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Merged
HeinrichApfelmus merged 2 commits into from
Apr 25, 2026
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Add comment explaining race condition #58

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tomjaguarpaw Apr 23, 2026
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Add comment explaining race condition
tomjaguarpaw Apr 23, 2026
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9 changes: 8 additions & 1 deletion src/Data/Vault/ST/backends/IORef.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,14 @@ lock (Key u ref) x = Locker u $ writeIORef ref $ Just x
unlock (Key k ref) (Locker k' m)
| k == k' = unsafePerformIO $ do
m
readIORef ref -- FIXME: race condition!
-- FIXME: race condition!
--
-- If another unlock action is run concurrently with this one
-- on the same Key but a different Locker then that one may
-- overwrite ref with its value before this one has had a
-- chance to read from it, so this one may obtain the wrong
-- result.
readIORef ref
| otherwise = Nothing

{-----------------------------------------------------------------------------
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