Cancelling a timer also aborts the cancelled task #292
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adwhit
changed the title
charypar
reviewed
Jan 6, 2025
crux_time/src/lib.rs
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| lock.remove(&self.timer_id) | ||
| }; | ||
| let this = self.project(); | ||
| *this.is_cleared = timer_is_cleared; |
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I'd have to try to have specific advice, but I think you might be able to avoid the pin_project by self.deref_mut() and an Unpin trait bound for whatever is complaining about not being guaranteed unpin.
Was that problematic?
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Have removed pin_project, you're right, it wasn't necessary in this instance.
| .resolve( | ||
| &mut debounce, | ||
| TimeResponse::DurationElapsed { id: timer_id }, | ||
| ) |
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A good test that this doesn't cause issues if the shell still fires the timer.
In a way, we could simply not tell the shell about the cancellation and just stop the task like you are doing which will ignore the timer when it fires.
Merged
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The existing timer logic can result in memory leaks.
Example: user creates a timer with
crux_timewhich will eventually call a closure to resolve to an event, which is fed back to the app. Let's suppose the closure contains some significant amount of state. If the user then clears the timer, the task containing the closure will never resolve (because the shell never returns from the timer effect), and the closure is leaked.This PR attempts to fix this by wrapping the timers in a
TimerFuturestruct. When theTimerFuturestruct is polled, it will check if the timer has been cleared, and if so return immediately rather than waiting on the shell.The implementation uses some global state which isn't very nice but might be unavoidable.