Measurement type conversion done at the MeterProvider.

[cijothomas]

Changes

Measurement type conversion done at the MeterProvider, as this is the earliest stage this can be done. The rest of the pipeline deals with just Long or Double. (We need more refactoring to see if we can use generic base classes, and concrete LongAggregator and DoubleAggregator , instead of Aggregator containing both long and double, and only one being used..)

Modify SumAggregator to be modified to be monotonic only, as the only instrument supported is Counter which is only for monotonic values.

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[cijothomas]

the public IDataValue Sum is not thread-safe. We may avoid that issue if we refactor to avoid SumMetricAggregator implementing both ISumMetric and IAggregator intefaces. The latter represents the thing which does the aggregation, and former is the "aggregation output". Will tackle this in another PR.

[codecov]

Codecov Report

Merging #2136 (0833ae7) into metrics (8f525df) will increase coverage by 0.14%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           metrics    #2136      +/-   ##
===========================================
+ Coverage    83.50%   83.64%   +0.14%     
===========================================
  Files          211      211              
  Lines         6692     6664      -28     
===========================================
- Hits          5588     5574      -14     
+ Misses        1104     1090      -14     

Impacted Files	Coverage Δ
src/OpenTelemetry/Metrics/AggregatorStore.cs	88.40% <100.00%> (ø)
src/OpenTelemetry/Metrics/MeterProviderSdk.cs	97.59% <100.00%> (ø)
...y/Metrics/MetricAggregators/SumMetricAggregator.cs	95.91% <100.00%> (+15.39%)	⬆️
...emetry/Metrics/Processors/MetricConsoleExporter.cs	85.18% <0.00%> (+3.70%)	⬆️