Allow goroutines not launched by the tracer to stop on tracer.Stop()

[mtoffl01]

What does this PR do?

Introduces a new package, contribroutines, which contains a stop channel and an API for getting the channel and closing the channel.
The contribs should get the channel to use as a stop condition for any goroutines they launch, and the tracer should be the only one to stop the channel.

Motivation

We needed a way for the tracer to stop any goroutines that it does not directly manage on tracer.Stop(); without this mechanism, we were dealing with runaway goroutines.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

Unsure? Have a question? Request a review!

[datadog-datadog-prod-us1]

Datadog Report

Branch report: mtoff/contrib-routines
Commit report: 1209807
Test service: dd-trace-go

❌ 3 Failed (0 Known Flaky), 5102 Passed, 67 Skipped, 2m 26.16s Total Time

❌ Failed Tests (3)

• TestOpenOptions - gopkg.in/DataDog/dd-trace-go.v1/contrib/database/sql - Details

  Expand for error

   Failed
   
   === RUN   TestOpenOptions
       testing.go:1398: race detected during execution of test
   --- FAIL: TestOpenOptions (1.22s)
  

• TestOpenOptions/WithDBStats - gopkg.in/DataDog/dd-trace-go.v1/contrib/database/sql - Details

  Expand for error

   Failed
   
   === RUN   TestOpenOptions/WithDBStats
       sql_test.go:292: Stats not collected in expected interval of 500ms
   ==================
   Write at 0x0000022247a8 by goroutine 493:
     gopkg.in/DataDog/dd-trace-go.v1/contrib/database/sql.TestOpenOptions.func1()
         /home/runner/work/dd-trace-go/dd-trace-go/contrib/database/sql/sql_test.go:137 +0x24
     testing.(*common).Cleanup.func1()
         /opt/hostedtoolcache/go/1.22.10/x64/src/testing/testing.go:1175 +0x179
   ...
  

• TestCollectCoverageAfterTestExecution - gopkg.in/DataDog/dd-trace-go.v1/internal/civisibility/integrations/gotesting/coverage - Details

  Expand for error

   Failed
   
   === RUN   TestCollectCoverageAfterTestExecution
       test_coverage_test.go:315: Expected postCoverageFilename /tmp/TestCollectCoverageAfterTestExecution296606244/001/1-2-3-post.out to exist
   --- FAIL: TestCollectCoverageAfterTestExecution (0.00s)
  

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-12-10 22:50:01

Comparing candidate commit f0f73af in PR branch mtoff/contrib-routines with baseline commit 9980c24 in branch main.

Found 0 performance improvements and 4 performance regressions! Performance is the same for 55 metrics, 0 unstable metrics.

scenario:BenchmarkSetTagMetric-24

• 🟥 execution_time [+4.382ns; +6.278ns] or [+3.626%; +5.194%]

scenario:BenchmarkSetTagString-24

• 🟥 execution_time [+7.831ns; +11.189ns] or [+6.703%; +9.577%]

scenario:BenchmarkSetTagStringPtr-24

• 🟥 execution_time [+6.300ns; +8.840ns] or [+3.641%; +5.109%]

scenario:BenchmarkSetTagStringer-24

• 🟥 execution_time [+5.692ns; +7.728ns] or [+3.999%; +5.430%]