Class MpscRelaxedAtomicArrayQueue<E>

    • Field Detail

      • mask

        private final long mask
      • capacity

        private final int capacity
      • cycleLength

        private final int cycleLength
      • cycleLengthLog2

        private final int cycleLengthLog2
      • buffer

        private final java.util.concurrent.atomic.AtomicReferenceArray<E> buffer
      • producerCycleClaim

        private final java.util.concurrent.atomic.AtomicLongArray producerCycleClaim
      • positionOnCycleMask

        private final int positionOnCycleMask
      • cycleIdBitShift

        private final int cycleIdBitShift
      • maxCycleId

        private final long maxCycleId
    • Constructor Detail

      • MpscRelaxedAtomicArrayQueue

        public MpscRelaxedAtomicArrayQueue​(int capacity)
    • Method Detail

      • iterator

        public java.util.Iterator<E> iterator()
        Specified by:
        iterator in interface java.util.Collection<E>
        Specified by:
        iterator in interface java.lang.Iterable<E>
        Specified by:
        iterator in class java.util.AbstractCollection<E>
      • positionOnCycle

        private static int positionOnCycle​(long producerCycleClaim,
                                           int positionOnCycleMask)
      • cycleId

        private static long cycleId​(long producerCycleClaim,
                                    int cycleIdBitShift)
      • producerPosition

        private static long producerPosition​(long cycleId,
                                             int positionWithinCycle,
                                             int cycleLengthLog2)
      • calcElementOffset

        private static int calcElementOffset​(int cycle,
                                             int positionWithinCycle,
                                             int cycleLengthLog2)
      • calcElementOffset

        private static int calcElementOffset​(long position,
                                             long mask)
      • isBackPressured

        private boolean isBackPressured​(long producerPosition)
      • rotateCycle

        private void rotateCycle​(java.util.concurrent.atomic.AtomicLongArray producerCycleClaims,
                                 int activeCycle,
                                 long producerCycleClaim,
                                 int cycleIdBitShift,
                                 long maxCycleId)
      • validateSlowProducerClaim

        private void validateSlowProducerClaim​(long cycleId,
                                               int positionOnCycle,
                                               int cycleLengthLog2)
      • 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 java.util.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 java.util.Queue<E>
        Returns:
        a message from the queue if one is available, null iff empty
      • pollMaybeEmpty

        private E pollMaybeEmpty​(java.util.concurrent.atomic.AtomicReferenceArray<E> buffer,
                                 int offset,
                                 long consumerPosition)
      • 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 java.util.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 java.util.Collection<E>
        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).
      • 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 java.util.Collection<E>
        Specified by:
        clear in interface MessagePassingQueue<E>
        Overrides:
        clear in class java.util.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 java.util.Collection<E>
        Specified by:
        isEmpty in interface MessagePassingQueue<E>
        Overrides:
        isEmpty in class java.util.AbstractCollection<E>
        Returns:
        true if empty, false otherwise
      • 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
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.util.AbstractCollection<E>