Struct tokio::sync::mpsc::WeakUnboundedSender

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

Available on crate feature sync only.

An unbounded sender that does not prevent the channel from being closed.

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

In order to send messages, the WeakUnboundedSender needs to be upgraded using WeakUnboundedSender::upgrade, which returns Option<UnboundedSender>. It returns None if all UnboundedSenders have been dropped, and otherwise it returns an UnboundedSender.

Examples

use tokio::sync::mpsc::unbounded_channel;

#[tokio::main]
async fn main() {
    let (tx, _rx) = unbounded_channel::<i32>();
    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> WeakUnboundedSender<T>

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

Tries to convert a WeakUnboundedSender into an UnboundedSender. 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 UnboundedSender handles.

pub fn weak_count(&self) -> usize

Returns the number of WeakUnboundedSender handles.

Trait Implementations

impl<T> Clone for WeakUnboundedSender<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 WeakUnboundedSender<T>

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

Formats the value using the given formatter.

impl<T> Drop for WeakUnboundedSender<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