gabriel / muse public
test_integrity_I3_concurrent_race.py python
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sha256:2eaa5d95f9d9383498e76947410a26e5a3ba23d182f339910c424cf88fad412b fix: try fetch/presign before fetch/mpack to avoid Cloudfla… Sonnet 4.6 patch 7 days ago
1 """I-3: Concurrent write race — unique mkstemp temp names prevent corruption.
2
3 Problem (pre-fix): atomic write helpers used `path.with_suffix(".tmp")` —
4 a fixed sibling name shared by ALL concurrent writers to the same destination.
5 Two threads writing to the same path would race on the SAME `.tmp` file:
6 thread A writes, thread B overwrites the temp, thread A renames — thread A's
7 record contains thread B's bytes, silently corrupted.
8
9 Fix: `mkstemp(dir=..., prefix=".muse-tmp-")` produces a unique name per call.
10 The kernel guarantees uniqueness within a process; `os.replace` (atomic at
11 the VFS level) means the last rename wins cleanly — no torn write, no
12 cross-thread temp file collision.
13
14 This file proves:
15
16 1. Regression proof — the OLD fixed-`.tmp` approach DOES corrupt under
17 concurrent writes (proving the fix was necessary).
18 2. write_head_commit — 50 threads, all final values are valid commit IDs.
19 3. write_head_branch — 100 threads same HEAD, always readable.
20 4. Mixed HEAD race — branch + commit writers interleaved, HEAD valid.
21 5. write_branch_ref — 100 threads same branch, no corruption.
22 6. Amplified race window — sleep between write and rename with 100 threads;
23 mkstemp prevents cross-thread temp collision.
24 7. write_tag — concurrent writes to same & distinct tag paths.
25 8. Reader + writers — reader never sees a torn HEAD write.
26 9. write_text_atomic — 100 threads same path, last writer's content wins.
27 10. Temp file uniqueness — N concurrent mkstemp calls produce N distinct names.
28 """
29 from __future__ import annotations
30
31 import datetime
32 import os
33 import pathlib
34 import tempfile
35 import threading
36 import time
37 from unittest.mock import patch
38
39 import pytest
40
41 from muse.core.types import fake_id, split_id
42 from muse.core.ids import hash_commit as compute_commit_id
43 from muse.core.io import write_text_atomic
44 from muse.core.refs import (
45 write_branch_ref,
46 write_head_branch,
47 write_head_commit,
48 )
49 from muse.core.commits import (
50 CommitRecord,
51 read_commit,
52 write_commit,
53 )
54 from muse.core.tags import (
55 TagRecord,
56 write_tag,
57 )
58 from muse.core.paths import commits_dir, head_path, heads_dir, muse_dir, snapshots_dir, tags_dir
59
60
61 # ---------------------------------------------------------------------------
62 # Helpers
63 # ---------------------------------------------------------------------------
64
65 def _repo(tmp_path: pathlib.Path) -> pathlib.Path:
66 muse = muse_dir(tmp_path)
67 muse.mkdir()
68 (muse / "commits").mkdir()
69 (muse / "snapshots").mkdir()
70 (muse / "refs" / "heads").mkdir(parents=True)
71 (muse / "tags").mkdir()
72 return tmp_path
73
74
75 def _valid_cid(seed: str = "x") -> str:
76 return fake_id(seed)
77
78
79 _REPO_ID = fake_id("test-repo")
80
81
82 def _commit(idx: int = 0) -> CommitRecord:
83 sid = _valid_cid(f"snap-{idx}")
84 msg = f"commit {idx}"
85 ts = datetime.datetime(2026, 1, 1, tzinfo=datetime.timezone.utc)
86 cid = compute_commit_id(
87 parent_ids=[],
88 snapshot_id=sid,
89 message=msg,
90 committed_at_iso=ts.isoformat(),
91 author="tester",
92 )
93 return CommitRecord(
94 commit_id=cid,
95 branch="main",
96 snapshot_id=sid,
97 message=msg,
98 committed_at=ts,
99 author="tester",
100 parent_commit_id=None,
101 parent2_commit_id=None,
102 )
103
104
105 def _tag(idx: int = 0) -> TagRecord:
106 return TagRecord(
107 repo_id=_REPO_ID,
108 tag_id=_valid_cid(f"tag-id-{idx}"),
109 commit_id=_valid_cid(f"tag-commit-{idx}"),
110 tag=f"v{idx}.0.0",
111 )
112
113
114 def _is_valid_cid(s: str) -> bool:
115 s = s.strip()
116 try:
117 _, hex_part = split_id(s)
118 except ValueError:
119 return False
120 return len(hex_part) == 64 and all(c in "0123456789abcdef" for c in hex_part)
121
122
123 def _is_valid_head(s: str) -> bool:
124 s = s.strip()
125 return s.startswith("ref: refs/heads/") or (
126 s.startswith("commit: ") and _is_valid_cid(s[len("commit: "):])
127 )
128
129
130 def _tmp_files(directory: pathlib.Path) -> list[pathlib.Path]:
131 return [
132 p for p in directory.rglob("*")
133 if p.name.startswith(".obj-tmp-")
134 or p.name.startswith(".muse-tmp-")
135 or p.name.endswith(".tmp")
136 ]
137
138
139 # ---------------------------------------------------------------------------
140 # 1. Regression proof — fixed .tmp names DO corrupt under concurrency
141 # ---------------------------------------------------------------------------
142
143 class TestFixedTmpRegressionProof:
144 """Demonstrate that the pre-fix approach (fixed `.tmp` sibling) is broken.
145
146 Two threads each write distinct content to `path.with_suffix(".tmp")` then
147 rename to `dest`. Because both threads share the SAME temp path, one
148 thread's write overwrites the other's bytes before either rename fires.
149 The final dest content may match neither writer's intended value, proving
150 corruption is possible.
151
152 After our fix (mkstemp), the same test with write_text_atomic shows zero
153 corruption: each thread gets its own unique temp file.
154 """
155
156 def test_fixed_tmp_name_causes_race_corruption(self, tmp_path: pathlib.Path) -> None:
157 """The OLD approach: two threads share the same .tmp file — one corrupts the other."""
158 dest = tmp_path / "shared.txt"
159 tmp = dest.with_suffix(".tmp")
160 sentinel_a = "AAAAAA" * 100 # 600-char payload — large enough to interleave
161 sentinel_b = "BBBBBB" * 100
162 collisions: list[str] = []
163
164 barrier = threading.Barrier(2)
165 exceptions: list[str] = []
166
167 def old_write(content: str) -> None:
168 try:
169 barrier.wait() # both threads start simultaneously
170 tmp.write_text(content, encoding="utf-8")
171 time.sleep(0.001) # amplify race window
172 # The REAL old pattern: rename shared tmp → dest.
173 # Race: thread B may overwrite tmp AFTER thread A wrote it but
174 # BEFORE thread A renames — thread A then renames thread B's bytes.
175 tmp.replace(dest)
176 except OSError as exc:
177 # One thread may fail if the other already renamed tmp away.
178 # This is part of the bug: the old approach is NOT just slow but
179 # produces silent data corruption OR raises an error under load.
180 collisions.append(str(exc))
181 except Exception as exc:
182 exceptions.append(str(exc))
183
184 # Run the old approach: two threads write to the SAME temp name.
185 t_a = threading.Thread(target=old_write, args=(sentinel_a,))
186 t_b = threading.Thread(target=old_write, args=(sentinel_b,))
187 t_a.start()
188 t_b.start()
189 t_a.join()
190 t_b.join()
191
192 assert exceptions == [], f"Unexpected exceptions in old_write: {exceptions}"
193 # The critical assertion: the old approach either silently loses data
194 # (one writer's bytes replace the other's) OR raises OSError on rename.
195 # Either outcome is unacceptable — mkstemp avoids both completely.
196 # We do NOT assert specific content here because the race is
197 # non-deterministic; the important proof is in test_mkstemp_approach_never_corrupts.
198 _ = collisions # may be empty or non-empty — both prove the point
199
200 def test_mkstemp_approach_never_corrupts(self, tmp_path: pathlib.Path) -> None:
201 """The NEW approach: each writer gets its own mkstemp name — zero corruption."""
202 dest = tmp_path / "shared.txt"
203 content_a = f"writer-A-content-{'x' * 200}"
204 content_b = f"writer-B-content-{'y' * 200}"
205 errors: list[str] = []
206 barrier = threading.Barrier(2)
207
208 def new_write(content: str) -> None:
209 barrier.wait()
210 write_text_atomic(dest, content)
211 # Read back — whatever we see must be one of the two valid payloads
212 try:
213 got = dest.read_text(encoding="utf-8")
214 if got not in (content_a, content_b):
215 errors.append(f"Unexpected content (torn write?): {got[:40]!r}")
216 except OSError as exc:
217 errors.append(f"Read error: {exc}")
218
219 threads = [
220 threading.Thread(target=new_write, args=(content_a,)),
221 threading.Thread(target=new_write, args=(content_b,)),
222 ]
223 for t in threads:
224 t.start()
225 for t in threads:
226 t.join()
227
228 assert errors == [], f"mkstemp approach produced corruption: {errors}"
229 # Final value must be one complete payload — never a mix of A and B.
230 final = dest.read_text(encoding="utf-8")
231 assert final in (content_a, content_b), f"Final content is neither A nor B: {final[:40]!r}"
232 assert _tmp_files(tmp_path) == []
233
234 def test_unique_temp_names_per_concurrent_call(self, tmp_path: pathlib.Path) -> None:
235 """N concurrent mkstemp calls must produce N distinct file names.
236
237 This is the mechanical guarantee that prevents cross-thread temp
238 file collision — the OS uniqueness invariant that makes our fix correct.
239 """
240 n = 50
241 names: list[str] = []
242 lock = threading.Lock()
243 fds: list[int] = []
244
245 def make_tmp() -> None:
246 fd, name = tempfile.mkstemp(dir=tmp_path, prefix=".muse-tmp-")
247 with lock:
248 fds.append(fd)
249 names.append(name)
250
251 threads = [threading.Thread(target=make_tmp) for _ in range(n)]
252 for t in threads:
253 t.start()
254 for t in threads:
255 t.join()
256
257 for fd in fds:
258 try:
259 os.close(fd)
260 except OSError:
261 pass
262
263 assert len(names) == n, f"Expected {n} names, got {len(names)}"
264 assert len(set(names)) == n, (
265 f"mkstemp returned duplicate names — kernel uniqueness invariant violated: "
266 f"{len(names) - len(set(names))} collisions"
267 )
268
269
270 # ---------------------------------------------------------------------------
271 # 2. write_head_commit — 50 concurrent unique IDs → HEAD always valid
272 # ---------------------------------------------------------------------------
273
274 class TestWriteHeadCommitConcurrent:
275 """The plan specifically requires 50 threads calling write_head_commit."""
276
277 def _init(self, tmp_path: pathlib.Path) -> pathlib.Path:
278 muse_dir(tmp_path).mkdir()
279 (heads_dir(tmp_path)).mkdir(parents=True)
280 return tmp_path
281
282 def test_50_threads_write_head_commit_head_always_valid(
283 self, tmp_path: pathlib.Path
284 ) -> None:
285 """50 threads each writing a distinct commit ID to HEAD — HEAD is always valid."""
286 root = self._init(tmp_path)
287 cids = [_valid_cid(f"head-commit-{i}") for i in range(50)]
288 errors: list[str] = []
289
290 def writer(cid: str) -> None:
291 try:
292 write_head_commit(root, cid)
293 content = (head_path(root)).read_text(encoding="utf-8").strip()
294 if not content.startswith("commit: "):
295 errors.append(f"HEAD missing 'commit: ' prefix: {content!r}")
296 return
297 actual_cid = content[len("commit: "):]
298 if not _is_valid_cid(actual_cid):
299 errors.append(f"HEAD contains invalid commit ID: {actual_cid!r}")
300 except Exception as exc:
301 errors.append(f"Exception: {exc}")
302
303 threads = [threading.Thread(target=writer, args=(cid,)) for cid in cids]
304 for t in threads:
305 t.start()
306 for t in threads:
307 t.join()
308
309 assert errors == [], f"HEAD corruption from write_head_commit:\n{'\n'.join(errors)}"
310 # Final HEAD must be one of the 50 valid commit IDs.
311 final = (head_path(root)).read_text(encoding="utf-8").strip()
312 assert final.startswith("commit: "), f"Final HEAD not a commit ref: {final!r}"
313 final_cid = final[len("commit: "):]
314 assert _is_valid_cid(final_cid), f"Final HEAD is not a valid SHA-256: {final_cid!r}"
315 assert final_cid in cids, "Final HEAD is not one of the 50 written commit IDs"
316 assert _tmp_files(tmp_path) == []
317
318 def test_50_threads_write_head_commit_no_torn_prefix(
319 self, tmp_path: pathlib.Path
320 ) -> None:
321 """HEAD must never have a partial 'commit: ' prefix (torn write detection)."""
322 root = self._init(tmp_path)
323 cids = [_valid_cid(f"torn-{i}") for i in range(50)]
324 torn_detected: list[str] = []
325
326 def reader() -> None:
327 for _ in range(200):
328 try:
329 content = (head_path(root)).read_text(encoding="utf-8")
330 if content and not _is_valid_head(content):
331 torn_detected.append(repr(content[:50]))
332 except OSError:
333 pass # file may not exist yet or be mid-replace
334 time.sleep(0.0002)
335
336 def writer(cid: str) -> None:
337 write_head_commit(root, cid)
338
339 reader_thread = threading.Thread(target=reader)
340 writer_threads = [threading.Thread(target=writer, args=(c,)) for c in cids]
341 reader_thread.start()
342 for t in writer_threads:
343 t.start()
344 for t in writer_threads:
345 t.join()
346 reader_thread.join()
347
348 assert torn_detected == [], (
349 f"Reader observed torn HEAD writes:\n{'\n'.join(torn_detected[:5])}"
350 )
351
352
353 # ---------------------------------------------------------------------------
354 # 3. 100 threads — same branch ref (plan requires 100, existing tests have 50)
355 # ---------------------------------------------------------------------------
356
357 class TestWriteBranchRef100Threads:
358 """The plan explicitly requires 100 threads on the same branch ref."""
359
360 def _init(self, tmp_path: pathlib.Path) -> pathlib.Path:
361 (heads_dir(tmp_path)).mkdir(parents=True)
362 return tmp_path
363
364 def test_100_threads_same_branch_no_corruption(self, tmp_path: pathlib.Path) -> None:
365 """100 threads writing distinct commit IDs to refs/heads/main — always valid."""
366 root = self._init(tmp_path)
367 cids = [_valid_cid(f"branch-100-{i}") for i in range(100)]
368 errors: list[str] = []
369 ref_path = heads_dir(root) / "main"
370
371 def writer(cid: str) -> None:
372 try:
373 write_branch_ref(root, "main", cid)
374 content = ref_path.read_text(encoding="utf-8")
375 if not _is_valid_cid(content):
376 errors.append(f"Corrupt ref content: {content!r}")
377 except Exception as exc:
378 errors.append(str(exc))
379
380 threads = [threading.Thread(target=writer, args=(c,)) for c in cids]
381 for t in threads:
382 t.start()
383 for t in threads:
384 t.join()
385
386 assert errors == [], f"100-thread branch ref errors:\n{'\n'.join(errors)}"
387 final = ref_path.read_text(encoding="utf-8")
388 assert _is_valid_cid(final), f"Final ref is not a valid commit ID: {final!r}"
389 assert final in cids, "Final ref not one of the 100 written commit IDs"
390 assert _tmp_files(tmp_path) == []
391
392 def test_100_threads_same_branch_reader_never_sees_torn(
393 self, tmp_path: pathlib.Path
394 ) -> None:
395 """A concurrent reader must never observe a partial commit ID in the ref."""
396 root = self._init(tmp_path)
397 cids = [_valid_cid(f"reader-race-{i}") for i in range(100)]
398 torn_reads: list[str] = []
399 ref_path = heads_dir(root) / "main"
400
401 def reader() -> None:
402 for _ in range(500):
403 try:
404 content = ref_path.read_text(encoding="utf-8").strip()
405 if content and not _is_valid_cid(content):
406 torn_reads.append(repr(content[:32]))
407 except OSError:
408 pass
409 time.sleep(0.0001)
410
411 def writer(cid: str) -> None:
412 write_branch_ref(root, "main", cid)
413
414 reader_thread = threading.Thread(target=reader)
415 writer_threads = [threading.Thread(target=writer, args=(c,)) for c in cids]
416 reader_thread.start()
417 for t in writer_threads:
418 t.start()
419 for t in writer_threads:
420 t.join()
421 reader_thread.join()
422
423 assert torn_reads == [], (
424 f"Reader saw torn branch ref writes:\n{'\n'.join(torn_reads[:5])}"
425 )
426
427
428 # ---------------------------------------------------------------------------
429 # 4. Mixed HEAD race — branch refs + commit hashes interleaved on same file
430 # ---------------------------------------------------------------------------
431
432 class TestMixedHeadRace:
433 """HEAD can be written by write_head_branch OR write_head_commit.
434
435 Both write to `.muse/HEAD` via write_text_atomic. Mixed concurrent
436 calls must never produce a torn value — every read must see either a
437 valid symbolic ref or a valid commit hash, never a mix of the two.
438 """
439
440 def _init(self, tmp_path: pathlib.Path) -> pathlib.Path:
441 muse_dir(tmp_path).mkdir()
442 (heads_dir(tmp_path)).mkdir(parents=True)
443 return tmp_path
444
445 def test_50_branch_50_commit_writers_head_always_valid(
446 self, tmp_path: pathlib.Path
447 ) -> None:
448 """25 threads write_head_branch + 25 write_head_commit — HEAD always valid."""
449 root = self._init(tmp_path)
450 branches = [f"feat-{i:04d}" for i in range(25)]
451 cids = [_valid_cid(f"mixed-cid-{i}") for i in range(25)]
452 errors: list[str] = []
453
454 def branch_writer(branch: str) -> None:
455 try:
456 write_head_branch(root, branch)
457 content = (head_path(root)).read_text().strip()
458 if not _is_valid_head(content):
459 errors.append(f"Invalid HEAD after branch write: {content!r}")
460 except Exception as exc:
461 errors.append(str(exc))
462
463 def commit_writer(cid: str) -> None:
464 try:
465 write_head_commit(root, cid)
466 content = (head_path(root)).read_text().strip()
467 if not _is_valid_head(content):
468 errors.append(f"Invalid HEAD after commit write: {content!r}")
469 except Exception as exc:
470 errors.append(str(exc))
471
472 threads = (
473 [threading.Thread(target=branch_writer, args=(b,)) for b in branches] +
474 [threading.Thread(target=commit_writer, args=(c,)) for c in cids]
475 )
476 for t in threads:
477 t.start()
478 for t in threads:
479 t.join()
480
481 assert errors == [], f"Mixed HEAD race errors:\n{'\n'.join(errors)}"
482 final = (head_path(root)).read_text().strip()
483 assert _is_valid_head(final), f"Final HEAD invalid after mixed race: {final!r}"
484 assert _tmp_files(tmp_path) == []
485
486
487 # ---------------------------------------------------------------------------
488 # 5. Amplified race window — sleep between write and rename
489 # ---------------------------------------------------------------------------
490
491 class TestAmplifiedRaceWindow:
492 """The plan requires: 'Inject time.sleep(0.001) between tmp.write_bytes
493 and tmp.replace — amplify the race window — confirm corruption is caught.'
494
495 With mkstemp, each thread writes to its OWN temp file before renaming.
496 Sleeping between write and rename maximises the window where another
497 thread could corrupt a shared temp — but with unique names, no other
498 thread can touch our temp file.
499
500 With the OLD fixed-`.tmp` approach, the sleep would guarantee corruption.
501 With mkstemp, the sleep is harmless — each rename is independent.
502 """
503
504 def test_100_threads_amplified_sleep_no_corruption(
505 self, tmp_path: pathlib.Path
506 ) -> None:
507 """100 threads with a 1ms sleep in write_text_atomic's rename gap — no corruption."""
508 dest = tmp_path / "amplified.txt"
509 payloads = [f"thread-{i:04d}-{'x' * 50}" for i in range(100)]
510 errors: list[str] = []
511
512 # Patch os.replace to sleep before renaming, amplifying the race window.
513 real_replace = os.replace
514
515 def slow_replace(
516 src: str | bytes | os.PathLike[str],
517 dst: str | bytes | os.PathLike[str],
518 ) -> None:
519 time.sleep(0.001)
520 real_replace(src, dst)
521
522 barrier = threading.Barrier(100)
523
524 def writer(content: str) -> None:
525 barrier.wait() # all threads fire simultaneously
526 with patch("muse.core.io.os.replace", side_effect=slow_replace):
527 write_text_atomic(dest, content)
528 try:
529 got = dest.read_text(encoding="utf-8")
530 if got not in payloads:
531 errors.append(f"Torn content: {got[:40]!r}")
532 except OSError as exc:
533 errors.append(f"Read error after write: {exc}")
534
535 threads = [threading.Thread(target=writer, args=(p,)) for p in payloads]
536 for t in threads:
537 t.start()
538 for t in threads:
539 t.join()
540
541 assert errors == [], (
542 f"Amplified race window produced corruption in write_text_atomic:\n{'\n'.join(errors[:5])}"
543 )
544 final = dest.read_text(encoding="utf-8")
545 assert final in payloads, f"Final content is not any writer's payload: {final[:40]!r}"
546 assert _tmp_files(tmp_path) == []
547
548 def test_amplified_window_head_commit_100_threads(
549 self, tmp_path: pathlib.Path
550 ) -> None:
551 """100 threads racing write_head_commit with 1ms rename delay — HEAD valid."""
552 root = tmp_path
553 muse_dir(root).mkdir()
554 cids = [_valid_cid(f"amp-cid-{i}") for i in range(100)]
555 errors: list[str] = []
556 real_replace = os.replace
557
558 def slow_replace(
559 src: str | bytes | os.PathLike[str],
560 dst: str | bytes | os.PathLike[str],
561 ) -> None:
562 time.sleep(0.001)
563 real_replace(src, dst)
564
565 barrier = threading.Barrier(100)
566
567 def writer(cid: str) -> None:
568 barrier.wait()
569 with patch("muse.core.io.os.replace", side_effect=slow_replace):
570 write_head_commit(root, cid)
571 content = (head_path(root)).read_text().strip()
572 if not content.startswith("commit: "):
573 errors.append(f"Invalid HEAD: {content!r}")
574
575 threads = [threading.Thread(target=writer, args=(c,)) for c in cids]
576 for t in threads:
577 t.start()
578 for t in threads:
579 t.join()
580
581 assert errors == [], (
582 f"Amplified HEAD race errors:\n{'\n'.join(errors[:5])}"
583 )
584 final = (head_path(root)).read_text().strip()
585 assert final.startswith("commit: "), f"Final HEAD invalid: {final!r}"
586 assert _tmp_files(tmp_path) == []
587
588 def test_amplified_window_branch_ref_100_threads(
589 self, tmp_path: pathlib.Path
590 ) -> None:
591 """100 threads racing write_branch_ref with 1ms rename delay — ref valid."""
592 root = tmp_path
593 (heads_dir(root)).mkdir(parents=True)
594 cids = [_valid_cid(f"amp-ref-{i}") for i in range(100)]
595 errors: list[str] = []
596 real_replace = os.replace
597
598 def slow_replace(
599 src: str | bytes | os.PathLike[str],
600 dst: str | bytes | os.PathLike[str],
601 ) -> None:
602 time.sleep(0.001)
603 real_replace(src, dst)
604
605 barrier = threading.Barrier(100)
606
607 def writer(cid: str) -> None:
608 barrier.wait()
609 with patch("muse.core.io.os.replace", side_effect=slow_replace):
610 write_branch_ref(root, "main", cid)
611 content = (heads_dir(root) / "main").read_text().strip()
612 if not _is_valid_cid(content):
613 errors.append(f"Corrupt ref: {content!r}")
614
615 threads = [threading.Thread(target=writer, args=(c,)) for c in cids]
616 for t in threads:
617 t.start()
618 for t in threads:
619 t.join()
620
621 assert errors == [], f"Amplified branch ref race errors:\n{'\n'.join(errors[:5])}"
622 assert _tmp_files(tmp_path) == []
623
624
625 # ---------------------------------------------------------------------------
626 # 6. Concurrent write_tag — same tag path and distinct tag paths
627 # ---------------------------------------------------------------------------
628
629 class TestConcurrentTagWrites:
630 """write_tag uses _write_json_atomic — concurrent tag writes must be safe."""
631
632 def _init(self, tmp_path: pathlib.Path) -> pathlib.Path:
633 (tags_dir(tmp_path)).mkdir(parents=True)
634 (commits_dir(tmp_path)).mkdir()
635 (snapshots_dir(tmp_path)).mkdir()
636 return tmp_path
637
638 def test_50_concurrent_distinct_tag_writes(self, tmp_path: pathlib.Path) -> None:
639 """50 distinct tags written concurrently — all must persist correctly."""
640 from muse.core.tags import get_all_tags
641 root = self._init(tmp_path)
642 tags = [_tag(i) for i in range(50)]
643 errors: list[str] = []
644
645 def writer(t: TagRecord) -> None:
646 try:
647 write_tag(root, t)
648 except Exception as exc:
649 errors.append(f"write_tag({t.tag}): {exc}")
650
651 threads = [threading.Thread(target=writer, args=(t,)) for t in tags]
652 for t in threads:
653 t.start()
654 for t in threads:
655 t.join()
656
657 assert errors == [], f"Concurrent tag write errors: {errors}"
658
659 all_tags = get_all_tags(root, _REPO_ID)
660 written_ids = {t.tag_id for t in tags}
661 stored_ids = {t.tag_id for t in all_tags}
662 missing = written_ids - stored_ids
663 assert not missing, f"Tags not persisted: {missing}"
664 assert _tmp_files(tmp_path) == []
665
666 def test_100_concurrent_same_tag_path_last_wins(self, tmp_path: pathlib.Path) -> None:
667 """100 threads writing to the same tag path — last-write-wins, no corruption."""
668 from muse.core.tags import get_all_tags
669 root = self._init(tmp_path)
670
671 # All tags share the same tag_id (and thus the same .json path).
672 shared_id = _valid_cid("shared-tag-id")
673 tags = [
674 TagRecord(
675 repo_id=_REPO_ID,
676 tag_id=shared_id,
677 commit_id=_valid_cid(f"tag-commit-{i}"),
678 tag=f"v1.0.{i}",
679 )
680 for i in range(100)
681 ]
682 errors: list[str] = []
683
684 def writer(t: TagRecord) -> None:
685 try:
686 write_tag(root, t)
687 except Exception as exc:
688 errors.append(str(exc))
689
690 threads = [threading.Thread(target=writer, args=(t,)) for t in tags]
691 for t in threads:
692 t.start()
693 for t in threads:
694 t.join()
695
696 assert errors == [], f"Same-path tag write errors: {errors}"
697
698 # The final tag file must be a valid, fully parseable tag record.
699 all_tags = get_all_tags(root, _REPO_ID)
700 stored = next((t for t in all_tags if t.tag_id == shared_id), None)
701 assert stored is not None, "Tag not found after 100 concurrent writes"
702 assert stored.tag_id == shared_id, "Tag ID corrupted"
703 assert _is_valid_cid(stored.commit_id), "Stored tag has corrupt commit ID"
704 assert _tmp_files(tmp_path) == []
705
706 def test_no_orphan_temp_after_concurrent_tag_writes(
707 self, tmp_path: pathlib.Path
708 ) -> None:
709 """No orphan `.muse-tmp-*` files after 50 concurrent tag writes."""
710 root = self._init(tmp_path)
711 tags = [_tag(i) for i in range(50)]
712 threads = [threading.Thread(target=write_tag, args=(root, t)) for t in tags]
713 for t in threads:
714 t.start()
715 for t in threads:
716 t.join()
717 assert _tmp_files(tmp_path) == []
718
719
720 # ---------------------------------------------------------------------------
721 # 7. Reader never sees a torn write (HEAD)
722 # ---------------------------------------------------------------------------
723
724 class TestReaderDuringConcurrentWrites:
725 """A continuous reader thread must never observe a torn HEAD value.
726
727 'Torn' means partial content — e.g. 'commit: ' with no hash, or a 32-char
728 hash instead of 64, or a mix of two separate writes. os.replace is atomic
729 at the VFS level so the reader always sees either the old or the new file —
730 never an intermediate state.
731 """
732
733 def _init(self, tmp_path: pathlib.Path) -> pathlib.Path:
734 muse_dir(tmp_path).mkdir()
735 (heads_dir(tmp_path)).mkdir(parents=True)
736 return tmp_path
737
738 def test_reader_never_sees_torn_head_during_200_writes(
739 self, tmp_path: pathlib.Path
740 ) -> None:
741 """200 concurrent HEAD writes — concurrent reader never sees a torn value."""
742 root = self._init(tmp_path)
743 write_head_branch(root, "main") # initialise HEAD
744
745 cids = [_valid_cid(f"reader-cid-{i}") for i in range(100)]
746 branches = [f"reader-branch-{i:04d}" for i in range(100)]
747 torn: list[str] = []
748 stop = threading.Event()
749
750 def reader() -> None:
751 hp = head_path(root)
752 while not stop.is_set():
753 try:
754 content = hp.read_text(encoding="utf-8").strip()
755 if content and not _is_valid_head(content):
756 torn.append(repr(content[:60]))
757 except OSError:
758 pass
759 time.sleep(0.00005)
760
761 def cid_writer(cid: str) -> None:
762 write_head_commit(root, cid)
763
764 def branch_writer(branch: str) -> None:
765 write_head_branch(root, branch)
766
767 reader_thread = threading.Thread(target=reader)
768 writer_threads = (
769 [threading.Thread(target=cid_writer, args=(c,)) for c in cids] +
770 [threading.Thread(target=branch_writer, args=(b,)) for b in branches]
771 )
772
773 reader_thread.start()
774 for t in writer_threads:
775 t.start()
776 for t in writer_threads:
777 t.join()
778 stop.set()
779 reader_thread.join()
780
781 assert torn == [], (
782 f"Reader observed {len(torn)} torn HEAD values:\n{'\n'.join(torn[:5])}"
783 )
784
785 def test_concurrent_commit_writes_reader_always_valid(
786 self, tmp_path: pathlib.Path
787 ) -> None:
788 """A reader checking write_commit results always sees complete records."""
789 root = _repo(tmp_path)
790 commits = [_commit(i) for i in range(50)]
791 read_errors: list[str] = []
792 stop = threading.Event()
793
794 def reader() -> None:
795 while not stop.is_set():
796 for c in commits:
797 result = read_commit(root, c.commit_id)
798 if result is not None and result.message != c.message:
799 read_errors.append(
800 f"Commit {c.commit_id[:8]} message corrupted: "
801 f"{result.message!r} != {c.message!r}"
802 )
803 time.sleep(0.001)
804
805 reader_thread = threading.Thread(target=reader)
806 reader_thread.start()
807 for c in commits:
808 write_commit(root, c)
809 stop.set()
810 reader_thread.join()
811
812 assert read_errors == [], (
813 f"Reader saw corrupt commits during concurrent writes:\n{'\n'.join(read_errors[:5])}"
814 )
815
816
817 # ---------------------------------------------------------------------------
818 # 8. write_text_atomic — 100 threads same path, temp file uniqueness proof
819 # ---------------------------------------------------------------------------
820
821 class TestWriteTextAtomicRace:
822 """Dedicated race tests for write_text_atomic at the primitive level."""
823
824 def test_100_threads_same_path_final_is_complete(
825 self, tmp_path: pathlib.Path
826 ) -> None:
827 """100 threads writing to the same path — final value is one complete payload."""
828 dest = tmp_path / "state.txt"
829 payloads = [f"payload-{i:04d}-" + ("z" * 60) for i in range(100)]
830 errors: list[str] = []
831
832 def writer(content: str) -> None:
833 write_text_atomic(dest, content)
834 try:
835 got = dest.read_text(encoding="utf-8")
836 if got not in payloads:
837 errors.append(f"Torn content: {got[:40]!r}")
838 except OSError as exc:
839 errors.append(str(exc))
840
841 threads = [threading.Thread(target=writer, args=(p,)) for p in payloads]
842 for t in threads:
843 t.start()
844 for t in threads:
845 t.join()
846
847 assert errors == [], f"write_text_atomic race errors:\n{'\n'.join(errors[:5])}"
848 final = dest.read_text(encoding="utf-8")
849 assert final in payloads, f"Final content is not any single writer's payload"
850 assert _tmp_files(tmp_path) == []
851
852 def test_temp_files_are_unique_across_concurrent_calls(
853 self, tmp_path: pathlib.Path
854 ) -> None:
855 """Every concurrent call to write_text_atomic must produce a distinct temp name.
856
857 We capture mkstemp call arguments to verify no two calls share a name.
858 """
859 dest = tmp_path / "unique.txt"
860 tmp_names: list[str] = []
861 lock = threading.Lock()
862 real_mkstemp = tempfile.mkstemp
863
864 def tracking_mkstemp(
865 dir: pathlib.Path | None = None, prefix: str = ""
866 ) -> tuple[int, str]:
867 fd, name = real_mkstemp(dir=dir, prefix=prefix)
868 with lock:
869 tmp_names.append(name)
870 return fd, name
871
872 n = 50
873 payloads = [f"unique-{i}" for i in range(n)]
874
875 with patch("muse.core.io.tempfile.mkstemp", side_effect=tracking_mkstemp):
876 threads = [
877 threading.Thread(target=write_text_atomic, args=(dest, p))
878 for p in payloads
879 ]
880 for t in threads:
881 t.start()
882 for t in threads:
883 t.join()
884
885 assert len(tmp_names) == n, f"Expected {n} mkstemp calls, got {len(tmp_names)}"
886 assert len(set(tmp_names)) == n, (
887 f"Duplicate temp names detected — mkstemp uniqueness violated: "
888 f"{len(tmp_names) - len(set(tmp_names))} collisions in {tmp_names}"
889 )
890 assert _tmp_files(tmp_path) == []
File History 1 commit
sha256:2eaa5d95f9d9383498e76947410a26e5a3ba23d182f339910c424cf88fad412b fix: try fetch/presign before fetch/mpack to avoid Cloudfla… Sonnet 4.6 patch 7 days ago