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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
use crate::{
rt::sleep::{AsyncSleep, Sleep},
test_util::ManualTimeSource,
};
use std::time::{Duration, SystemTime};
use std::{
collections::VecDeque,
sync::{Arc, Mutex},
};
use tokio::sync::oneshot;
use tokio::sync::Barrier;
use tokio::time::timeout;
/// A sleep implementation where calls to [`AsyncSleep::sleep`] block until [`SleepGate::expect_sleep`] is called
///
/// Create a [`ControlledSleep`] with [`controlled_time_and_sleep`]
#[derive(Debug, Clone)]
pub struct ControlledSleep {
barrier: Arc<Barrier>,
log: Arc<Mutex<Vec<Duration>>>,
duration: Arc<Mutex<VecDeque<Duration>>>,
advance_guard: Arc<Mutex<Option<oneshot::Sender<()>>>>,
}
impl ControlledSleep {
fn new(log: Arc<Mutex<Vec<Duration>>>) -> (ControlledSleep, SleepGate) {
let gate = Arc::new(Barrier::new(2));
let pending = Arc::new(Mutex::new(VecDeque::new()));
let advance_guard: Arc<Mutex<Option<oneshot::Sender<()>>>> = Default::default();
(
ControlledSleep {
barrier: gate.clone(),
log,
duration: pending.clone(),
advance_guard: advance_guard.clone(),
},
SleepGate {
gate,
pending,
advance_guard,
},
)
}
}
/// Guard returned from [`SleepGate::expect_sleep`]
///
/// # Examples
/// ```rust
/// # use std::sync::Arc;
/// use std::sync::atomic::{AtomicUsize, Ordering};
/// # async {
/// use std::time::{Duration, UNIX_EPOCH};
/// use aws_smithy_async::rt::sleep::AsyncSleep;
/// use aws_smithy_async::test_util::controlled_time_and_sleep;
/// let (time, sleep, mut gate) = controlled_time_and_sleep(UNIX_EPOCH);
/// let progress = Arc::new(AtomicUsize::new(0));
/// let task_progress = progress.clone();
/// let task = tokio::spawn(async move {
/// let progress = task_progress;
/// progress.store(1, Ordering::Release);
/// sleep.sleep(Duration::from_secs(1)).await;
/// progress.store(2, Ordering::Release);
/// sleep.sleep(Duration::from_secs(2)).await;
/// });
/// while progress.load(Ordering::Acquire) != 1 {}
/// let guard = gate.expect_sleep().await;
/// assert_eq!(guard.duration(), Duration::from_secs(1));
/// assert_eq!(progress.load(Ordering::Acquire), 1);
/// guard.allow_progress();
///
/// let guard = gate.expect_sleep().await;
/// assert_eq!(progress.load(Ordering::Acquire), 2);
/// assert_eq!(task.is_finished(), false);
/// guard.allow_progress();
/// task.await.expect("successful completion");
/// # };
/// ```
#[allow(dead_code)] // unused fields retained for their `Drop` impls
pub struct CapturedSleep<'a>(oneshot::Sender<()>, &'a SleepGate, Duration);
impl CapturedSleep<'_> {
/// Allow the calling code to advance past the call to [`AsyncSleep::sleep`]
///
/// In order to facilitate testing with no flakiness, the future returned by the call to `sleep`
/// will not resolve until [`CapturedSleep`] is dropped or this method is called.
///
/// ```rust
/// use std::time::Duration;
/// use aws_smithy_async::rt::sleep::AsyncSleep;
/// async fn do_something(sleep: &dyn AsyncSleep) {
/// println!("before sleep");
/// sleep.sleep(Duration::from_secs(1)).await;
/// println!("after sleep");
/// }
/// ```
///
/// To be specific, when `do_something` is called, the code will advance to `sleep.sleep`.
/// When [`SleepGate::expect_sleep`] is called, the 1 second sleep will be captured, but `after sleep`
/// WILL NOT be printed, until `allow_progress` is called.
pub fn allow_progress(self) {
drop(self)
}
/// Duration in the call to [`AsyncSleep::sleep`]
pub fn duration(&self) -> Duration {
self.2
}
}
impl AsRef<Duration> for CapturedSleep<'_> {
fn as_ref(&self) -> &Duration {
&self.2
}
}
/// Gate that allows [`ControlledSleep`] to advance.
///
/// See [`controlled_time_and_sleep`] for more details
pub struct SleepGate {
gate: Arc<Barrier>,
pending: Arc<Mutex<VecDeque<Duration>>>,
advance_guard: Arc<Mutex<Option<oneshot::Sender<()>>>>,
}
impl SleepGate {
/// Expect the time source to sleep
///
/// This returns the duration that was slept and a [`CapturedSleep`]. The drop guard is used
/// to precisely control
pub async fn expect_sleep(&mut self) -> CapturedSleep<'_> {
timeout(Duration::from_secs(1), self.gate.wait())
.await
.expect("timeout");
let dur = self
.pending
.lock()
.unwrap()
.pop_front()
.unwrap_or(Duration::from_secs(123456));
let guard = CapturedSleep(
self.advance_guard.lock().unwrap().take().unwrap(),
self,
dur,
);
guard
}
/// Skips any sleep that may be queued up, returning its duration
pub async fn skip_sleep(&mut self) -> Option<Duration> {
if timeout(Duration::from_millis(1), self.gate.wait())
.await
.is_ok()
{
let _ = self.advance_guard.lock().unwrap().take();
self.pending.lock().unwrap().pop_front()
} else {
None
}
}
}
impl AsyncSleep for ControlledSleep {
fn sleep(&self, duration: Duration) -> Sleep {
let barrier = self.barrier.clone();
let log = self.log.clone();
let pending = self.duration.clone();
let drop_guard = self.advance_guard.clone();
Sleep::new(async move {
// 1. write the duration into the shared mutex
pending.lock().unwrap().push_back(duration);
let (tx, rx) = oneshot::channel();
*drop_guard.lock().unwrap() = Some(tx);
// 2. first wait on the barrier—this is how we wait for an invocation of `expect_sleep`
barrier.wait().await;
log.lock().unwrap().push(duration);
let _ = rx.await;
})
}
}
/// Returns a trio of tools to test interactions with time
///
/// 1. [`ManualTimeSource`] which starts at a specific time and only advances when `sleep` is called.
/// It MUST be paired with [`ControlledSleep`] in order to function.
pub fn controlled_time_and_sleep(
start_time: SystemTime,
) -> (ManualTimeSource, ControlledSleep, SleepGate) {
let log = Arc::new(Mutex::new(vec![]));
let (sleep, gate) = ControlledSleep::new(log.clone());
(ManualTimeSource { start_time, log }, sleep, gate)
}
#[cfg(test)]
mod test {
use crate::rt::sleep::AsyncSleep;
use crate::test_util::controlled_time_and_sleep;
use crate::time::TimeSource;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::time::{Duration, UNIX_EPOCH};
use tokio::task::yield_now;
use tokio::time::timeout;
#[tokio::test]
async fn test_sleep_gate() {
let start = UNIX_EPOCH;
let (time, sleep, mut gate) = controlled_time_and_sleep(UNIX_EPOCH);
let progress = Arc::new(AtomicUsize::new(0));
let task_progress = progress.clone();
let task = tokio::spawn(async move {
assert_eq!(time.now(), start);
let progress = task_progress;
progress.store(1, Ordering::Release);
sleep.sleep(Duration::from_secs(1)).await;
assert_eq!(time.now(), start + Duration::from_secs(1));
progress.store(2, Ordering::Release);
sleep.sleep(Duration::from_secs(2)).await;
assert_eq!(time.now(), start + Duration::from_secs(3));
});
while progress.load(Ordering::Acquire) != 1 {
yield_now().await
}
let guard = gate.expect_sleep().await;
assert_eq!(guard.duration(), Duration::from_secs(1));
assert_eq!(progress.load(Ordering::Acquire), 1);
guard.allow_progress();
let guard = gate.expect_sleep().await;
assert_eq!(progress.load(Ordering::Acquire), 2);
assert!(!task.is_finished(), "task should not be finished");
guard.allow_progress();
timeout(Duration::from_secs(1), task)
.await
.expect("no timeout")
.expect("successful completion");
}
#[tokio::test]
async fn sleep_gate_multiple_sleeps() {
let (time, sleep, mut gate) = controlled_time_and_sleep(UNIX_EPOCH);
let one = sleep.sleep(Duration::from_secs(1));
let two = sleep.sleep(Duration::from_secs(2));
let three = sleep.sleep(Duration::from_secs(3));
let spawn = tokio::spawn(async move {
let _ = (one.await, two.await, three.await);
});
assert_eq!(Duration::from_secs(1), gate.expect_sleep().await.duration());
gate.skip_sleep().await;
assert_eq!(Duration::from_secs(3), gate.expect_sleep().await.duration());
let _ = spawn.await;
assert_eq!(UNIX_EPOCH + Duration::from_secs(6), time.now());
}
#[tokio::test]
async fn sleep_gate_skipping_a_sleep_doesnt_blow_up_if_no_sleep() {
let (time, sleep, mut gate) = controlled_time_and_sleep(UNIX_EPOCH);
let some_sleep = sleep.sleep(Duration::from_secs(1));
let spawn = tokio::spawn(async move {
let _ = some_sleep.await;
});
assert_eq!(Some(Duration::from_secs(1)), gate.skip_sleep().await);
assert_eq!(None, gate.skip_sleep().await);
let _ = spawn.await;
assert_eq!(UNIX_EPOCH + Duration::from_secs(1), time.now());
}
}