Package info.monitorenter.util.collections

Class RingBufferArrayFast<T>

java.lang.Object
info.monitorenter.util.collections.RingBufferArrayFast<T>
Type Parameters:
T - the type of instances to store.
All Implemented Interfaces:
IRingBuffer<T>, Serializable, Cloneable, Iterable<T>
Direct Known Subclasses:
RingBufferArray
public class RingBufferArrayFast<T> extends Object implements Cloneable, IRingBuffer<T>
Fast ring buffer implementation.

This implementation differs from the RingBufferArray in one point:
If setBufferSize(int asize) decreases the size of the buffer and it will get smaller than the actual amount of elements stored, they will get lost. This avoids the need for an internal List to store elements overhanging. Some tests may be left out that may speed up this IRingBuffer. Adding 5000000 elements was about 25 % faster compared to the RingBufferArray on an Athlon 1200, 256 MB RAM.

For allowing high performance single-threaded use this implementation and the implementations of the retrievable Iterator- instances are not synchronized at all.

Author:
Achim Westermann
See Also:

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    protected class 
    RingBufferArrayFast.ARingBufferIterator
    Base for ring buffer iterators that has access to the ring buffer by being an non-static inner class.

    Nested classes/interfaces inherited from interface info.monitorenter.util.collections.IRingBuffer

    IRingBuffer.RingBufferException

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final boolean
    DEBUG
    Flip the switch and you will see how the compiler changes the size of the class file.
    protected Object[]
    m_buffer
    The internal array used as buffer.
    protected boolean
    m_empty
    Flag that marks whether this buffer is empty or not.
    protected int
    m_headpointer
    The internal index to buffer where the next element is going to be placed (not placed yet!).
    protected int
    m_size
    The internal size of the buffer.
    protected int
    m_tailpointer
    The internal index to buffer where the next element is going to be read.

  • Constructor Summary

    Constructors
    Constructor
    Description
    RingBufferArrayFast(int aSize)
    Constructs a RingBuffer with the given size.

  • Method Summary

    Modifier and Type
    Method
    Description
    T
    add(T anObject)
    Adds an element to the ring buffer, potentially removing the first element to make more room.
    void
    clear()
    Fast method to clear the buffer - only needs to set three primitive members.
    protected Object
    clone()
     
    boolean
    equals(Object obj)
     
    int
    getBufferSize()
    Returns the absolute amount of space in the buffer.
    T
    getOldest()
    Returns the oldest element from the buffer.
    T
    getYoungest()
    Returns the last element added.
    int
    hashCode()
     
    boolean
    isEmpty()
    Tests whether no elements are stored in the buffer.
    boolean
    isFull()
    Returns true if no more space in the buffer is available.
    Iterator<T>
    iterator()
    Delegates to iteratorL2F().
    Iterator<T>
    iteratorF2L()
    Returns an Iterator that will return the elements in exactly the inverse order the subsequent call to remove() would do.
    Iterator<T>
    iteratorL2F()
    Returns an Iterator that will return the elements in exactly the order the subsequent call to remove() would do.
    T
    remove()
    Removes the oldest element from the buffer.
    T[]
    removeAll()
    Clears the buffer.
    void
    setBufferSize(int newSize)
    Sets a new buffer- size.
    int
    size()
    Returns the actual amount of elements stored in the buffer.
    String
    toString()
    Returns a string representation of the RingBuffer and it's contents.

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.lang.Iterable

    forEach, spliterator

  • Field Details

    • DEBUG

      public static final boolean DEBUG
      Flip the switch and you will see how the compiler changes the size of the class file.
      See Also:

    • m_buffer

      protected Object[] m_buffer
      The internal array used as buffer.

    • m_empty

      protected boolean m_empty
      Flag that marks whether this buffer is empty or not. 

       
             headpointer
              |
        +---+---+---+---+
        | 0 | 1 | 2 | 3 |
        +---+---+---+---+
              |
             tailpointer
    
        From where to where are the elements?
        Where is empty space?
        empty == true:  0 elements are contained: buffer empty
        empty == false:  4 elements are contained: buffer full
        remember:
            -the headpointer points to the space where the next element will be inserted.
            -the tailpointer points to the space to read the next element from.

    • m_headpointer

      protected int m_headpointer
      The internal index to buffer where the next element is going to be placed (not placed yet!).

    • m_size

      protected int m_size
      The internal size of the buffer.

      For performance reasons the size of the buffer -1!

    • m_tailpointer

      protected int m_tailpointer
      The internal index to buffer where the next element is going to be read.

  • Constructor Details

    • RingBufferArrayFast

      public RingBufferArrayFast(int aSize)
      Constructs a RingBuffer with the given size.
      Parameters:
      aSize - the size of the buffer.

  • Method Details

    • add

      public T add(T anObject)
      Adds an element to the ring buffer, potentially removing the first element to make more room.

      Specified by:
      add in interface IRingBuffer<T>
      Parameters:
      anObject - the instance to add.
      Returns:
      the oldest Object, if RingBuffer was filled with 'maxsize' elements before, or null.

    • clear

      public void clear()
      Fast method to clear the buffer - only needs to set three primitive members.

      Specified by:
      clear in interface IRingBuffer<T>
      See Also:

    • clone

      protected Object clone() throws CloneNotSupportedException
      Overrides:
      clone in class Object
      Throws:
      CloneNotSupportedException
      See Also:

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object
      See Also:

    • getBufferSize

      public int getBufferSize()
      Description copied from interface: IRingBuffer
      Returns the absolute amount of space in the buffer.

      Specified by:
      getBufferSize in interface IRingBuffer<T>
      Returns:
      the absolute amount of space in the buffer.
      See Also:

    • getOldest

      public T getOldest() throws IRingBuffer.RingBufferException
      Description copied from interface: IRingBuffer
      Returns the oldest element from the buffer. This method does not remove the element.

      Specified by:
      getOldest in interface IRingBuffer<T>
      Returns:
      the oldest element from the buffer.
      Throws:
      IRingBuffer.RingBufferException - if the buffer is empty.
      See Also:

    • getYoungest

      public T getYoungest() throws IRingBuffer.RingBufferException
      Description copied from interface: IRingBuffer
      Returns the last element added. This method does not remove the element.

      Specified by:
      getYoungest in interface IRingBuffer<T>
      Returns:
      the last element added.
      Throws:
      IRingBuffer.RingBufferException - if the buffer is empty.
      See Also:

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object
      See Also:

    • isEmpty

      public boolean isEmpty()
      Description copied from interface: IRingBuffer
      Tests whether no elements are stored in the buffer.

      Specified by:
      isEmpty in interface IRingBuffer<T>
      Returns:
      true if no element is stored in the buffer.
      See Also:

    • isFull

      public boolean isFull()
      Description copied from interface: IRingBuffer
      Returns true if no more space in the buffer is available. This method should be used to test before calling IRingBuffer.add(Object).

      Specified by:
      isFull in interface IRingBuffer<T>
      Returns:
      true if no more space in the buffer is available.
      See Also:

    • iterator

      public Iterator<T> iterator()
      Delegates to iteratorL2F().

      Specified by:
      iterator in interface Iterable<T>
      See Also:

    • iteratorF2L

      public Iterator<T> iteratorF2L()
      Returns an Iterator that will return the elements in exactly the inverse order the subsequent call to remove() would do.

      The youngest elements are returned first. The Iterator returned is not thread- safe!

      Specified by:
      iteratorF2L in interface IRingBuffer<T>
      Returns:
      an Iterator that will return the elements in exactly the inverse order the subsequent call to remove() would do.

    • iteratorL2F

      public Iterator<T> iteratorL2F()
      Returns an Iterator that will return the elements in exactly the order the subsequent call to remove() would do.

      The oldest elements are returned first. The Iterator returned is not thread- safe!

      Specified by:
      iteratorL2F in interface IRingBuffer<T>
      Returns:
      an Iterator that will return the elements in exactly the order the subsequent call to remove() would do.

    • remove

      public T remove()
      Description copied from interface: IRingBuffer
      Removes the oldest element from the buffer.

      Specified by:
      remove in interface IRingBuffer<T>
      Returns:
      the removed oldest element from the buffer.
      See Also:

    • removeAll

      public T[] removeAll()
      Description copied from interface: IRingBuffer
      Clears the buffer. It will return all of it's stored elements.

      Specified by:
      removeAll in interface IRingBuffer<T>
      Returns:
      all removed elements.
      See Also:

    • setBufferSize

      public void setBufferSize(int newSize)
      Sets a new buffer- size.

      A new size is assigned but the elements "overhanging" are returned by the Object remove()- method first. This may take time until the buffer has its actual size again. Don't pretend on calling this method for saving of memory very often as the whole buffer has to be copied into a new array every time- and if newSize < getSize() additional the overhanging elements references have to be moved to the internal List pendingremove.

      Specified by:
      setBufferSize in interface IRingBuffer<T>
      Parameters:
      newSize - the new size of the buffer.

    • size

      public int size()
      Description copied from interface: IRingBuffer
      Returns the actual amount of elements stored in the buffer.

      Specified by:
      size in interface IRingBuffer<T>
      Returns:
      the actual amount of elements stored in the buffer.
      See Also:

    • toString

      public String toString()
      Returns a string representation of the RingBuffer and it's contents.

      Don't call this in your application too often: hard arraycopy - operation an malloc are triggered.

      Overrides:
      toString in class Object
      Returns:
      a string representation of the RingBuffer and it's contents.