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Nanaloveyuki
81 lines
2.6 KiB
Markdown
81 lines
2.6 KiB
Markdown
---
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name: file-sink-rotation-failures
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group: api
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category: sink
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update-time: 20260717
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description: Read the number of rotation failures recorded by a FileSink.
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key-word:
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- file
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- sink
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- rotation
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- public
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---
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## File-sink-rotation-failures
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Read the number of rotation attempts whose critical file-rotation steps failed for a `FileSink`.
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### Interface
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```moonbit
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pub fn FileSink::rotation_failures(self : FileSink) -> Int {
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```
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#### input
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- `self : FileSink` - File sink whose rotation-failure counter should be inspected.
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#### output
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- `Int` - Number of recorded rotation failures.
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### Explanation
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Detailed rules explaining key parameters and behaviors
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- The sink reports its recorded rotation-failure count directly.
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- The counter increases when a rotation attempt cannot complete its critical file steps, such as removing the active file with zero backups, renaming a live file into `.1`, shifting an existing backup to a higher slot, or reopening the fresh active file afterward.
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- Missing optional backup slots do not count by themselves; only steps that fail while their source path still exists are treated as rotation failures.
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- When a critical rotation step fails, the triggering record is not written and the sink remains unavailable until an explicit reopen succeeds.
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- The counter is cumulative until reset.
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- This helper is observation-only and does not mutate sink state.
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### How to Use
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Here are some specific examples provided.
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#### When Need Rotation-specific Diagnostics
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When support output should reveal whether direct sink rotation is failing:
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```moonbit
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let count = sink.rotation_failures()
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```
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In this example, the concrete file sink exposes whether a rotation attempt hit a critical file-step failure.
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#### When Validate Runtime Rotation Tuning
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When changed rotation settings should be checked in operation:
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```moonbit
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ignore(sink.rotation_failures())
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```
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In this example, callers can observe whether runtime rotation changes started producing incomplete rotations.
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### Error Case
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e.g.:
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- If callers need both rotation config and failure metrics, they should combine this helper with `rotation_config()` or `state()`.
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- This counter alone does not identify which rename/remove/reopen step failed.
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- This counter alone does not say whether the sink is currently available.
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- After a recorded rotation failure, use `reopen_append()` only after the underlying filesystem condition has been resolved.
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### Notes
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1. Use this helper when diagnosing incomplete direct file rotations.
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2. It is especially relevant when runtime rotation policy can change after startup.
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