Crate event_listener

Notify async tasks or threads.

This is a synchronization primitive similar to eventcounts invented by Dmitry Vyukov.

You can use this crate to turn non-blocking data structures into async or blocking data structures. See a simple mutex implementation that exposes an async and a blocking interface for acquiring locks.

Examples

Wait until another thread sets a boolean flag:

use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread;
use std::time::Duration;
use event_listener::Event;

let flag = Arc::new(AtomicBool::new(false));
let event = Arc::new(Event::new());

// Spawn a thread that will set the flag after 1 second.
thread::spawn({
    let flag = flag.clone();
    let event = event.clone();
    move || {
        // Wait for a second.
        thread::sleep(Duration::from_secs(1));

        // Set the flag.
        flag.store(true, Ordering::SeqCst);

        // Notify all listeners that the flag has been set.
        event.notify(usize::MAX);
    }
});

// Wait until the flag is set.
loop {
    // Check the flag.
    if flag.load(Ordering::SeqCst) {
        break;
    }

    // Start listening for events.
    let listener = event.listen();

    // Check the flag again after creating the listener.
    if flag.load(Ordering::SeqCst) {
        break;
    }

    // Wait for a notification and continue the loop.
    listener.wait();
}

Structs

Event	A synchronization primitive for notifying async tasks and threads.
EventListener	A guard waiting for a notification from an Event.