delay_queue/delayed.rs
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use std::time::{Duration, Instant};
/// A value that is delayed until some `Instant`.
///
/// The `DelayQueue` only accepts values that implement this trait.
/// In most situations you do not need to implement this trait yourself. You can use the helper
/// struct `Delay`.
pub trait Delayed {
/// Returns the `Instant` until which this value is delayed.
fn delayed_until(&self) -> Instant;
}
/// Wraps a value that should be delayed.
///
/// Implements `Delayed` and `Eq`. Two `Delay` objects are equal iff their wrapped `value`s are
/// equal and they are delayed until the same `Instant`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use delay_queue::{Delay, Delayed};
/// use std::time::{Duration, Instant};
///
/// let delayed_one_hour = Delay::for_duration(123, Duration::from_secs(3600));
/// let delayed_now = Delay::until_instant("abc", Instant::now());
///
/// assert!(delayed_one_hour.delayed_until() > delayed_now.delayed_until());
/// assert_eq!(delayed_one_hour.value, 123);
/// ```
#[derive(Debug, PartialEq, Eq)]
pub struct Delay<T> {
/// The value that is delayed.
pub value: T,
/// The `Instant` until which `value` is delayed.
until: Instant,
}
impl<T> Delay<T> {
/// Creates a new `Delay<T>` holding `value` and that is delayed until the given `Instant`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use delay_queue::Delay;
/// use std::time::Instant;
///
/// let delayed_now = Delay::until_instant("abc", Instant::now());
/// ```
pub fn until_instant(value: T, until: Instant) -> Delay<T> {
Delay { value, until }
}
/// Creates a new `Delay<T>` holding `value` and that is delayed until the given `Duration` has
/// elapsed.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use delay_queue::Delay;
/// use std::time::Duration;
///
/// let delayed_one_hour = Delay::for_duration("abc", Duration::from_secs(3600));
/// ```
pub fn for_duration(value: T, duration: Duration) -> Delay<T> {
Delay::until_instant(value, Instant::now() + duration)
}
}
impl<T> Delayed for Delay<T> {
fn delayed_until(&self) -> Instant {
self.until
}
}
impl<T: Default> Default for Delay<T> {
/// Creates an expired `Delay<T>` with a default `value`.
fn default() -> Delay<T> {
Delay {
value: Default::default(),
until: Instant::now(),
}
}
}
#[cfg(test)]
mod tests {
use std::time::{Duration, Instant};
use super::{Delay, Delayed};
#[test]
fn compare_until() {
let delayed_one_hour = Delay::for_duration(123, Duration::from_secs(3600));
let delayed_now = Delay::until_instant("abc", Instant::now());
assert!(delayed_one_hour.delayed_until() > delayed_now.delayed_until());
}
#[test]
fn correct_value() {
let delayed_one_hour = Delay::for_duration(123, Duration::from_secs(3600));
let delayed_now = Delay::until_instant("abc", Instant::now());
assert_eq!(delayed_one_hour.value, 123);
assert_eq!(delayed_now.value, "abc");
}
}