Function at

pub fn at(when: Instant) -> Receiver<Instant>

Creates a receiver that delivers a message at a certain instant in time.

The channel is bounded with capacity of 1 and never gets disconnected. Exactly one message will be sent into the channel at the moment in time when. The message is the instant at which it is sent, which is the same as when. If when is in the past, the message will be delivered instantly to the receiver.

Examples

Using an at channel for timeouts:

use std::time::{Instant, Duration};
use crossbeam_channel::{at, select, unbounded};

let (s, r) = unbounded::<i32>();
let deadline = Instant::now() + Duration::from_millis(500);

select! {
    recv(r) -> msg => println!("received {:?}", msg),
    recv(at(deadline)) -> _ => println!("timed out"),
}

When the message gets sent:

use std::time::{Duration, Instant};
use crossbeam_channel::at;

// Converts a number of milliseconds into a `Duration`.
let ms = |ms| Duration::from_millis(ms);

let start = Instant::now();
let end = start + ms(100);

let r = at(end);

// This message was sent 100 ms from the start
assert_eq!(r.recv().unwrap(), end);
assert!(Instant::now() > start + ms(100));