pub struct Sender<T> { /* private fields */ }
Expand description

Sending-half of the broadcast channel.

May be used from many threads. Messages can be sent with send.

Examples

use tokio::sync::broadcast;

#[tokio::main]
async fn main() {
    let (tx, mut rx1) = broadcast::channel(16);
    let mut rx2 = tx.subscribe();

    tokio::spawn(async move {
        assert_eq!(rx1.recv().await.unwrap(), 10);
        assert_eq!(rx1.recv().await.unwrap(), 20);
    });

    tokio::spawn(async move {
        assert_eq!(rx2.recv().await.unwrap(), 10);
        assert_eq!(rx2.recv().await.unwrap(), 20);
    });

    tx.send(10).unwrap();
    tx.send(20).unwrap();
}

Implementations

Attempts to send a value to all active Receiver handles, returning it back if it could not be sent.

A successful send occurs when there is at least one active Receiver handle. An unsuccessful send would be one where all associated Receiver handles have already been dropped.

Return

On success, the number of subscribed Receiver handles is returned. This does not mean that this number of receivers will see the message as a receiver may drop before receiving the message.

Note

A return value of Ok does not mean that the sent value will be observed by all or any of the active Receiver handles. Receiver handles may be dropped before receiving the sent message.

A return value of Err does not mean that future calls to send will fail. New Receiver handles may be created by calling subscribe.

Examples
use tokio::sync::broadcast;

#[tokio::main]
async fn main() {
    let (tx, mut rx1) = broadcast::channel(16);
    let mut rx2 = tx.subscribe();

    tokio::spawn(async move {
        assert_eq!(rx1.recv().await.unwrap(), 10);
        assert_eq!(rx1.recv().await.unwrap(), 20);
    });

    tokio::spawn(async move {
        assert_eq!(rx2.recv().await.unwrap(), 10);
        assert_eq!(rx2.recv().await.unwrap(), 20);
    });

    tx.send(10).unwrap();
    tx.send(20).unwrap();
}

Creates a new Receiver handle that will receive values sent after this call to subscribe.

Examples
use tokio::sync::broadcast;

#[tokio::main]
async fn main() {
    let (tx, _rx) = broadcast::channel(16);

    // Will not be seen
    tx.send(10).unwrap();

    let mut rx = tx.subscribe();

    tx.send(20).unwrap();

    let value = rx.recv().await.unwrap();
    assert_eq!(20, value);
}

Returns the number of active receivers

An active receiver is a Receiver handle returned from channel or subscribe. These are the handles that will receive values sent on this Sender.

Note

It is not guaranteed that a sent message will reach this number of receivers. Active receivers may never call recv again before dropping.

Examples
use tokio::sync::broadcast;

#[tokio::main]
async fn main() {
    let (tx, _rx1) = broadcast::channel(16);

    assert_eq!(1, tx.receiver_count());

    let mut _rx2 = tx.subscribe();

    assert_eq!(2, tx.receiver_count());

    tx.send(10).unwrap();
}

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Executes the destructor for this type. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.