Struct tokio::time::Interval

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pub struct Interval { /* private fields */ }

Expand description

Interval returned by interval and interval_at.

This type allows you to wait on a sequence of instants with a certain duration between each instant. Unlike calling sleep in a loop, this lets you count the time spent between the calls to sleep as well.

An Interval can be turned into a Stream with IntervalStream.

Implementations§

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impl Interval

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pub async fn tick(&mut self) -> Instant

Completes when the next instant in the interval has been reached.

Cancel safety

This method is cancellation safe. If tick is used as the branch in a tokio::select! and another branch completes first, then no tick has been consumed.

Examples

use tokio::time;

use std::time::Duration;

#[tokio::main]
async fn main() {
    let mut interval = time::interval(Duration::from_millis(10));

    interval.tick().await;
    // approximately 0ms have elapsed. The first tick completes immediately.
    interval.tick().await;
    interval.tick().await;

    // approximately 20ms have elapsed.
}

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pub fn poll_tick(&mut self, cx: &mut Context<'_>) -> Poll<Instant>

Polls for the next instant in the interval to be reached.

This method can return the following values:

Poll::Pending if the next instant has not yet been reached.
Poll::Ready(instant) if the next instant has been reached.

When this method returns Poll::Pending, the current task is scheduled to receive a wakeup when the instant has elapsed. Note that on multiple calls to poll_tick, only the Waker from the Context passed to the most recent call is scheduled to receive a wakeup.

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pub fn reset(&mut self)

Resets the interval to complete one period after the current time.

This method ignores MissedTickBehavior strategy.

This is equivalent to calling reset_at(Instant::now() + period).

Examples

use tokio::time;

use std::time::Duration;

#[tokio::main]
async fn main() {
    let mut interval = time::interval(Duration::from_millis(100));

    interval.tick().await;

    time::sleep(Duration::from_millis(50)).await;
    interval.reset();

    interval.tick().await;
    interval.tick().await;

    // approximately 250ms have elapsed.
}

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pub fn reset_immediately(&mut self)

Resets the interval immediately.

This method ignores MissedTickBehavior strategy.

This is equivalent to calling reset_at(Instant::now()).

Examples

use tokio::time;

use std::time::Duration;

#[tokio::main]
async fn main() {
    let mut interval = time::interval(Duration::from_millis(100));

    interval.tick().await;

    time::sleep(Duration::from_millis(50)).await;
    interval.reset_immediately();

    interval.tick().await;
    interval.tick().await;

    // approximately 150ms have elapsed.
}

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pub fn reset_after(&mut self, after: Duration)

Resets the interval after the specified std::time::Duration.

This method ignores MissedTickBehavior strategy.

This is equivalent to calling reset_at(Instant::now() + after).

Examples

use tokio::time;

use std::time::Duration;

#[tokio::main]
async fn main() {
    let mut interval = time::interval(Duration::from_millis(100));
    interval.tick().await;

    time::sleep(Duration::from_millis(50)).await;

    let after = Duration::from_millis(20);
    interval.reset_after(after);

    interval.tick().await;
    interval.tick().await;

    // approximately 170ms have elapsed.
}

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pub fn reset_at(&mut self, deadline: Instant)

Resets the interval to a crate::time::Instant deadline.

Sets the next tick to expire at the given instant. If the instant is in the past, then the MissedTickBehavior strategy will be used to catch up. If the instant is in the future, then the next tick will complete at the given instant, even if that means that it will sleep for longer than the duration of this Interval. If the Interval had any missed ticks before calling this method, then those are discarded.

Examples

use tokio::time::{self, Instant};

use std::time::Duration;

#[tokio::main]
async fn main() {
    let mut interval = time::interval(Duration::from_millis(100));
    interval.tick().await;

    time::sleep(Duration::from_millis(50)).await;

    let deadline = Instant::now() + Duration::from_millis(30);
    interval.reset_at(deadline);

    interval.tick().await;
    interval.tick().await;

    // approximately 180ms have elapsed.
}