Package org.jctools.queues.atomic

Class MpscRelaxedAtomicArrayQueue<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue<E>

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

All Implemented Interfaces:

Iterable<E>, Collection<E>, Queue<E>, MessagePassingQueue<E>

public final class MpscRelaxedAtomicArrayQueue<E>
extends AbstractQueue<E>
implements MessagePassingQueue<E>

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 long	consumerPosition

Fields inherited from interface org.jctools.queues.MessagePassingQueue

UNBOUNDED_CAPACITY

Constructor Summary

Constructors

Constructor	Description
MpscRelaxedAtomicArrayQueue(int capacity)

Method Summary

Modifier and Type	Method	Description
static int	activeCycleIndex(long activeCycleId)
int	capacity()
boolean	casActiveCycleId(long expected, long value)
void	clear()	Removes all items from the queue.
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 w, MessagePassingQueue.ExitCondition exit)	Remove elements from the queue and hand to consume forever.
int	fill(MessagePassingQueue.Supplier<E> s)	Stuff the queue with elements from the supplier.
int	fill(MessagePassingQueue.Supplier<E> s, int limit)	Stuff the queue with up to limit elements from the supplier.
void	fill(MessagePassingQueue.Supplier<E> s, MessagePassingQueue.WaitStrategy w, MessagePassingQueue.ExitCondition exit)	Stuff the queue with elements from the supplier forever.
boolean	isEmpty()	This method's accuracy is subject to concurrent modifications happening as the observation is carried out.
Iterator<E>	iterator()
long	lvActiveCycleId()
protected long	lvConsumerPosition()
protected long	lvProducerLimit()
boolean	offer(E e)	Called from a producer thread subject to the restrictions appropriate to the implementation and according to the Queue.offer(Object) interface.
E	peek()	Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.peek() interface.
E	poll()	Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.poll() interface.
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.
void	soActiveCycleId(long value)
protected void	soConsumerPosition(long newValue)
protected void	soProducerLimit(long newValue)
String	toString()

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

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, toArray

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

consumerPosition

protected volatile long consumerPosition

Constructor Detail

MpscRelaxedAtomicArrayQueue

public MpscRelaxedAtomicArrayQueue(int capacity)

Method Detail

iterator

public Iterator<E> iterator()

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in class AbstractCollection<E>

offer

public boolean offer(E e)

Description copied from interface: MessagePassingQueue

Called from a producer thread subject to the restrictions appropriate to the implementation and according to the Queue.offer(Object) interface.

Specified by:

offer in interface MessagePassingQueue<E>

Specified by:

offer in interface Queue<E>

Parameters:

e - not null, will throw NPE if it is

Returns:

true if element was inserted into the queue, false iff full

poll

public E poll()

Description copied from interface: MessagePassingQueue

Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.poll() interface.

Specified by:

poll in interface MessagePassingQueue<E>

Specified by:

poll in interface Queue<E>

Returns:

a message from the queue if one is available, null iff empty

peek

public E peek()

Description copied from interface: MessagePassingQueue

Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.peek() interface.

Specified by:

peek in interface MessagePassingQueue<E>

Specified by:

peek in interface Queue<E>

Returns:

a message from the queue if one is available, null iff empty

size

public int size()

Description copied from interface: MessagePassingQueue

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).

Specified by:

size in interface Collection<E>

Specified by:

size in interface MessagePassingQueue<E>

Specified by:

size in class AbstractCollection<E>

Returns:

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

clear

public void clear()

Description copied from interface: MessagePassingQueue

Removes all items from the queue. Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Collection.clear() interface.

Specified by:

clear in interface Collection<E>

Specified by:

clear in interface MessagePassingQueue<E>

Overrides:

clear in class AbstractQueue<E>

isEmpty

public boolean isEmpty()

Description copied from interface: MessagePassingQueue

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

Specified by:

isEmpty in interface Collection<E>

Specified by:

isEmpty in interface MessagePassingQueue<E>

Overrides:

isEmpty in class AbstractCollection<E>

Returns:

true if empty, false otherwise

capacity

public int capacity()

Specified by:

capacity in interface MessagePassingQueue<E>

Returns:

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

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.

Specified by:

relaxedOffer in interface MessagePassingQueue<E>

Parameters:

e - not null, will throw NPE if it is

Returns:

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

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.

Specified by:

relaxedPoll in interface MessagePassingQueue<E>

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.

Specified by:

relaxedPeek in interface MessagePassingQueue<E>

Returns:

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

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.

WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Consumer.accept(T) make sure you have read and understood these before using this method.

Specified by:

drain in interface MessagePassingQueue<E>

Returns:

the number of polled elements

fill

public int fill(MessagePassingQueue.Supplier<E> s)

Description copied from interface: MessagePassingQueue

Stuff the queue with elements from the supplier. Semantically similar to:

 while(relaxedOffer(s.get());
 

There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation.

Unbounded queues will fill up the queue with a fixed amount rather than fill up to oblivion. WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Supplier.get() make sure you have read and understood these before using this method.

Specified by:

fill in interface MessagePassingQueue<E>

Returns:

the number of offered 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.

WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Consumer.accept(T) make sure you have read and understood these before using this method.

Specified by:

drain in interface MessagePassingQueue<E>

Returns:

the number of polled elements

fill

public int fill(MessagePassingQueue.Supplier<E> s,
                int limit)

Description copied from interface: MessagePassingQueue

Stuff the queue with up to limit elements from the supplier. Semantically similar to:

   for(int i=0; i < limit && relaxedOffer(s.get()); i++);
 

There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation. WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Supplier.get() make sure you have read and understood these before using this method.

Specified by:

fill in interface MessagePassingQueue<E>

Returns:

the number of offered elements

drain

public void drain(MessagePassingQueue.Consumer<E> c,
                  MessagePassingQueue.WaitStrategy w,
                  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.

WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Consumer.accept(T) make sure you have read and understood these before using this method.

Specified by:

drain in interface MessagePassingQueue<E>

fill

public void fill(MessagePassingQueue.Supplier<E> s,
                 MessagePassingQueue.WaitStrategy w,
                 MessagePassingQueue.ExitCondition exit)

Description copied from interface: MessagePassingQueue

Stuff the queue with elements from the supplier forever. Semantically similar to:

 
  int idleCounter = 0;
  while (exit.keepRunning()) {
      E e = s.get();
      while (!relaxedOffer(e)) {
          idleCounter = wait.idle(idleCounter);
          continue;
      }
      idleCounter = 0;
  }
 
 

Called from a producer thread subject to the restrictions appropriate to the implementation. The main difference being that implementors MUST assure room in the queue is available BEFORE calling MessagePassingQueue.Supplier.get(). WARNING: Explicit assumptions are made with regards to MessagePassingQueue.Supplier.get() make sure you have read and understood these before using this method.

Specified by:

fill in interface MessagePassingQueue<E>

toString

public String toString()

Overrides:

toString in class AbstractCollection<E>

lvConsumerPosition

protected final long lvConsumerPosition()

soConsumerPosition

protected void soConsumerPosition(long newValue)

lvProducerLimit

protected final long lvProducerLimit()

soProducerLimit

protected final void soProducerLimit(long newValue)

activeCycleIndex

public static int activeCycleIndex(long activeCycleId)

lvActiveCycleId

public final long lvActiveCycleId()

soActiveCycleId

public final void soActiveCycleId(long value)

casActiveCycleId

public final boolean casActiveCycleId(long expected,
                                      long value)