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#![warn(rust_2018_idioms)]
#![cfg(feature = "full")]
use std::pin::Pin;
use std::task::{Context, Poll};
use futures::{Stream, StreamExt};
use tokio::time::{self, Duration, Instant, Interval, MissedTickBehavior};
use tokio_test::{assert_pending, assert_ready_eq, task};
// Takes the `Interval` task, `start` variable, and optional time deltas
// For each time delta, it polls the `Interval` and asserts that the result is
// equal to `start` + the specific time delta. Then it asserts that the
// `Interval` is pending.
macro_rules! check_interval_poll {
($i:ident, $start:ident, $($delta:expr),*$(,)?) => {
$(
assert_ready_eq!(poll_next(&mut $i), $start + ms($delta));
)*
assert_pending!(poll_next(&mut $i));
};
($i:ident, $start:ident) => {
check_interval_poll!($i, $start,);
};
}
#[tokio::test]
#[should_panic]
async fn interval_zero_duration() {
let _ = time::interval_at(Instant::now(), ms(0));
}
// Expected ticks: | 1 | 2 | 3 | 4 | 5 | 6 |
// Actual ticks: | work -----| delay | work | work | work -| work -----|
// Poll behavior: | | | | | | | |
// | | | | | | | |
// Ready(s) | | Ready(s + 2p) | | | |
// Pending | Ready(s + 3p) | | |
// Ready(s + p) Ready(s + 4p) | |
// Ready(s + 5p) |
// Ready(s + 6p)
#[tokio::test(start_paused = true)]
async fn burst() {
let start = Instant::now();
// This is necessary because the timer is only so granular, and in order for
// all our ticks to resolve, the time needs to be 1ms ahead of what we
// expect, so that the runtime will see that it is time to resolve the timer
time::advance(ms(1)).await;
let mut i = task::spawn(time::interval_at(start, ms(300)));
check_interval_poll!(i, start, 0);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
time::advance(ms(200)).await;
check_interval_poll!(i, start, 300);
time::advance(ms(650)).await;
check_interval_poll!(i, start, 600, 900);
time::advance(ms(200)).await;
check_interval_poll!(i, start);
time::advance(ms(100)).await;
check_interval_poll!(i, start, 1200);
time::advance(ms(250)).await;
check_interval_poll!(i, start, 1500);
time::advance(ms(300)).await;
check_interval_poll!(i, start, 1800);
}
// Expected ticks: | 1 | 2 | 3 | 4 | 5 | 6 |
// Actual ticks: | work -----| delay | work -----| work -----| work -----|
// Poll behavior: | | | | | | | |
// | | | | | | | |
// Ready(s) | | Ready(s + 2p) | | | |
// Pending | Pending | | |
// Ready(s + p) Ready(s + 2p + d) | |
// Ready(s + 3p + d) |
// Ready(s + 4p + d)
#[tokio::test(start_paused = true)]
async fn delay() {
let start = Instant::now();
// This is necessary because the timer is only so granular, and in order for
// all our ticks to resolve, the time needs to be 1ms ahead of what we
// expect, so that the runtime will see that it is time to resolve the timer
time::advance(ms(1)).await;
let mut i = task::spawn(time::interval_at(start, ms(300)));
i.set_missed_tick_behavior(MissedTickBehavior::Delay);
check_interval_poll!(i, start, 0);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
time::advance(ms(200)).await;
check_interval_poll!(i, start, 300);
time::advance(ms(650)).await;
check_interval_poll!(i, start, 600);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
// We have to add one here for the same reason as is above.
// Because `Interval` has reset its timer according to `Instant::now()`,
// we have to go forward 1 more millisecond than is expected so that the
// runtime realizes that it's time to resolve the timer.
time::advance(ms(201)).await;
// We add one because when using the `Delay` behavior, `Interval`
// adds the `period` from `Instant::now()`, which will always be off by one
// because we have to advance time by 1 (see above).
check_interval_poll!(i, start, 1251);
time::advance(ms(300)).await;
// Again, we add one.
check_interval_poll!(i, start, 1551);
time::advance(ms(300)).await;
check_interval_poll!(i, start, 1851);
}
// Expected ticks: | 1 | 2 | 3 | 4 | 5 | 6 |
// Actual ticks: | work -----| delay | work ---| work -----| work -----|
// Poll behavior: | | | | | | |
// | | | | | | |
// Ready(s) | | Ready(s + 2p) | | |
// Pending | Ready(s + 4p) | |
// Ready(s + p) Ready(s + 5p) |
// Ready(s + 6p)
#[tokio::test(start_paused = true)]
async fn skip() {
let start = Instant::now();
// This is necessary because the timer is only so granular, and in order for
// all our ticks to resolve, the time needs to be 1ms ahead of what we
// expect, so that the runtime will see that it is time to resolve the timer
time::advance(ms(1)).await;
let mut i = task::spawn(time::interval_at(start, ms(300)));
i.set_missed_tick_behavior(MissedTickBehavior::Skip);
check_interval_poll!(i, start, 0);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
time::advance(ms(200)).await;
check_interval_poll!(i, start, 300);
time::advance(ms(650)).await;
check_interval_poll!(i, start, 600);
time::advance(ms(250)).await;
check_interval_poll!(i, start, 1200);
time::advance(ms(300)).await;
check_interval_poll!(i, start, 1500);
time::advance(ms(300)).await;
check_interval_poll!(i, start, 1800);
}
#[tokio::test(start_paused = true)]
async fn reset() {
let start = Instant::now();
// This is necessary because the timer is only so granular, and in order for
// all our ticks to resolve, the time needs to be 1ms ahead of what we
// expect, so that the runtime will see that it is time to resolve the timer
time::advance(ms(1)).await;
let mut i = task::spawn(time::interval_at(start, ms(300)));
check_interval_poll!(i, start, 0);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
time::advance(ms(200)).await;
check_interval_poll!(i, start, 300);
time::advance(ms(100)).await;
check_interval_poll!(i, start);
i.reset();
time::advance(ms(250)).await;
check_interval_poll!(i, start);
time::advance(ms(50)).await;
// We add one because when using `reset` method, `Interval` adds the
// `period` from `Instant::now()`, which will always be off by one
check_interval_poll!(i, start, 701);
time::advance(ms(300)).await;
check_interval_poll!(i, start, 1001);
}
fn poll_next(interval: &mut task::Spawn<time::Interval>) -> Poll<Instant> {
interval.enter(|cx, mut interval| interval.poll_tick(cx))
}
fn ms(n: u64) -> Duration {
Duration::from_millis(n)
}
/// Helper struct to test the [tokio::time::Interval::poll_tick()] method.
///
/// `poll_tick()` should register the waker in the context only if it returns
/// `Poll::Pending`, not when returning `Poll::Ready`. This struct contains an
/// interval timer and counts up on every tick when used as stream. When the
/// counter is a multiple of four, it yields the current counter value.
/// Depending on the value for `wake_on_pending`, it will reschedule itself when
/// it returns `Poll::Pending` or not. When used with `wake_on_pending=false`,
/// we expect that the stream stalls because the timer will **not** reschedule
/// the next wake-up itself once it returned `Poll::Ready`.
struct IntervalStreamer {
counter: u32,
timer: Interval,
wake_on_pending: bool,
}
impl Stream for IntervalStreamer {
type Item = u32;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = Pin::into_inner(self);
if this.counter > 12 {
return Poll::Ready(None);
}
match this.timer.poll_tick(cx) {
Poll::Pending => Poll::Pending,
Poll::Ready(_) => {
this.counter += 1;
if this.counter % 4 == 0 {
Poll::Ready(Some(this.counter))
} else {
if this.wake_on_pending {
// Schedule this task for wake-up
cx.waker().wake_by_ref();
}
Poll::Pending
}
}
}
}
}
#[tokio::test(start_paused = true)]
async fn stream_with_interval_poll_tick_self_waking() {
let stream = IntervalStreamer {
counter: 0,
timer: tokio::time::interval(tokio::time::Duration::from_millis(10)),
wake_on_pending: true,
};
let (res_tx, mut res_rx) = tokio::sync::mpsc::channel(12);
// Wrap task in timeout so that it will finish eventually even if the stream
// stalls.
tokio::spawn(tokio::time::timeout(
tokio::time::Duration::from_millis(150),
async move {
tokio::pin!(stream);
while let Some(item) = stream.next().await {
res_tx.send(item).await.ok();
}
},
));
let mut items = Vec::with_capacity(3);
while let Some(result) = res_rx.recv().await {
items.push(result);
}
// We expect the stream to yield normally and thus three items.
assert_eq!(items, vec![4, 8, 12]);
}
#[tokio::test(start_paused = true)]
async fn stream_with_interval_poll_tick_no_waking() {
let stream = IntervalStreamer {
counter: 0,
timer: tokio::time::interval(tokio::time::Duration::from_millis(10)),
wake_on_pending: false,
};
let (res_tx, mut res_rx) = tokio::sync::mpsc::channel(12);
// Wrap task in timeout so that it will finish eventually even if the stream
// stalls.
tokio::spawn(tokio::time::timeout(
tokio::time::Duration::from_millis(150),
async move {
tokio::pin!(stream);
while let Some(item) = stream.next().await {
res_tx.send(item).await.ok();
}
},
));
let mut items = Vec::with_capacity(0);
while let Some(result) = res_rx.recv().await {
items.push(result);
}
// We expect the stream to stall because it does not reschedule itself on
// `Poll::Pending` and neither does [tokio::time::Interval] reschedule the
// task when returning `Poll::Ready`.
assert_eq!(items, vec![]);
}