tick 0.3.3

Provides primitives to interact with and manipulate machine time.
Documentation 
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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

use std::io::ErrorKind;
use std::pin::Pin;
use std::task::{Context, Poll};

use pin_project_lite::pin_project;

use crate::Error;

pin_project! {
    /// A future that races between an inner future and a deadline.
    ///
    /// - If the inner future completes before the deadline, the future's output is returned.
    /// - If the deadline is reached before the inner future completes, an error is returned.
    #[derive(Debug)]
    pub struct Timeout<F, D> {
        #[pin]
        future: F,
        #[pin]
        deadline: D,
    }
}

impl<F, D> Timeout<F, D> {
    pub(super) const fn new(future: F, deadline: D) -> Self {
        Self { future, deadline }
    }
}

impl<F: Future, D: Future> Future for Timeout<F, D> {
    type Output = Result<F::Output, Error>;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let this = self.project();

        match this.future.poll(cx) {
            Poll::Ready(v) => Poll::Ready(Ok(v)),
            Poll::Pending => match this.deadline.poll(cx) {
                Poll::Ready(_) => {
                    let io_err = std::io::Error::new(ErrorKind::TimedOut, "future timed out");
                    Poll::Ready(Err(Error::other(io_err)))
                }
                Poll::Pending => Poll::Pending,
            },
        }
    }
}