConverter converter_;
 };
+
+/**
+ * Class for storing attributes.
+ */
+class OrderedAttributeMap : public std::map<std::string, OwnedAttributeValue>
+{
+public:
+  // Contruct empty attribute map
+  OrderedAttributeMap() : std::map<std::string, OwnedAttributeValue>(){};
+
+  // Contruct attribute map and populate with attributes
+  OrderedAttributeMap(const opentelemetry::common::KeyValueIterable &attributes)
+      : OrderedAttributeMap()
+  {
+    attributes.ForEachKeyValue(
+        [&](nostd::string_view key, opentelemetry::common::AttributeValue value) noexcept {
+          SetAttribute(key, value);
+          return true;
+        });
+  }
+
+  // Construct map from initializer list by applying `SetAttribute` transform for every attribute
+  OrderedAttributeMap(
+      std::initializer_list<std::pair<nostd::string_view, opentelemetry::common::AttributeValue>>
+          attributes)
+      : OrderedAttributeMap()
+  {
+    for (auto &kv : attributes)
+    {
+      SetAttribute(kv.first, kv.second);
+    }
+  }
+
+  // Returns a reference to this map
+  const std::map<std::string, OwnedAttributeValue> &GetAttributes() const noexcept
+  {
+    return (*this);
+  }
+
+  // Convert non-owning key-value to owning std::string(key) and OwnedAttributeValue(value)
+  void SetAttribute(nostd::string_view key,
+                    const opentelemetry::common::AttributeValue &value) noexcept
+  {
+    (*this)[std::string(key)] = nostd::visit(converter_, value);
+  }
+
+private:
+  AttributeConverter converter_;
+};
+
 }  // namespace common
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/common/attributemap_hash.h

@@ -0,0 +1,62 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <iostream>
+#include <string>
+#include "opentelemetry/sdk/common/attribute_utils.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace common
+{
+
+template <class T>
+inline void GetHashForAttributeValue(size_t &seed, const T arg)
+{
+  std::hash<T> hasher;
+  // reference -
+  // https://www.boost.org/doc/libs/1_37_0/doc/html/hash/reference.html#boost.hash_combine
+  seed ^= hasher(arg) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+}
+
+template <class T>
+inline void GetHashForAttributeValue(size_t &seed, const std::vector<T> &arg)
+{
+  for (auto v : arg)
+  {
+    GetHashForAttributeValue<T>(seed, v);
+  }
+}
+
+struct GetHashForAttributeValueVisitor
+{
+  GetHashForAttributeValueVisitor(size_t &seed) : seed_(seed) {}
+  template <class T>
+  void operator()(T &v)
+  {
+    GetHashForAttributeValue(seed_, v);
+  }
+  size_t &seed_;
+};
+
+// Calculate hash of keys and values of attribute map
+inline size_t GetHashForAttributeMap(const OrderedAttributeMap &attribute_map)
+{
+  size_t seed = 0UL;
+  for (auto &kv : attribute_map)
+  {
+    std::hash<std::string> hasher;
+    // reference -
+    // https://www.boost.org/doc/libs/1_37_0/doc/html/hash/reference.html#boost.hash_combine
+    seed ^= hasher(kv.first) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+    nostd::visit(GetHashForAttributeValueVisitor(seed), kv.second);
+  }
+  return seed;
+}
+
+}  // namespace common
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/metrics/view/attributes_processor.h

@@ -9,15 +9,27 @@ namespace sdk
 {
 namespace metrics
 {
-using MetricAttributes = opentelemetry::sdk::common::AttributeMap;
+using MetricAttributes = opentelemetry::sdk::common::OrderedAttributeMap;
+
+/**
+ * The AttributesProcessor is responsible for customizing which
+ * attribute(s) are to be reported as metrics dimension(s).
+ */
 
 class AttributesProcessor
 {
 public:
+  // Process the metric instrument attributes.
+  // @returns The processed attributes
   virtual MetricAttributes process(
       const opentelemetry::common::KeyValueIterable &attributes) noexcept = 0;
 };
 
+/**
+ * DefaultAttributesProcessor returns copy of input instrument attributes without
+ * any modification.
+ */
+
 class DefaultAttributesProcessor : public AttributesProcessor
 {
   MetricAttributes process(
@@ -28,6 +40,39 @@ class DefaultAttributesProcessor : public AttributesProcessor
   }
 };
 
+/**
+ * FilteringAttributesProcessor  filters by allowed attribute names and drops any names
+ * that are not in the allow list.
+ */
+
+class FilteringAttributesProcessor : public AttributesProcessor
+{
+public:
+  FilteringAttributesProcessor(
+      const std::unordered_map<std::string, bool> allowed_attribute_keys = {})
+      : allowed_attribute_keys_(std::move(allowed_attribute_keys))
+  {}
+
+  MetricAttributes process(
+      const opentelemetry::common::KeyValueIterable &attributes) noexcept override
+  {
+    MetricAttributes result;
+    attributes.ForEachKeyValue(
+        [&](nostd::string_view key, opentelemetry::common::AttributeValue value) noexcept {
+          if (allowed_attribute_keys_.find(key.data()) != allowed_attribute_keys_.end())
+          {
+            result.SetAttribute(key, value);
+            return true;
+          }
+          return true;
+        });
+    return result;
+  }
+
+private:
+  std::unordered_map<std::string, bool> allowed_attribute_keys_;
+};
+
 }  // namespace metrics
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE

sdk/test/common/BUILD

@@ -127,3 +127,26 @@ cc_test(
         "@com_google_googletest//:gtest_main",
     ],
 )
+
+cc_test(
+    name = "attributemap_hash_test",
+    srcs = [
+        "attributemap_hash_test.cc",
+    ],
+    tags = ["test"],
+    deps = [
+        "//api",
+        "//sdk:headers",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+otel_cc_benchmark(
+    name = "attributemap_hash_benchmark",
+    srcs = ["attributemap_hash_benchmark.cc"],
+    tags = ["test"],
+    deps = [
+        "//api",
+        "//sdk:headers",
+    ],
+)

sdk/test/common/CMakeLists.txt

@@ -6,6 +6,7 @@ foreach(
   circular_buffer_range_test
   circular_buffer_test
   attribute_utils_test
+  attributemap_hash_test
   global_log_handle_test)
 
   add_executable(${testname} "${testname}.cc")
@@ -30,3 +31,7 @@ target_link_libraries(random_benchmark benchmark::benchmark
 add_executable(circular_buffer_benchmark circular_buffer_benchmark.cc)
 target_link_libraries(circular_buffer_benchmark benchmark::benchmark
                       ${CMAKE_THREAD_LIBS_INIT} opentelemetry_api)
+
+add_executable(attributemap_hash_benchmark attributemap_hash_benchmark.cc)
+target_link_libraries(attributemap_hash_benchmark benchmark::benchmark
+                      ${CMAKE_THREAD_LIBS_INIT} opentelemetry_common)

sdk/test/common/attribute_utils_test.cc

@@ -7,8 +7,15 @@
 
 TEST(AttributeMapTest, DefaultConstruction)
 {
-  opentelemetry::sdk::common::AttributeMap map;
-  EXPECT_EQ(map.GetAttributes().size(), 0);
+
+  opentelemetry::sdk::common::AttributeMap attribute_map;
+  EXPECT_EQ(attribute_map.GetAttributes().size(), 0);
+}
+
+TEST(OrderedAttributeMapTest, DefaultConstruction)
+{
+  opentelemetry::sdk::common::OrderedAttributeMap attribute_map;
+  EXPECT_EQ(attribute_map.GetAttributes().size(), 0);
 }
 
 TEST(AttributeMapTest, AttributesConstruction)
@@ -20,10 +27,27 @@ TEST(AttributeMapTest, AttributesConstruction)
       {keys[0], values[0]}, {keys[1], values[1]}, {keys[2], values[2]}};
 
   opentelemetry::common::KeyValueIterableView<std::map<std::string, int>> iterable(attributes);
-  opentelemetry::sdk::common::AttributeMap map(iterable);
+  opentelemetry::sdk::common::AttributeMap attribute_map(iterable);
+
+  for (int i = 0; i < kNumAttributes; i++)
+  {
+    EXPECT_EQ(opentelemetry::nostd::get<int>(attribute_map.GetAttributes().at(keys[i])), values[i]);
+  }
+}
+
+TEST(OrderedAttributeMapTest, AttributesConstruction)
+{
+  const int kNumAttributes              = 3;
+  std::string keys[kNumAttributes]      = {"attr1", "attr2", "attr3"};
+  int values[kNumAttributes]            = {15, 24, 37};
+  std::map<std::string, int> attributes = {
+      {keys[0], values[0]}, {keys[1], values[1]}, {keys[2], values[2]}};
+
+  opentelemetry::common::KeyValueIterableView<std::map<std::string, int>> iterable(attributes);
+  opentelemetry::sdk::common::OrderedAttributeMap attribute_map(iterable);
 
   for (int i = 0; i < kNumAttributes; i++)
   {
-    EXPECT_EQ(opentelemetry::nostd::get<int>(map.GetAttributes().at(keys[i])), values[i]);
+    EXPECT_EQ(opentelemetry::nostd::get<int>(attribute_map.GetAttributes().at(keys[i])), values[i]);
   }
 }

sdk/test/common/attributemap_hash_benchmark.cc

@@ -0,0 +1,22 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include <benchmark/benchmark.h>
+#include "opentelemetry/sdk/common/attributemap_hash.h"
+
+using namespace opentelemetry::sdk::common;
+namespace
+{
+void BM_AttributeMapHash(benchmark::State &state)
+{
+  OrderedAttributeMap map1 = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"},  {"k4", "v4"},
+                              {"k5", true}, {"k6", 12},   {"k7", 12.209}};
+  while (state.KeepRunning())
+  {
+    benchmark::DoNotOptimize(GetHashForAttributeMap(map1));
+  }
+}
+BENCHMARK(BM_AttributeMapHash);
+
+}  // namespace
+BENCHMARK_MAIN();

sdk/test/common/attributemap_hash_test.cc

@@ -0,0 +1,32 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "opentelemetry/sdk/common/attributemap_hash.h"
+#include <gtest/gtest.h>
+
+using namespace opentelemetry::sdk::common;
+TEST(AttributeMapHashTest, BasicTests)
+{
+  {
+    OrderedAttributeMap map1 = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"}};
+    OrderedAttributeMap map2 = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"}, {"k4", "v4"}};
+    OrderedAttributeMap map3 = {{"k3", "v3"}, {"k1", "v1"}, {"k2", "v2"}};
+
+    EXPECT_TRUE(GetHashForAttributeMap(map1) != 0);
+    EXPECT_TRUE(GetHashForAttributeMap(map1) == GetHashForAttributeMap(map1));
+    EXPECT_TRUE(GetHashForAttributeMap(map1) != GetHashForAttributeMap(map2));
+    EXPECT_TRUE(GetHashForAttributeMap(map1) == GetHashForAttributeMap(map3));
+  }
+
+  {
+    OrderedAttributeMap map1 = {{"k1", 10}, {"k2", true}, {"k3", 12.22}};
+    OrderedAttributeMap map2 = {{"k3", 12.22}, {"k1", 10}, {"k2", true}};
+    EXPECT_TRUE(GetHashForAttributeMap(map1) == GetHashForAttributeMap(map2));
+    EXPECT_TRUE(GetHashForAttributeMap(map1) != 0);
+  }
+
+  {
+    OrderedAttributeMap map1 = {};
+    EXPECT_TRUE(GetHashForAttributeMap(map1) == 0);
+  }
+}

sdk/test/metrics/BUILD

@@ -1,11 +1,46 @@
+load("//bazel:otel_cc_benchmark.bzl", "otel_cc_benchmark")
+
 cc_test(
     name = "meter_provider_sdk_test",
     srcs = [
         "meter_provider_sdk_test.cc",
     ],
+    tags = [
+        "metrics",
+        "test",
+    ],
     deps = [
         "//sdk/src/metrics",
         "//sdk/src/resource",
         "@com_google_googletest//:gtest_main",
     ],
 )
+
+cc_test(
+    name = "attributes_processor_test",
+    srcs = [
+        "attributes_processor_test.cc",
+    ],
+    tags = [
+        "metrics",
+        "test",
+    ],
+    deps = [
+        "//sdk/src/metrics",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+otel_cc_benchmark(
+    name = "attributes_processor_benchmark",
+    srcs = [
+        "attributes_processor_benchmark.cc",
+    ],
+    tags = [
+        "metrics",
+        "test",
+    ],
+    deps = [
+        "//sdk/src/metrics",
+    ],
+)