# Struct std::task::RawWakerVTable

1.36.0 · source ·

    pub struct RawWakerVTable { /* private fields */ }

Expand description

A virtual function pointer table (vtable) that specifies the behavior of a `RawWaker`.

The pointer passed to all functions inside the vtable is the `data` pointer from the enclosing `RawWaker` object.

The functions inside this struct are only intended to be called on the `data` pointer of a properly constructed `RawWaker` object from inside the `RawWaker` implementation. Calling one of the contained functions using any other `data` pointer will cause undefined behavior.

These functions must all be thread-safe (even though `RawWaker` is `!Send + !Sync`) because `Waker` is `Send + Sync`, and thus wakers may be moved to arbitrary threads or invoked by `&` reference. For example, this means that if the `clone` and `drop` functions manage a reference count, they must do so atomically.

## Implementations§

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### impl RawWakerVTable

const: 1.36.0 · source

#### pub const fn new( clone: unsafe fn(_: *const ()) -> RawWaker, wake: unsafe fn(_: *const ()), wake_by_ref: unsafe fn(_: *const ()), drop: unsafe fn(_: *const ()) ) -> RawWakerVTable

Creates a new `RawWakerVTable` from the provided `clone`, `wake`, `wake_by_ref`, and `drop` functions.

These functions must all be thread-safe (even though `RawWaker` is `!Send + !Sync`) because `Waker` is `Send + Sync`, and thus wakers may be moved to arbitrary threads or invoked by `&` reference. For example, this means that if the `clone` and `drop` functions manage a reference count, they must do so atomically.

##### `clone`

This function will be called when the `RawWaker` gets cloned, e.g. when the `Waker` in which the `RawWaker` is stored gets cloned.

The implementation of this function must retain all resources that are required for this additional instance of a `RawWaker` and associated task. Calling `wake` on the resulting `RawWaker` should result in a wakeup of the same task that would have been awoken by the original `RawWaker`.

##### `wake`

This function will be called when `wake` is called on the `Waker`. It must wake up the task associated with this `RawWaker`.

The implementation of this function must make sure to release any resources that are associated with this instance of a `RawWaker` and associated task.

##### `wake_by_ref`

This function will be called when `wake_by_ref` is called on the `Waker`. It must wake up the task associated with this `RawWaker`.

This function is similar to `wake`, but must not consume the provided data pointer.

##### `drop`

This function gets called when a `Waker` gets dropped.

The implementation of this function must make sure to release any resources that are associated with this instance of a `RawWaker` and associated task.

## Trait Implementations§

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### impl Clone for RawWakerVTable

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#### fn clone(&self) -> RawWakerVTable

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from `source`. Read more
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### impl Debug for RawWakerVTable

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

Formats the value using the given formatter. Read more
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### impl PartialEq for RawWakerVTable

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#### fn eq(&self, other: &RawWakerVTable) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl Copy for RawWakerVTable

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### impl StructuralPartialEq for RawWakerVTable

## Auto Trait Implementations§

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### impl RefUnwindSafe for RawWakerVTable

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### impl Send for RawWakerVTable

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### impl Sync for RawWakerVTable

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### impl Unpin for RawWakerVTable

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### impl UnwindSafe for RawWakerVTable

## Blanket Implementations§

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### impl<T> Any for Twhere 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 Twhere 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 Twhere 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 Twhere 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 Twhere 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 Twhere 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 Twhere 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.