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Make check-then-hold atomic (double-booking race) #4

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opened 2026-07-18 22:19:51 +00:00 by padreug · 1 comment

padreug commented

2026-07-18 22:19:51 +00:00

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crud.is_available() followed by writing the held booking is a critical section. Two concurrent requests for the same nights can both pass the availability read before either writes → double booking. Marked TODO(concurrency) in views_api.py:api_request_booking.

Options

Wrap check + insert in a single DB transaction (db.reuse_conn / async with db.connect()), or
Take a per-room asyncio.Lock around the section (simpler; single-process only — fine for one castle instance).

Because the availability check counts held as occupying, once one request writes held the loser's re-check fails → 409. The fix only needs to make the read→write atomic.

Acceptance

A test firing two simultaneous requests for identical dates results in exactly one held booking and one 409.

`crud.is_available()` followed by writing the `held` booking is a critical section. Two concurrent requests for the same nights can both pass the availability read before either writes → double booking. Marked `TODO(concurrency)` in `views_api.py:api_request_booking`. ### Options - Wrap check + insert in a single DB transaction (`db.reuse_conn` / `async with db.connect()`), **or** - Take a per-room `asyncio.Lock` around the section (simpler; single-process only — fine for one castle instance). Because the availability check counts `held` as occupying, once one request writes `held` the loser's re-check fails → `409`. The fix only needs to make the read→write atomic. ### Acceptance A test firing two simultaneous requests for identical dates results in exactly one `held` booking and one `409`.

padreug referenced this issue

2026-07-18 22:26:36 +00:00

feat: wire FX + deposit invoice into the booking hold (#3) #7

padreug referenced this issue

2026-07-18 22:26:48 +00:00

Wire relay publish + inbound subscription in nostr/service.py #2

padreug referenced this issue

2026-07-19 13:38:42 +00:00

Wire relay publish + inbound subscription in nostr/service.py #2

padreug referenced this issue from a commit

2026-07-19 15:08:47 +00:00

fix: make check-then-hold atomic against concurrent bookings (#4)

padreug referenced this issue

2026-07-19 15:09:00 +00:00

fix: make check-then-hold atomic against concurrent bookings (#4) #9

padreug referenced this issue from a commit

2026-07-19 15:09:30 +00:00

Merge pull request 'fix: make check-then-hold atomic against concurrent bookings (#4)' (#9) from feat/atomic-hold into main

padreug referenced this issue from a commit

2026-07-19 15:48:15 +00:00

test: booking-flow, availability, and #4 concurrency regression

padreug referenced this issue

2026-07-19 15:48:31 +00:00

test: add test harness + suite (incl. #4 concurrency regression) #10

padreug referenced this issue from a commit

2026-07-19 15:49:26 +00:00

Merge pull request 'test: add test harness + suite (incl. #4 concurrency regression)' (#10) from feat/tests-harness into main

padreug commented

2026-07-19 22:20:25 +00:00

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Shipped in PR #9 (per-room asyncio.Lock around check-then-hold), with a real-DB concurrency regression test in #10 and the migration test in #15; released in catalog v0.1.0. Closing (auto-close phrasing never fired).

Shipped in PR #9 (per-room `asyncio.Lock` around check-then-hold), with a real-DB concurrency regression test in #10 and the migration test in #15; released in catalog v0.1.0. Closing (auto-close phrasing never fired).

padreug closed this issue

2026-07-19 22:20:45 +00:00

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aiolabs/chatelet#4

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