Struct async_std::sync::Receiver

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

👎 Deprecated:

new channel api at async_std::channel

The receiving side of a channel.

This type receives messages by calling recv. But it also implements the Stream trait, which means it can act as an asynchronous iterator. This struct is created by the channel function. See its documentation for more.

Examples

#![allow(deprecated)]
use std::time::Duration;

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

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

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

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

Implementations

impl<T> Receiver<T>

pub async fn recv(&self) -> Result<T, RecvError>

Receives a message from the channel.

If the channel is empty and still has senders, this method will wait until a message is sent into it. Once all senders have been dropped it will return RecvError.

Examples

#![allow(deprecated)]
use async_std::sync::channel;
use async_std::task;

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

task::spawn(async move {
    s.send(1usize).await;
    s.send(2).await;
    // Then we drop the sender
});

assert_eq!(r.recv().await?, 1);
assert_eq!(r.recv().await?, 2);
assert!(r.recv().await.is_err());

pub fn try_recv(&self) -> Result<T, TryRecvError>

Attempts to receive a message from the channel.

If the channel is empty, this method will return an error.

Examples

#![allow(deprecated)]
use async_std::sync::channel;

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

s.send(1u8).await;

assert!(r.try_recv().is_ok());
assert!(r.try_recv().is_err());

pub fn capacity(&self) -> usize

Returns the channel capacity.

Examples

#![allow(deprecated)]
use async_std::sync::channel;

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

pub fn is_empty(&self) -> bool

Returns true if the channel is empty.

Examples

#![allow(deprecated)]
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

Returns true if the channel is full.

Examples

#![allow(deprecated)]
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

Returns the number of messages in the channel.

Examples

#![allow(deprecated)]
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> Clone for Receiver<T>

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

Returns a copy of the value.

pub 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> Drop for Receiver<T>

fn drop(&mut self)

Executes the destructor for this type.

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.

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

Returns the bounds on the remaining length of the stream.