Type Parameters:

E - the element type of the queue

All Implemented Interfaces:

SimplePlainQueue<E>, SimpleQueue<E>, Serializable

public final class SpscArrayQueue<E>
extends AtomicReferenceArray<E>
implements SimplePlainQueue<E>

Since:

3.1.1

See Also:

Serialized Form

• Constructor Summary

  Constructors

  Constructor and Description
  SpscArrayQueue (int capacity) Constructs an array-backed queue with the given capacity rounded up to the next power of 2 size.

• Method Summary

  All Methods

  Modifier and Type	Method and Description
  void	clear () Removes all enqueued items from this queue.
  boolean	isEmpty () Returns true if the queue is empty.
  boolean	offer (E e) Atomically enqueue a single value.
  boolean	offer (E v1, E v2) Atomically enqueue two values.
  E	poll () Tries to dequeue a value (non-null) or returns null if the queue is empty.

  • Methods inherited from class java.util.concurrent.atomic.AtomicReferenceArray

    accumulateAndGet, compareAndSet, get, getAndAccumulate, getAndSet, getAndUpdate, lazySet, length, set, toString, updateAndGet, weakCompareAndSet

  • Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

• Constructor Detail

  • SpscArrayQueue

    public SpscArrayQueue(int capacity)

    Constructs an array-backed queue with the given capacity rounded up to the next power of 2 size.

    Parameters:

    capacity - the maximum number of elements the queue would hold, rounded up to the next power of 2

• Method Detail

  • offer

    public boolean offer(E e)

    Description copied from interface: SimpleQueue
    Atomically enqueue a single value.

    Specified by:

    offer in interface SimpleQueue<E>

    Parameters:

    e - the value to enqueue, not null

    Returns:

    true if successful, false if the value was not enqueued likely due to reaching the queue capacity)

  • offer

    public boolean offer(E v1,
     E v2)

    Description copied from interface: SimpleQueue
    Atomically enqueue two values.

    Specified by:

    offer in interface SimpleQueue<E>

    Parameters:

    v1 - the first value to enqueue, not null

    v2 - the second value to enqueue, not null

    Returns:

    true if successful, false if the value was not enqueued likely due to reaching the queue capacity)

  • poll

    @Nullable
    public E poll()

    Description copied from interface: SimpleQueue
    Tries to dequeue a value (non-null) or returns null if the queue is empty.

    If the producer uses SimpleQueue.offer(Object, Object) and when polling in pairs, if the first poll() returns a non-null item, the second poll() is guaranteed to return a non-null item as well.

    Specified by:

    poll in interface SimplePlainQueue<E>

    Specified by:

    poll in interface SimpleQueue<E>

    Returns:

    the item or null to indicate an empty queue

  • isEmpty

    public boolean isEmpty()

    Description copied from interface: SimpleQueue
    Returns true if the queue is empty.

    Note however that due to potential fused functions in SimpleQueue.poll() it is possible this method returns false but then poll() returns null because the fused function swallowed the available item(s).

    Specified by:

    isEmpty in interface SimpleQueue<E>

    Returns:

    true if the queue is empty

  • clear

    public void clear()

    Description copied from interface: SimpleQueue
    Removes all enqueued items from this queue.

    Specified by:

    clear in interface SimpleQueue<E>