james7132/event-listener-strategy

A wrapper around event-listener to handle dual blocking/async use cases

event-listener-strategy

A strategy for using the event-listener crate in both blocking and non-blocking contexts.

One of the stand-out features of the event-listener crate is the ability to use it in both asynchronous and synchronous contexts. However, sometimes using it like this causes a lot of boilerplate to be duplicated. This crate aims to reduce that boilerplate by providing an EventListenerFuture trait that implements both blocking and non-blocking functionality.

Examples

use event_listener::{Event, EventListener};
use event_listener_strategy::{EventListenerFuture, FutureWrapper, Strategy};

use std::pin::Pin;
use std::task::Poll;
use std::thread;
use std::sync::Arc;

// A future that waits three seconds for an event to be fired.
fn wait_three_seconds() -> WaitThreeSeconds {
    let event = Event::new();
    let listener = event.listen();

    thread::spawn(move || {
        thread::sleep(std::time::Duration::from_secs(3));
        event.notify(1);
    });

    WaitThreeSeconds { listener }
}

struct WaitThreeSeconds {
    listener: Pin<Box<EventListener>>,
}

impl EventListenerFuture for WaitThreeSeconds {
    type Output = ();

    fn poll_with_strategy<'a, S: Strategy<'a>>(
        mut self: Pin<&'a mut Self>,
        strategy: &mut S,
        context: &mut S::Context,
    ) -> Poll<Self::Output> {
        strategy.poll(self.listener.as_mut(), context)
    }
}

// Use the future in a blocking context.
let future = wait_three_seconds();
future.wait();

// Use the future in a non-blocking context.
futures_lite::future::block_on(async {
    let future = FutureWrapper::new(wait_three_seconds());
    future.await;
});

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.