Artifact Description [ab733544a9]

Artifact ab733544a9f1716b2d4d64db5761d59ca7b39a266587bf310f266b462ececc00:

• File src/logstore.zig
  • 2026-07-31 20:52:45 — part of check-in [bcb9f8eb6e] on branch logstore-open-cost — verify: the explicit fsck verb

    Slice 2 will extend header-only scanning to openReadOnly and delete verified_on_open, which removes eager corruption detection entirely. This is the on-demand replacement that has to exist first -- the same split git makes between normal operation and git fsck.

    Two passes over the store. FrameVerifier walks every frame under .verify_payloads, which is the mode the open paths are shedding; it is built on StorageFile rather than an opened LogStore, so it still works on a store that will not open -- the case an fsck exists for. Then openForVerify opens .headers_only and reconstructs each artifact, which catches a frame whose checksum is honest about bytes that are not what their name claims.

    Both passes report rather than abort. A payload CRC fault carries a header-proven frame_len, so the walk steps over it and inventories the rest; only a header-window fault, whose length cannot be trusted, stops the walk. A torn tail is not a fault -- open recovers it silently, and it means an interrupted write, not rot. An unreadable payload is a finding too, not the end of the inventory.

    Exit codes stay 0/1/2 as every other verb documents them; 2 remains usage error and never corruption. Findings stream to stderr as they are found, the clean summary goes to stdout, and on any fault stdout is empty.

    Scope stops at content artifacts. A manifest whose bytes hash correctly is byte-identical to what commit wrote and what sync validated on ingest, so re-parsing it would catch a zit bug rather than storage rot. The help text says so.

    openForVerify is deliberately not openReadOnly: openReadOnly sets verified_on_open, which makes readFrameAt skip the per-read whole-frame CRC, and it scans .verify_payloads, so on exactly the damaged store an operator is fsck-ing it aborts before pass 2 runs. Slice 2 makes the two identical and openForVerify is deleted in that commit; its doc comment says so.

    The chunk buffer in scanOneFrame's payload loop widens from 4 KiB to 64 KiB, matching cloneInto's existing precedent. Post-Slice-2 that loop runs only under verify, where an operator's wall-clock is what it costs.

    zit verify is not an RFC-mandated verb. repo-state 7.3 blesses full rebuild as a fallback, but the verb's shape is a local design decision, not a protocol requirement.

    Verified: fmt clean, test 2327/2327, gate 19/19, e2e 671/671. Four mutants, all compiling, each red for its own semantic reason: pointing the frame pass at .headers_only, stubbing artifact.verify to true, dropping the unreadable-store tally, and reverting the payload read to a hard error. Exit arms smoke-checked against the built binary. (user: dmestas, size: 215612) [annotate] [blame] [check-ins using]

  • 2026-07-31 20:54:53 — part of check-in [90bd1b8015] on branch trunk — merge logstore-open-cost: header-only open scan and the verify verb

    Opening a repository checksummed every payload byte, so open cost scaled with the whole store rather than with what the caller asked for. The append path now scans header-only:

    10k frames 42 MB 42.2ms -> 11.2ms 10k frames 410 MB 298.0ms -> 12.7ms 100k frames 416 MB 511.9ms -> 119.2ms 100 frames 419 MB 321.4ms -> 0.10ms

    openReadOnly -- the path every CLI verb reaches -- deliberately still verifies payloads. Nothing has moved on the production path yet. That is Slice 2, and it is gated on this merge's other half: zit verify, the on-demand fsck that has to exist before eager detection is removed.

    The 100k-frame run settles a question the plan left open. Slice 4's gate was 'build the sidecar index only if that shape exceeds 150ms after the scan change'; it lands at 119ms. The sidecar is dead, and mmap with it -- separately, a mapping would keep shunned bytes resident and readable until every mapping dropped, which defeats the reclamation guarantee rather than merely slowing it. Both should be recorded as evaluated-and-rejected at the logstore extension comment; that is not done here.

    Also adds --mode append|read-only to the open benchmark. Every open number this effort had produced measured LogStore.open, which no CLI verb enters; the two modes agreed within noise before the scan change, which is what makes the after numbers above a comparison rather than two guesses.

    Verified on the merged tree: fmt clean, test 2327/2327. gate 19/19 and e2e 671/671 were watched green at the branch tip, which is content-identical -- trunk did not move between the branch point and this merge. (user: dmestas, size: 215612) [annotate] [blame] [check-ins using]