s2n-quic-dc 0.45.0

Internal crate used by s2n-quic
Documentation 
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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

use super::SleepHandle;
use core::{
    fmt,
    future::Future,
    pin::Pin,
    task::{Context, Poll},
    time::Duration,
};
use pin_project_lite::pin_project;
use s2n_quic_core::{ready, time::Timestamp};
use tokio::time::{self, sleep_until, Instant};
use tracing::trace;

#[derive(Clone, Debug)]
pub struct Clock(Instant);

impl Default for Clock {
    #[inline]
    fn default() -> Self {
        Self(Instant::now())
    }
}

impl s2n_quic_core::time::Clock for Clock {
    #[inline]
    fn get_time(&self) -> Timestamp {
        let time = self.0.elapsed();
        unsafe { Timestamp::from_duration(time) }
    }
}

pin_project!(
    pub struct Sleep {
        clock: Clock,
        #[pin]
        sleep: time::Sleep,
    }
);

impl s2n_quic_core::time::Clock for Sleep {
    #[inline]
    fn get_time(&self) -> Timestamp {
        self.clock.get_time()
    }
}

impl Future for Sleep {
    type Output = ();

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let this = self.project();
        ready!(core::future::Future::poll(this.sleep, cx));
        Poll::Ready(())
    }
}

impl super::Sleep for Sleep {
    #[inline]
    fn update(self: Pin<&mut Self>, target: Timestamp) {
        let target = unsafe { target.as_duration() };

        // floor the delay to milliseconds to reduce timer churn
        let delay = Duration::from_millis(target.as_millis() as u64);

        let target = self.clock.0 + delay;

        // if the clock has changed let the sleep future know
        trace!(update = ?target);
        self.project().sleep.reset(target);
    }
}

impl super::Clock for Sleep {
    #[inline]
    fn sleep(&self, amount: Duration) -> (SleepHandle, Timestamp) {
        self.clock.sleep(amount)
    }
}

impl fmt::Debug for Sleep {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Sleep")
            .field("clock", &self.clock)
            .field("sleep", &self.sleep)
            .finish()
    }
}

impl super::Clock for Clock {
    #[inline]
    fn sleep(&self, amount: Duration) -> (SleepHandle, Timestamp) {
        let now = Instant::now();
        let sleep = sleep_until(now + amount);
        let sleep = Sleep {
            clock: self.clone(),
            sleep,
        };
        let sleep = Box::pin(sleep);
        let target = now.saturating_duration_since(self.0);
        let target = unsafe { Timestamp::from_duration(target) };
        (sleep, target)
    }
}

#[cfg(test)]
mod tests {
    use crate::clock::{tokio::Clock, Timer};
    use core::time::Duration;
    use s2n_quic_core::time::{clock::Timer as _, Clock as _};

    #[tokio::test]
    async fn clock_test() {
        let clock = Clock::default();
        let mut timer = Timer::new(&clock);
        timer.ready().await;
        timer.update(clock.get_time() + Duration::from_secs(1));
        timer.ready().await;
    }
}