Struct WeakSender

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

Available on crate feature sync only.

A sender that does not prevent the channel from being closed.

If all Sender instances of a channel were dropped and only WeakSender instances remain, the channel is closed.

In order to send messages, the WeakSender needs to be upgraded using WeakSender::upgrade, which returns Option<Sender>. It returns None if all Senders have been dropped, and otherwise it returns a Sender.

Examples

use tokio::sync::mpsc::channel;

#[tokio::main]
async fn main() {
    let (tx, _rx) = channel::<i32>(15);
    let tx_weak = tx.downgrade();

    // Upgrading will succeed because `tx` still exists.
    assert!(tx_weak.upgrade().is_some());

    // If we drop `tx`, then it will fail.
    drop(tx);
    assert!(tx_weak.clone().upgrade().is_none());
}

Implementations

impl<T> WeakSender<T>

pub fn upgrade(&self) -> Option<Sender<T>>

Tries to convert a WeakSender into a Sender. This will return Some if there are other Sender instances alive and the channel wasn’t previously dropped, otherwise None is returned.

pub fn strong_count(&self) -> usize

Returns the number of Sender handles.

pub fn weak_count(&self) -> usize

Returns the number of WeakSender handles.

Trait Implementations

impl<T> Clone for WeakSender<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 WeakSender<T>

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

Formats the value using the given formatter.

impl<T> Drop for WeakSender<T>

fn drop(&mut self)

Executes the destructor for this type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes