Struct UnboundedReceiver

pub struct UnboundedReceiver<T> { /* private fields */ }

Available on crate feature sync only.

Receive values from the associated UnboundedSender.

Instances are created by the unbounded_channel function.

Implementations

impl<T> UnboundedReceiver<T>

pub async fn recv(&mut self) -> Option<T>

Receive the next value for this receiver.

None is returned when all Sender halves have dropped, indicating that no further values can be sent on the channel.

Examples

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    let (tx, mut rx) = mpsc::unbounded_channel();

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

    assert_eq!(Some("hello"), rx.recv().await);
    assert_eq!(None, rx.recv().await);
}

Values are buffered:

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    let (tx, mut rx) = mpsc::unbounded_channel();

    tx.send("hello").unwrap();
    tx.send("world").unwrap();

    assert_eq!(Some("hello"), rx.recv().await);
    assert_eq!(Some("world"), rx.recv().await);
}

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

Attempts to return a pending value on this receiver 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.

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).

pub fn close(&mut self)

Closes the receiving half of a channel, without dropping it.

This prevents any further messages from being sent on the channel while still enabling the receiver to drain messages that are buffered.

Trait Implementations

impl<T> Clone for UnboundedReceiver<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 for UnboundedReceiver<T>

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

Formats the value using the given formatter.

impl<T> Stream for UnboundedReceiver<T>

type Item = T

Values yielded by the stream.

fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>>

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.