info.monitorenter.util.collections
Class RingBufferArray

java.lang.Object
  info.monitorenter.util.collections.RingBufferArrayFast
      info.monitorenter.util.collections.RingBufferArray

All Implemented Interfaces:

IRingBuffer, Serializable, Cloneable

public class RingBufferArray
extends RingBufferArrayFast

A RingBuffer can be used to store a limited number of entries of any type within a buffer.

As soon as the maximum number of entries is reached, the next entry is added to the end and the first entry is removed from it. In this case, all elements are stored in a Object[]. But don't worry there will not be a single call to System.arraycopy caused by invocation of the add(Object element)- method. Internal indexes into the array for the head and tail allow to reuse the same memory again and again.
No element is lost: 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 cached until removed.

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

Version:

$Revision: 1.5 $

Author:

Achim Westermann

See Also:

Serialized Form

Nested Class Summary

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

IRingBuffer.RingBufferException

Field Summary

protected List

m_pendingremove Elements that stores elements that have to be removed due to an invocation to setBufferSize(int) with a smaller argument than the amount of elements stored.

Fields inherited from class info.monitorenter.util.collections.RingBufferArrayFast

DEBUG, m_buffer, m_empty, m_headpointer, m_size, m_tailpointer

Constructor Summary

RingBufferArray(int aSize)
Constructs a RingBuffer with the given size.

Method Summary

boolean	isEmpty() Tests wether no elements are stored in the buffer.
Iterator	iteratorF2L() Returns an Iterator that will return the elements in exactly the inverse order the subsequent call to remove() would do.
Iterator	iteratorL2F() Returns an Iterator that will return the elements in exactly the order the subsequent call to remove() would do.
Object	remove() Removes the oldest element from the buffer.
Object[]	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 info.monitorenter.util.collections.RingBufferArrayFast

add, clear, clone, getBufferSize, getOldest, getYoungest, isFull

Methods inherited from class java.lang.Object

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

Field Detail

m_pendingremove

protected List m_pendingremove

Elements that stores elements that have to be removed due to an invocation to setBufferSize(int) with a smaller argument than the amount of elements stored.

Constructor Detail

RingBufferArray

public RingBufferArray(int aSize)

Constructs a RingBuffer with the given size.

Parameters:

aSize - the size of the buffer.

Method Detail

isEmpty

public boolean isEmpty()

Description copied from interface: IRingBuffer

Tests wether no elements are stored in the buffer.

Specified by:

isEmpty in interface IRingBuffer

Overrides:

isEmpty in class RingBufferArrayFast

Returns:

true if no element is stored in the buffer.

See Also:

IRingBuffer.isEmpty()

iteratorF2L

public Iterator iteratorF2L()

Description copied from class: RingBufferArrayFast

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

Overrides:

iteratorF2L in class RingBufferArrayFast

Returns:

an Iterator that will return the elements in exactly the inverse order the subsequent call to remove() would do.

See Also:

IRingBuffer.iteratorF2L()

iteratorL2F

public Iterator iteratorL2F()

Description copied from class: RingBufferArrayFast

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

Overrides:

iteratorL2F in class RingBufferArrayFast

Returns:

an Iterator that will return the elements in exactly the order the subsequent call to remove() would do.

See Also:

IRingBuffer.iteratorL2F()

remove

public Object remove()

Description copied from interface: IRingBuffer

Removes the oldest element from the buffer.

Specified by:

remove in interface IRingBuffer

Overrides:

remove in class RingBufferArrayFast

Returns:

the removed oldest element from the buffer.

See Also:

IRingBuffer.remove()

removeAll

public Object[] removeAll()

Description copied from interface: IRingBuffer

Clears the buffer. It will return all of it's stored elements.

Specified by:

removeAll in interface IRingBuffer

Overrides:

removeAll in class RingBufferArrayFast

Returns:

all removed elements.

See Also:

IRingBuffer.removeAll()

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

Overrides:

setBufferSize in class RingBufferArrayFast

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

Overrides:

size in class RingBufferArrayFast

Returns:

the actual amount of elements stored in the buffer.

See Also:

IRingBuffer.size()

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 memalloc are triggered.

Overrides:

toString in class RingBufferArrayFast

Returns:

a string representation of the RingBuffer and it's contents.