Struct DelayQueue

pub struct DelayQueue<T: Delayed> { /* private fields */ }

A concurrent unbounded blocking queue where each item can only be removed when its delay expires.

The queue supports multiple producers and multiple consumers.

Items of the queue must implement the Delayed trait. In most situations you can just use the helper struct Delay to wrap the values to be used by the queue.

If you implement the Delayed trait for your types, keep in mind that the DelayQueue assumes that the Instant until which each item is delayed does not change while that item is in the queue.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::{Duration, Instant};

let mut queue = DelayQueue::new();
queue.push(Delay::for_duration("2nd", Duration::from_secs(5)));
queue.push(Delay::until_instant("1st", Instant::now()));

println!("First pop: {}", queue.pop().value);
println!("Second pop: {}", queue.pop().value);
assert!(queue.is_empty());

Implementations

impl<T: Delayed> DelayQueue<T>

pub fn new() -> DelayQueue<T>

Creates an empty DelayQueue<T>.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};

let mut queue : DelayQueue<Delay<i32>>  = DelayQueue::new();

pub fn with_capacity(capacity: usize) -> DelayQueue<T>

Creates an empty DelayQueue<T> with a specific capacity. This preallocates enough memory for capacity elements, so that the DelayQueue does not have to be reallocated until it contains at least that many values.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};

let mut queue : DelayQueue<Delay<&str>>  = DelayQueue::with_capacity(10);

pub fn push(&mut self, item: T)

Pushes an item onto the queue.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::Duration;

let mut queue = DelayQueue::new();
queue.push(Delay::for_duration("2nd", Duration::from_secs(5)));

pub fn pop(&mut self) -> T

Pops the next item from the queue, blocking if necessary until an item is available and its delay has expired.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::{Duration, Instant};

let mut queue = DelayQueue::new();

queue.push(Delay::until_instant("1st", Instant::now()));

// The pop will not block, since the delay has expired.
println!("First pop: {}", queue.pop().value);

queue.push(Delay::for_duration("2nd", Duration::from_secs(5)));

// The pop will block for approximately 5 seconds before returning the item.
println!("Second pop: {}", queue.pop().value);

pub fn try_pop_for(&mut self, timeout: Duration) -> Option<T>

Pops the next item from the queue, blocking if necessary until an item is available and its delay has expired or until the given timeout expires.

Returns None if the given timeout expires and no item became available to be popped.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::Duration;

let mut queue = DelayQueue::new();

queue.push(Delay::for_duration("1st", Duration::from_secs(5)));

// The pop will block for approximately 2 seconds before returning None.
println!("First pop: {:?}",
         queue.try_pop_for(Duration::from_secs(2))); // Prints "None"

// The pop will block for approximately 3 seconds before returning the item.
println!("Second pop: {}",
         queue.try_pop_for(Duration::from_secs(5)).unwrap().value); // Prints "1st"

pub fn try_pop_until(&mut self, try_until: Instant) -> Option<T>

Pops the next item from the queue, blocking if necessary until an item is available and its delay has expired or until the given Instant is reached.

Returns None if the given Instant is reached and no item became available to be popped.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::{Duration, Instant};

let mut queue = DelayQueue::new();

queue.push(Delay::for_duration("1st", Duration::from_secs(5)));

// The pop will block for approximately 2 seconds before returning None.
println!("First pop: {:?}",
         queue.try_pop_until(Instant::now() + Duration::from_secs(2))); // Prints "None"

// The pop will block for approximately 3 seconds before returning the item.
println!("Second pop: {}",
         queue.try_pop_until(Instant::now() + Duration::from_secs(5))
              .unwrap().value); // Prints "1st"

pub fn is_empty(&self) -> bool

Checks if the queue is empty.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::Instant;

let mut queue = DelayQueue::new();
queue.push(Delay::until_instant("val", Instant::now()));

assert!(!queue.is_empty());

println!("First pop: {}", queue.pop().value);

assert!(queue.is_empty());

Trait Implementations

impl<T: Delayed> Clone for DelayQueue<T>

fn clone(&self) -> DelayQueue<T>

Returns a new DelayQueue that points to the same underlying data.

This method can be used to share a queue between different threads.

Examples

Basic usage:

use delay_queue::{Delay, DelayQueue};
use std::time::Duration;
use std::thread;

let mut queue = DelayQueue::new();

queue.push(Delay::for_duration("1st", Duration::from_secs(1)));

let mut cloned_queue = queue.clone();

let handle = thread::spawn(move || {
    println!("First pop: {}", cloned_queue.pop().value);
    println!("Second pop: {}", cloned_queue.pop().value);
});

queue.push(Delay::for_duration("2nd", Duration::from_secs(2)));

handle.join().unwrap();

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + Delayed> Debug for DelayQueue<T>

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

Formats the value using the given formatter.

impl<T: Delayed> Default for DelayQueue<T>

fn default() -> DelayQueue<T>

Creates an empty DelayQueue<T>.