Make repo locks exception safe #718
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thomashoneyman
commented
Jan 16, 2026
thomashoneyman
commented
Jan 16, 2026
| -> Process | ||
| -> RepoLocks | ||
| -> RepoKey | ||
| -> Run (LOG + AFF + EFFECT + EXCEPT String + ()) a |
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This is a closed row restricted just to the actions we intend to 'lower' to Aff. If we wanted to expand locking outside this module we'd have to add explicit handling for anything else we want to run to Aff.
thomashoneyman
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Jan 16, 2026
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| { logs, outcome } <- Run.liftAff do | ||
| logsRef <- liftEffect $ Ref.new [] | ||
| outcome <- withRepoLockAff repoLock timeout (runWithLogs logsRef action) | ||
| logs <- liftEffect $ Ref.read logsRef | ||
| pure { logs, outcome } |
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cc: @natefaubion I couldn't think of a better way to do this, but if you have ideas I'm all ears
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Closing as we are going to drop concurrency after all. |
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The repo-locking flow in #715 has a couple issues, namely:
Aff(though it does catch run exceptions)All along we wanted to use
Aff.bracket, which is the typical approach to this kind of design. But this doesn't work withRun. In this change I've made a change to lower the action toAff, captureLOGeffects into aRef, then replay them after the lock is released to preserve logging behavior. This lets us remove the orphan-cleanupclearOwnLocks, which was only compensating for the previous non–exception-safe path.The new helper (
runWithLogs) usesRun.runContto interpretLOG,AFF,EFFECT, andEXCEPT String, not supporting any other effects, and the change is localized to the registry module. Logs are replayed afterwards, and we still throw exceptions if needed, but the lock will be released. The lock timeout currently produces anAfferror and a warning log with the owning process name.I also added a new
Test.Registry.App.Effect.Registrymodule which acquires a lock, throws an exception, and makes sure everything's still clean. Might add a couple more tests.