Struct Permit

pub struct Permit<'a, T> { /* private fields */ }

Permits to send one value into the channel.

Permit values are returned by Sender::reserve() and Sender::try_reserve() and are used to guarantee channel capacity before generating a message to send.

Implementations

impl<T> Permit<'_, T>

pub fn send(self, value: T)

Sends a value using the reserved capacity.

Capacity for the message has already been reserved. The message is sent to the receiver and the permit is consumed. The operation will succeed even if the receiver half has been closed. See Receiver::close for more details on performing a clean shutdown.

Examples

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    let (tx, mut rx) = mpsc::channel(1);

    // Reserve capacity
    let permit = tx.reserve().await.unwrap();

    // Trying to send directly on the `tx` will fail due to no
    // available capacity.
    assert!(tx.try_send(123).is_err());

    // Send a message on the permit
    permit.send(456);

    // The value sent on the permit is received
    assert_eq!(rx.recv().await.unwrap(), 456);
}

Trait Implementations

impl<T> Debug for Permit<'_, T>

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

Formats the value using the given formatter.

impl<T> Drop for Permit<'_, T>

fn drop(&mut self)

Executes the destructor for this type.