fix(frontseat-store): GH-266 bound the slice, not the subscribe cursor - #267
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fix(frontseat-store): GH-266 bound the slice, not the subscribe cursor#267joaodinissf wants to merge 1 commit into
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Subscribe clamped its cursor down to len(events) as it stood when the delivery goroutine happened to start. The clamp was there to stop a cursor past the end panicking on the first wake, but bounding the cursor rather than the slice left a subscriber that over-asked tailing from wherever the journal was at that instant, delivering sequences below the one it asked for. Keep the cursor at fromSeq-1 as a permanent floor and bound the slice instead, so an over-asking subscriber yields nothing — matching the replay path. Carrying it as an int64 also removes the wrap-to-negative index a wire value near math.MaxInt64 could produce. TestJournalSubscribeBeyondEnd/finished caught this about once in 3000 runs; 4000 iterations and the race detector are clean now. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Subscribeclamped its cursor down tolen(events)as it stood when thedelivery goroutine happened to start. The clamp was there to stop a cursor past
the end panicking on the first wake, but bounding the cursor rather than the
slice left a subscriber that over-asked tailing from wherever the journal was
at that instant — delivering sequences below the one it asked for.
The cursor now stays at
fromSeq-1as a permanent floor and the slice isbounded instead, so an over-asking subscriber yields nothing, matching the
replay path. Carrying it as an
int64also removes the wrap-to-negative indexa wire value near
math.MaxInt64could produce.TestJournalSubscribeBeyondEnd/finishedcaught this about once in 3000 runs,which was enough to redden unrelated PRs. 4000 iterations and the race detector
are clean now.
Fixes #266
This pull request was published with assistance from Claude.