impl<T> Receiver<T>

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

Attempts to receive a message from the channel without blocking.

This method will never block the caller in order to wait for data to become available. Instead, this will always return immediately with a possible option of pending data on the channel.

If called on a zero-capacity channel, this method will receive a message only if there happens to be a send operation on the other side of the channel at the same time.

This is useful for a flavor of "optimistic check" before deciding to block on a receiver.

Compared with recv, this function has two failure cases instead of one (one for disconnection, one for an empty buffer).

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc::{Receiver, channel};

let (_, receiver): (_, Receiver<i32>) = channel();

assert!(receiver.try_recv().is_err());

fn recv(self: &Self) -> Result<T, RecvError>

Attempts to wait for a value on this receiver, returning an error if the corresponding channel has hung up.

This function will always block the current thread if there is no data available and it's possible for more data to be sent (at least one sender still exists). Once a message is sent to the corresponding Sender, this receiver will wake up and return that message.

If the corresponding Sender has disconnected, or it disconnects while this call is blocking, this call will wake up and return Err to indicate that no more messages can ever be received on this channel. However, since channels are buffered, messages sent before the disconnect will still be properly received.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;

let (send, recv) = mpmc::channel();
let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
});

handle.join().unwrap();

assert_eq!(Ok(1), recv.recv());

Buffering behavior:

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;
use std::sync::mpmc::RecvError;

let (send, recv) = mpmc::channel();
let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
    send.send(2).unwrap();
    send.send(3).unwrap();
    drop(send);
});

// wait for the thread to join so we ensure the sender is dropped
handle.join().unwrap();

assert_eq!(Ok(1), recv.recv());
assert_eq!(Ok(2), recv.recv());
assert_eq!(Ok(3), recv.recv());
assert_eq!(Err(RecvError), recv.recv());

fn recv_timeout(self: &Self, timeout: Duration) -> Result<T, RecvTimeoutError>

Attempts to wait for a value on this receiver, returning an error if the corresponding channel has hung up, or if it waits more than timeout.

This function will always block the current thread if there is no data available and it's possible for more data to be sent (at least one sender still exists). Once a message is sent to the corresponding Sender, this receiver will wake up and return that message.

If the corresponding Sender has disconnected, or it disconnects while this call is blocking, this call will wake up and return Err to indicate that no more messages can ever be received on this channel. However, since channels are buffered, messages sent before the disconnect will still be properly received.

Examples

Successfully receiving value before encountering timeout:

#![feature(mpmc_channel)]

use std::thread;
use std::time::Duration;
use std::sync::mpmc;

let (send, recv) = mpmc::channel();

thread::spawn(move || {
    send.send('a').unwrap();
});

assert_eq!(
    recv.recv_timeout(Duration::from_millis(400)),
    Ok('a')
);

Receiving an error upon reaching timeout:

#![feature(mpmc_channel)]

use std::thread;
use std::time::Duration;
use std::sync::mpmc;

let (send, recv) = mpmc::channel();

thread::spawn(move || {
    thread::sleep(Duration::from_millis(800));
    send.send('a').unwrap();
});

assert_eq!(
    recv.recv_timeout(Duration::from_millis(400)),
    Err(mpmc::RecvTimeoutError::Timeout)
);

fn recv_deadline(self: &Self, deadline: Instant) -> Result<T, RecvTimeoutError>

Attempts to wait for a value on this receiver, returning an error if the corresponding channel has hung up, or if deadline is reached.

This function will always block the current thread if there is no data available and it's possible for more data to be sent. Once a message is sent to the corresponding Sender, then this receiver will wake up and return that message.

If the corresponding Sender has disconnected, or it disconnects while this call is blocking, this call will wake up and return Err to indicate that no more messages can ever be received on this channel. However, since channels are buffered, messages sent before the disconnect will still be properly received.

Examples

Successfully receiving value before reaching deadline:

#![feature(mpmc_channel)]

use std::thread;
use std::time::{Duration, Instant};
use std::sync::mpmc;

let (send, recv) = mpmc::channel();

thread::spawn(move || {
    send.send('a').unwrap();
});

assert_eq!(
    recv.recv_deadline(Instant::now() + Duration::from_millis(400)),
    Ok('a')
);

Receiving an error upon reaching deadline:

#![feature(mpmc_channel)]

use std::thread;
use std::time::{Duration, Instant};
use std::sync::mpmc;

let (send, recv) = mpmc::channel();

thread::spawn(move || {
    thread::sleep(Duration::from_millis(800));
    send.send('a').unwrap();
});

assert_eq!(
    recv.recv_deadline(Instant::now() + Duration::from_millis(400)),
    Err(mpmc::RecvTimeoutError::Timeout)
);

fn try_iter(self: &Self) -> TryIter<'_, T>

Returns an iterator that will attempt to yield all pending values. It will return None if there are no more pending values or if the channel has hung up. The iterator will never [panic!] or block the user by waiting for values.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc::channel;
use std::thread;
use std::time::Duration;

let (sender, receiver) = channel();

// nothing is in the buffer yet
assert!(receiver.try_iter().next().is_none());

thread::spawn(move || {
    thread::sleep(Duration::from_secs(1));
    sender.send(1).unwrap();
    sender.send(2).unwrap();
    sender.send(3).unwrap();
});

// nothing is in the buffer yet
assert!(receiver.try_iter().next().is_none());

// block for two seconds
thread::sleep(Duration::from_secs(2));

let mut iter = receiver.try_iter();
assert_eq!(iter.next(), Some(1));
assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), Some(3));
assert_eq!(iter.next(), None);

impl<T> Receiver<T>

fn is_empty(self: &Self) -> bool

Returns true if the channel is empty.

Note: Zero-capacity channels are always empty.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;

let (send, recv) = mpmc::channel();

assert!(recv.is_empty());

let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
});

handle.join().unwrap();

assert!(!recv.is_empty());

fn is_full(self: &Self) -> bool

Returns true if the channel is full.

Note: Zero-capacity channels are always full.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;

let (send, recv) = mpmc::sync_channel(1);

assert!(!recv.is_full());

let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
});

handle.join().unwrap();

assert!(recv.is_full());

fn len(self: &Self) -> usize

Returns the number of messages in the channel.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;

let (send, recv) = mpmc::channel();

assert_eq!(recv.len(), 0);

let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
});

handle.join().unwrap();

assert_eq!(recv.len(), 1);

fn capacity(self: &Self) -> Option<usize>

If the channel is bounded, returns its capacity.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;
use std::thread;

let (send, recv) = mpmc::sync_channel(3);

assert_eq!(recv.capacity(), Some(3));

let handle = thread::spawn(move || {
    send.send(1u8).unwrap();
});

handle.join().unwrap();

assert_eq!(recv.capacity(), Some(3));

fn same_channel(self: &Self, other: &Receiver<T>) -> bool

Returns true if receivers belong to the same channel.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc;

let (_, rx1) = mpmc::channel::<i32>();
let (_, rx2) = mpmc::channel::<i32>();

assert!(rx1.same_channel(&rx1));
assert!(!rx1.same_channel(&rx2));

fn iter(self: &Self) -> Iter<'_, T>

Returns an iterator that will block waiting for messages, but never [panic!]. It will return None when the channel has hung up.

Examples

#![feature(mpmc_channel)]

use std::sync::mpmc::channel;
use std::thread;

let (send, recv) = channel();

thread::spawn(move || {
    send.send(1).unwrap();
    send.send(2).unwrap();
    send.send(3).unwrap();
});

let mut iter = recv.iter();
assert_eq!(iter.next(), Some(1));
assert_eq!(iter.next(), Some(2));
assert_eq!(iter.next(), Some(3));
assert_eq!(iter.next(), None);

impl<T> Any for Receiver<T>

fn type_id(self: &Self) -> TypeId

impl<T> Borrow for Receiver<T>

fn borrow(self: &Self) -> &T

impl<T> BorrowMut for Receiver<T>

fn borrow_mut(self: &mut Self) -> &mut T

impl<T> Clone for Receiver<T>

fn clone(self: &Self) -> Self

impl<T> CloneToUninit for Receiver<T>

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

impl<T> Debug for Receiver<T>

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

impl<T> Drop for Receiver<T>

fn drop(self: &mut Self)

impl<T> Freeze for Receiver<T>

impl<T> From for Receiver<T>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> IntoIterator for Receiver<T>

fn into_iter(self: Self) -> IntoIter<T>

impl<T> RefUnwindSafe for Receiver<T>

impl<T> ToOwned for Receiver<T>

fn to_owned(self: &Self) -> T

fn clone_into(self: &Self, target: &mut T)

impl<T> Unpin for Receiver<T>

impl<T> UnwindSafe for Receiver<T>

impl<T, U> Into for Receiver<T>

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom for Receiver<T>

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto for Receiver<T>

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>

impl<T: Send> Send for Receiver<T>

impl<T: Send> Sync for Receiver<T>