Struct async_std::sync::Receiver

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

This is supported on unstable only.

The receiving side of a channel.

This type implements the Stream trait, which means it can act as an asynchronous iterator.

Examples

use std::time::Duration;

use async_std::sync::channel;
use async_std::task;

let (s, r) = channel(100);

task::spawn(async move {
    s.send(1).await;
    task::sleep(Duration::from_secs(1)).await;
    s.send(2).await;
});

assert_eq!(r.recv().await, Some(1)); // Received immediately.
assert_eq!(r.recv().await, Some(2)); // Received after 1 second.

Methods

impl<T> Receiver<T>

pub async fn recv<'_>(&'_ self) -> Option<T>

This is supported on unstable only.

Receives a message from the channel.

If the channel is empty and it still has senders, this method will block the current task until the receive operation can proceed. If the channel is empty and there are no more senders, this method returns None.

Examples

use async_std::sync::channel;
use async_std::task;

let (s, r) = channel(1);

task::spawn(async move {
    s.send(1).await;
    s.send(2).await;
});

assert_eq!(r.recv().await, Some(1));
assert_eq!(r.recv().await, Some(2));
assert_eq!(r.recv().await, None);

pub fn capacity(&self) -> usize

This is supported on unstable only.

Returns the channel capacity.

Examples

use async_std::sync::channel;

let (_, r) = channel::<i32>(5);
assert_eq!(r.capacity(), 5);

pub fn is_empty(&self) -> bool

This is supported on unstable only.

Returns true if the channel is empty.

Examples

use async_std::sync::channel;

let (s, r) = channel(1);

assert!(r.is_empty());
s.send(0).await;
assert!(!r.is_empty());

pub fn is_full(&self) -> bool

This is supported on unstable only.

Returns true if the channel is full.

Examples

use async_std::sync::channel;

let (s, r) = channel(1);

assert!(!r.is_full());
s.send(0).await;
assert!(r.is_full());

pub fn len(&self) -> usize

This is supported on unstable only.

Returns the number of messages in the channel.

Examples

use async_std::sync::channel;

let (s, r) = channel(2);
assert_eq!(r.len(), 0);

s.send(1).await;
s.send(2).await;
assert_eq!(r.len(), 2);

Trait Implementations

impl<T> Drop for Receiver<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> Clone for Receiver<T>

fn clone(&self) -> Receiver<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for Receiver<T>

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

Formats the value using the given formatter.

impl<T> Stream for Receiver<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.

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

Returns the bounds on the remaining length of the stream.