Async channels in Rust

tokio's mpsc is the async twin of the std channel: send and recv both await.

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    let (tx, mut rx) = mpsc::channel::<String>(8);

    for id in 0..3 {
        let tx = tx.clone();
        tokio::spawn(async move {
            tx.send(format!("job {id} done")).await.unwrap();
        });
    }
    drop(tx);

    while let Some(message) = rx.recv().await {
        println!("{message}");
    }
}

How it works

1. channel(n) bounds the queue, applying backpressure.
2. recv returns None once every sender is dropped.
3. The producer and consumer are ordinary tasks.

Keywords and builtins used here

• Some
• String
• async
• await
• drop
• fn
• for
• in
• let
• main
• move
• mut
• use
• while

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Step 5 of 6 in Async with tokio, step 13 of 15 in Concurrency & async.

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