writeonce/database
shoney.arickathil 76d80cc027 feat(db): one barrier per drain, replies held — T2
databasev2 4 part A, task 2. The core change, and mostly deletion.

- the REQUEST path (wo_db_exec_req) no longer commits after each append.
  Applying to RAM and staging stay exactly where they were
- wo_vm_adopt holds each DB reply envelope in a local FIFO instead of
  pushing it as the statement finishes. Pushing there would unpark the
  requester before its record is durable — the ack contract this
  iteration exists to make literally true rather than true by accident
  of every batch having one member
- at the end of the drain: ONE wo_wal_commit_fatal for everything staged,
  then every held reply. Locals rather than per-shard state: nothing
  needs to outlive the batch it describes
- "did this statement stage anything" is asked of the buffer, not guessed
  from the opcode, and that count is what the failure diagnostic reports
- the drain commits unconditionally when anything is staged, because the
  inline path relies on finding the buffer empty (task 3 documents that)
- staging failure on the request path is now FATAL via wo_wal_stage_fatal:
  the row is already in RAM and of the three verbs only insert could undo
  itself, so continuing means RAM ahead of disk. One rule
- wal_die is now shared by both fatal points

Verified — the ack contract is the thing that could break, so it is what
was tested:

- just wovm-test: 36 suites (18 x both dispatch flavors) 0 fail, cli_smoke OK
- just db-bench-quick: 85 checks, 0 failures. The legs that matter:
  crash.sN.0 — 612 acked rows all present after kill -9, which is the
  BATCHING path (multi-shard requests, held replies, one barrier);
  crash.s1.0 — 800 acked rows; restart.s1 and restart.sN replay byte-true

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-28 09:25:10 +02:00
..
src feat(db): one barrier per drain, replies held — T2 2026-08-28 09:25:10 +02:00