Struct `Instant`

struct Instant { ... }

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`

fn now() -> Instant

Returns an instant corresponding to "now".

Examples

use tokio::time::Instant;

let now = Instant::now();

fn from_std(std: Instant) -> Instant

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

fn into_std(self: Self) -> Instant

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

fn duration_since(self: &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.

fn checked_duration_since(self: &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
}

fn saturating_duration_since(self: &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
}

fn elapsed(self: &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);
}

fn checked_add(self: &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.

fn checked_sub(self: &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.

`impl Add for Instant`

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

`impl AddAssign for Instant`

fn add_assign(self: &mut Self, rhs: Duration)

`impl Clone for Instant`

fn clone(self: &Self) -> Instant

`impl Copy for Instant`

`impl Debug for Instant`

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

`impl Eq for Instant`

`impl Freeze for Instant`

`impl From for Instant`

fn from(time: Instant) -> Instant

`impl Hash for Instant`

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

`impl Ord for Instant`

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

`impl PartialEq for Instant`

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

`impl PartialOrd for Instant`

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

`impl RefUnwindSafe for Instant`

`impl Send for Instant`

`impl StructuralPartialEq for Instant`

`impl Sub for Instant`

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

`impl Sub for Instant`

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

`impl SubAssign for Instant`

fn sub_assign(self: &mut Self, rhs: Duration)

`impl Sync for Instant`

`impl Unpin for Instant`

`impl UnsafeUnpin for Instant`

`impl UnwindSafe for Instant`

`impl<T> Any for Instant`

fn type_id(self: &Self) -> TypeId

`impl<T> Borrow for Instant`

fn borrow(self: &Self) -> &T

`impl<T> BorrowMut for Instant`

fn borrow_mut(self: &mut Self) -> &mut T

`impl<T> CloneToUninit for Instant`

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

`impl<T> From for Instant`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T> ToOwned for Instant`

fn to_owned(self: &Self) -> T
fn clone_into(self: &Self, target: &mut T)

`impl<T, U> Into for Instant`

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

`impl<T, U> TryFrom for Instant`

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

`impl<T, U> TryInto for Instant`

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>