Struct core::task::RawWakerVTable

pub struct RawWakerVTable {
    clone: unsafe fn(_: *const ()) -> RawWaker,
    wake: unsafe fn(_: *const ()),
    wake_by_ref: unsafe fn(_: *const ()),
    drop: unsafe fn(_: *const ()),
}

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.

Fields

clone: unsafe fn(_: *const ()) -> RawWaker

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: unsafe fn(_: *const ())

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: unsafe fn(_: *const ())

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: unsafe fn(_: *const ())

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.

Implementations

impl RawWakerVTable

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

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

impl Clone for RawWakerVTable

fn clone(&self) -> RawWakerVTable

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for RawWakerVTable

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

Formats the value using the given formatter.

impl PartialEq<RawWakerVTable> for RawWakerVTable

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

This method tests for self and other values to be equal, and is used by ==.

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.

impl Copy for RawWakerVTable

impl StructuralPartialEq for RawWakerVTable