Rust tokio channels demo

tokio_channels_demo.rs

use tokio::sync::broadcast;
use tokio::sync::mpsc;
use tokio::sync::oneshot;

#[tokio::main]
async fn main() {
    let (tx, rx) = oneshot::channel();

    tokio::spawn(async move {
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
        if let Err(_) = tx.send(99) {
            println!("the receiver dropped");
        }
    });

    println!("Waiting on rx");

    match rx.await {
        Ok(v) => println!("got oneshot = {:?}", v),
        Err(_) => println!("the sender dropped"),
    }

    // Buffer of 3 will create back pressure when full
    let (tx, mut rx) = mpsc::channel(3);

    tokio::spawn(async move {
        for i in 0..10 {
            println!("Sending {}", i);
            if let Err(_) = tx.send(i).await {
                println!("receiver dropped");
                return;
            }
        }
    });

    while let Some(i) = rx.recv().await {
        // We read slowly so that we can see sender block when buffer is full
        tokio::time::sleep(std::time::Duration::from_millis(500)).await;
        println!("got mpsc = {}", i);
    }

    // Creating a broadcast channel for strings, multiple producer and consumers
    let (tx, mut _rx) = broadcast::channel::<String>(3);
    let tx1 = tx.clone();
    let tx2 = tx.clone();
    tokio::spawn(async move {
        tx1.send("hello".to_string()).unwrap();
        tx2.send("world".to_string()).unwrap();
    });

    let mut rx1 = tx.subscribe();
    let mut rx2 = tx.subscribe();

    // We see the sent messages
    for _i in 0..2 {
        let msg = rx1.recv().await.unwrap();
        println!("Got rx1 {}", msg);
    }
    // Sent messages are seen again, as we use a different receiver
    for _i in 0..2 {
        let msg = rx2.recv().await.unwrap();
        println!("Got rx2 {}", msg);
    }
}

Waiting on rx
got oneshot = 99
Sending 0
Sending 1
Sending 2
Sending 3
Sending 4
got mpsc = 0
Sending 5
got mpsc = 1
Sending 6
got mpsc = 2
Sending 7
got mpsc = 3
Sending 8
got mpsc = 4
Sending 9
got mpsc = 5
got mpsc = 6
got mpsc = 7
got mpsc = 8
got mpsc = 9
Got rx1 hello
Got rx1 world
Got rx2 hello
Got rx2 world