StatsModel: narrow dogpile cache-overwrite race can extend stale stats up to another full TTL after invalidation #91

New Issue

2026-09-01T00:08:20-04:00

jared commented

2026-09-01 00:08:20 -04:00

Severity: Low

helpers/CacheHelper.php (remember()) has no locking around cache-miss recomputation. If Request A starts computing stats just before a ticket mutation + invalidateCache(), and Request B starts just after the mutation (correctly computing fresh, post-mutation stats), it's possible for A to finish computing (using stale pre-mutation data) AFTER B and overwrite B's fresh cache entry — extending staleness by up to another full 60s TTL.

Window is narrow in practice (only as wide as the stats query's execution time, likely well under 100ms), and this is a genuine race rather than a design gap, but worth a low-priority fix.

Fix: Add a simple compute-generation/version check before writing the cache (only write if no newer invalidation happened since this computation started), or accept the narrow risk as-is given how small the window is — flagging for a decision either way.

**Severity:** Low `helpers/CacheHelper.php` (`remember()`) has no locking around cache-miss recomputation. If Request A starts computing stats just before a ticket mutation + `invalidateCache()`, and Request B starts just after the mutation (correctly computing fresh, post-mutation stats), it's possible for A to finish computing (using stale pre-mutation data) AFTER B and overwrite B's fresh cache entry — extending staleness by up to another full 60s TTL. Window is narrow in practice (only as wide as the stats query's execution time, likely well under 100ms), and this is a genuine race rather than a design gap, but worth a low-priority fix. **Fix:** Add a simple compute-generation/version check before writing the cache (only write if no newer invalidation happened since this computation started), or accept the narrow risk as-is given how small the window is — flagging for a decision either way.

jared added the performance priority/low labels 2026-09-08 10:15:49 -04:00

jared referenced this issue from a commit

2026-09-08 14:35:21 -04:00

Fix dogpile cache-overwrite race in CacheHelper::remember() (#91)

jared referenced this issue from a commit

2026-09-08 15:39:42 -04:00

Merge development into main: 15-issue triage + fix batch

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