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5 commits

Author SHA1 Message Date
0c9b2c45d8 feat(db-bench): measure the RAM ceiling — databasev2 1
- `Wide` text-heavy reference shape beside Int-only `Item`
- `growth N int|text`: per-decile RSS read from own /proc/self/status
- `growth-verify`: survivor of a crash must be a contiguous intact prefix
- four footprint legs under a rootless cgroup v2 cap, swap on/off
- `ceiling` leg: die at the cap, then replay must come back intact
- footprint read as median-of-marginals; doublings a separate metric
- 121 checks, 0 failures; footprint gated ±10%, kill-timing ±100%

Measured, and it inverted two of the iteration's own predictions:

- footprint 96.5-100 B/row Int vs 320.6-324 B/row text = 3.3x, NOT the
  "order of magnitude" three docs asserted
- table storage has NO checked ceiling: SIGKILL signal 9, not a catchable
  WO_T_OOM. overcommit lets malloc succeed; kernel kills on page touch
- swap is NOT latency collapse: 900k rows 148s capped-with-swap vs 150s
  uncapped. Append-mostly never re-touches cold pages
- ack-after-fsync survives an OOM kill: ~40k rows, no holes, no corruption
- iteration 2's budget dependency is REMOVED not satisfied — there is no
  "swap onset" to derive a fraction from

- fix: subprocess returncode -9 was labelled a "checked refusal"; 137 is
  the shell spelling of the same signal

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-27 20:18:47 +02:00
dd7dd42bd1 feat: bounded mailboxes + WO_T_ACTOR (trap 13); try-arm place-copy fix
- cap 1024 (WO_MAILBOX override at boot): sender-side atomic
  reserve/release on every path — same-shard, cross-shard envelope,
  OOM rollbacks; full mailbox traps the SENDER catchably; delivery
  pop releases; overshoot bounded by in-flight sends (disclosed)
- test_mailbox 12/0: exact cap single-threaded, two racing senders win
  exactly cap slots, drain/refill clean
- corpus run/mailbox-full-trap: parked sleeper, send loop catches
  "actor mailbox full" after >= 1024 sends
- pre-existing compiler bug found + fixed: a try ARM yielding a Text
  PLACE (bare e.msg, try box.field) aliased a register the arm's scope
  end freed — ASan use-after-free, SEGV on the next unwind's
  double-walk; emit_try now applies copy_place_text to both arm
  results; pinned by corpus run/catch-msg-place
- db-bench driver: msgrate keeps iteration 22's unbounded-flood
  contract via WO_MAILBOX=MSG_N (the cap is 24's policy, not 22's)
- battery 12/12 fresh-built

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-23 01:05:13 +02:00
881b90e9c7 feat: O(1) read path — index probe wired end to end
- engine: wo_idx_probe answers single-column equality from the index
  hash buckets (idx_hash_key1 reproduces idx_hash bit for bit; verify
  compares exactly as the slab walk did, so results identical);
  composite indexes keep the walk; both executors wired (local + DB
  actor RPC)
- compiler: probe_key_of_where lowers "var.col == key" on an indexed
  column to DB_PROBE; all where guards still run (guard stays the
  final arbiter); keys = ident/int-literal only; Float/Bytes excluded
  (engine raw-eq narrower than VM float-eq)
- measured: reads 1.3k -> 1.3M ops/s, p50 600us -> 1us (~x850);
  query x830; mixread 1.3k -> 89k s1, 21 -> ~1.9k sN
- gate policy moved into the driver (tolerance_for: refresh-proof);
  latency floors max(4x,100us); quick mode skips poll-bound mix
  floors; both tolerance classes proven to bite
- proof: test_table wo_idx_probe suite (RED first), corpus
  query-index-probe 105/0, full battery green, TSan clean, two
  campaigns pass the refreshed baseline

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-22 16:44:56 +02:00
3a30b4ac3b feat(db-bench): first baseline — the measurement contract (T5)
- bench/baseline.json: 74 metrics from the first full campaign;
  tolerances tuned by a two-run repeatability check (mix* 50%,
  read/query 35%, rest 15% — rationale in _config)
- gate bites: --check mode; doctored copy fails, both real runs 74/0
- headline: durable seed 4.5k/s vs ram 297k/s (23's case); reads
  O(table) at ~1.5k/s; mixread 1280 vs 21 ops/s single-vs-multi
  (the arc's price); msgrate 13.4M vs 2.45M (mutex-inbox number)
- arc delta recorded in story 8; findings in sample README

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-21 16:54:13 +02:00
d1cdf3ed6c feat(db-bench): campaign driver + gate + recipes (T4)
- scripts/db-bench.py (one python driver — bash+python deviation,
  disclosed): ram+durable x 1/N shards, msgrate per shard count,
  restart proof, kill -9 battery vs acked high-water, RSS/fd
  sampling from the mix phase, results JSON, relative+floor gates
- just db-bench / db-bench-quick (quick = floors only)
- quick campaign 14 checks green; gate honestly fails without a
  baseline (--write-baseline is Task 5's first full run)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-08-21 16:44:25 +02:00