tests: runtime: Stabilize out_lib test case

[cosmo0920]

In our CI environments, some of the out_lib tests are flaky. So, we need to stabilize it.

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Testing
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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

Summary by CodeRabbit

• Tests
  • Improved timeout measurement and polling logic in testing suite for more robust timeout validation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fda56e0e-f7e0-4ff1-b02c-c4800e7c9251

📥 Commits

Reviewing files that changed from the base of the PR and between 19cc8f9 and b61608e.

📒 Files selected for processing (1)

• tests/runtime/out_lib.c

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📝 Walkthrough

Walkthrough

The PR refines timeout handling in the test_max_records() runtime test by replacing a generic timeout helper with an explicit polling loop that uses precise time measurement via flb_time_* functions to reliably detect when the output count reaches the expected max_records value or when 1000ms elapses.

Changes

Explicit Polling Timeout in test_max_records

Layer / File(s)	Summary
Explicit polling loop with precise time measurement tests/runtime/out_lib.c	test_max_records() declares flb_time variables to track elapsed time and replaces wait_with_timeout() with an inline polling loop that calls get_output_num() every 100ms, measures elapsed nanoseconds using flb_time_diff() and flb_time_to_nanosec(), and breaks when num >= expected or timeout exceeds 1000ms. Comment style in wait_with_timeout() updated to block comment.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• fluent/fluent-bit#11810: Both PRs update runtime test timeout/wait logic to poll get_output_num() until an expected output count is reached before timing out.

Suggested labels

docs-required

Suggested reviewers

• edsiper

Poem

🐰 A timeout loop hops through the test,
Measuring time with flb_time's quest,
Polling for output with patience so keen,
Till records arrive or milliseconds gleam,
The test now waits with precision refined! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and specifically relates to the main change: stabilizing a flaky test case in out_lib by improving timeout handling logic.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch cosmo0920-stabilize-out_lib-test

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