Struct futures_util::future::PollImmediate

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

Future for the poll_immediate function.

It will never return Poll::Pending

Trait Implementations

impl<T: Clone> Clone for PollImmediate<T>

fn clone(&self) -> PollImmediate<T>

Returns a copy of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for PollImmediate<T>

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

Formats the value using the given formatter.

impl<T: Future> FusedFuture for PollImmediate<T>

fn is_terminated(&self) -> bool

Returns true if the underlying future should no longer be polled.

impl<T, F> Future for PollImmediate<F>where
    F: Future<Output = T>,

type Output = Option<T>

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>>

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

impl<T, F> Stream for PollImmediate<F>where
    F: Future<Output = T>,

A Stream implementation that can be polled repeatedly until the future is done. The stream will never return Poll::Pending so polling it in a tight loop is worse than using a blocking synchronous function.

use futures::task::Poll;
use futures::{StreamExt, future, pin_mut};
use future::FusedFuture;

let f = async { 1_u32 };
pin_mut!(f);
let mut r = future::poll_immediate(f);
assert_eq!(r.next().await, Some(Poll::Ready(1)));

let f = async {futures::pending!(); 42_u8};
pin_mut!(f);
let mut p = future::poll_immediate(f);
assert_eq!(p.next().await, Some(Poll::Pending));
assert!(!p.is_terminated());
assert_eq!(p.next().await, Some(Poll::Ready(42)));
assert!(p.is_terminated());
assert_eq!(p.next().await, None);

type Item = Poll<T>

Values yielded by the stream.

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.

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

Returns the bounds on the remaining length of the stream.

impl<'__pin, T> Unpin for PollImmediate<T>where
    __Origin<'__pin, T>: Unpin,