Package com.jogamp.common.util

Class LFRingbuffer<T>

  • All Implemented Interfaces:
    Ringbuffer<T>
    public class LFRingbuffer<T>
extends Object
implements Ringbuffer<T>
    Simple implementation of Ringbuffer, exposing lock-free get*(..) and put*(..) methods.

    Implementation utilizes the Always Keep One Slot Open, hence implementation maintains an internal array of capacity plus one!

    Implementation is thread safe if:

    Following methods utilize global synchronization:

    User needs to synchronize above methods w/ the lock-free w/ get*(..) and put*(..) methods, e.g. by controlling their threads before invoking the above.

    Characteristics:

    • Read position points to the last read element.
    • Write position points to the last written element.
    EmptywritePos == readPossize == 0
    FullwritePos == readPos - 1size == capacity

    • Constructor Summary

      Constructors 
      Constructor Description
      LFRingbuffer​(Class<? extends T[]> arrayType, int capacity)
      Create an empty ring buffer instance w/ the given net capacity.
      LFRingbuffer​(T[] copyFrom)
      Create a full ring buffer instance w/ the given array's net capacity and content.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int capacity()
      Returns the net capacity of this ring buffer.
      void clear()
      Resets the read and write position according to an empty ring buffer and set all ring buffer slots to null.
      void dump​(PrintStream stream, String prefix)
      Debug functionality - Dumps the contents of the internal array.
      T get()
      Dequeues the oldest enqueued element if available, otherwise null.
      T getBlocking()
      Dequeues the oldest enqueued element.
      int getFreeSlots()
      Returns the number of free slots available to put.
      void growEmptyBuffer​(T[] newElements)
      Grows an empty ring buffer, increasing it's capacity about the amount.
      void growFullBuffer​(int growAmount)
      Grows a full ring buffer, increasing it's capacity about the amount.
      boolean isEmpty()
      Returns true if this ring buffer is empty, otherwise false.
      boolean isFull()
      Returns true if this ring buffer is full, otherwise false.
      T peek()
      Peeks the next element at the read position w/o modifying pointer, nor blocking.
      T peekBlocking()
      Peeks the next element at the read position w/o modifying pointer, but w/ blocking.
      boolean put​(T e)
      Enqueues the given element.
      void putBlocking​(T e)
      Enqueues the given element.
      boolean putSame​(boolean blocking)
      Enqueues the same element at it's write position, if not full.
      void resetFull​(T[] copyFrom)
      Resets the read and write position according to a full ring buffer and fill all slots w/ elements of array copyFrom.
      int size()
      Returns the number of elements in this ring buffer.
      String toString()
      Returns a short string representation incl.
      void waitForFreeSlots​(int count)
      Blocks until at least count free slots become available.

    • Constructor Detail

      • LFRingbuffer

        public LFRingbuffer​(T[] copyFrom)
             throws IllegalArgumentException
        Create a full ring buffer instance w/ the given array's net capacity and content.

        Example for a 10 element Integer array: 

          Integer[] source = new Integer[10];
  // fill source with content ..
  Ringbuffer rb = new LFRingbuffer(source);

        isFull() returns true on the newly created full ring buffer.

        Implementation will allocate an internal array with size of array copyFrom plus one, and copy all elements from array copyFrom into the internal array.

        Parameters:
        copyFrom - mandatory source array determining ring buffer's net capacity() and initial content.
        Throws:
        IllegalArgumentException - if copyFrom is null

      • LFRingbuffer

        public LFRingbuffer​(Class<? extends T[]> arrayType,
                    int capacity)
        Create an empty ring buffer instance w/ the given net capacity.

        Example for a 10 element Integer array: 

          Ringbuffer rb = new LFRingbuffer(10, Integer[].class);

        isEmpty() returns true on the newly created empty ring buffer.

        Implementation will allocate an internal array of size capacity plus one.

        Parameters:
        arrayType - the array type of the created empty internal array.
        capacity - the initial net capacity of the ring buffer

    • Method Detail

      • toString

        public final String toString()
        Description copied from interface: Ringbuffer
        Returns a short string representation incl. size/capacity and internal r/w index (impl. dependent).
        Specified by:
        toString in interface Ringbuffer<T>
        Overrides:
        toString in class Object

      • dump

        public final void dump​(PrintStream stream,
                       String prefix)
        Description copied from interface: Ringbuffer
        Debug functionality - Dumps the contents of the internal array.
        Specified by:
        dump in interface Ringbuffer<T>

      • capacity

        public final int capacity()
        Description copied from interface: Ringbuffer
        Returns the net capacity of this ring buffer.
        Specified by:
        capacity in interface Ringbuffer<T>

      • clear

        public final void clear()
        Description copied from interface: Ringbuffer
        Resets the read and write position according to an empty ring buffer and set all ring buffer slots to null.

        Ringbuffer.isEmpty() will return true after calling this method.

        Specified by:
        clear in interface Ringbuffer<T>

      • size

        public final int size()
        Description copied from interface: Ringbuffer
        Returns the number of elements in this ring buffer.
        Specified by:
        size in interface Ringbuffer<T>

      • getFreeSlots

        public final int getFreeSlots()
        Description copied from interface: Ringbuffer
        Returns the number of free slots available to put.
        Specified by:
        getFreeSlots in interface Ringbuffer<T>

      • isEmpty

        public final boolean isEmpty()
        Description copied from interface: Ringbuffer
        Returns true if this ring buffer is empty, otherwise false.
        Specified by:
        isEmpty in interface Ringbuffer<T>

      • isFull

        public final boolean isFull()
        Description copied from interface: Ringbuffer
        Returns true if this ring buffer is full, otherwise false.
        Specified by:
        isFull in interface Ringbuffer<T>

      • get

        public final T get()
        Dequeues the oldest enqueued element if available, otherwise null.

        The returned ring buffer slot will be set to null to release the reference and move ownership to the caller.

        Method is non blocking and returns immediately;.

        Implementation advances the read position and returns the element at it, if not empty.

        Specified by:
        get in interface Ringbuffer<T>
        Returns:
        the oldest put element if available, otherwise null.

      • getBlocking

        public final T getBlocking()
                    throws InterruptedException
        Dequeues the oldest enqueued element.

        The returned ring buffer slot will be set to null to release the reference and move ownership to the caller.

        Methods blocks until an element becomes available via put.

        Implementation advances the read position and returns the element at it, if not empty.

        Specified by:
        getBlocking in interface Ringbuffer<T>
        Returns:
        the oldest put element
        Throws:
        InterruptedException

      • peek

        public final T peek()
        Description copied from interface: Ringbuffer
        Peeks the next element at the read position w/o modifying pointer, nor blocking.
        Specified by:
        peek in interface Ringbuffer<T>
        Returns:
        null if empty, otherwise the element which would be read next.

      • put

        public final boolean put​(T e)
        Enqueues the given element.

        Returns true if successful, otherwise false in case buffer is full.

        Method is non blocking and returns immediately;.

        Implementation advances the write position and stores the given element at it, if not full.

        Specified by:
        put in interface Ringbuffer<T>

      • putBlocking

        public final void putBlocking​(T e)
                       throws InterruptedException
        Enqueues the given element.

        Method blocks until a free slot becomes available via get.

        Implementation advances the write position and stores the given element at it, if not full.

        Specified by:
        putBlocking in interface Ringbuffer<T>
        Throws:
        InterruptedException

      • putSame

        public final boolean putSame​(boolean blocking)
                      throws InterruptedException
        Enqueues the same element at it's write position, if not full.

        Returns true if successful, otherwise false in case buffer is full.

        If blocking is true, method blocks until a free slot becomes available via get.

        Implementation advances the write position and keeps the element at it, if not full.

        Specified by:
        putSame in interface Ringbuffer<T>
        Parameters:
        blocking - if true, wait until a free slot becomes available via get.
        Throws:
        InterruptedException