Merge pull request #8 from open-telemetry/main

Fix observable attributes drop (open-telemetry#2557)

Author: malkia

examples/common/metrics_foo_library/foo_library.cc

@@ -40,9 +40,10 @@ class MeasurementFetcher
     {
       double random_incr = (rand() % 5) + 1.1;
       value_ += random_incr;
+      std::map<std::string, std::string> labels = get_random_attr();
       nostd::get<nostd::shared_ptr<opentelemetry::metrics::ObserverResultT<double>>>(
           observer_result)
-          ->Observe(value_ /*, labelkv */);
+          ->Observe(value_, labels);
     }
   }
   static double value_;

sdk/include/opentelemetry/sdk/metrics/observer_result.h

@@ -26,11 +26,15 @@ class ObserverResultT final : public opentelemetry::metrics::ObserverResultT<T>
 
   ~ObserverResultT() override = default;
 
-  void Observe(T value) noexcept override { data_.insert({{}, value}); }
+  void Observe(T value) noexcept override
+  {
+    data_[MetricAttributes{{}, attributes_processor_}] = value;
+  }
 
   void Observe(T value, const opentelemetry::common::KeyValueIterable &attributes) noexcept override
   {
-    data_.insert({MetricAttributes{attributes, attributes_processor_}, value});
+    data_[MetricAttributes{attributes, attributes_processor_}] =
+        value;  // overwrites the previous value if present
   }
 
   const std::unordered_map<MetricAttributes, T, AttributeHashGenerator> &GetMeasurements()

sdk/src/metrics/state/observable_registry.cc

@@ -50,6 +50,7 @@ void ObservableRegistry::CleanupCallback(opentelemetry::metrics::ObservableInstr
 
 void ObservableRegistry::Observe(opentelemetry::common::SystemTimestamp collection_ts)
 {
+  static DefaultAttributesProcessor default_attribute_processor;
   std::lock_guard<std::mutex> lock_guard{callbacks_m_};
   for (auto &callback_wrap : callbacks_)
   {
@@ -69,7 +70,7 @@ void ObservableRegistry::Observe(opentelemetry::common::SystemTimestamp collecti
     if (value_type == InstrumentValueType::kDouble)
     {
       nostd::shared_ptr<opentelemetry::metrics::ObserverResultT<double>> ob_res(
-          new opentelemetry::sdk::metrics::ObserverResultT<double>());
+          new opentelemetry::sdk::metrics::ObserverResultT<double>(&default_attribute_processor));
       callback_wrap->callback(ob_res, callback_wrap->state);
       storage->RecordDouble(
           static_cast<opentelemetry::sdk::metrics::ObserverResultT<double> *>(ob_res.get())
@@ -79,7 +80,7 @@ void ObservableRegistry::Observe(opentelemetry::common::SystemTimestamp collecti
     else
     {
       nostd::shared_ptr<opentelemetry::metrics::ObserverResultT<int64_t>> ob_res(
-          new opentelemetry::sdk::metrics::ObserverResultT<int64_t>());
+          new opentelemetry::sdk::metrics::ObserverResultT<int64_t>(&default_attribute_processor));
       callback_wrap->callback(ob_res, callback_wrap->state);
       storage->RecordLong(
           static_cast<opentelemetry::sdk::metrics::ObserverResultT<int64_t> *>(ob_res.get())