Package org.jctools.queues

Class MpscLinkedQueue8<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

org.jctools.queues.MpscLinkedQueue<E>

org.jctools.queues.MpscLinkedQueue8<E>

Type Parameters:

E -

All Implemented Interfaces:

MessagePassingQueue<E>

public class MpscLinkedQueue8<E>
extends MpscLinkedQueue<E>

Author:

nitsanw

See Also:

MpscLinkedQueue

Nested Class Summary

Nested classes/interfaces inherited from interface org.jctools.queues.MessagePassingQueue

MessagePassingQueue.Consumer<T>, MessagePassingQueue.ExitCondition, MessagePassingQueue.Supplier<T>, MessagePassingQueue.WaitStrategy

Field Summary

Fields

Modifier and Type	Field	Description
protected static long	C_NODE_OFFSET
protected org.jctools.queues.LinkedQueueNode<E>	consumerNode
protected static long	P_NODE_OFFSET
protected org.jctools.queues.LinkedQueueNode<E>	producerNode

Fields inherited from interface org.jctools.queues.MessagePassingQueue

UNBOUNDED_CAPACITY

Constructor Summary

Constructors

Constructor	Description
MpscLinkedQueue8()

Method Summary

Modifier and Type	Method	Description
int	capacity()
protected boolean	casProducerNode(org.jctools.queues.LinkedQueueNode<E> expect, org.jctools.queues.LinkedQueueNode<E> newValue)
int	drain(MessagePassingQueue.Consumer<E> c)	Remove all available item from the queue and hand to consume.
int	drain(MessagePassingQueue.Consumer<E> c, int limit)	Remove up to limit elements from the queue and hand to consume.
void	drain(MessagePassingQueue.Consumer<E> c, MessagePassingQueue.WaitStrategy wait, MessagePassingQueue.ExitCondition exit)	Remove elements from the queue and hand to consume forever.
protected E	getSingleConsumerNodeValue(org.jctools.queues.LinkedQueueNode<E> currConsumerNode, org.jctools.queues.LinkedQueueNode<E> nextNode)
boolean	isEmpty()	This method's accuracy is subject to concurrent modifications happening as the observation is carried out.
java.util.Iterator<E>	iterator()
protected org.jctools.queues.LinkedQueueNode<E>	lpConsumerNode()
protected org.jctools.queues.LinkedQueueNode<E>	lpProducerNode()
protected org.jctools.queues.LinkedQueueNode<E>	lvConsumerNode()
protected org.jctools.queues.LinkedQueueNode<E>	lvProducerNode()
protected org.jctools.queues.LinkedQueueNode<E>	newNode()
protected org.jctools.queues.LinkedQueueNode<E>	newNode(E e)
boolean	relaxedOffer(E e)	Called from a producer thread subject to the restrictions appropriate to the implementation.
E	relaxedPeek()	Called from the consumer thread subject to the restrictions appropriate to the implementation.
E	relaxedPoll()	Called from the consumer thread subject to the restrictions appropriate to the implementation.
int	size()	This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value.
protected void	spConsumerNode(org.jctools.queues.LinkedQueueNode<E> newValue)
protected void	spProducerNode(org.jctools.queues.LinkedQueueNode<E> newValue)
java.lang.String	toString()
protected org.jctools.queues.LinkedQueueNode<E>	xchgProducerNode(org.jctools.queues.LinkedQueueNode<E> newVal)

Methods inherited from class java.util.AbstractCollection

contains, containsAll, removeAll, retainAll, toArray, toArray

Methods inherited from class java.util.AbstractQueue

add, addAll, clear, element, remove

Methods inherited from interface java.util.Collection

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

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface org.jctools.queues.MessagePassingQueue

clear

Methods inherited from class org.jctools.queues.MpscLinkedQueue

fill, fill, fill, newMpscLinkedQueue, offer, peek, poll, remove

Methods inherited from class java.lang.Object

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

Field Detail

C_NODE_OFFSET

protected static final long C_NODE_OFFSET

consumerNode

protected org.jctools.queues.LinkedQueueNode<E> consumerNode

P_NODE_OFFSET

protected static final long P_NODE_OFFSET

producerNode

protected org.jctools.queues.LinkedQueueNode<E> producerNode

Constructor Detail

MpscLinkedQueue8

public MpscLinkedQueue8()

Method Detail

xchgProducerNode

protected final org.jctools.queues.LinkedQueueNode<E> xchgProducerNode(org.jctools.queues.LinkedQueueNode<E> newVal)

Specified by:

xchgProducerNode in class MpscLinkedQueue<E>

iterator

public final java.util.Iterator<E> iterator()

Specified by:

iterator in class java.util.AbstractCollection<E>

toString

public java.lang.String toString()

Overrides:

toString in class java.util.AbstractCollection<E>

newNode

protected final org.jctools.queues.LinkedQueueNode<E> newNode()

newNode

protected final org.jctools.queues.LinkedQueueNode<E> newNode(E e)

size

public final int size()

This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value. For some implementations this method may be O(n) rather than O(1).

IMPLEMENTATION NOTES:
This is an O(n) operation as we run through all the nodes and count them.
The accuracy of the value returned by this method is subject to races with producer/consumer threads. In particular when racing with the consumer thread this method may under estimate the size.

Specified by:

size in interface MessagePassingQueue<E>

Specified by:

size in class java.util.AbstractCollection<E>

Returns:

number of messages in the queue, between 0 and Integer.MAX_VALUE but less or equals to capacity (if bounded).

See Also:

Collection.size()

isEmpty

public final boolean isEmpty()

This method's accuracy is subject to concurrent modifications happening as the observation is carried out.

IMPLEMENTATION NOTES:
Queue is empty when producerNode is the same as consumerNode. An alternative implementation would be to observe the producerNode.value is null, which also means an empty queue because only the consumerNode.value is allowed to be null.

Specified by:

isEmpty in interface MessagePassingQueue<E>

Overrides:

isEmpty in class java.util.AbstractCollection<E>

Returns:

true if empty, false otherwise

See Also:

MessagePassingQueue.isEmpty()

getSingleConsumerNodeValue

protected E getSingleConsumerNodeValue(org.jctools.queues.LinkedQueueNode<E> currConsumerNode,
                                       org.jctools.queues.LinkedQueueNode<E> nextNode)

relaxedPoll

public E relaxedPoll()

Description copied from interface: MessagePassingQueue

Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.poll() this method may return null without the queue being empty.

Returns:

a message from the queue if one is available, null if unable to poll

relaxedPeek

public E relaxedPeek()

Description copied from interface: MessagePassingQueue

Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.peek() this method may return null without the queue being empty.

Returns:

a message from the queue if one is available, null if unable to peek

relaxedOffer

public boolean relaxedOffer(E e)

Description copied from interface: MessagePassingQueue

Called from a producer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.offer(Object) this method may return false without the queue being full.

Parameters:

e - not null, will throw NPE if it is

Returns:

true if element was inserted into the queue, false if unable to offer

drain

public int drain(MessagePassingQueue.Consumer<E> c)

Description copied from interface: MessagePassingQueue

Remove all available item from the queue and hand to consume. This should be semantically similar to:
M m;
while((m = relaxedPoll()) != null){
c.accept(m);
}
There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.

Returns:

the number of polled elements

drain

public int drain(MessagePassingQueue.Consumer<E> c,
                 int limit)

Description copied from interface: MessagePassingQueue

Remove up to limit elements from the queue and hand to consume. This should be semantically similar to:

 
   M m;
   int i = 0;
   for(;i < limit && (m = relaxedPoll()) != null; i++){
     c.accept(m);
   }
   return i;
 
 

There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.

Returns:

the number of polled elements

drain

public void drain(MessagePassingQueue.Consumer<E> c,
                  MessagePassingQueue.WaitStrategy wait,
                  MessagePassingQueue.ExitCondition exit)

Description copied from interface: MessagePassingQueue

Remove elements from the queue and hand to consume forever. Semantically similar to:

 
  int idleCounter = 0;
  while (exit.keepRunning()) {
      E e = relaxedPoll();
      if(e==null){
          idleCounter = wait.idle(idleCounter);
          continue;
      }
      idleCounter = 0;
      c.accept(e);
  }
 
 

Called from a consumer thread subject to the restrictions appropriate to the implementation.

capacity

public int capacity()

Returns:

the capacity of this queue or MessagePassingQueue.UNBOUNDED_CAPACITY if not bounded

spConsumerNode

protected final void spConsumerNode(org.jctools.queues.LinkedQueueNode<E> newValue)

lvConsumerNode

protected final org.jctools.queues.LinkedQueueNode<E> lvConsumerNode()

lpConsumerNode

protected final org.jctools.queues.LinkedQueueNode<E> lpConsumerNode()

spProducerNode

protected final void spProducerNode(org.jctools.queues.LinkedQueueNode<E> newValue)

lvProducerNode

protected final org.jctools.queues.LinkedQueueNode<E> lvProducerNode()

casProducerNode

protected final boolean casProducerNode(org.jctools.queues.LinkedQueueNode<E> expect,
                                        org.jctools.queues.LinkedQueueNode<E> newValue)

lpProducerNode

protected final org.jctools.queues.LinkedQueueNode<E> lpProducerNode()