feat: add low memory to TEMPORALITY_PREFERENCE (#1886)

* feat: add low memory to TEMPORALITY_PREFERENCE

* add aggregation_temporality test case

* add low_memory

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: xuan-cao-swi

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/aggregation_temporality.rb

@@ -28,6 +28,31 @@ def delta
             def cumulative
               new(CUMULATIVE)
             end
+
+            # | Preference Value | Counter    | Async Counter    | Histogram  | UpDownCounter | Async UpDownCounter |
+            # |------------------|------------|------------------|----------- |---------------|-------------------- |
+            # | **Cumulative**   | Cumulative | Cumulative       | Cumulative | Cumulative    | Cumulative          |
+            # | **Delta**        | Delta      | Delta            | Delta      | Cumulative    | Cumulative          |
+            # | **LowMemory**    | Delta      | Cumulative       | Delta      | Cumulative    | Cumulative          |
+            def determine_temporality(aggregation_temporality: nil, instrument_kind: nil, default: nil)
+              # aggregation_temporality can't be nil because it always has default value in symbol
+              if aggregation_temporality.is_a?(::Symbol)
+                aggregation_temporality == :delta ? delta : cumulative
+
+              elsif aggregation_temporality.is_a?(::String)
+                case aggregation_temporality
+                when 'LOWMEMORY', 'lowmemory', 'low_memory'
+                  instrument_kind == :observable_counter ? cumulative : delta
+                when 'DELTA', 'delta'
+                  delta
+                when 'CUMULATIVE', 'cumulative'
+                  cumulative
+                else
+                  default == :delta ? delta : cumulative
+                end
+
+              end
+            end
           end
 
           attr_reader :temporality

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/explicit_bucket_histogram.rb

@@ -23,7 +23,7 @@ def initialize(
             boundaries: DEFAULT_BOUNDARIES,
             record_min_max: true
           )
-            @aggregation_temporality = aggregation_temporality.to_sym == :delta ? AggregationTemporality.delta : AggregationTemporality.cumulative
+            @aggregation_temporality = AggregationTemporality.determine_temporality(aggregation_temporality: aggregation_temporality, default: :cumulative)
             @boundaries = boundaries && !boundaries.empty? ? boundaries.sort : nil
             @record_min_max = record_min_max
           end

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb

@@ -16,8 +16,6 @@ module Metrics
       module Aggregation
         # Contains the implementation of the {https://opentelemetry.io/docs/specs/otel/metrics/data-model/#exponentialhistogram ExponentialBucketHistogram} aggregation
         class ExponentialBucketHistogram # rubocop:disable Metrics/ClassLength
-          attr_reader :aggregation_temporality
-
           # relate to min max scale: https://opentelemetry.io/docs/specs/otel/metrics/sdk/#support-a-minimum-and-maximum-scale
           DEFAULT_SIZE  = 160
           DEFAULT_SCALE = 20
@@ -34,7 +32,7 @@ def initialize(
             record_min_max: true,
             zero_threshold: 0
           )
-            @aggregation_temporality = aggregation_temporality.to_sym
+            @aggregation_temporality = AggregationTemporality.determine_temporality(aggregation_temporality: aggregation_temporality, default: :delta)
             @record_min_max = record_min_max
             @min            = Float::INFINITY
             @max            = -Float::INFINITY
@@ -49,7 +47,7 @@ def initialize(
           end
 
           def collect(start_time, end_time, data_points)
-            if @aggregation_temporality == :delta
+            if @aggregation_temporality.delta?
               # Set timestamps and 'move' data point values to result.
               hdps = data_points.values.map! do |hdp|
                 hdp.start_time_unix_nano = start_time
@@ -168,6 +166,10 @@ def update(amount, attributes, data_points)
           end
           # rubocop:enable Metrics/MethodLength
 
+          def aggregation_temporality
+            @aggregation_temporality.temporality
+          end
+
           private
 
           def grow_buckets(span, buckets)

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/sum.rb

@@ -11,8 +11,8 @@ module Aggregation
         # Contains the implementation of the Sum aggregation
         # https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#sum-aggregation
         class Sum
-          def initialize(aggregation_temporality: ENV.fetch('OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE', :cumulative), monotonic: false)
-            @aggregation_temporality = aggregation_temporality.to_sym == :delta ? AggregationTemporality.delta : AggregationTemporality.cumulative
+          def initialize(aggregation_temporality: ENV.fetch('OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE', :cumulative), monotonic: false, instrument_kind: nil)
+            @aggregation_temporality = AggregationTemporality.determine_temporality(aggregation_temporality: aggregation_temporality, instrument_kind: instrument_kind, default: :cumulative)
             @monotonic = monotonic
           end
 

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/observable_counter.rb

@@ -32,7 +32,7 @@ def observe(timeout: nil, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(monotonic: true)
+            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(monotonic: true, instrument_kind: instrument_kind)
           end
         end
       end

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/observable_up_down_counter.rb

@@ -32,7 +32,7 @@ def observe(timeout: nil, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(aggregation_temporality: :delta, monotonic: false)
+            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(aggregation_temporality: :cumulative, monotonic: false)
           end
         end
       end

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/up_down_counter.rb

@@ -35,7 +35,7 @@ def add(amount, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(monotonic: false)
+            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(aggregation_temporality: :cumulative, monotonic: false)
           end
         end
       end