rtic-sync: deal with dropping & re-splitting channels. #1040
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datdenkikniet
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korken89
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Mar 23, 2025
rtic-sync/src/channel.rs
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| pub fn split(&mut self) -> (Sender<'_, T, N>, Receiver<'_, T, N>) { | ||
| assert!( | ||
| self.readyq.get_mut().is_empty(), |
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Since we have &mut channel here, can't we do self.clear()?
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Yes, we could. When writing this felt weird to drop the items in the queue on split, but not any earlier. Since most callers won't ever re-split() their queue I figured we could get away with never calling clear if they do not.
If you think we should clear(), should we do it in Receiver::drop too? It just feels kind of arbitrary to drop leftover items on split() and not earlier (i.e. Receiver::drop), but I have no clue what the usual thing to do is, here.
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Have rebased on the latest master. Any opinions on the above?
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Currently
split-ing a channel is technically allowed, but there is no non-panicway of actually doing so.Currently it will either
paniciffreeqis full (andreadyqis empty), or succesfully re-split and always produceErr(NoReceiver)when sending, and/orpaniceventually when returning a free slot whilerecv-ing.Additionally, items in the ready queue are never dropped if the channel is dropped.
This is not a particularly often-used use-case, but that doesn't mean we cannot try fixing it :)
An alternative approach is to just have a
split: boolin theChanneland alwayspanicif that bool is already set, or always callingChannel::clearwhensplit-ing.To see concrete use-cases that this PR fixes, please check out the introduced tests.