org.apache.turbine.util.pool
Class BoundedBuffer

java.lang.Object
  org.apache.turbine.util.pool.BoundedBuffer

public class BoundedBuffer
extends java.lang.Object

Efficient array-based bounded buffer class. Adapted from CPJ, chapter 8, which describes design. Originally written by Doug Lea and released into the public domain.

[ Introduction to this package. ]

Version:

$Id: BoundedBuffer.java 534527 2007-05-02 16:10:59Z tv $

Author:

Ilkka Priha

Field Summary

protected java.lang.Object[]	buffer
static int	DEFAULT_CAPACITY The default capacity.
protected int	emptySlots
protected int	putPtr
protected int	takePtr
protected int	usedSlots

Constructor Summary

BoundedBuffer()
Creates a buffer with the default capacity

BoundedBuffer(int capacity)
Creates a buffer with the given capacity.

Method Summary

int	capacity() Returns the capacity of the buffer.
boolean	offer(java.lang.Object x) Puts an item in the buffer only if there is capacity available.
java.lang.Object	peek() Peeks, but does not remove the top item from the buffer.
java.lang.Object	poll() Polls and removes the top item from the buffer if one is available.
int	size() Returns the number of elements in the buffer.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CAPACITY

public static final int DEFAULT_CAPACITY

The default capacity.

See Also:

Constant Field Values

buffer

protected final java.lang.Object[] buffer

takePtr

protected int takePtr

putPtr

protected int putPtr

usedSlots

protected int usedSlots

emptySlots

protected int emptySlots

Constructor Detail

BoundedBuffer

public BoundedBuffer(int capacity)
              throws java.lang.IllegalArgumentException

Creates a buffer with the given capacity.

Parameters:

capacity - the capacity.

Throws:

java.lang.IllegalArgumentException - if capacity less or equal to zero.

BoundedBuffer

public BoundedBuffer()

Creates a buffer with the default capacity

Method Detail

size

public int size()

Returns the number of elements in the buffer. This is only a snapshot value, that may change immediately after returning.

Returns:

the size.

capacity

public int capacity()

Returns the capacity of the buffer.

Returns:

the capacity.

peek

public java.lang.Object peek()

Peeks, but does not remove the top item from the buffer.

Returns:

the object or null.

offer

public boolean offer(java.lang.Object x)

Puts an item in the buffer only if there is capacity available.

Parameters:

item - the item to be inserted.

Returns:

true if accepted, else false.

poll

public java.lang.Object poll()

Polls and removes the top item from the buffer if one is available.

Returns:

the oldest item from the buffer, or null if the buffer is empty.