Package org.jctools.queues

Class MpscUnboundedArrayQueue<E>

    • Field Detail

      • producerMask

        protected long producerMask

      • producerBuffer

        protected E[] producerBuffer

      • consumerMask

        protected long consumerMask

      • consumerBuffer

        protected E[] consumerBuffer

    • Constructor Detail

      • MpscUnboundedArrayQueue

        public MpscUnboundedArrayQueue​(int chunkSize)

    • Method Detail

      • availableInQueue

        protected long availableInQueue​(long pIndex,
                                long cIndex)
        Returns:
        available elements in queue * 2

      • 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

      • getNextBufferSize

        protected int getNextBufferSize​(E[] buffer)
        Returns:
        next buffer size(inclusive of next array pointer)

      • getCurrentBufferCapacity

        protected long getCurrentBufferCapacity​(long mask)
        Returns:
        current buffer capacity for elements (excluding next pointer and jump entry) * 2

      • 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).

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

        This implementation is correct for single consumer thread use only.

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

        This implementation is correct for single consumer thread use only.

        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

      • 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

      • 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

      • 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 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

      • iterator

        public Iterator<E> iterator()
        Get an iterator for this queue. This method is thread safe.

        The iterator provides a best-effort snapshot of the elements in the queue. The returned iterator is not guaranteed to return elements in queue order, and races with the consumer thread may cause gaps in the sequence of returned elements. Like {link #relaxedPoll}, the iterator may not immediately return newly inserted elements.

        Specified by:
        iterator in interface Collection<E>
        Specified by:
        iterator in interface Iterable<E>
        Specified by:
        iterator in class AbstractCollection<E>
        Returns:
        The iterator.

      • lvConsumerIndex

        public final long lvConsumerIndex()

      • lvProducerIndex

        public final long lvProducerIndex()