pagination: don't hold onto the waited_for_initial_prev_token lock for long
#3501
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…r too long While this mutex is taken, in `oldest_token()` we can get a hold of the RoomEvent mutex, making it so that the `waited_...` token covers the critical region of room events. Unfortunately, in `clear()`, we're taking these two locks in the opposite order, implying that the room events critical region now overlaps that of the `waited_...` lock. The way to break the cycle is to keep the `waited_` token for as short as possible.
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Tested ok on EXA! |
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #3501 +/- ##
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Coverage 83.73% 83.73%
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Files 255 255
Lines 25778 25778
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Hits 21584 21584
Misses 4194 4194 ☔ View full report in Codecov by Sentry. |
bnjbvr
changed the title
waited_for_initial_prev_token lock for long
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Well done! 👏 |
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While this mutex is taken, in
oldest_token()we can get a hold of the RoomEvent mutex, making it so that thewaited_...token covers the critical region of room events.Unfortunately, in
clear(), we're taking these two locks in the opposite order, implying that the room events critical region now overlaps that of thewaited_...lock.The way to break the cycle is to keep the
waited_token for as short as possible.