1.8.0[][src]Struct std::time::Instant

pub 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.

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());
}Run

Underlying System calls

Currently, the following system calls are being used to get the current time using now():

PlatformSystem call
Cloud ABIclock_time_get (Monotonic Clock)
SGXinsecure_time usercall. More information on timekeeping in SGX
UNIXclock_time_get (Monotonic Clock)
Darwinmach_absolute_time
VXWorksclock_gettime (Monotonic Clock)
WASI__wasi_clock_time_get (Monotonic Clock)
WindowsQueryPerformanceCounter

Disclaimer: These system calls might change over time.

Methods

impl Instant[src]

pub fn now() -> Instant[src]

Returns an instant corresponding to "now".

Examples

use std::time::Instant;

let now = Instant::now();Run

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

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));Run

pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration>1.39.0[src]

Returns the amount of time elapsed from another instant to this one, or None 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.checked_duration_since(now));
println!("{:?}", now.checked_duration_since(new_now)); // NoneRun

pub fn saturating_duration_since(&self, earlier: Instant) -> Duration1.39.0[src]

Returns the amount of time elapsed from another instant to this one, or zero duration if that instant is earlier 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)); // 0nsRun

pub fn elapsed(&self) -> Duration[src]

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);Run

pub fn checked_add(&self, duration: Duration) -> Option<Instant>1.34.0[src]

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>1.34.0[src]

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 Debug for Instant[src]

impl Sub<Duration> for Instant[src]

type Output = Instant

The resulting type after applying the - operator.

impl Sub<Instant> for Instant[src]

type Output = Duration

The resulting type after applying the - operator.

impl PartialEq<Instant> for Instant[src]

impl Eq for Instant[src]

impl Ord for Instant[src]

impl PartialOrd<Instant> for Instant[src]

impl Add<Duration> for Instant[src]

type Output = Instant

The resulting type after applying the + operator.

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

Panics

This function may panic if the resulting point in time cannot be represented by the underlying data structure. See checked_add for a version without panic.

impl AddAssign<Duration> for Instant1.9.0[src]

impl SubAssign<Duration> for Instant1.9.0[src]

impl Hash for Instant[src]

impl Copy for Instant[src]

impl Clone for Instant[src]

Auto Trait Implementations

impl UnwindSafe for Instant

impl RefUnwindSafe for Instant

impl Unpin for Instant

impl Send for Instant

impl Sync for Instant

Blanket Implementations

impl<T> From<T> for T[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.