Struct crossbeam_deque::deque::Injector

source ·

pub struct Injector<T> {
    head: CachePadded<Position<T>>,
    tail: CachePadded<Position<T>>,
    _marker: PhantomData<T>,
}

Expand description

An injector queue.

This is a FIFO queue that can be shared among multiple threads. Task schedulers typically have a single injector queue, which is the entry point for new tasks.

§Examples

use crossbeam_deque::{Injector, Steal};

let q = Injector::new();
q.push(1);
q.push(2);

assert_eq!(q.steal(), Steal::Success(1));
assert_eq!(q.steal(), Steal::Success(2));
assert_eq!(q.steal(), Steal::Empty);

Fields§

§head: CachePadded<Position<T>>

The head of the queue.

§tail: CachePadded<Position<T>>

The tail of the queue.

§_marker: PhantomData<T>

Indicates that dropping a Injector<T> may drop values of type T.

Implementations§

source §

impl<T> Injector<T>

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pub fn new() -> Injector<T>

Creates a new injector queue.

§Examples

use crossbeam_deque::Injector;

let q = Injector::<i32>::new();

source

pub fn push(&self, task: T)

Pushes a task into the queue.

§Examples

use crossbeam_deque::Injector;

let w = Injector::new();
w.push(1);
w.push(2);

source

pub fn steal(&self) -> Steal<T>

Steals a task from the queue.

§Examples

use crossbeam_deque::{Injector, Steal};

let q = Injector::new();
q.push(1);
q.push(2);

assert_eq!(q.steal(), Steal::Success(1));
assert_eq!(q.steal(), Steal::Success(2));
assert_eq!(q.steal(), Steal::Empty);

source

pub fn steal_batch(&self, dest: &Worker<T>) -> Steal<()>

Steals a batch of tasks and pushes them into a worker.

How many tasks exactly will be stolen is not specified. That said, this method will try to steal around half of the tasks in the queue, but also not more than some constant limit.

§Examples

use crossbeam_deque::{Injector, Worker};

let q = Injector::new();
q.push(1);
q.push(2);
q.push(3);
q.push(4);

let w = Worker::new_fifo();
let _ = q.steal_batch(&w);
assert_eq!(w.pop(), Some(1));
assert_eq!(w.pop(), Some(2));

source

pub fn steal_batch_with_limit( &self, dest: &Worker<T>, limit: usize, ) -> Steal<()>

Steals no more than of tasks and pushes them into a worker.

How many tasks exactly will be stolen is not specified. That said, this method will try to steal around half of the tasks in the queue, but also not more than some constant limit.

§Examples

use crossbeam_deque::{Injector, Worker};

let q = Injector::new();
q.push(1);
q.push(2);
q.push(3);
q.push(4);
q.push(5);
q.push(6);

let w = Worker::new_fifo();
let _ = q.steal_batch_with_limit(&w, 2);
assert_eq!(w.pop(), Some(1));
assert_eq!(w.pop(), Some(2));
assert_eq!(w.pop(), None);

q.push(7);
q.push(8);
// Setting a large limit does not guarantee that all elements will be popped. In this case,
// half of the elements are currently popped, but the number of popped elements is considered
// an implementation detail that may be changed in the future.
let _ = q.steal_batch_with_limit(&w, std::usize::MAX);
assert_eq!(w.len(), 3);

source

pub fn steal_batch_and_pop(&self, dest: &Worker<T>) -> Steal<T>

Steals a batch of tasks, pushes them into a worker, and pops a task from that worker.

How many tasks exactly will be stolen is not specified. That said, this method will try to steal around half of the tasks in the queue, but also not more than some constant limit.

§Examples

use crossbeam_deque::{Injector, Steal, Worker};

let q = Injector::new();
q.push(1);
q.push(2);
q.push(3);
q.push(4);

let w = Worker::new_fifo();
assert_eq!(q.steal_batch_and_pop(&w), Steal::Success(1));
assert_eq!(w.pop(), Some(2));

source

pub fn steal_batch_with_limit_and_pop( &self, dest: &Worker<T>, limit: usize, ) -> Steal<T>

Steals no more than limit of tasks, pushes them into a worker, and pops a task from that worker.

How many tasks exactly will be stolen is not specified. That said, this method will try to steal around half of the tasks in the queue, but also not more than the given limit.

§Examples

use crossbeam_deque::{Injector, Steal, Worker};

let q = Injector::new();
q.push(1);
q.push(2);
q.push(3);
q.push(4);
q.push(5);
q.push(6);

let w = Worker::new_fifo();
assert_eq!(q.steal_batch_with_limit_and_pop(&w, 2), Steal::Success(1));
assert_eq!(w.pop(), Some(2));
assert_eq!(w.pop(), None);

q.push(7);
// Setting a large limit does not guarantee that all elements will be popped. In this case,
// half of the elements are currently popped, but the number of popped elements is considered
// an implementation detail that may be changed in the future.
assert_eq!(q.steal_batch_with_limit_and_pop(&w, std::usize::MAX), Steal::Success(3));
assert_eq!(w.pop(), Some(4));
assert_eq!(w.pop(), Some(5));
assert_eq!(w.pop(), None);

source

pub fn is_empty(&self) -> bool

Returns true if the queue is empty.

§Examples

use crossbeam_deque::Injector;

let q = Injector::new();

assert!(q.is_empty());
q.push(1);
assert!(!q.is_empty());

source

pub fn len(&self) -> usize

Returns the number of tasks in the queue.

§Examples

use crossbeam_deque::Injector;

let q = Injector::new();

assert_eq!(q.len(), 0);
q.push(1);
assert_eq!(q.len(), 1);
q.push(1);
assert_eq!(q.len(), 2);