Type Alias ServerTask

type ServerTask = JoinHandle<Result<(), BoxError>>;

Aliased Type

struct ServerTask { /* private fields */ }

Implementations

impl<T> JoinHandle<T>

pub fn abort(&self)

Abort the task associated with the handle.

Awaiting a cancelled task might complete as usual if the task was already completed at the time it was cancelled, but most likely it will fail with a cancelled JoinError.

Be aware that tasks spawned using spawn_blocking cannot be aborted because they are not async. If you call abort on a spawn_blocking task, then this will not have any effect, and the task will continue running normally. The exception is if the task has not started running yet; in that case, calling abort may prevent the task from starting.

See also the module level docs for more information on cancellation.

use tokio::time;

let mut handles = Vec::new();

handles.push(tokio::spawn(async {
   time::sleep(time::Duration::from_secs(10)).await;
   true
}));

handles.push(tokio::spawn(async {
   time::sleep(time::Duration::from_secs(10)).await;
   false
}));

for handle in &handles {
    handle.abort();
}

for handle in handles {
    assert!(handle.await.unwrap_err().is_cancelled());
}

pub fn is_finished(&self) -> bool

Checks if the task associated with this JoinHandle has finished.

Please note that this method can return false even if abort has been called on the task. This is because the cancellation process may take some time, and this method does not return true until it has completed.

use tokio::time;

let handle1 = tokio::spawn(async {
    // do some stuff here
});
let handle2 = tokio::spawn(async {
    // do some other stuff here
    time::sleep(time::Duration::from_secs(10)).await;
});
// Wait for the task to finish
handle2.abort();
time::sleep(time::Duration::from_secs(1)).await;
assert!(handle1.is_finished());
assert!(handle2.is_finished());

pub fn abort_handle(&self) -> AbortHandle

Returns a new AbortHandle that can be used to remotely abort this task.

Awaiting a task cancelled by the AbortHandle might complete as usual if the task was already completed at the time it was cancelled, but most likely it will fail with a cancelled JoinError.

use tokio::{time, task};

let mut handles = Vec::new();

handles.push(tokio::spawn(async {
   time::sleep(time::Duration::from_secs(10)).await;
   true
}));

handles.push(tokio::spawn(async {
   time::sleep(time::Duration::from_secs(10)).await;
   false
}));

let abort_handles: Vec<task::AbortHandle> = handles.iter().map(|h| h.abort_handle()).collect();

for handle in abort_handles {
    handle.abort();
}

for handle in handles {
    assert!(handle.await.unwrap_err().is_cancelled());
}

pub fn id(&self) -> Id

Returns a task ID that uniquely identifies this task relative to other currently spawned tasks.

Trait Implementations

impl<T> Debug for JoinHandle<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Drop for JoinHandle<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> Future for JoinHandle<T>

type Output = Result<T, JoinError>

The type of value produced on completion.

fn poll( self: Pin<&mut JoinHandle<T>>, cx: &mut Context<'_>, ) -> Poll<<JoinHandle<T> as Future>::Output>

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

impl<T> WaitForPanics for JoinHandle<T>

where T: Send + 'static,

fn wait_for_panics_with( self, panic_on_unexpected_termination: bool, ) -> <JoinHandle<T> as WaitForPanics>::Output

Returns a future which waits for self to finish, then checks if its output is:

• a panic payload: resume that panic,
• an unexpected termination:
  • if panic_on_unexpected_termination is true, panic with that error,
  • otherwise, hang waiting for shutdown,
• an expected termination: hang waiting for shutdown.

Otherwise, returns the task return value of self.

Panics

If self contains a panic payload, or [JoinHandle::abort()] has been called on self.

Hangs

If self contains an expected termination, and we’re shutting down anyway. If we’re ignoring terminations because panic_on_unexpected_termination is false. Futures hang by returning Pending and not setting a waker, so this uses minimal resources.

type Output = Pin<Box<dyn Future<Output = T> + Send>>

The underlying task output, after removing panics and unwrapping termination results.

fn wait_and_panic_on_unexpected_termination(self) -> Self::Output

Waits for self to finish, then check if its output is:

fn wait_for_panics(self) -> Self::Output

Waits for self to finish, then check if its output is:

impl<T> RefUnwindSafe for JoinHandle<T>

impl<T> Send for JoinHandle<T>

where T: Send,

impl<T> Sync for JoinHandle<T>

where T: Send,

impl<T> Unpin for JoinHandle<T>

impl<T> UnwindSafe for JoinHandle<T>