Struct async_task::FallibleTask

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pub struct FallibleTask<T, M = ()> { /* private fields */ }
Expand description

A spawned task with a fallible response.

This type behaves like Task, however it produces an Option<T> when polled and will return None if the executor dropped its Runnable without being run.

This can be useful to avoid the panic produced when polling the Task future if the executor dropped its Runnable.

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impl<T, M> FallibleTask<T, M>

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pub fn detach(self)

Detaches the task to let it keep running in the background.

§Examples
use smol::{Executor, Timer};
use std::time::Duration;

let ex = Executor::new();

// Spawn a deamon future.
ex.spawn(async {
    loop {
        println!("I'm a daemon task looping forever.");
        Timer::after(Duration::from_secs(1)).await;
    }
})
.fallible()
.detach();
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pub async fn cancel(self) -> Option<T>

Cancels the task and waits for it to stop running.

Returns the task’s output if it was completed just before it got canceled, or None if it didn’t complete.

While it’s possible to simply drop the Task to cancel it, this is a cleaner way of canceling because it also waits for the task to stop running.

§Examples
use smol::{future, Executor, Timer};
use std::thread;
use std::time::Duration;

let ex = Executor::new();

// Spawn a deamon future.
let task = ex.spawn(async {
    loop {
        println!("Even though I'm in an infinite loop, you can still cancel me!");
        Timer::after(Duration::from_secs(1)).await;
    }
})
.fallible();

// Run an executor thread.
thread::spawn(move || future::block_on(ex.run(future::pending::<()>())));

future::block_on(async {
    Timer::after(Duration::from_secs(3)).await;
    task.cancel().await;
});
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pub fn is_finished(&self) -> bool

Returns true if the current task is finished.

Note that in a multithreaded environment, this task can change finish immediately after calling this function.

Trait Implementations§

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impl<T, M: Debug> Debug for FallibleTask<T, M>

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

Formats the value using the given formatter. Read more
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impl<T, M> Future for FallibleTask<T, M>

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type Output = Option<T>

The type of value produced on completion.
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

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

Auto Trait Implementations§

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impl<T, M> Freeze for FallibleTask<T, M>

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impl<T, M> RefUnwindSafe for FallibleTask<T, M>

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impl<T, M> Send for FallibleTask<T, M>
where T: Send, M: Send + Sync,

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impl<T, M> Sync for FallibleTask<T, M>
where M: Send + Sync,

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impl<T, M> Unpin for FallibleTask<T, M>

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impl<T, M> UnwindSafe for FallibleTask<T, M>

Blanket Implementations§

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impl<T> Any for T
where 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 T
where 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 T
where 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 T
where 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<F> IntoFuture for F
where F: Future,

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type Output = <F as Future>::Output

The output that the future will produce on completion.
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type IntoFuture = F

Which kind of future are we turning this into?
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fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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impl<T, U> TryFrom<U> for T
where 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 T
where 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.