Function futures_util::stream::select

source ·
pub fn select<St1, St2>(stream1: St1, stream2: St2) -> Select<St1, St2>
where St1: Stream, St2: Stream<Item = St1::Item>,
Expand description

This function will attempt to pull items from both streams. Each stream will be polled in a round-robin fashion, and whenever a stream is ready to yield an item that item is yielded.

After one of the two input streams completes, the remaining one will be polled exclusively. The returned stream completes when both input streams have completed.

Note that this function consumes both streams and returns a wrapped version of them.


use futures::stream::{ repeat, select, StreamExt };

let left = repeat(1);
let right = repeat(2);

let mut out = select(left, right);

for _ in 0..100 {
    // We should be alternating.
    assert_eq!(1, out.select_next_some().await);
    assert_eq!(2, out.select_next_some().await);