* fix: sync EC volume files before copying to fix deleted needles not being marked when decoding (#7751)
When a file is deleted from an EC volume, the deletion is written to both
the .ecx and .ecj files. However, these writes were not synced to disk
before the files were copied during ec.decode. This caused the copied
files to miss the deletion markers, resulting in 'leaked' space where
deleted files were not properly tracked after decoding.
This fix:
1. Adds a Sync() method to EcVolume that flushes .ecx and .ecj files
to disk without closing them
2. Calls Sync() in CopyFile before copying EC volume files to ensure
all deletions are visible to the copy operation
Fixes#7751
* test: add integration tests for EC volume deletion sync (issue #7751)
Add comprehensive tests to verify that deleted needles are properly
visible after EcVolume.Sync() is called. These tests cover:
1. TestWriteIdxFileFromEcIndex_PreservesDeletedNeedles
- Verifies that WriteIdxFileFromEcIndex preserves deletion markers
from .ecx files when generating .idx files
2. TestWriteIdxFileFromEcIndex_ProcessesEcjJournal
- Verifies that deletions from .ecj journal file are correctly
appended to the generated .idx file
3. TestEcxFileDeletionVisibleAfterSync
- Verifies that MarkNeedleDeleted changes are visible after Sync()
4. TestEcxFileDeletionWithSeparateHandles
- Tests that synced changes are visible across separate file handles
5. TestEcVolumeSyncEnsuresDeletionsVisible
- Integration test for the full EcVolume.DeleteNeedleFromEcx +
Sync() workflow that validates the fix for issue #7751
* refactor: log sync errors in EcVolume.Sync() instead of ignoring them
Per code review feedback: sync errors could reintroduce the bug this PR
fixes, so logging warnings helps with debugging.
* fix(ec.decode): purge EC shards when volume is empty
When an EC volume has no live entries (all deleted), ec.decode should not generate an empty normal volume. Instead, treat decode as a no-op and allow shard purge to proceed cleanly.\n\nFixes: #7748
* chore: address PR review comments
* test: cover live EC index + avoid magic string
* chore: harden empty-EC handling
- Make shard cleanup best-effort (collect errors)\n- Remove unreachable EOF handling in HasLiveNeedles\n- Add empty ecx test case\n- Share no-live-entries substring between server/client\n
* perf: parallelize EC shard unmount/delete across locations
* refactor: combine unmount+delete into single goroutine per location
* refactor: use errors.Join for multi-error aggregation
* refactor: use existing ErrorWaitGroup for parallel execution
* fix: capture loop variables + clarify SuperBlockSize safety
