org.jctools.queues.atomic

Class MpmcAtomicArrayQueue<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

org.jctools.queues.atomic.AtomicReferenceArrayQueue<E>

org.jctools.queues.atomic.SequencedAtomicReferenceArrayQueue<E>

org.jctools.queues.atomic.MpmcAtomicArrayQueue<E>

All Implemented Interfaces:

java.lang.Iterable<E>, java.util.Collection<E>, java.util.Queue<E>, QueueProgressIndicators

public class MpmcAtomicArrayQueue<E>
extends SequencedAtomicReferenceArrayQueue<E>
implements QueueProgressIndicators

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.concurrent.atomic.AtomicLong	consumerIndex
private java.util.concurrent.atomic.AtomicLong	producerIndex

Fields inherited from class org.jctools.queues.atomic.SequencedAtomicReferenceArrayQueue

sequenceBuffer

Fields inherited from class org.jctools.queues.atomic.AtomicReferenceArrayQueue

buffer, mask

Constructor Summary

Constructors

Constructor and Description
MpmcAtomicArrayQueue(int capacity)

Method Summary

Modifier and Type	Method and Description
protected boolean	casConsumerIndex(long expect, long newValue)
protected boolean	casProducerIndex(long expect, long newValue)
long	currentConsumerIndex() This method has no concurrent visibility semantics.
long	currentProducerIndex() This method has no concurrent visibility semantics.
boolean	isEmpty()
protected long	lvConsumerIndex()
protected long	lvProducerIndex()
boolean	offer(E e)
E	peek()
E	poll()
int	size()
private static int	validateCapacity(int capacity)

Methods inherited from class org.jctools.queues.atomic.SequencedAtomicReferenceArrayQueue

calcSequenceOffset, calcSequenceOffset, lvSequence, soSequence

Methods inherited from class org.jctools.queues.atomic.AtomicReferenceArrayQueue

calcElementOffset, calcElementOffset, clear, iterator, lpElement, lpElement, lvElement, lvElement, soElement, soElement, spElement, spElement, svElement

Methods inherited from class java.util.AbstractQueue

add, addAll, element, remove

Methods inherited from class java.util.AbstractCollection

contains, containsAll, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

contains, containsAll, equals, hashCode, parallelStream, remove, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

producerIndex

private final java.util.concurrent.atomic.AtomicLong producerIndex

consumerIndex

private final java.util.concurrent.atomic.AtomicLong consumerIndex

Constructor Detail

MpmcAtomicArrayQueue

public MpmcAtomicArrayQueue(int capacity)

Method Detail

validateCapacity

private static int validateCapacity(int capacity)

offer

public boolean offer(E e)

Specified by:

offer in interface java.util.Queue<E>

poll

public E poll()

Because return null indicates queue is empty we cannot simply rely on next element visibility for poll and must test producer index when next element is not visible.

Specified by:

poll in interface java.util.Queue<E>

peek

public E peek()

Specified by:

peek in interface java.util.Queue<E>

size

public int size()

Specified by:

size in interface java.util.Collection<E>

Specified by:

size in class java.util.AbstractCollection<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Collection<E>

Overrides:

isEmpty in class java.util.AbstractCollection<E>

currentProducerIndex

public long currentProducerIndex()

Description copied from interface: QueueProgressIndicators

This method has no concurrent visibility semantics. The value returned may be negative. Under normal circumstances 2 consecutive calls to this method can offer an idea of progress made by producer threads by subtracting the 2 results though in extreme cases (if producers have progressed by more than 2^64) this may also fail.
This value will normally indicate number of elements passed into the queue, but may under some circumstances be a derivative of that figure. This method should not be used to derive size or emptiness.

Specified by:

currentProducerIndex in interface QueueProgressIndicators

Returns:

the current value of the producer progress index

currentConsumerIndex

public long currentConsumerIndex()

Description copied from interface: QueueProgressIndicators

This method has no concurrent visibility semantics. The value returned may be negative. Under normal circumstances 2 consecutive calls to this method can offer an idea of progress made by consumer threads by subtracting the 2 results though in extreme cases (if consumers have progressed by more than 2^64) this may also fail.
This value will normally indicate number of elements taken out of the queue, but may under some circumstances be a derivative of that figure. This method should not be used to derive size or emptiness.

Specified by:

currentConsumerIndex in interface QueueProgressIndicators

Returns:

the current value of the consumer progress index

lvProducerIndex

protected final long lvProducerIndex()

casProducerIndex

protected final boolean casProducerIndex(long expect,
                                         long newValue)

lvConsumerIndex

protected final long lvConsumerIndex()

casConsumerIndex

protected final boolean casConsumerIndex(long expect,
                                         long newValue)