Update Processor.Shutdown to meet with the latest spec

[reyang]

The latest spec requires the processor Shutdown to provide a way to indicate whether it succeeded or not.

Changes

• Changed ActivityProcessor.Shutdown to return bool.

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

[ThomsonTan]

Put this return true to the end of this function (right before })?

[reyang]

The way I look at try { return } catch() { return } is similar to if() { return } else { return }. Do you see some benefit of putting it outside?

[ThomsonTan]

I thought normal execution flow would end at }, besides that, I don't see any advantage to move return true to the end of the function.

[codecov]

Codecov Report

Merging #1282 into master will decrease coverage by 0.02%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master    #1282      +/-   ##
==========================================
- Coverage   79.13%   79.10%   -0.03%     
==========================================
  Files         215      215              
  Lines        6174     6170       -4     
==========================================
- Hits         4886     4881       -5     
- Misses       1288     1289       +1     

Impacted Files	Coverage Δ
src/OpenTelemetry/Trace/ActivityExporter.cs	66.66% <33.33%> (ø)
src/OpenTelemetry/Trace/ActivityProcessor.cs	58.33% <50.00%> (-1.67%)	⬇️
...OpenTelemetry/Trace/BaseExportActivityProcessor.cs	78.57% <100.00%> (-1.43%)	⬇️
...penTelemetry/Trace/BatchExportActivityProcessor.cs	93.05% <100.00%> (-0.28%)	⬇️
.../OpenTelemetry/Trace/CompositeActivityProcessor.cs	92.95% <100.00%> (+0.10%)	⬆️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	61.76% <0.00%> (-2.95%)	⬇️

[CodeBlanch]

Interesting! What is user to do if shutdown comes back false?

[CodeBlanch]

LGTM

[reyang]

Interesting! What is user to do if shutdown comes back false?

I guess 99% users won't consume the return value.
For folks who build nuclear power plants, they could leverage the boolean value and decide if it is time for emergency escalation 😄

One real world scenario: one can check the return value == true and write a local file indicating the clean shutdown, when the app started/restarted, it could check if there was a clean shutdown or not.