Class MpscAtomicArrayQueue<E>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
org.jctools.queues.atomic.AtomicReferenceArrayQueue<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueL1Pad<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueProducerIndexField<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueMidPad<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueProducerLimitField<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueL2Pad<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueConsumerIndexField<E>
org.jctools.queues.atomic.MpscAtomicArrayQueueL3Pad<E>
org.jctools.queues.atomic.MpscAtomicArrayQueue<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, Queue<E>, IndexedQueueSizeUtil.IndexedQueue, MessagePassingQueue<E>, QueueProgressIndicators, SupportsIterator
public class MpscAtomicArrayQueue<E> extends MpscAtomicArrayQueueL3Pad<E>
NOTE: This class was automatically generated by org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator which can found in the jctools-build module. The original source file is MpscArrayQueue.java. A Multi-Producer-Single-Consumer queue based on a ConcurrentCircularArrayQueue<E>. This implies that any thread may call the offer method, but only a single thread may call poll/peek for correctness to maintained.
This implementation follows patterns documented on the package level for False Sharing protection.
This implementation is using the Fast Flow method for polling from the queue (with minor change to correctly publish the index) and an extension of the Leslie Lamport concurrent queue algorithm (originated by Martin Thompson) on the producer side.

  • Constructor Details

    • MpscAtomicArrayQueue

      public MpscAtomicArrayQueue(int capacity)

  • Method Details

    • offerIfBelowThreshold

      public boolean offerIfBelowThreshold(E e, int threshold)
      offer(E)} if AtomicReferenceArrayQueue.size() is less than threshold.
      Parameters:
      e - the object to offer onto the queue, not null
      threshold - the maximum allowable size
      Returns:
      true if the offer is successful, false if queue size exceeds threshold
      Since:
      1.0.1

    • offer

      public 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.

      IMPLEMENTATION NOTES:
      Lock free offer using a single CAS. As class name suggests access is permitted to many threads concurrently.

      Parameters:
      e - not null, will throw NPE if it is
      Returns:
      true if element was inserted into the queue, false iff full
      See Also:

    • failFastOffer

      public final int failFastOffer(E e)
      A wait free alternative to offer which fails on CAS failure.
      Parameters:
      e - new element, not null
      Returns:
      1 if next element cannot be filled, -1 if CAS failed, 0 if successful

    • poll

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

      IMPLEMENTATION NOTES:
      Lock free poll using ordered loads/stores. As class name suggests access is limited to a single thread.

      Returns:
      a message from the queue if one is available, null iff empty
      See Also:

    • peek

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

      IMPLEMENTATION NOTES:
      Lock free peek using ordered loads. As class name suggests access is limited to a single thread.

      Returns:
      a message from the queue if one is available, null iff empty
      See Also:

    • 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

    • 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

    • 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.

      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.

      Returns:
      the number of offered elements

    • 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.

      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.

      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.

    • fill

      public void fill(MessagePassingQueue.Supplier<E> s, MessagePassingQueue.WaitStrategy wait, 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.

    • weakOffer

      @Deprecated public int weakOffer(E e)
      Deprecated.
      This was renamed to failFastOffer please migrate