Timeouts

Sometimes a task takes too long and you don’t want to wait forever. A timeout puts a time limit on a task. If it finishes in time you get the result, if it doesn’t, it is cancelled and you get an error back.

In this example, a network request is given 5 milliseconds to complete. If it finishes in time, the result is printed. If it runs over, the program reports a timeout.

use std::time::Duration;
use tokio::time::timeout;

async fn fetch_network_request() -> u32 {
    89
}

#[tokio::main]
async fn main() {
    match timeout(Duration::from_millis(5), fetch_network_request()).await {
        Ok(x) => println!("Received {x}"),
        Err(_) => eprintln!("Timed Out!"),
    }
}

Add tokio to Cargo.toml with the macros and time features enabled.

[dependencies]
tokio = { version = "*", features = ["macros", "time"] }