Crate stream_broadcast

source ·
Expand description

Runtime independent broadcast, which only polls it’s underlying stream if no pending data is available.

use futures::StreamExt;
use stream_broadcast::StreamBroadcastExt;

#[tokio::main]
async fn main() {
    let broadcast = futures::stream::iter(0..4).broadcast(3);
    let broadcast2 = broadcast.clone();
    assert_eq!(4, broadcast.count().await);
    // Number Zero wasn't available anymore due to BroadcastSize=3
    assert_eq!(vec![(1, 1), (0,2), (0,3)], broadcast2.collect::<Vec<_>>().await);
}

Uses #![forbid(unsafe_code)]

Difference to other libraries:

shared_stream:

  • Caches the entire stream from start, which is not practical for big datasets. This crate streams from the same position where the clone-origin is currently at
  • shared_stream never skips an entry. This library only provides information about missing data
  • High risk of leaking memory

tokio::sync::broadcast:

  • Broadcasts don’t implement Stream directly, but tokio_stream provides a wrapper.
  • Entries are pushed actively to the sender (No Lazy evaluation when stream is paused). This requires a subroutine, which has to be managed somehow.
  • Instead of returning missing frames in the ErrorVariant (tokio_stream), this library returns a tuple (missing_frames_since_last_frame, TData) to mitigate errors when doing stuff like stream.count()

Structs

Traits