impl<T> UnboundedSender<T>

fn send(&self, message: T) -> Result<(), SendError<T>>

Attempts to send a message on this UnboundedSender without blocking.

This method is not marked as async because sending a message to an unbounded channel never requires any form of waiting. This is due to the channel's infinite capacity, allowing the send operation to complete immediately. As a result, the send method can be used in both synchronous and asynchronous code without issues.

If the receive half of the channel is closed, either due to close being called or the UnboundedReceiver having been dropped, this function returns an error. The error includes the value passed to send.

async fn closed(&self)

Completes when the receiver has dropped.

This allows the producers to get notified when interest in the produced values is canceled and immediately stop doing work.

Cancel safety

This method is cancel safe. Once the channel is closed, it stays closed forever and all future calls to closed will return immediately.

Examples

use tokio::sync::mpsc;

# #[tokio::main(flavor = "current_thread")]
# async fn main() {
let (tx1, rx) = mpsc::unbounded_channel::<()>();
let tx2 = tx1.clone();
let tx3 = tx1.clone();
let tx4 = tx1.clone();
let tx5 = tx1.clone();
tokio::spawn(async move {
    drop(rx);
});

futures::join!(
    tx1.closed(),
    tx2.closed(),
    tx3.closed(),
    tx4.closed(),
    tx5.closed()
);
println!("Receiver dropped");
# }

fn is_closed(&self) -> bool

Checks if the channel has been closed. This happens when the UnboundedReceiver is dropped, or when the UnboundedReceiver::close method is called.

let (tx, rx) = tokio::sync::mpsc::unbounded_channel::<()>();
assert!(!tx.is_closed());

let tx2 = tx.clone();
assert!(!tx2.is_closed());

drop(rx);
assert!(tx.is_closed());
assert!(tx2.is_closed());

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

Returns true if senders belong to the same channel.

Examples

let (tx, rx) = tokio::sync::mpsc::unbounded_channel::<()>();
let  tx2 = tx.clone();
assert!(tx.same_channel(&tx2));

let (tx3, rx3) = tokio::sync::mpsc::unbounded_channel::<()>();
assert!(!tx3.same_channel(&tx2));

fn downgrade(&self) -> WeakUnboundedSender<T>

Converts the UnboundedSender to a WeakUnboundedSender that does not count towards RAII semantics, i.e. if all UnboundedSender instances of the channel were dropped and only WeakUnboundedSender instances remain, the channel is closed.

fn strong_count(&self) -> usize

Returns the number of UnboundedSender handles.

fn weak_count(&self) -> usize

Returns the number of WeakUnboundedSender handles.