tokio::time::interval is not working

[rcitsz]

tokio::time::interval is not working

[mox692]

After the completion of the first loop, subsequent loops are almost always expected to terminate the second arm first, so the tick print will not continue as you expected.

[Darksonn]

You need to use an if precondition instead of placing the if inside the async block. That way, the branch will be disabled instead of triggering immediately.

See the documentation on select! for more info on if preconditions.

[rcitsz]

@Darksonn
Thanks!
But in another form.
If the select arm is not async block but async function：

async fn waitfor(s: &mut bool) {
    if *s {
        *s = false;

       //   If comment out this line, the timer will work properly
        tokio::time::sleep(tokio::time::Duration::from_secs(3)).await;
    }
}

#[test]
fn test() {
    tokio::runtime::Runtime::new().unwrap().block_on(async {
        tokio::spawn(async move {
            let mut timer = tokio::time::interval(tokio::time::Duration::from_secs(1));
            let mut s = true; 
            loop {
                tokio::select! {
                    _= timer.tick() => {
                       println!("----tick");
                    }
                _ = waitfor(&mut s) => {}
                }
            }
        })
        .await
        .unwrap();
    });
}

[Darksonn]

You can also await std::future::pending() to have waitfor sleep forever / until timer.tick() triggers.