Struct tokio::sync::watch::Receiver

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

This is supported on crate feature sync only.

Receives values from the associated Sender.

Instances are created by the channel function.

To turn this receiver into a Stream, you can use the WatchStream wrapper.

Implementations

impl<T> Receiver<T>

pub fn borrow(&self) -> Ref<'_, T>

Returns a reference to the most recently sent value

Outstanding borrows hold a read lock. This means that long lived borrows could cause the send half to block. It is recommended to keep the borrow as short lived as possible.

Examples

use tokio::sync::watch;

let (_, rx) = watch::channel("hello");
assert_eq!(*rx.borrow(), "hello");

pub async fn changed(&mut self) -> Result<(), RecvError>

Wait for a change notification

Returns when a new value has been sent by the Sender since the last time changed() was called. When the Sender half is dropped, Err is returned.

Examples

use tokio::sync::watch;

#[tokio::main]
async fn main() {
    let (tx, mut rx) = watch::channel("hello");

    tokio::spawn(async move {
        tx.send("goodbye").unwrap();
    });

    assert!(rx.changed().await.is_ok());
    assert_eq!(*rx.borrow(), "goodbye");

    // The `tx` handle has been dropped
    assert!(rx.changed().await.is_err());
}

Trait Implementations

impl<T> Clone for Receiver<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Receiver<T>

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

Formats the value using the given formatter.

impl<T> Drop for Receiver<T>

fn drop(&mut self)

Executes the destructor for this type.