Struct tokio::sync::mpsc::WeakSender

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

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());
}

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impl<T> WeakSender<T>

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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.

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pub fn strong_count(&self) -> usize

Returns the number of Sender handles.

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pub fn weak_count(&self) -> usize

Returns the number of WeakSender handles.

Trait Implementations§

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impl<T> Clone for WeakSender<T>

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T> Debug for WeakSender<T>

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

Formats the value using the given formatter. Read more
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impl<T> Drop for WeakSender<T>

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fn drop(&mut self)

Executes the destructor for this type. Read more

Auto Trait Implementations§

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impl<T> Freeze for WeakSender<T>

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impl<T> RefUnwindSafe for WeakSender<T>

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

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

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impl<T> Unpin for WeakSender<T>

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impl<T> UnwindSafe for WeakSender<T>

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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

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fn into(self) -> U

Calls U::from(self).

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

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

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.