pub struct Instant(/* private fields */);
Expand description
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.
Example:
use std::time::{Duration, Instant};
use std::thread::sleep;
fn main() {
let now = Instant::now();
// we sleep for 2 seconds
sleep(Duration::new(2, 0));
// it prints '2'
println!("{}", now.elapsed().as_secs());
}
Implementations§
source§impl Instant
impl Instant
sourcepub fn now() -> Instant
pub fn now() -> Instant
Returns an instant corresponding to “now”.
§Examples
use std::time::Instant;
let now = Instant::now();
sourcepub fn duration_since(&self, earlier: Instant) -> Duration
pub fn duration_since(&self, earlier: Instant) -> Duration
Returns the amount of time elapsed from another instant to this one.
§Panics
This function will panic if earlier
is later than self
.
§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));
sourcepub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration>
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 earlier than this one.
§Examples
#![feature(checked_duration_since)]
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
sourcepub fn saturating_duration_since(&self, earlier: Instant) -> Duration
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 earlier than this one.
§Examples
#![feature(checked_duration_since)]
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
sourcepub fn elapsed(&self) -> Duration
pub fn elapsed(&self) -> Duration
Returns the amount of time elapsed since this instant was created.
§Panics
This function may panic if the current time is earlier than this
instant, which is something that can happen if an Instant
is
produced synthetically.
§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);
sourcepub fn checked_add(&self, duration: Duration) -> Option<Instant>
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.
sourcepub fn checked_sub(&self, duration: Duration) -> Option<Instant>
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§
source§impl AddAssign<Duration> for Instant
impl AddAssign<Duration> for Instant
source§fn add_assign(&mut self, other: Duration)
fn add_assign(&mut self, other: Duration)
+=
operation. Read moresource§impl Ord for Instant
impl Ord for Instant
source§impl PartialEq for Instant
impl PartialEq for Instant
source§impl PartialOrd for Instant
impl PartialOrd for Instant
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read moresource§impl SubAssign<Duration> for Instant
impl SubAssign<Duration> for Instant
source§fn sub_assign(&mut self, other: Duration)
fn sub_assign(&mut self, other: Duration)
-=
operation. Read more