Switch PersistenceNotifierGuard persist closure to FnOnce #3835
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This allows us to move owned and mutable values into the closure, with the assumption that the closure can only be invoked once. As a result, we now have to track `should_persist` as an `Option`, such that we can `take` the owned closure and invoke it within the `PersistenceNotifierGuard::drop` implementation.
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## main #3835 +/- ##
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- Coverage 89.92% 89.84% -0.09%
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Lines 129581 129655 +74
Branches 129581 129655 +74
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| event_persist_notifier: &'a Notifier, | ||
| needs_persist_flag: &'a AtomicBool, | ||
| should_persist: F, | ||
| should_persist: Option<F>, |
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The explanation why this needs to be an option could be helpful in the code rather than in the commit message.
| @@ -2815,10 +2815,10 @@ enum NotifyOption { | |||
| /// We allow callers to either always notify by constructing with `notify_on_drop` or choose to | |||
| /// notify or not based on whether relevant changes have been made, providing a closure to | |||
| /// `optionally_notify` which returns a `NotifyOption`. | |||
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Background question: it seems that in some instances, the persist_check isn't just checking, but also making the actual changes to the chan mgr state. Is that fine, or indicative of the PersistenceNotifierGuard not fully matching its desired use cases?
| @@ -2833,20 +2833,20 @@ impl<'a> PersistenceNotifierGuard<'a, fn() -> NotifyOption> { | |||
| /// isn't ideal. | |||
| fn notify_on_drop<C: AChannelManager>( | |||
| cm: &'a C, | |||
| ) -> PersistenceNotifierGuard<'a, impl FnMut() -> NotifyOption> { | |||
| ) -> PersistenceNotifierGuard<'a, impl FnOnce() -> NotifyOption> { | |||
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So this means that only single-use closure may be provided now. And it seems we are lucky that nowhere a closure was reused, so no other refactoring needed? (questions for me to understand this better)
This allows us to move owned and mutable values into the closure, with the assumption that the closure can only be invoked once. As a result, we now have to track
should_persistas anOption, such that we cantakethe owned closure and invoke it within thePersistenceNotifierGuard::dropimplementation.Motivated by #3736 (comment).