Fix open-telemetry#1588 - Observable Gauge does not reflect updated v…

…alues, and send the old value always (open-telemetry#1641)

examples/common/metrics_foo_library/foo_library.cc

@@ -39,13 +39,16 @@ class MeasurementFetcher
  if (nostd::holds_alternative<
  nostd::shared_ptr<opentelemetry::metrics::ObserverResultT<double>>>(observer_result))
  {
- double val = (rand() % 700) + 1.1;
+ double random_incr = (rand() % 5) + 1.1;
+ value_ += random_incr;
  nostd::get<nostd::shared_ptr<opentelemetry::metrics::ObserverResultT<double>>>(
  observer_result)
- ->Observe(val /*, labelkv */);
+ ->Observe(value_ /*, labelkv */);
  }
  }
+ static double value_;
 };
+double MeasurementFetcher::value_ = 0.0;
 } // namespace
 
 void foo_library::counter_example(const std::string &name)

examples/metrics_simple/metrics_ostream.cc

@@ -62,7 +62,7 @@ void initMetrics(const std::string &name)
  std::unique_ptr<metric_sdk::MeterSelector> observable_meter_selector{
  new metric_sdk::MeterSelector(name, version, schema)};
  std::unique_ptr<metric_sdk::View> observable_sum_view{
- new metric_sdk::View{name, "description", metric_sdk::AggregationType::kSum}};
+ new metric_sdk::View{name, "test_description", metric_sdk::AggregationType::kSum}};
  p->AddView(std::move(observable_instrument_selector), std::move(observable_meter_selector),
  std::move(observable_sum_view));
 

sdk/include/opentelemetry/sdk/metrics/state/async_metric_storage.h

@@ -43,7 +43,9 @@ class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStora
  void Record(const std::unordered_map<MetricAttributes, T, AttributeHashGenerator> &measurements,
  opentelemetry::common::SystemTimestamp /* observation_time */) noexcept
  {
- // process the read measurements - aggregate and store in hashmap
+ // Async counter always record monotonically increasing values, and the
+ // exporter/reader can request either for delta or cumulative value.
+ // So we convert the async counter value to delta before passing it to temporal storage.
  std::lock_guard<opentelemetry::common::SpinLockMutex> guard(hashmap_lock_);
  for (auto &measurement : measurements)
  {
@@ -53,13 +55,14 @@ class AsyncMetricStorage : public MetricStorage, public AsyncWritableMetricStora
  if (prev)
  {
  auto delta = prev->Diff(*aggr);
- cumulative_hash_map_->Set(measurement.first,
-  DefaultAggregation::CloneAggregation(
-  aggregation_type_, instrument_descriptor_, *delta));
+ // store received value in cumulative map, and the diff in delta map (to pass it to temporal
+ // storage)
+ cumulative_hash_map_->Set(measurement.first, std::move(aggr));
  delta_hash_map_->Set(measurement.first, std::move(delta));
  }
  else
  {
+ // store received value in cumulative and delta map.
  cumulative_hash_map_->Set(
  measurement.first,
  DefaultAggregation::CloneAggregation(aggregation_type_, instrument_descriptor_, *aggr));

sdk/src/metrics/meter.cc

@@ -293,7 +293,6 @@ std::unique_ptr<AsyncWritableMetricStorage> Meter::RegisterAsyncMetricStorage(
 std::vector<MetricData> Meter::Collect(CollectorHandle *collector,
  opentelemetry::common::SystemTimestamp collect_ts) noexcept
 {
-
  observable_registry_->Observe(collect_ts);
  std::vector<MetricData> metric_data_list;
  auto ctx = meter_context_.lock();

sdk/src/metrics/state/temporal_metric_storage.cc

@@ -34,6 +34,7 @@ bool TemporalMetricStorage::buildMetrics(CollectorHandle *collector,
  opentelemetry::common::SystemTimestamp last_collection_ts = sdk_start_ts;
  AggregationTemporality aggregation_temporarily =
  collector->GetAggregationTemporality(instrument_descriptor_.type_);
+
  if (delta_metrics->Size())
  {
  for (auto &col : collectors)

sdk/test/metrics/async_metric_storage_test.cc

@@ -107,12 +107,12 @@ TEST_P(WritableMetricStorageTestFixture, TestAggregation)
  opentelemetry::sdk::metrics::AsyncMetricStorage storage(
  instr_desc, AggregationType::kSum, default_attributes_processor.get(),
  std::shared_ptr<opentelemetry::sdk::metrics::AggregationConfig>{});
- long get_count = 20l;
- long put_count = 10l;
- size_t attribute_count = 2;
- std::unordered_map<MetricAttributes, long, AttributeHashGenerator> measurements = {
- {{{"RequestType", "GET"}}, get_count}, {{{"RequestType", "PUT"}}, put_count}};
- storage.RecordLong(measurements,
+ long get_count1 = 20l;
+ long put_count1 = 10l;
+ size_t attribute_count  = 2;
+ std::unordered_map<MetricAttributes, long, AttributeHashGenerator> measurements1 = {
+ {{{"RequestType", "GET"}}, get_count1}, {{{"RequestType", "PUT"}}, put_count1}};
+ storage.RecordLong(measurements1,
  opentelemetry::common::SystemTimestamp(std::chrono::system_clock::now()));
 
  storage.Collect(collector.get(), collectors, sdk_start_ts, collection_ts,
@@ -123,20 +123,57 @@ TEST_P(WritableMetricStorageTestFixture, TestAggregation)
  if (opentelemetry::nostd::get<std::string>(
  data_attr.attributes.find("RequestType")->second) == "GET")
  {
- EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), get_count);
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), get_count1);
  }
  else if (opentelemetry::nostd::get<std::string>(
  data_attr.attributes.find("RequestType")->second) == "PUT")
  {
- EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), put_count);
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), put_count1);
  }
  }
  return true;
  });
  // subsequent recording after collection shouldn't fail
- storage.RecordLong(measurements,
+ // monotonic increasing values;
+ long get_count2 = 50l;
+ long put_count2 = 70l;
+
+ std::unordered_map<MetricAttributes, long, AttributeHashGenerator> measurements2 = {
+ {{{"RequestType", "GET"}}, get_count2}, {{{"RequestType", "PUT"}}, put_count2}};
+ storage.RecordLong(measurements2,
  opentelemetry::common::SystemTimestamp(std::chrono::system_clock::now()));
- EXPECT_EQ(MeasurementFetcher::number_of_attributes, attribute_count);
+ storage.Collect(
+ collector.get(), collectors, sdk_start_ts, collection_ts, [&](const MetricData data) {
+ for (auto data_attr : data.point_data_attr_)
+ {
+ auto data = opentelemetry::nostd::get<SumPointData>(data_attr.point_data);
+ if (opentelemetry::nostd::get<std::string>(
+ data_attr.attributes.find("RequestType")->second) == "GET")
+ {
+ if (temporality == AggregationTemporality::kCumulative)
+ {
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), get_count2);
+ }
+ else
+ {
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), get_count2 - get_count1);
+ }
+ }
+ else if (opentelemetry::nostd::get<std::string>(
+ data_attr.attributes.find("RequestType")->second) == "PUT")
+ {
+ if (temporality == AggregationTemporality::kCumulative)
+ {
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), put_count2);
+ }
+ else
+ {
+ EXPECT_EQ(opentelemetry::nostd::get<long>(data.value_), put_count2 - put_count1);
+ }
+ }
+ }
+ return true;
+ });
 }
 
 INSTANTIATE_TEST_SUITE_P(WritableMetricStorageTestLong,