[Metrics] New Attribute Processor for Exclude list (open-telemetry#3633)

Author: nikhilbhatia08

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

@@ -80,7 +80,7 @@ class FilteringAttributesProcessor : public AttributesProcessor
     MetricAttributes result;
     attributes.ForEachKeyValue(
         [&](nostd::string_view key, opentelemetry::common::AttributeValue value) noexcept {
-          if (allowed_attribute_keys_.find(key.data()) != allowed_attribute_keys_.end())
+          if (allowed_attribute_keys_.find(std::string(key)) != allowed_attribute_keys_.end())
           {
             result.SetAttribute(key, value);
             return true;
@@ -94,13 +94,57 @@ class FilteringAttributesProcessor : public AttributesProcessor
 
   bool isPresent(nostd::string_view key) const noexcept override
   {
-    return (allowed_attribute_keys_.find(key.data()) != allowed_attribute_keys_.end());
+    return (allowed_attribute_keys_.find(std::string(key)) != allowed_attribute_keys_.end());
   }
 
 private:
   std::unordered_map<std::string, bool> allowed_attribute_keys_;
 };
 
+/**
+ * FilteringExcludeAttributeProcessor filters by exclude attribute list and drops names if they are
+ * present in the exclude list
+ */
+
+class FilteringExcludeAttributesProcessor : public AttributesProcessor
+{
+public:
+  FilteringExcludeAttributesProcessor(std::unordered_map<std::string, bool> &&exclude_list = {})
+      : exclude_list_(std::move(exclude_list))
+  {}
+
+  FilteringExcludeAttributesProcessor(
+      const std::unordered_map<std::string, bool> &exclude_list = {})
+      : exclude_list_(exclude_list)
+  {}
+
+  MetricAttributes process(
+      const opentelemetry::common::KeyValueIterable &attributes) const noexcept override
+  {
+    MetricAttributes result;
+    attributes.ForEachKeyValue(
+        [&](nostd::string_view key, opentelemetry::common::AttributeValue value) noexcept {
+          if (exclude_list_.find(std::string(key)) == exclude_list_.end())
+          {
+            result.SetAttribute(key, value);
+            return true;
+          }
+          return true;
+        });
+
+    result.UpdateHash();
+    return result;
+  }
+
+  bool isPresent(nostd::string_view key) const noexcept override
+  {
+    return (exclude_list_.find(std::string(key)) == exclude_list_.end());
+  }
+
+private:
+  std::unordered_map<std::string, bool> exclude_list_;
+};
+
 }  // namespace metrics
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE

sdk/test/metrics/attributes_processor_test.cc

@@ -51,3 +51,40 @@ TEST(AttributesProcessor, FilteringAllAttributesProcessor)
   auto filtered_attributes = attributes_processor.process(iterable);
   EXPECT_EQ(filter.size(), kNumFilterAttributes);
 }
+
+TEST(AttributesProcessor, FilteringExcludeAttributesProcessor)
+{
+  std::unordered_map<std::string, bool> filter = {
+      {"attr2", true}, {"attr4", true}, {"attr6", true}};
+  const int kNumAttributes              = 7;
+  std::string keys[kNumAttributes]      = {"attr1", "attr2", "attr3", "attr4",
+                                           "attr5", "attr6", "attr7"};
+  int values[kNumAttributes]            = {10, 20, 30, 40, 50, 60, 70};
+  std::map<std::string, int> attributes = {
+      {keys[0], values[0]}, {keys[1], values[1]}, {keys[2], values[2]}, {keys[3], values[3]},
+      {keys[4], values[4]}, {keys[5], values[5]}, {keys[6], values[6]}};
+  FilteringExcludeAttributesProcessor attributes_processor(filter);
+  opentelemetry::common::KeyValueIterableView<std::map<std::string, int>> iterable(attributes);
+  auto filtered_attributes = attributes_processor.process(iterable);
+  for (auto &e : filtered_attributes)
+  {
+    EXPECT_TRUE(filter.find(e.first) == filter.end());
+  }
+  int expected_filtered_attributes_size = 4;
+  EXPECT_EQ(filtered_attributes.size(), expected_filtered_attributes_size);
+}
+
+TEST(AttributesProcessor, FilteringExcludeAllAttributesProcessor)
+{
+  std::unordered_map<std::string, bool> filter = {};
+  const int kNumAttributes                     = 6;
+  std::string keys[kNumAttributes]      = {"attr1", "attr2", "attr3", "attr4", "attr5", "attr6"};
+  int values[kNumAttributes]            = {10, 20, 30, 40, 50, 60};
+  std::map<std::string, int> attributes = {{keys[0], values[0]}, {keys[1], values[1]},
+                                           {keys[2], values[2]}, {keys[3], values[3]},
+                                           {keys[4], values[4]}, {keys[5], values[5]}};
+  FilteringExcludeAttributesProcessor attributes_processor(filter);
+  opentelemetry::common::KeyValueIterableView<std::map<std::string, int>> iterable(attributes);
+  auto filtered_attributes = attributes_processor.process(iterable);
+  EXPECT_EQ(filtered_attributes.size(), kNumAttributes);
+}