Struct std::time::Instant

pub struct Instant(_);

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

Instants are always guaranteed to be greater 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).

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());
}

Methods

impl Instant

fn now() -> Instant

Returns an instant corresponding to "now".

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, which should only be possible if earlier was created after self. Because Instant is monotonic, the only time that this should happen should be a bug.

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);

Trait Implementations

impl Copy for Instant

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 PartialEq for Instant

fn eq(&self, __arg_0: &Instant) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &Instant) -> bool

This method tests for !=.

impl Eq for Instant

impl PartialOrd for Instant

fn partial_cmp(&self, __arg_0: &Instant) -> Option<Ordering>

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

fn lt(&self, __arg_0: &Instant) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, __arg_0: &Instant) -> bool

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

fn gt(&self, __arg_0: &Instant) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, __arg_0: &Instant) -> bool

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

impl Ord for Instant

fn cmp(&self, __arg_0: &Instant) -> Ordering

This method returns an Ordering between self and other.

impl Add<Duration> for Instant

type Output = Instant

The resulting type after applying the + operator

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

The method for the + operator

impl AddAssign<Duration> for Instant

fn add_assign(&mut self, other: Duration)

The method for the += operator

impl Sub<Duration> for Instant

type Output = Instant

The resulting type after applying the - operator

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

The method for the - operator

impl SubAssign<Duration> for Instant

fn sub_assign(&mut self, other: Duration)

The method for the -= operator

impl Sub<Instant> for Instant

type Output = Duration

The resulting type after applying the - operator

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

The method for the - operator

impl Debug for Instant

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.