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
impl Instant
impl Instant
pub fn now() -> Instant
pub fn now() -> Instant
Returns an instant corresponding to “now”.
Examples
use tokio::time::Instant;
let now = Instant::now();
pub 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.
pub 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
}
pub 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
}
pub 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);
}
pub 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.
pub 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
impl AddAssign<Duration> for Instant
impl AddAssign<Duration> for Instant
fn add_assign(&mut self, rhs: Duration)
fn add_assign(&mut self, rhs: Duration)
Performs the +=
operation. Read more
impl Ord for Instant
impl Ord for Instant
1.21.0 · sourcefn max(self, other: Self) -> Self
fn max(self, other: Self) -> Self
Compares and returns the maximum of two values. Read more
1.21.0 · sourcefn min(self, other: Self) -> Self
fn min(self, other: Self) -> Self
Compares and returns the minimum of two values. Read more
1.50.0 · sourcefn clamp(self, min: Self, max: Self) -> Selfwhere
Self: PartialOrd<Self>,
fn clamp(self, min: Self, max: Self) -> Selfwhere
Self: PartialOrd<Self>,
Restrict a value to a certain interval. Read more
impl PartialEq<Instant> for Instant
impl PartialEq<Instant> for Instant
impl PartialOrd<Instant> for Instant
impl PartialOrd<Instant> for Instant
fn partial_cmp(&self, other: &Instant) -> Option<Ordering>
fn partial_cmp(&self, other: &Instant) -> Option<Ordering>
This method returns an ordering between self
and other
values if one exists. Read more
1.0.0 · sourcefn lt(&self, other: &Rhs) -> bool
fn lt(&self, other: &Rhs) -> bool
This method tests less than (for self
and other
) and is used by the <
operator. Read more
1.0.0 · sourcefn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
impl SubAssign<Duration> for Instant
impl SubAssign<Duration> for Instant
fn sub_assign(&mut self, rhs: Duration)
fn sub_assign(&mut self, rhs: Duration)
Performs the -=
operation. Read more
impl Copy for Instant
impl Eq for Instant
impl StructuralEq for Instant
impl StructuralPartialEq for Instant
Auto Trait Implementations
impl RefUnwindSafe for Instant
impl Send for Instant
impl Sync for Instant
impl Unpin for Instant
impl UnwindSafe for Instant
Blanket Implementations
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> CallHasher for Twhere
T: Hash + ?Sized,
impl<T> CallHasher for Twhere
T: Hash + ?Sized,
sourceimpl<Q, K> Equivalent<K> for Qwhere
Q: Eq + ?Sized,
K: Borrow<Q> + ?Sized,
impl<Q, K> Equivalent<K> for Qwhere
Q: Eq + ?Sized,
K: Borrow<Q> + ?Sized,
sourcefn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
Compare self to key
and return true
if they are equal.
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
sourcefn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
impl<V, T> VZip<V> for Twhere
V: MultiLane<T>,
impl<V, T> VZip<V> for Twhere
V: MultiLane<T>,
fn vzip(self) -> V
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where
S: Into<Dispatch>,
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
sourcefn with_current_subscriber(self) -> WithDispatch<Self>
fn with_current_subscriber(self) -> WithDispatch<Self>
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more