Struct JoinHandle 

pub struct JoinHandle<T> { /* private fields */ }

An owned permission to join on a task (await its termination).

This can be seen as an equivalent to std::thread::JoinHandle but for Future tasks rather than a thread. Note that the task associated with this JoinHandle will start running when Executor::spawn is called according to the selected runtime, even if the JoinHandle has not been awaited.

Dropping JoinHandle will not abort or cancel the task. In other words, the task will continue to run in the background and any return value will be lost.

This struct is created by the Executor::spawn.

Implementations

impl<T> JoinHandle<T>

pub fn empty() -> Self

Provide an empty JoinHandle with no associated task.

impl<T> JoinHandle<T>

pub fn abort(&self)

Abort the task associated with the handle.

If cancellation is observed after this method is called, awaiting the handle returns JoinError::Aborted. Cancellation without an abort request through this handle returns JoinError::Cancelled.

pub fn is_finished(&self) -> bool

Check if the task associated with this JoinHandle has finished.

Note that this method can return false even if JoinHandle::abort has been called on the task due to the time it may take for the task to cancel.

pub fn replace(&mut self, handle: JoinHandle<T>)

Replace the current handle with the provided JoinHandle, while dropping the source.

Warning

Note that if this is called with a non-empty handle, the existing task will not be terminated when it is replaced and could run indefinitely. Best to use when JoinHandle is JoinHandle::empty where empty is a used placeholder.

pub fn replace_in_place(&mut self, handle: &mut JoinHandle<T>)

Replace the current handle with the provided JoinHandle, making the source become an equivalent to JoinHandle::empty.

Warning

Note that if this is called with a non-empty handle, the existing task will not be terminated when it is replaced and could run indefinitely. Best to use when JoinHandle is JoinHandle::empty where empty is a used placeholder, and you want to update the source later with another task handle.

Trait Implementations

impl<T> Debug for JoinHandle<T>

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

Formats the value using the given formatter.

impl<T> From<JoinHandle<T>> for AbortableJoinHandle<T>

fn from(handle: JoinHandle<T>) -> Self

Converts to this type from the input type.

impl<T> Future for JoinHandle<T>

type Output = Result<T, JoinError>

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.