Trait completion_core::CompletionStream

#[must_use = "streams do nothing unless you use them"]pub trait CompletionStream {
    type Item;
    unsafe fn poll_next(
        self: Pin<&mut Self>, 
        cx: &mut Context<'_>
    ) -> Poll<Option<Self::Item>>;
    unsafe fn poll_cancel(
        self: Pin<&mut Self>, 
        cx: &mut Context<'_>
    ) -> Poll<()>;

    fn size_hint(&self) -> (usize, Option<usize>) { ... }
}

A Stream where each value must be polled to completion.

All types that implement Stream should also implement this.

A completion stream has three states: running, cancelling and exhausted. Streams initially start out in the running state. To progress the running state, users will call poll_next, which either returns Poll::Pending to continue the running state, Poll::Ready(Some) to yield a value and continue the running state, or Poll::Ready(None) to reach the exhausted state.

At any time during the running state, users may call poll_cancel to initiate the cancelling state. During this state, only poll_cancel should be called, and it can return Poll::Pending to continue the cancelling state or Poll::Ready(()) to reach the exhausted state.

Once the exhausted state has been reached, either by poll_next returning Poll::Ready(None) or by poll_cancel returning Poll::Ready, neither poll_next nor poll_cancel should be called again.

Associated Types

type Item

Values yielded by the stream.

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Required methods

unsafe fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

This function should only be called when the stream is in the running state.

Safety

Once this function has been called and the type does not also implement Stream, the user must not drop or forget the stream until it has returned Poll::Ready or panicked. Note that users may drop the stream in between finishing polling one item and starting to poll the next.

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

Attempt to cancel the stream, registering the current task for wakeup if it has not finished cancelling yet.

This function should only be called when the stream is in the running state or in the cancelling state. Once this function returns Poll::Ready, the stream should be considered exhausted and should not be polled again.

Safety

Once this function has been called and the type does not also implement Stream, the user must not drop or forget the stream until it has returned Poll::Ready or panicked. Note that users may drop the stream in between cancelling one item and starting to poll the next.

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Provided methods

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.

See Stream::size_hint for more details.

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Implementations on Foreign Types

impl<S: CompletionStream + Unpin + ?Sized> CompletionStream for &mut S

type Item = S::Item

unsafe fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

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

fn size_hint(&self) -> (usize, Option<usize>)

impl<S: CompletionStream + Unpin + ?Sized> CompletionStream for Box<S>

type Item = S::Item

unsafe fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

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

fn size_hint(&self) -> (usize, Option<usize>)

impl<P> CompletionStream for Pin<P> where
    P: Unpin + DerefMut,
    P::Target: CompletionStream, 

type Item = <P::Target as CompletionStream>::Item

unsafe fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

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

fn size_hint(&self) -> (usize, Option<usize>)

impl<S: CompletionStream> CompletionStream for AssertUnwindSafe<S>

type Item = S::Item

unsafe fn poll_next(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>
) -> Poll<Option<Self::Item>>

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

fn size_hint(&self) -> (usize, Option<usize>)

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Implementors

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