Struct tokio::time::Instant [−][src]
pub struct Instant { /* fields omitted */ }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
Returns an instant corresponding to “now”.
Examples
use tokio::time::Instant;
let now = Instant::now();Create a tokio::time::Instant from a std::time::Instant.
Returns the amount of time elapsed from another instant to this one.
Panics
This function will panic if earlier is later than self.
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
}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
}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 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);
}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.
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
Performs the += operation. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Performs the -= operation. Read more
Auto Trait Implementations
impl RefUnwindSafe for Instant
impl UnwindSafe for Instant
Blanket Implementations
Mutably borrows from an owned value. Read more