in_tail: drop redundant fstat() on event collection

[edsiper]

The event collection path in in_tail_collect_event() performed an early fstat() only to remove the file on failure, then immediately called flb_tail_file_chunk(), which already reaches adjust_counters() and does its own fstat()-based validation and counter update.

Removing the pre-check reduces one fstat() per event-driven collection cycle without changing truncation, rotation, deletion, or pending-byte handling. Those behaviors remain in the backend-specific handlers and in adjust_counters().

This change is intentionally narrow and is based on a conversation about Fluent Bit tail syscall cost with Fabian Ponce from OpenAI (@FabianPonce).

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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

• Refactor
  • Optimized file collection event handling by removing redundant file operations and streamlining error handling logic.

[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: fec31583-c5eb-4842-8d2a-a97c4f988eff

📥 Commits

Reviewing files that changed from the base of the PR and between 40a6d4a and 58fce33.

📒 Files selected for processing (1)

• plugins/in_tail/tail.c

💤 Files with no reviewable changes (1)

• plugins/in_tail/tail.c

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📝 Walkthrough

Walkthrough

The change removes an upfront fstat() validation check from in_tail_collect_event(), instead relying on flb_tail_file_chunk() to handle error conditions directly. The function now bypasses the early error path and delegates file descriptor validation to downstream processing.

Changes

Cohort / File(s)	Summary
Event Collection Refactoring plugins/in_tail/tail.c	Removed fstat() validation call and its associated -1 error handling path from in_tail_collect_event(). Error detection now depends on flb_tail_file_chunk() return values (FLB_TAIL_ERROR, FLB_TAIL_OK, FLB_TAIL_WAIT).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Suggested reviewers

• koleini
• fujimotos

Poem

🐰 No fstat check at the gate today,
Let the chunk handler show the way!
Streamlined paths where errors dwell,
Simpler logic, cleaner spell! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: removing a redundant fstat() call during event collection in the in_tail plugin.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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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 openai-tail

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