local_waker

# Struct LocalWaker

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    pub struct LocalWaker { /* private fields */ }

Expand description

A synchronization primitive for task wakeup.

Sometimes the task interested in a given event will change over time. A `LocalWaker` can coordinate concurrent notifications with the consumer, potentially “updating” the underlying task to wake up. This is useful in scenarios where a computation completes in another task and wants to notify the consumer, but the consumer is in the process of being migrated to a new logical task.

Consumers should call `register` before checking the result of a computation and producers should call `wake` after producing the computation (this differs from the usual `thread::park` pattern). It is also permitted for `wake` to be called before `register`. This results in a no-op.

A single `LocalWaker` may be reused for any number of calls to `register` or `wake`.

## Implementations§

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### impl LocalWaker

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#### pub fn new() -> Self

Creates a new, empty `LocalWaker`.

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#### pub fn register(&self, waker: &Waker) -> bool

Registers the waker to be notified on calls to `wake`.

Returns `true` if waker was registered before.

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#### pub fn wake(&self)

Calls `wake` on the last `Waker` passed to `register`.

If `register` has not been called yet, then this does nothing.

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#### pub fn take(&self) -> Option<Waker>

Returns the last `Waker` passed to `register`, so that the user can wake it.

If a waker has not been registered, this returns `None`.

## Trait Implementations§

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### impl Debug for LocalWaker

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

Formats the value using the given formatter. Read more
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### impl Default for LocalWaker

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#### fn default() -> LocalWaker

Returns the “default value” for a type. Read more

## Auto Trait Implementations§

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### impl !Freeze for LocalWaker

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### impl !RefUnwindSafe for LocalWaker

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### impl !Send for LocalWaker

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### impl !Sync for LocalWaker

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### impl Unpin for LocalWaker

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### impl UnwindSafe for LocalWaker

## 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> 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, 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.