tokio-js-set-interval

The crate tokio-js-set-interval allows you to use setInterval(callback, ms) and setTimeout(callback, ms) as in Javascript inside a tokio runtime (https://tokio.rs/). For this, it offers the macros set_interval!(callback, ms) and set_timeout!(callback, ms).

How to use

Cargo.toml

[dependencies]
# don't forget that you also need "tokio" for the tokio runtime!
tokio-js-set-interval = "<latest-version>"

code.rs

use std::time::Duration;
use tokio_js_set_interval::{set_interval, set_timeout, clear_interval};

#[tokio::main]
async fn main() {
    set_timeout!(println!("hello from timeout"), 25);
    set_interval!(println!("hello from interval"), 10);
    // you can clear intervals if you want
    let id = set_interval!(println!("hello from interval"), 10);
    clear_interval(id);
    
    // give enough time before tokios runtime exits
    tokio::time::sleep(Duration::from_millis(40)).await;
}

Restrictions

They behave similar to their Javascript counterparts, with a few exceptions:

• They only get executed if the tokio runtime lives long enough.
• on order to compile, the callback must return the union type, i.e. ()
• => all actions must be done via side effects
• again, there is NO GUARANTEE that the tasks will get executed
  (--> but useful/convenient for low priority background tasks and for the learning effect of course)

Trivia

⚠ I'm not an expert in tokio (or async/await/futures in Rust in general) and I don't know if this follows best practises. But it helped me to understand how tokio works. I hope it may be helpful to some of you too. ⚠

The functionality itself is really simple. The biggest part are the convenient macros. I over-engineered them a little to learn more about macros.

Compatibility

Version 1.0.0 is developed with:

• tokio @ 1.6.0 (but should also work with 1.0.0)
• rustc @ 1.52.1 (but should also work with 1.45.2)