Struct Instant

Source

pub struct Instant(/* private fields */);

Expand description

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

This type wraps std::time::Duration so we can implement traits on it without coherence issues, just like if we were implementing this in the stdlib.

Implementations§

Source §

impl Instant

Source

pub fn now() -> Self

Returns an instant corresponding to “now”.

§Examples

use futures_time::time::Instant;

let now = Instant::now();

Methods from Deref<Target = Instant>§

1.8.0 · Source

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.

§Panics

Previous Rust versions panicked when earlier was later than self. Currently this method saturates. Future versions may reintroduce the panic in some circumstances. See Monotonicity.

§Examples

use std::time::{Duration, Instant};
use std::thread::sleep;

let now = Instant::now();
sleep(Duration::new(1, 0));
let new_now = Instant::now();
println!("{:?}", new_now.duration_since(now));
println!("{:?}", now.duration_since(new_now)); // 0ns

1.39.0 · Source

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.

Due to monotonicity bugs, even under correct logical ordering of the passed Instants, this method can return None.

§Examples

use std::time::{Duration, Instant};
use std::thread::sleep;

let now = Instant::now();
sleep(Duration::new(1, 0));
let new_now = Instant::now();
println!("{:?}", new_now.checked_duration_since(now));
println!("{:?}", now.checked_duration_since(new_now)); // None

1.39.0 · Source

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 std::time::{Duration, Instant};
use std::thread::sleep;

let now = Instant::now();
sleep(Duration::new(1, 0));
let new_now = Instant::now();
println!("{:?}", new_now.saturating_duration_since(now));
println!("{:?}", now.saturating_duration_since(new_now)); // 0ns

1.8.0 · Source

pub fn elapsed(&self) -> Duration

Returns the amount of time elapsed since this instant.

§Panics

Previous Rust versions panicked when the current time was earlier than self. Currently this method returns a Duration of zero in that case. Future versions may reintroduce the panic. See Monotonicity.

§Examples

use std::thread::sleep;
use std::time::{Duration, Instant};

let instant = Instant::now();
let three_secs = Duration::from_secs(3);
sleep(three_secs);
assert!(instant.elapsed() >= three_secs);

1.34.0 · Source

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.

1.34.0 · Source

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.