Struct Instant

pub struct Instant { /* private fields */ }

A measurement of a monotonically nondecreasing clock. Opaque and useful only with Duration.

Instants are always guaranteed to be no less than any previously measured instant when created, and are often useful for tasks such as measuring benchmarks or timing how long an operation takes.

Note, however, that instants are not guaranteed to be steady. In other words, each tick of the underlying clock may not be the same length (e.g. some seconds may be longer than others). An instant may jump forwards or experience time dilation (slow down or speed up), but it will never go backwards.

Instants are opaque types that can only be compared to one another. There is no method to get “the number of seconds” from an instant. Instead, it only allows measuring the duration between two instants (or comparing two instants).

The size of an Instant struct may vary depending on the target operating system.

Note

This type wraps the inner std variant and is used to align the Tokio clock for uses of now(). This can be useful for testing where you can take advantage of time::pause() and time::advance().

Implementations

impl Instant

pub fn now() -> Instant

Returns an instant corresponding to “now”.

Examples

use tokio::time::Instant;

let now = Instant::now();

pub fn from_std(std: Instant) -> Instant

Create a tokio::time::Instant from a std::time::Instant.

pub fn into_std(self) -> Instant

Convert the value into a std::time::Instant.

pub fn duration_since(&self, earlier: Instant) -> Duration

Returns the amount of time elapsed from another instant to this one, or zero duration if that instant is later than this one.

pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration>

Returns the amount of time elapsed from another instant to this one, or None if that instant is later than this one.

Examples

use tokio::time::{Duration, Instant, sleep};

#[tokio::main]
async fn main() {
    let now = Instant::now();
    sleep(Duration::new(1, 0)).await;
    let new_now = Instant::now();
    println!("{:?}", new_now.checked_duration_since(now));
    println!("{:?}", now.checked_duration_since(new_now)); // None
}

pub fn saturating_duration_since(&self, earlier: Instant) -> Duration

Returns the amount of time elapsed from another instant to this one, or zero duration if that instant is later than this one.

Examples

use tokio::time::{Duration, Instant, sleep};

#[tokio::main]
async fn main() {
    let now = Instant::now();
    sleep(Duration::new(1, 0)).await;
    let new_now = Instant::now();
    println!("{:?}", new_now.saturating_duration_since(now));
    println!("{:?}", now.saturating_duration_since(new_now)); // 0ns
}

pub fn elapsed(&self) -> Duration

Returns the amount of time elapsed since this instant was created, or zero duration if this instant is in the future.

Examples

use tokio::time::{Duration, Instant, sleep};

#[tokio::main]
async fn main() {
    let instant = Instant::now();
    let three_secs = Duration::from_secs(3);
    sleep(three_secs).await;
    assert!(instant.elapsed() >= three_secs);
}

pub fn checked_add(&self, duration: Duration) -> Option<Instant>

Returns Some(t) where t is the time self + duration if t can be represented as Instant (which means it’s inside the bounds of the underlying data structure), None otherwise.

pub fn checked_sub(&self, duration: Duration) -> Option<Instant>

Returns Some(t) where t is the time self - duration if t can be represented as Instant (which means it’s inside the bounds of the underlying data structure), None otherwise.

Trait Implementations

impl Add<Duration> for Instant

type Output = Instant

The resulting type after applying the + operator.

fn add(self, other: Duration) -> Instant

Performs the + operation.

impl AddAssign<Duration> for Instant

fn add_assign(&mut self, rhs: Duration)

Performs the += operation.

impl Clone for Instant

fn clone(&self) -> Instant

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Instant

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<Instant> for Instant

fn from(time: Instant) -> Instant

Converts to this type from the input type.

impl From<Instant> for Instant

fn from(time: Instant) -> Instant

Converts to this type from the input type.

impl Hash for Instant

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Instant

fn cmp(&self, other: &Instant) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Instant

fn eq(&self, other: &Instant) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Instant

fn partial_cmp(&self, other: &Instant) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Sub<Duration> for Instant

type Output = Instant

The resulting type after applying the - operator.

fn sub(self, rhs: Duration) -> Instant

Performs the - operation.

impl Sub for Instant

type Output = Duration

The resulting type after applying the - operator.

fn sub(self, rhs: Instant) -> Duration

Performs the - operation.

impl SubAssign<Duration> for Instant

fn sub_assign(&mut self, rhs: Duration)

Performs the -= operation.

impl Copy for Instant

impl Eq for Instant

impl StructuralPartialEq for Instant