org.apache.excalibur.event.impl

Class DefaultQueue

java.lang.Object

org.apache.excalibur.event.impl.AbstractQueue

org.apache.excalibur.event.impl.DefaultQueue

All Implemented Interfaces:

org.apache.excalibur.event.Queue, org.apache.excalibur.event.Sink, org.apache.excalibur.event.Source

public final class DefaultQueue
extends AbstractQueue

The default queue implementation is a variable size queue. This queue is thread safe, however the overhead in synchronization costs a few extra milliseconds.

Author:

Avalon Development Team

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	DefaultQueue.DefaultPreparedEnqueue

Field Summary

Fields

Modifier and Type	Field and Description
private org.apache.commons.collections.Buffer	m_elements
private int	m_maxSize
private EDU.oswego.cs.dl.util.concurrent.ReentrantLock	m_mutex
protected int	m_reserve

Fields inherited from class org.apache.excalibur.event.impl.AbstractQueue

EMPTY_ARRAY, m_interceptor, m_predicate, m_timeout

Fields inherited from interface org.apache.excalibur.event.Queue

ROLE

Constructor Summary

Constructors

Constructor and Description
DefaultQueue() Create an unbounded DefaultQueue.
DefaultQueue(org.apache.excalibur.event.EnqueuePredicate predicate)
DefaultQueue(int size) Construct a new DefaultQueue with the specified number of elements.

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	dequeue()
java.lang.Object[]	dequeue(int numElements)
java.lang.Object[]	dequeueAll()
void	enqueue(java.lang.Object element)
void	enqueue(java.lang.Object[] elements)
int	maxSize() Return the maximum number of elements that will fit in the Queue.
org.apache.excalibur.event.PreparedEnqueue	prepareEnqueue(java.lang.Object[] elements)
private static java.lang.Object[]	retrieveElements(org.apache.commons.collections.Buffer buf, int count) Removes the given number of elements from the given buf and returns them in an array.
int	size() Return the number of elements currently in the Queue.
boolean	tryEnqueue(java.lang.Object element)

Methods inherited from class org.apache.excalibur.event.impl.AbstractQueue

block, canAccept, getDequeueInterceptor, getEnqueuePredicate, isFull, setDequeueInterceptor, setEnqueuePredicate, setTimeout

Methods inherited from class java.lang.Object

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

Field Detail

m_elements

private final org.apache.commons.collections.Buffer m_elements

m_mutex

private final EDU.oswego.cs.dl.util.concurrent.ReentrantLock m_mutex

m_reserve

protected int m_reserve

m_maxSize

private final int m_maxSize

Constructor Detail

DefaultQueue

public DefaultQueue(int size)

Construct a new DefaultQueue with the specified number of elements. if the number of elements is greater than zero, then the Queue is bounded by that number. Otherwise, the Queue is not bounded at all.

Parameters:

size - The maximum number of elements in the Queue. Any number less than 1 means there is no limit.

DefaultQueue

public DefaultQueue(org.apache.excalibur.event.EnqueuePredicate predicate)

DefaultQueue

public DefaultQueue()

Create an unbounded DefaultQueue.

Method Detail

size

public int size()

Return the number of elements currently in the Queue.

Returns:

int representing the number of elements (including the reserved ones).

maxSize

public int maxSize()

Return the maximum number of elements that will fit in the Queue. A number below 1 indecates an unbounded Queue, which means there is no limit.

Specified by:

maxSize in interface org.apache.excalibur.event.Sink

Overrides:

maxSize in class AbstractQueue

Returns:

int representing the maximum number of elements

prepareEnqueue

public org.apache.excalibur.event.PreparedEnqueue prepareEnqueue(java.lang.Object[] elements)
                                                          throws org.apache.excalibur.event.SinkException

Throws:

org.apache.excalibur.event.SinkException

tryEnqueue

public boolean tryEnqueue(java.lang.Object element)

enqueue

public void enqueue(java.lang.Object[] elements)
             throws org.apache.excalibur.event.SinkException

Throws:

org.apache.excalibur.event.SinkException

enqueue

public void enqueue(java.lang.Object element)
             throws org.apache.excalibur.event.SinkException

Throws:

org.apache.excalibur.event.SinkException

dequeue

public java.lang.Object[] dequeue(int numElements)

dequeueAll

public java.lang.Object[] dequeueAll()

retrieveElements

private static java.lang.Object[] retrieveElements(org.apache.commons.collections.Buffer buf,
                                  int count)

Removes the given number of elements from the given buf and returns them in an array. Trusts the caller to pass in a buffer full of Objects and with at least count elements available.

Parameters:

buf - to remove elements from, the caller is responsible for synchronizing access

count - number of elements to remove/return

Returns:

requested number of elements

dequeue

public java.lang.Object dequeue()