Server-Sent Events

[davidpdrsn]

Example usage:

use axum::{prelude::*, sse::{sse, Event, KeepAlive}};
use tokio_stream::StreamExt as _;
use futures::stream::{self, Stream};
use std::{
    time::Duration,
    convert::Infallible,
};

let app = route("/sse", sse(make_stream).keep_alive(KeepAlive::default()));

async fn make_stream(
    // you can also put extractors here
) -> Result<impl Stream<Item = Result<Event, Infallible>>, Infallible> {
    // A `Stream` that repeats an event every second
    let stream = stream::repeat_with(|| Event::default().data("hi!"))
        .map(Ok)
        .throttle(Duration::from_secs(1));

    Ok(stream)
}

Implementation is based on warp's

Fixes #51