Struct tokio_stream::wrappers::WatchStream

pub struct WatchStream<T> { /* fields omitted */ }

This is supported on crate feature sync only.

A wrapper around tokio::sync::watch::Receiver that implements Stream.

This stream will always start by yielding the current value when the WatchStream is polled, regardles of whether it was the initial value or sent afterwards.

Examples

use tokio_stream::{StreamExt, wrappers::WatchStream};
use tokio::sync::watch;

let (tx, rx) = watch::channel("hello");
let mut rx = WatchStream::new(rx);

assert_eq!(rx.next().await, Some("hello"));

tx.send("goodbye").unwrap();
assert_eq!(rx.next().await, Some("goodbye"));

use tokio_stream::{StreamExt, wrappers::WatchStream};
use tokio::sync::watch;

let (tx, rx) = watch::channel("hello");
let mut rx = WatchStream::new(rx);

tx.send("goodbye").unwrap();
assert_eq!(rx.next().await, Some("goodbye"));

Implementations

impl<T: 'static + Clone + Unpin + Send + Sync> WatchStream<T>

pub fn new(rx: Receiver<T>) -> Self

Create a new WatchStream.

Trait Implementations

impl<T> Debug for WatchStream<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Clone + 'static + Send + Sync> Stream for WatchStream<T>

type Item = T

Values yielded by the stream.

fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

pub fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

impl<T> Unpin for WatchStream<T>