/*
* Copyright (c) 2003-2004, KNOPFLERFISH project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* - Neither the name of the KNOPFLERFISH project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.knopflerfish.bundle.desktop.swing.console;
import java.util.Vector;
// ******************** Queue ********************
/**
** The Queue
class represents a first-in-first-out
** (FIFO) queue of objects.
** @author Per Lundgren
** @version $Revision: 1.2 $
*/
public class Queue extends Vector {
/** @serial */
private int m_nMaxSize = -1;
/** @serial */
private boolean queueClosed = false;
// ==================== Queue ====================
/**
** Constructs an Queue with the specifies maximum size.
**
** @param size maximum queue size.
*/
public Queue(int size)
{
m_nMaxSize = size;
}
// ==================== insert ====================
/**
** Inserts an item into the queue. If there are threads blocked on
** remove
, one of them is unblocked.
**
** @param item the item to be inserted.
** @exception IndexOutOfBoundsException if maximum queue size is reached.
*/
public synchronized void insert(Object item) throws IndexOutOfBoundsException
{
// Check if queue is full
if (m_nMaxSize > 0 && size() >= m_nMaxSize)
throw new IndexOutOfBoundsException("Queue full");
addElement(item);
notify();
}
// ==================== insertFirst ====================
/**
** Inserts an item first into the queue. If there are threads blocked on
** remove
, one of them is unblocked.
**
** @param item the item to be inserted.
*/
public synchronized void insertFirst(Object item)
{
insertElementAt(item, 0);
notify();
}
// ==================== remove ====================
/**
** Removes and returns the first item in the queue.
** If the queue is empty, the calling thread will block.
**
** @param timeout timeout in seconds.
** @return The first item in the queue, or null
if a
** timeout occurred. To distinguish timeouts, null
** items should not be inserted in the queue.
*/
public synchronized Object removeWait(float timeout)
{
Object obj = null;
// If queue is empty wait for object to be inserted
if (isEmpty() && !queueClosed) {
try {
if (timeout > 0) {
wait(Math.round(timeout * 1000.0f));
} else
wait();
} catch (InterruptedException e) {}
}
if (queueClosed) {
return null;
}
try {
obj = firstElement();
removeElementAt(0);
} catch (Exception e) {}
return obj;
}
// ==================== remove ====================
/**
** Removes and returns the first object in the queue.
** Same as remove(float timeout)
but this function
** blocks forever.
**
** @return The first item in the queue.
*/
public Object remove()
{
return removeWait(0);
}
// ==================== close ====================
/**
** Closes the queue, i.e. wakes up all threads blocking on
** a call to remove().
*/
public synchronized void close() {
queueClosed = true;
notifyAll();
}
}