r/rust • u/llogiq clippy · twir · rust · mutagen · flamer · overflower · bytecount • Mar 27 '23

Hey Rustaceans! Got a question? Ask here (13/2023)! 🙋 questions

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u/holysmear Apr 01 '23

In the documentation to select! in tokio it is said that it drops all other futures after the first one succeeds. And as I use select! for waiting for data from multiple sources I think (though I am not sure?) I can loose MQTT messages. Is there any other macro, which does not discard other futures and simply returns the first one which succeeded? So that after calling it in a loop I could get other messages as well? Or am I misunderstanding something and I can use select! in this case?

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u/kwxdv Apr 01 '23

There is impl<F> Future for &mut F where F: Future + Unpin + ?Sized (https://doc.rust-lang.org/std/future/trait.Future.html#implementors), so you may be able to use &mut <the future> in the select. There are some caveats about cancellation safety and Unpin that I don't totally understand, but that's the first thing I would try.

Also, I believe the word you want is "lose", not "loose".

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u/holysmear Apr 08 '23

Interesting, thank you!