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.
§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§
source§impl Instant
impl Instant
sourcepub fn now() -> Instant
pub fn now() -> Instant
Returns an instant corresponding to “now”.
§Examples
use tokio::time::Instant;
let now = Instant::now();
sourcepub fn from_std(std: Instant) -> Instant
pub fn from_std(std: Instant) -> Instant
Create a tokio::time::Instant
from a std::time::Instant
.
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, or zero duration if that instant is later than this one.
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 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
}
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 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
}
sourcepub fn elapsed(&self) -> Duration
pub fn elapsed(&self) -> Duration
Returns the amount of time elapsed since this instant was created, or zero duration if that 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);
}
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, rhs: Duration)
fn add_assign(&mut self, rhs: 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, rhs: Duration)
fn sub_assign(&mut self, rhs: Duration)
-=
operation. Read moreimpl Copy for Instant
impl Eq for Instant
impl StructuralPartialEq for Instant
Auto Trait Implementations§
impl Freeze for Instant
impl RefUnwindSafe for Instant
impl Send for Instant
impl Sync for Instant
impl Unpin for Instant
impl UnwindSafe for Instant
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§default unsafe fn clone_to_uninit(&self, dst: *mut T)
default unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)source§impl<T> CloneToUninit for Twhere
T: Copy,
impl<T> CloneToUninit for Twhere
T: Copy,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)