[EXPORTER] Fixes tsan warnings

[owent]

Fixes #3530

Changes

• It's OK when callback_thread has data race in HttpOperation. So just ignore it.

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

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[netlify]

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[Copilot]

Pull Request Overview

This PR suppresses ThreadSanitizer warnings for callback_thread in HttpOperation by introducing a dedicated accessor with TSAN-ignore annotations and memory fences.

• Add HttpOperationAccessor with OPENTELEMETRY_SANITIZER_NO_THREAD wrappers and memory fences around callback_thread access.
• Replace direct async_data_->callback_thread reads/writes with HttpOperationAccessor::GetThreadId/SetThreadId.
• Declare HttpOperationAccessor as a friend in the HttpOperation class header.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
ext/src/http/client/curl/http_operation_curl.cc	Introduces HttpOperationAccessor and replaces direct callback_thread accesses with accessor calls.
ext/include/opentelemetry/ext/http/client/curl/http_operation_curl.h	Adds friend class HttpOperationAccessor; to grant the accessor private access to HttpOperation::AsyncData.

Comments suppressed due to low confidence (2)

ext/src/http/client/curl/http_operation_curl.cc:53

• [nitpick] It may be helpful to add a brief comment explaining why OPENTELEMETRY_SANITIZER_NO_THREAD is applied here, clarifying the intent to silence TSAN warnings for this accessor.

  OPENTELEMETRY_SANITIZER_NO_THREAD static std::thread::id GetThreadId(

ext/src/http/client/curl/http_operation_curl.cc:360

• Consider adding unit tests that verify callback_thread is correctly set, read, and reset through the accessor functions to prevent regressions in callback synchronization.

        if (HttpOperationAccessor::GetThreadId(*async_data_) != std::this_thread::get_id())

[Copilot]

[nitpick] Consider placing HttpOperationAccessor in an anonymous namespace since it’s only used within this translation unit, to avoid exporting an internal utility.

Suggested change

	namespace
	{

[owent]

anonymous namespace will break the friend access.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.00%. Comparing base (ac1172e) to head (80a9bea).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3531      +/-   ##
==========================================
- Coverage   90.03%   90.00%   -0.02%     
==========================================
  Files         220      220              
  Lines        7069     7069              
==========================================
- Hits         6364     6362       -2     
- Misses        705      707       +2     

see 2 files with indirect coverage changes

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[marcalff]

Thanks for the patch.

See some questions on the ifdef logic.

[marcalff]

LGTM