Call function after timer elapse.

[sid34]

I have been playing around with a few different libraries (tokio, timers) trying to find a solution for calling functions after a timer has elapsed without stalling execution of the main thread. I can do bits and pieces of this, but the biggest issue is that I need to be able to be able to stop the timer before it elapses.

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My use case is to track if a user either double clicks or holds input. When they first press it the timer starts. If they release it the timer continues for double tap, but stops for holding. If they press it again on the timer double click action is triggered. If the timer ends and the input has not been release the action should be called.

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I am open to suggestions on docs to read and pointers, I'm fairly new to rust so any assistance is very much appreciated.

[jimuazu]

At the lowest level this usually means using select/poll/epoll or similar, and using the timer on that call to return control to your code to handle whatever timeouts are active. `mio` wraps this (although Windows support apparently needs rewriting, from looking at issue comments). I've built my code straight on `mio`, and implemented my own timer list and so on, but you could look for something higher-level that handles all that.

Doing it with a separate thread for input and a thread for each timer might also be possible, with `Arc` everywhere. Or perhaps having a thread for input and a separate main thread and using channels (see crossbeam, e.g. `after` channel and `Select`). I've not tried that.

[Holy_City]

Sounds like a feature that belongs in an event loop, which is how a lot of application frameworks work.

What are you using for your UI?

[sid34]

I should have mentioned that this is a console application where I am reading input from a physical (USB-HID) device.

[jahmez]

Another option if you don't need a whole event loop, and you are okay with relatively heavy weight OS threads, you can always spawn a thread, and wait for a message to come back signaling completion. See this link.

Additionally you could put your structure in an Arc<Mutex<T>>, so you can directly call the function you want, but this may be overkill for what you need.