Struct TaskRef

pub struct TaskRef(/* private fields */);

A type-erased, reference-counted pointer to a spawned Task.

Once a task has been spawned, it is generally referenced by a TaskRef. When a spawned task is placed in a scheduler’s run queue, dequeuing the next task will yield a TaskRef, and a TaskRef may be converted into a Waker or used to await a spawned task’s completion.

TaskRefs are reference-counted, and the task will be deallocated when the last TaskRef pointing to it is dropped.

Implementations

impl TaskRef

pub fn id(&self) -> TaskId

Returns a TaskId that uniquely identifies this task.

The returned ID does not increment the task’s reference count, and may persist even after the task it identifies has completed and been deallocated.

pub fn cancel(&self) -> bool

Forcibly cancel the task.

Canceling a task sets a flag indicating that it has been canceled and should terminate. The next time a canceled task is polled by the scheduler, it will terminate instead of polling the inner Future. If the task has a JoinHandle, that JoinHandle will complete with a JoinError. The task then will be deallocated once all JoinHandles and TaskRefs referencing it have been dropped.

This method returns true if the task was canceled successfully, and false if the task could not be canceled (i.e., it has already completed, has already been canceled, cancel culture has gone TOO FAR, et cetera).

pub fn is_complete(&self) -> bool

Returns true if this task has completed.

Tasks are considered completed when the spawned Future has returned Poll::Ready, or if the task has been canceled by the cancel() method.

Note: This method can return false after cancel() has been called. This is because calling cancel begins the process of cancelling a task. The task is not considered canceled until it has been polled by the scheduler after calling cancel().

Trait Implementations

impl Clone for TaskRef

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for TaskRef

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

Formats the value using the given formatter.

impl Drop for TaskRef

fn drop(&mut self)

Executes the destructor for this type.

impl<T> PartialEq<&JoinHandle<T>> for TaskRef

fn eq(&self, other: &&JoinHandle<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialEq<&TaskRef> for JoinHandle<T>

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialEq<JoinHandle<T>> for TaskRef

fn eq(&self, other: &JoinHandle<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialEq<TaskRef> for JoinHandle<T>

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq for TaskRef

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Pointer for TaskRef

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

Formats the value using the given formatter.

impl Eq for TaskRef

impl Send for TaskRef

impl StructuralPartialEq for TaskRef

impl Sync for TaskRef