Struct tokio_stream::wrappers::WatchStream
source · pub struct WatchStream<T> { /* private fields */ }
Expand description
A wrapper around tokio::sync::watch::Receiver
that implements Stream
.
This stream will start by yielding the current value when the WatchStream
is polled,
regardless of whether it was the initial value or sent afterwards,
unless you use WatchStream<T>::from_changes
.
§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);
// existing rx output with "hello" is ignored here
tx.send("goodbye").unwrap();
assert_eq!(rx.next().await, Some("goodbye"));
Example with WatchStream<T>::from_changes
:
use futures::future::FutureExt;
use tokio::sync::watch;
use tokio_stream::{StreamExt, wrappers::WatchStream};
let (tx, rx) = watch::channel("hello");
let mut rx = WatchStream::from_changes(rx);
// no output from rx is available at this point - let's check this:
assert!(rx.next().now_or_never().is_none());
tx.send("goodbye").unwrap();
assert_eq!(rx.next().await, Some("goodbye"));
Implementations§
Trait Implementations§
source§impl<T> Debug for WatchStream<T>
impl<T> Debug for WatchStream<T>
source§impl<T: Clone + 'static + Send + Sync> Stream for WatchStream<T>
impl<T: Clone + 'static + Send + Sync> Stream for WatchStream<T>
impl<T> Unpin for WatchStream<T>
Auto Trait Implementations§
impl<T> Freeze for WatchStream<T>
impl<T> !RefUnwindSafe for WatchStream<T>
impl<T> Send for WatchStream<T>
impl<T> Sync for WatchStream<T>
impl<T> !UnwindSafe for WatchStream<T>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
source§impl<St> StreamExt for St
impl<St> StreamExt for St
source§fn next(&mut self) -> Next<'_, Self>where
Self: Unpin,
fn next(&mut self) -> Next<'_, Self>where
Self: Unpin,
Consumes and returns the next value in the stream or
None
if the
stream is finished. Read moresource§fn try_next<T, E>(&mut self) -> TryNext<'_, Self>
fn try_next<T, E>(&mut self) -> TryNext<'_, Self>
Consumes and returns the next item in the stream. If an error is
encountered before the next item, the error is returned instead. Read more
source§fn map<T, F>(self, f: F) -> Map<Self, F>
fn map<T, F>(self, f: F) -> Map<Self, F>
Maps this stream’s items to a different type, returning a new stream of
the resulting type. Read more
source§fn map_while<T, F>(self, f: F) -> MapWhile<Self, F>
fn map_while<T, F>(self, f: F) -> MapWhile<Self, F>
Map this stream’s items to a different type for as long as determined by
the provided closure. A stream of the target type will be returned,
which will yield elements until the closure returns
None
. Read moresource§fn then<F, Fut>(self, f: F) -> Then<Self, Fut, F>
fn then<F, Fut>(self, f: F) -> Then<Self, Fut, F>
Maps this stream’s items asynchronously to a different type, returning a
new stream of the resulting type. Read more
source§fn merge<U>(self, other: U) -> Merge<Self, U>
fn merge<U>(self, other: U) -> Merge<Self, U>
Combine two streams into one by interleaving the output of both as it
is produced. Read more
source§fn filter<F>(self, f: F) -> Filter<Self, F>
fn filter<F>(self, f: F) -> Filter<Self, F>
Filters the values produced by this stream according to the provided
predicate. Read more
source§fn filter_map<T, F>(self, f: F) -> FilterMap<Self, F>
fn filter_map<T, F>(self, f: F) -> FilterMap<Self, F>
Filters the values produced by this stream while simultaneously mapping
them to a different type according to the provided closure. Read more
source§fn fuse(self) -> Fuse<Self>where
Self: Sized,
fn fuse(self) -> Fuse<Self>where
Self: Sized,
Creates a stream which ends after the first
None
. Read moresource§fn take(self, n: usize) -> Take<Self>where
Self: Sized,
fn take(self, n: usize) -> Take<Self>where
Self: Sized,
Creates a new stream of at most
n
items of the underlying stream. Read moresource§fn take_while<F>(self, f: F) -> TakeWhile<Self, F>
fn take_while<F>(self, f: F) -> TakeWhile<Self, F>
Take elements from this stream while the provided predicate
resolves to
true
. Read moresource§fn skip(self, n: usize) -> Skip<Self>where
Self: Sized,
fn skip(self, n: usize) -> Skip<Self>where
Self: Sized,
Creates a new stream that will skip the
n
first items of the
underlying stream. Read moresource§fn skip_while<F>(self, f: F) -> SkipWhile<Self, F>
fn skip_while<F>(self, f: F) -> SkipWhile<Self, F>
Skip elements from the underlying stream while the provided predicate
resolves to
true
. Read moresource§fn all<F>(&mut self, f: F) -> AllFuture<'_, Self, F>
fn all<F>(&mut self, f: F) -> AllFuture<'_, Self, F>
Tests if every element of the stream matches a predicate. Read more
source§fn any<F>(&mut self, f: F) -> AnyFuture<'_, Self, F>
fn any<F>(&mut self, f: F) -> AnyFuture<'_, Self, F>
Tests if any element of the stream matches a predicate. Read more
source§fn chain<U>(self, other: U) -> Chain<Self, U>
fn chain<U>(self, other: U) -> Chain<Self, U>
Combine two streams into one by first returning all values from the
first stream then all values from the second stream. Read more
source§fn fold<B, F>(self, init: B, f: F) -> FoldFuture<Self, B, F>
fn fold<B, F>(self, init: B, f: F) -> FoldFuture<Self, B, F>
A combinator that applies a function to every element in a stream
producing a single, final value. Read more
source§fn collect<T>(self) -> Collect<Self, T>
fn collect<T>(self) -> Collect<Self, T>
Drain stream pushing all emitted values into a collection. Read more
source§fn timeout(self, duration: Duration) -> Timeout<Self>where
Self: Sized,
fn timeout(self, duration: Duration) -> Timeout<Self>where
Self: Sized,
Applies a per-item timeout to the passed stream. Read more
source§fn timeout_repeating(self, interval: Interval) -> TimeoutRepeating<Self>where
Self: Sized,
fn timeout_repeating(self, interval: Interval) -> TimeoutRepeating<Self>where
Self: Sized,
Applies a per-item timeout to the passed stream. Read more
source§fn throttle(self, duration: Duration) -> Throttle<Self>where
Self: Sized,
fn throttle(self, duration: Duration) -> Throttle<Self>where
Self: Sized,
Slows down a stream by enforcing a delay between items. Read more
source§fn chunks_timeout(
self,
max_size: usize,
duration: Duration,
) -> ChunksTimeout<Self>where
Self: Sized,
fn chunks_timeout(
self,
max_size: usize,
duration: Duration,
) -> ChunksTimeout<Self>where
Self: Sized,
Batches the items in the given stream using a maximum duration and size for each batch. Read more