tokio::sync::Notify usage

notify.rs

use std::sync::Arc;
use tokio::sync::Notify;

#[tokio::main]
async fn main() {
    let notify = Arc::new(Notify::new());

    // 注册两个等候者
    let notified1 = notify.notified();
    let notified2 = notify.notified();

    let handle = tokio::spawn({
        let notify2 = notify.clone();
        async move {
            println!("waiting for 1 seconds");
            tokio::time::sleep(std::time::Duration::from_secs(1)).await;
            println!("sending notifications");
            notify2.notify_waiters();
        }
    });

    println!("waiting for notifications");
    // 两个等候者的 await 都会直接通过
    notified1.await;
    notified2.await;
    println!("received notifications");
    handle.await.unwrap();
}

// output:
//
// waiting for notifications
// waiting for 1 seconds
// sending notifications
// received notifications