rust 同时处理多个异步任务

use tokio::{sync::oneshot, time::{sleep, Duration}};

async fn check_for_one() {
    // This loop will continuously print "write" every second until interrupted
    loop {
        println!("write");
        sleep(Duration::from_secs(1)).await; // Non-blocking sleep in async context
    }
}

#[tokio::main]
async fn main() {
    // Create a oneshot channel
    let (tx1, rx1) = oneshot::channel::<&str>();

    // Spawn a task that sends a message after 2 seconds
    tokio::spawn(async move {
        sleep(Duration::from_secs(2)).await;    
        let _ = tx1.send("one");
    });

    // Use tokio::select! to wait for either the print task or the message on rx1
    tokio::select! {
        _ = check_for_one() => {
            // This branch will continuously print "write" every second
            println!("check_for_one completed");
        }
        val = rx1 => {
            // This branch will be executed once the message is received from rx1
            match val {
                Ok(val) => println!("rx1 completed first with {:?}", val),
                Err(e) => println!("Failed to receive from rx1: {:?}", e),
            }
        }
    }

    println!("main thread exiting"); 
}

只要有一个异步任务完成，就会退出select！ 。