Expand description

Asynchronous values.


Futures can be cancelled by dropping them before they finish executing. This is useful when we’re no longer interested in the result of an operation, as it allows us to stop doing needless work. This also means that a future may cancel at any .await point, and so just like with ? we have to be careful to roll back local state if our future halts there.

In order to perform a cancellation remotely, you can use the channel::bounded function to create a sender/receiver pair. When the sender side of this pair emits a message, all receivers are trigered. Receivers can be passed to Future::timeout or Stream::timeout to perform a cancellation when the message is received.

use futures_lite::prelude::*;
use futures_time::prelude::*;
use futures_time::channel;
use futures_time::time::Duration;

fn main() {
    async_io::block_on(async {
        let (send, mut recv) = channel::bounded::<()>(1); // create a new send/receive pair
        let mut counter = 0;
        let value = async { "meow" }
            .timeout(recv.next()) // time-out if the sender is dropped.

        assert_eq!(value.unwrap(), "meow");


Suspends a future until the specified deadline.

Suspend or resume execution of a future.

A future that times out after a duration of time.


Extend Future with time-based operations.

Conversion into a Future.

A future which holds a deadline relative to now.