[receiver/filelog] Suppress repeated permission denied errors

[khpeet]

Description

Added logic to suppress repeated error logs due to file permission errors within the filelog receiver.

• Updated makeFingerprint to check for permission errors via os.isPermission
• Log an error only on the first occurrence for a given file path and add it to an in-memory map, guarded by a mutex to avoid race conditions for concurrent read/writes.
• Debug log only for subsequent read attempt (to avoid spam)
• When the file becomes readable, info log a message and remove the path from the stored set

Link to tracking issue

Fixes #39491

Testing

New unit test verifying:

• First unreadable-open produces exactly one Error-level log.
• Second attempt does not produce another Error-level log.
• When permissions are restored, an Info-level Previously unreadable... message appears.

NOTE: Test skips Windows due to unreliable os.Chmod behavior

Documentation

Added changelog yaml entry summarizing the issue and fix.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: khpeet / name: Keagan Peet (993e8b0)

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[khpeet]

@andrzej-stencel @atoulme - gentle bump on this PR

[VihasMakwana]

Do we need a mutex? AFAIK, calls to makeFingerprint are serialised. Could you confirm this?

Also, @andrzej-stencel is on sick leave until starting of December. It might take some time to get this merged.

[khpeet]

Do we need a mutex? AFAIK, calls to makeFingerprint are serialised. Could you confirm this?

Also, @andrzej-stencel is on sick leave until starting of December. It might take some time to get this merged.

Hey @VihasMakwana - You are correct! Taking a second deeper look, I saw that only a single goroutine calls poll() and everything looks sequential. I've removed the mutex.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.