* fix(lbug): wait for read stream close in splitRelCsvByLabelPair (Windows ENOTEMPTY)
The windows-latest CI job intermittently failed:
FAIL test/unit/rel-csv-split.test.ts > splitRelCsvByLabelPair > handles empty CSV (header only) without errors
Error: ENOTEMPTY: directory not empty, rmdir 'C:\Users\RUNNER~1\AppData\Local\Temp\rel-csv-test-XW5KOu'
Cause: splitRelCsvByLabelPair resolved its Promise on readline's 'close'
event, but the underlying fs.ReadStream's file descriptor is released
asynchronously after that — especially on Windows. For the empty-CSV
test the function returns so quickly that afterEach fires rmSync while
the relations.csv fd is still held, so Windows reports ENOTEMPTY on
the directory.
Fixes:
- Production: after readline 'close', wait for inputStream 'close' (or
resolve immediately if already closed/destroyed). Call inputStream
.destroy() defensively so we never hang if the fd never emits 'close'.
- Test: afterEach now retries rmSync up to 5 times on ENOTEMPTY/EBUSY/
EPERM with a brief back-off — defense-in-depth so the test doesn't
flake on slow CI runners independent of the production change.
The production fix benefits every caller, not just the test: any code
that deletes the CSV's parent directory right after the Promise
resolves previously hit the same race on Windows.
* refactor(lbug): replace custom stream state machines with stdlib primitives
Full audit of splitRelCsvByLabelPair's stream usage after the original
ENOTEMPTY fix. Replaced three hand-rolled mechanisms with their
standard-library equivalents — 147 -> 71 lines in the function, and
the caller's WriteStream closure dropped from 13 lines to 5.
- readline: 'on(line)' + pause/resume/waitingForDrain state machine
-> 'for await (const line of rl)'. Async-iterator delivery naturally
serializes line processing with our awaits, so at most one ws is in
backpressure at a time. We just 'await once(ws, "drain")' when
'write()' returns false — the custom Set, the settled flag and the
'only resume when all streams have drained' logic all go away.
- Multi-stream error coordination: hand-rolled cleanup() that had to
be entered exactly once and had to destroy the inputStream and every
pair ws -> single AbortController shared across every 'once(ws,
'drain', { signal })'. Any stream error aborts every pending wait.
- 'stream/promises.finished(inputStream)' in the 'finally' block
replaces the manual 'rl.on('close', () => inputStream.once('close',
...))' dance, and covers both the success and error paths with the
same primitive. This closes the Windows ENOTEMPTY race root cause —
we never return while the fd might still be in flight.
- Caller closure: 'new Promise((res, rej) => ws.end(cb) + remove
listener on error)' -> 'ws.end(); await finished(ws)'.
- Test 'afterEach': custom retry loop -> 'fs.rmSync(..., { maxRetries:
5, retryDelay: 50 })' (Node added these options specifically for
cross-platform tmpdir cleanup).
- Test 'destroys all streams when one errors': old code leaked
backpressure and created multiple pair streams before the first
blocked; new strict serial backpressure doesn't, so the test now
unblocks the first stream once to advance the loop and create the
second stream before triggering the error.
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