myxce/.wolf/bugs/bug-1426.md
Rongsong Shen d26ff8870d
feat(buglog): one Markdown record per bug, checked against a record standard
The buglog was one 27K-line JSON file whose fields covered only symptom,
root cause and fix, as free text: 2% of entries named the code version a
bug was found on, 12% the build profile, 36% a way to reproduce, and 58% of
the file was OpenWolf hook auto-detections ("Missing guard clause",
"Function not marked async" on .md files).

- .claude/skills/buglog/bug-record.md: the record standard. Eight
  sections (Summary as the title, Description, Environment, Reproduction;
  Root cause, Fix, Verification, References once fixed), each with the
  content it must contain -- e.g. Environment needs the OS, the libc the
  failing binary loads (from its ELF interpreter: glibc 2.42 in the nix
  shell vs 2.40 on the host), toolchain, build profile and commit.
- .wolf/bugs/<id>.md: 500 records migrated from buglog.json; every field
  verified to round-trip. They carry legacy: true and an explicit "not
  recorded" where the old log had no such field; component derived from
  file paths, severity from keywords (else unknown), fix_commits from
  hashes in status_note/fix that git resolves (91 of 463 fixed).
- .wolf/buglog-archive.json: the 710 hook auto-detections, verbatim.
- .wolf/buglog.json is now an index generated from the records, keeping
  the fields OpenWolf's hooks and `openwolf bug search` read.
- scripts/buglog.py rewritten: new (template + Environment collected from
  the machine and --binary), check, status (refuses a status the record
  doesn't support; fixed needs Root cause, Fix, Verification and
  --commit hashes git resolves), note, recur, set, show, list, triage,
  env, index. 29 unittest cases in scripts/tests/test_buglog.py.
- scripts/git-hooks/pre-commit runs `check --staged`: incomplete staged
  records, a legacy record hand-changed to fixed without the fix-time
  sections, a new record claiming legacy: true, or a stale index refuse
  the commit.
- scripts/gitea-sync.py reads the records: issue body = the record's
  sections plus linked fix commits (origin remote, GITEA_COMMIT_REPO to
  override), and a body hash so an issue's text is refreshed when the
  record changes.
- bug-1866 rewritten to the full standard as the worked example.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 03:40:11 +00:00

4.3 KiB

id status status_updated status_note component severity timestamp last_seen occurrences files tags related legacy
bug-1426 fixed 2026-09-24 controller unknown 2026-07-09T21:15:00.000Z 2026-09-19T09:00:00Z 1
src/controller/persist.c (trim_wal_segments
apply_pump_read_entry cache)
ha
persistence
wal-trim
apply-pump
low-priority
raft-apply-decoupling-followup
true

bug-1426: trim_wal_segments's retention floor has no awareness of the local apply pump's own lag — a…

Description

trim_wal_segments's retention floor has no awareness of the local apply pump's own lag — a reachable scenario since apply-lag-behind-commit is raft-apply-decoupling's entire premise.

Environment

Not recorded (migrated from buglog.json).

Reproduction

Not recorded (migrated from buglog.json).

Root cause

Identified during raft-apply-decoupling task 7.4's apply-pump segment-read cache fix (round-2 review finding): the new fast-path cache can (POSIX unlink-keeps-fd-alive) silently advance last_applied_lsn past already-deleted data if the pump is lagging when trim_wal_segments fires. Currently bounded by the pre-existing APPLY_DIVERGENT boot fence (deferred loud fencing on next restart, not silent corruption) — a real behavior change from the pre-cache code, not literally risk-free, but not an active defect either. Same family as an already-tracked standby-cursor variant (per task 7.4's own notes).

Fix

FIXED (TDD RED->GREEN). trim_wal_segments() now caps its trim floor at the local apply pump's own progress (last_applied_lsn), not just remote standby-acked positions: floor = min(repl_trim_lsn's standby/disconnect-guard floor, last_applied_lsn+1). The +1 matters -- repl_trim_lsn's floor treats equality as 'still needed, preserve' (a standby acked through LSN N might still need that segment for retry/resync), but the LOCAL apply cursor's equality case means the opposite: last_applied_lsn==N means this process is DONE with entry N and will never re-read it, so a segment starting exactly at N is safe to delete. Feeding last_applied_lsn+1 into the same shared 'seg_start_lsn < floor' comparison gets correct delete-on-equal semantics for this term without a second, differently-shaped check. This closes the real gap: apply_pump_read_entry()'s fast-path cache holds an open fd into whatever segment it's currently reading; POSIX unlink-keeps-fd-alive meant a lagging pump could keep reading via that stale fd even after trim_wal_segments deleted the segment out from under it (no immediate corruption, since the fd's data was still valid) -- but a FRESH read of the same range (a restart's persist_recover() replay, or the pump's own cache falling back to its slow path after an unrelated miss) would find the segment already gone, producing a genuine APPLY_DIVERGENT-class gap between what the live process quietly caught up to and what a fresh read of disk state can see. Regression test (test_e2e_checkpoint.c's test_trim_guard_preserves_unapplied_local_segments): no standbys registered (so the pre-fix floor alone would allow trimming everything below the active segment) but last_applied_lsn deliberately lags behind one segment -- proves the already-applied segment IS trimmed (no unnecessary retention) while the not-yet-applied one is preserved (the actual guard). Also had to advance last_applied_lsn in the 3 pre-existing trim tests in the same file (test_checkpoint_wal_trim_after_checkpoint, test_trim_guard_preserves_standby_segments, test_trim_without_standbys_proceeds_normally), which call persist_wal_async directly (bypassing the whole apply path) and so never advance last_applied_lsn on their own -- without the added stamp, this fix would have correctly-but-unexpectedly blocked ALL trimming in those fixtures, since last_applied_lsn defaults to 0. Full controller_unit_test suite: 1099 tests, 2 pre-existing unrelated failures (bug-1561), no regressions.

[Original entry] NOT FIXED — deliberately deferred. task 7.4's own scope explicitly excluded redesigning trim_wal_segments's retention-floor awareness of apply-pump lag; documented via an accurate code comment instead. A future fix would give trim_wal_segments a floor input derived from the local apply cursor, not just standby-acked LSNs.

Verification

Not recorded (migrated from buglog.json).

References

Not recorded (migrated from buglog.json).