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;

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 duplicate of the value. Read more

1.0.0 (const: unstable) ·

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

impl<T> Debug for WeakSender<T>

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

Formats the value using the given formatter. Read more

impl<T> Drop for WeakSender<T>

fn drop(&mut self)

Executes the destructor for this type. Read more

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned. Read more

Auto Trait Implementations

impl<T> Freeze for WeakSender<T>

impl<T> RefUnwindSafe for WeakSender<T>

impl<T> Send for WeakSender<T>
where T: Send,

impl<T> Sync for WeakSender<T>
where T: Send,

impl<T> Unpin for WeakSender<T>

impl<T> UnsafeUnpin for WeakSender<T>

impl<T> UnwindSafe for WeakSender<T>

Blanket Implementations

impl<T> Any for T
where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T
where T: ?Sized,

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T
where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> CloneToUninit for T
where T: Clone,

unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)

Performs copy-assignment from self to dest. Read more

impl<T> From<T> for T

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

fn in_current_span(self) -> Instrumented<Self> ⓘ

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

impl<T, U> Into for T
where U: From<T>,

fn into(self) -> U

Calls U::from(self).

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

impl<T> ToOwned for T
where T: Clone,

type Owned = T

The resulting type after obtaining ownership.

fn to_owned(&self) -> T

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

fn clone_into(&self, target: &mut T)

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

impl<T, U> TryFrom for T
where U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

impl<T, U> TryInto for T
where U: TryFrom<T>,

type Error = >::Error

The type returned in the event of a conversion error.

fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

impl<T> WithSubscriber for T

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> ⓘ
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more