Package rx.internal.util.atomic

Class SpscUnboundedAtomicArrayQueue<T>

  • Type Parameters:
    T - the value type held by this queue
    All Implemented Interfaces:
    java.lang.Iterable<T>, java.util.Collection<T>, java.util.Queue<T>
    public final class SpscUnboundedAtomicArrayQueue<T>
extends java.lang.Object
implements java.util.Queue<T>
    A single-producer single-consumer queue with unbounded capacity.

    The implementation uses fixed, power-of-2 arrays to store elements and turns into a linked-list like structure if the production overshoots the consumption.

    Note that the minimum capacity of the 'islands' are 8 due to how the look-ahead optimization works.

    The implementation uses field updaters and thus should be platform-safe.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean add​(T e)  
      boolean addAll​(java.util.Collection<? extends T> c)  
      private void adjustLookAheadStep​(int capacity)  
      private static int calcDirectOffset​(int index)  
      private static int calcWrappedOffset​(long index, int mask)  
      void clear()  
      boolean contains​(java.lang.Object o)  
      boolean containsAll​(java.util.Collection<?> c)  
      T element()  
      boolean isEmpty()  
      java.util.Iterator<T> iterator()  
      private long lpConsumerIndex()  
      private long lpProducerIndex()  
      private long lvConsumerIndex()  
      private static <E> java.lang.Object lvElement​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer, int offset)  
      private java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> lvNext​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> curr)  
      private long lvProducerIndex()  
      private T newBufferPeek​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> nextBuffer, long index, int mask)  
      private T newBufferPoll​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> nextBuffer, long index, int mask)  
      boolean offer​(T e)
      T peek()
      T poll()
      T remove()  
      boolean remove​(java.lang.Object o)  
      boolean removeAll​(java.util.Collection<?> c)  
      private void resize​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> oldBuffer, long currIndex, int offset, T e, long mask)  
      boolean retainAll​(java.util.Collection<?> c)  
      int size()  
      private void soConsumerIndex​(long v)  
      private static void soElement​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer, int offset, java.lang.Object e)  
      private void soNext​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> curr, java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> next)  
      private void soProducerIndex​(long v)  
      java.lang.Object[] toArray()  
      <E> E[] toArray​(E[] a)  
      private boolean writeToQueue​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer, T e, long index, int offset)  

      • Methods inherited from class java.lang.Object

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

      • Methods inherited from interface java.util.Collection

        equals, hashCode, parallelStream, removeIf, spliterator, stream, toArray

      • Methods inherited from interface java.lang.Iterable

        forEach

    • Field Detail

      • MAX_LOOK_AHEAD_STEP

        static final int MAX_LOOK_AHEAD_STEP

      • producerIndex

        final java.util.concurrent.atomic.AtomicLong producerIndex

      • producerLookAheadStep

        int producerLookAheadStep

      • producerLookAhead

        long producerLookAhead

      • producerMask

        int producerMask

      • producerBuffer

        java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> producerBuffer

      • consumerMask

        int consumerMask

      • consumerBuffer

        java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> consumerBuffer

      • consumerIndex

        final java.util.concurrent.atomic.AtomicLong consumerIndex

      • HAS_NEXT

        private static final java.lang.Object HAS_NEXT

    • Constructor Detail

      • SpscUnboundedAtomicArrayQueue

        public SpscUnboundedAtomicArrayQueue​(int bufferSize)

    • Method Detail

      • offer

        public boolean offer​(T e)

        This implementation is correct for single producer thread use only.

        Specified by:
        offer in interface java.util.Queue<T>

      • writeToQueue

        private boolean writeToQueue​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer,
                             T e,
                             long index,
                             int offset)

      • resize

        private void resize​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> oldBuffer,
                    long currIndex,
                    int offset,
                    T e,
                    long mask)

      • soNext

        private void soNext​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> curr,
                    java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> next)

      • lvNext

        private java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> lvNext​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> curr)

      • poll

        public T poll()

        This implementation is correct for single consumer thread use only.

        Specified by:
        poll in interface java.util.Queue<T>

      • newBufferPoll

        private T newBufferPoll​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> nextBuffer,
                        long index,
                        int mask)

      • peek

        public T peek()

        This implementation is correct for single consumer thread use only.

        Specified by:
        peek in interface java.util.Queue<T>

      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<T>

      • newBufferPeek

        private T newBufferPeek​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> nextBuffer,
                        long index,
                        int mask)

      • size

        public int size()
        Specified by:
        size in interface java.util.Collection<T>

      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<T>

      • adjustLookAheadStep

        private void adjustLookAheadStep​(int capacity)

      • lvProducerIndex

        private long lvProducerIndex()

      • lvConsumerIndex

        private long lvConsumerIndex()

      • lpProducerIndex

        private long lpProducerIndex()

      • lpConsumerIndex

        private long lpConsumerIndex()

      • soProducerIndex

        private void soProducerIndex​(long v)

      • soConsumerIndex

        private void soConsumerIndex​(long v)

      • calcWrappedOffset

        private static int calcWrappedOffset​(long index,
                                     int mask)

      • calcDirectOffset

        private static int calcDirectOffset​(int index)

      • soElement

        private static void soElement​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer,
                              int offset,
                              java.lang.Object e)

      • lvElement

        private static <E> java.lang.Object lvElement​(java.util.concurrent.atomic.AtomicReferenceArray<java.lang.Object> buffer,
                                              int offset)

      • iterator

        public java.util.Iterator<T> iterator()
        Specified by:
        iterator in interface java.util.Collection<T>
        Specified by:
        iterator in interface java.lang.Iterable<T>

      • contains

        public boolean contains​(java.lang.Object o)
        Specified by:
        contains in interface java.util.Collection<T>

      • toArray

        public java.lang.Object[] toArray()
        Specified by:
        toArray in interface java.util.Collection<T>

      • toArray

        public <E> E[] toArray​(E[] a)
        Specified by:
        toArray in interface java.util.Collection<T>

      • remove

        public boolean remove​(java.lang.Object o)
        Specified by:
        remove in interface java.util.Collection<T>

      • containsAll

        public boolean containsAll​(java.util.Collection<?> c)
        Specified by:
        containsAll in interface java.util.Collection<T>

      • addAll

        public boolean addAll​(java.util.Collection<? extends T> c)
        Specified by:
        addAll in interface java.util.Collection<T>

      • removeAll

        public boolean removeAll​(java.util.Collection<?> c)
        Specified by:
        removeAll in interface java.util.Collection<T>

      • retainAll

        public boolean retainAll​(java.util.Collection<?> c)
        Specified by:
        retainAll in interface java.util.Collection<T>

      • add

        public boolean add​(T e)
        Specified by:
        add in interface java.util.Collection<T>
        Specified by:
        add in interface java.util.Queue<T>

      • remove

        public T remove()
        Specified by:
        remove in interface java.util.Queue<T>

      • element

        public T element()
        Specified by:
        element in interface java.util.Queue<T>