Struct maitake_sync::wait_map::Wait

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pub struct Wait<'a, K: PartialEq, V> { /* private fields */ }
Expand description

Future returned from WaitMap::wait().

This future is fused, so once it has completed, any future calls to poll will immediately return Poll::Ready.

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impl<'map, 'wait, K: PartialEq, V> Wait<'map, K, V>

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pub fn enqueue(self: Pin<&'wait mut Self>) -> EnqueueWait<'wait, 'map, K, V>

Returns a future that completes when the Wait item has been added to the WaitMap, and is ready to receive data

This is useful for ensuring that a receiver is ready before sending a message that will elicit the expected response.

§Example
use std::sync::Arc;
use maitake::scheduler;
use maitake_sync::wait_map::{WaitMap, WakeOutcome};
use futures_util::pin_mut;

let scheduler = Scheduler::new();
let q = Arc::new(WaitMap::new());

let q2 = q.clone();
scheduler.spawn(async move {
    let wait = q2.wait(0);

    // At this point, we have created the future, but it has not yet
    // been added to the queue. We could immediately await 'wait',
    // but then we would be unable to progress further. We must
    // first pin the `wait` future, to ensure that it does not move
    // until it has been completed.
    pin_mut!(wait);
    wait.as_mut().enqueue().await.unwrap();

    // We now know the waiter has been enqueued, at this point we could
    // send a message that will cause key == 0 to be returned, without
    // worrying about racing with the expected response, e.g:
    //
    // sender.send_with_id(0, SomeMessage).await?;
    //
    let val = wait.await.unwrap();
    assert_eq!(val, 10);
});

assert!(matches!(q.wake(&0, 100), WakeOutcome::NoMatch(_)));

let tick = scheduler.tick();

assert!(matches!(q.wake(&0, 100), WakeOutcome::Woke));

Trait Implementations§

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impl<'a, K: Debug + PartialEq, V: Debug> Debug for Wait<'a, K, V>

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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<'a, K: PartialEq, V> Drop for Wait<'a, K, V>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<K: PartialEq, V> Future for Wait<'_, K, V>

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type Output = Result<V, WaitError>

The type of value produced on completion.
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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. Read more
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impl<'pin, 'a, K: PartialEq, V> Unpin for Wait<'a, K, V>
where __Wait<'pin, 'a, K, V>: Unpin,

Auto Trait Implementations§

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impl<'a, K, V> !Freeze for Wait<'a, K, V>

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impl<'a, K, V> !RefUnwindSafe for Wait<'a, K, V>

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impl<'a, K, V> Send for Wait<'a, K, V>
where K: Send, V: Send,

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impl<'a, K, V> !Sync for Wait<'a, K, V>

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impl<'a, K, V> !UnwindSafe for Wait<'a, K, V>

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.