Parents and children of check-in [e56a663b7a]
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2026-07-31
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| 19:24 |
logstore: scan header-only on the append path
The open-time scan streamed every payload byte through the crc, making open cost O(repository bytes) rather than O(what the caller asked for). ScanMode.headers_only validates each frame's header window and then steps over the payload by frameSpan arithmetic, leaving open cost O(frame count). Measured, same binary, both modes in one run: 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 Every fault that lives in a header window is still caught: readFrameHeader runs unchanged, so a bad prefix crc, a bad header crc, an out-of-range hash_len and an unknown flag kind all still void the open. Torn-tail detection survives intact -- a torn frame is a clean prefix, never damaged bytes, so offset + frame_len > total catches every truncation the payload and trailer short-read checks used to, using a length the header window already proved trustworthy. What is no longer caught at open is a bitflip in already-landed payload bytes, which becomes content()'s job; it crc-checks the frame it reads regardless. openReadOnly -- the path every CLI verb reaches -- deliberately keeps .verify_payloads. No guarantee has moved on the production path yet, and none should until the explicit fsck verb exists to replace it. This half is what makes the cost measurable without taking on that decision. The one test that changed is the one that had to: a corrupted payload on a complete frame no longer voids open. It now asserts the fault surfaces on the first content() read AND that openReadOnly still rejects the file eagerly. That second assertion is the tripwire for deleting verified_on_open without shipping the verb first. check-in: bae910f00e user: dmestas tags: logstore-open-cost | |
| 19:23 |
bench: measure openReadOnly, not just open
benchOpen timed LogStore.open -- the append path. Production never takes it: Repository.open falls back to openReadOnly, and Repository.logStore, the lazy content channel behind blob, cat, checkout and sync, calls openReadOnly with no cache in front. Every open number this effort has produced described a path no CLI verb enters. That was survivable while the two paths ran the same scan. It stops being survivable the moment either one scans header-only, at which point the bench would report the optimized path while production still paid the full cost. --mode append|read-only defaults to append so existing invocations report unchanged numbers, and the mode is in the output line because the two are only comparable when a captured log can tell them apart. Calibration on this tree, before any scan change: the modes agree within noise on all four shapes -- run B is 1% apart. That agreement is the check that the flag measures what it claims. check-in: e56a663b7a user: dmestas tags: logstore-open-cost | |
| 02:43 |
build: split the unit lane from the full gate
zig build test was 9m13s, and the tests it actually ran were a small fraction of that: it also compiled the e2e and smoke harnesses in the pinned ReleaseSafe and then never executed them. test is now unit tests only -- 2m54s cold, 1m42s warm -- and the new gate step carries those two compile proofs. The dst, bench and smoke UNIT tests deliberately stay on test. They are unit tests despite their siblings' names, zig build dst/smoke run the simulation and the interop check rather than them, and CI invokes the lanes one by one and never invokes gate -- so moving them would have dropped them from CI while every step still looked green. ci_test's declared_steps records gate as intentionally not-in-CI, and names that failure mode for the next lane someone adds. check-in: 7363238ad5 user: dmestas tags: trunk | |