fix: incorrect order when getting the last active span.

[robersonliou]

Here is an active span order issue.

when I started multi active span in the same transaction, the span tree in sentry ui was not what I expected.
For example, it should be:

--- http.server
      |
      --- controller span
            |
            --- service span
                  |
                  --- repository span

but what I got was:

--- http.server
      |
      --- controller span
            |
            --- service span
            |
            --- repository span

Here is the actual screenshot:

I've traced the source code, and found this issue was cause by TransactionTrace.GetLastActiveSpan().
The TransactionTrace stored the ongoing span in the ConcurrentBag<ISpan>, it worked fine!
But the default order of ConcurrentBag is just like FILO, if I put several active spans sequentially, the result would like as following table:

SpanName	IsFinished	StartTime
repository span	false	2021/6/30 00:00:02
service span	false	2021/6/30 00:00:01
controller span	false	2021/6/30 00:00:00

It could be solved by reordering the span.

# before
public ISpan? GetLastActiveSpan() => Spans.LastOrDefault(s => !s.IsFinished);

# after
public ISpan? GetLastActiveSpan() => Spans.OrderBy(s => s.StartTimestamp).LastOrDefault(s => !s.IsFinished);

[Tyrrrz]

Thank you!

Can you please add a changelog entry inside Changelog.md/Unreleased/Fixes section?

- Fixed incorrect order when getting the last active span ([#1094](https://github.com/getsentry/sentry-dotnet/pull/1094))

[codecov-commenter]

Codecov Report

Merging #1094 (5a9cedf) into main (4c91cc6) will decrease coverage by 1.63%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1094      +/-   ##
==========================================
- Coverage   80.70%   79.06%   -1.64%     
==========================================
  Files         194      194              
  Lines        6359     6359              
  Branches     1411     1411              
==========================================
- Hits         5132     5028     -104     
- Misses        764      876     +112     
+ Partials      463      455       -8     

Impacted Files	Coverage Δ
src/Sentry/TransactionTracer.cs	95.50% <100.00%> (ø)
src/Sentry/PlatformAbstractions/FrameworkInfo.cs	0.00% <0.00%> (-100.00%)	⬇️
...ntry/PlatformAbstractions/RegistryKeyExtensions.cs	0.00% <0.00%> (-100.00%)	⬇️
...Sentry/PlatformAbstractions/FrameworkInfo.NetFx.cs	0.00% <0.00%> (-71.24%)	⬇️
...rmAbstractions/NetFxInstallationsEventProcessor.cs	4.54% <0.00%> (-68.19%)	⬇️
...ntry/Integrations/NetFxInstallationsIntegration.cs	33.33% <0.00%> (-66.67%)	⬇️
...ntry/PlatformAbstractions/FrameworkInstallation.cs	25.00% <0.00%> (-37.50%)	⬇️
src/Sentry/PlatformAbstractions/RuntimeInfo.cs	53.44% <0.00%> (-5.18%)	⬇️
src/Sentry/Internal/MainExceptionProcessor.cs	88.52% <0.00%> (-4.92%)	⬇️
src/Sentry/Internal/AppDomainAdapter.cs	66.66% <0.00%> (ø)

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[bruno-garcia]

Thanks @robersonliou !

[robersonliou]

@bruno-garcia It seems nothing update in v3.6.1 assembly.