Struct async_watch::Receiver

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

Receives values from the associated Sender.

Instances are created by the channel function.

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

let (_, rx) = async_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

let (tx, mut rx) = async_watch::channel("hello");

let task = executor.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());

task.await;
});

impl<T: Clone> Receiver<T>

pub async fn recv<'_>(&'_ mut self) -> Result<T, RecvError>

A convenience helper which combines calling Receiver::changed() and Receiver::borrow() where the borrowed value is cloned and returned.

Note: If this is the first time the function is called on a Receiver instance, then the function will wait until a new value is sent into the channel.

None is returned if the Sender half is dropped.

Examples

let (tx, mut rx) = async_watch::channel("hello");

let task = executor.spawn(async move {
    tx.send("goodbye").unwrap();
});

assert_eq!(*rx.borrow(), "hello");

// Waits for the new task to spawn and send the value.
let v = rx.recv().await.unwrap();
assert_eq!(v, "goodbye");

let v = rx.recv().await;
assert!(v.is_err());

task.await;

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.