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1 /*** 2 * Redistribution and use of this software and associated documentation 3 * ("Software"), with or without modification, are permitted provided 4 * that the following conditions are met: 5 * 6 * 1. Redistributions of source code must retain copyright 7 * statements and notices. Redistributions must also contain a 8 * copy of this document. 9 * 10 * 2. Redistributions in binary form must reproduce the 11 * above copyright notice, this list of conditions and the 12 * following disclaimer in the documentation and/or other 13 * materials provided with the distribution. 14 * 15 * 3. The name "Exolab" must not be used to endorse or promote 16 * products derived from this Software without prior written 17 * permission of Exoffice Technologies. For written permission, 18 * please contact info@exolab.org. 19 * 20 * 4. Products derived from this Software may not be called "Exolab" 21 * nor may "Exolab" appear in their names without prior written 22 * permission of Exoffice Technologies. Exolab is a registered 23 * trademark of Exoffice Technologies. 24 * 25 * 5. Due credit should be given to the Exolab Project 26 * (http://www.exolab.org/). 27 * 28 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS 29 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT 30 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 31 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 32 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 33 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 34 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 35 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 37 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 39 * OF THE POSSIBILITY OF SUCH DAMAGE. 40 * 41 * Copyright 2000 (C) Exoffice Technologies Inc. All Rights Reserved. 42 * 43 * $Id: BlockingWorkerQueue.java,v 1.4 2003/08/07 13:33:12 tanderson Exp $ 44 * 45 * Date Author Changes 46 * 5/15/2001 jima Created 47 */ 48 49 50 package org.exolab.jms.util; 51 52 import java.util.LinkedList; 53 54 55 /*** 56 * A BlockingWorkerQueue is attached to a QueueWorker. Any thread can add 57 * work to the queue. The BlockingWorkerQueue, which extends Thread, blocks 58 * waiting for work to arrive. When work arrives it will be dequeued and 59 * passed down to the QueueWorker for processing. 60 * <p> 61 * The owner can use <code>close</code> to gracefully shutdown the thread. 62 * 63 * @version $Revision: 1.4 $ $Date: 2003/08/07 13:33:12 $ 64 * @author <a href="mailto:jima@exolab.org">Jim Alateras</a> 65 */ 66 public class BlockingWorkerQueue 67 extends Thread { 68 69 /*** 70 * This is the runnable that will perform the work 71 */ 72 private QueueWorker _worker = null; 73 74 /*** 75 * The list is used to queue work 76 */ 77 private LinkedList _queue = new LinkedList(); 78 79 /*** 80 * If this is set to true then we must close the worker queue 81 */ 82 private boolean _closed = false; 83 84 85 /*** 86 * Construct a blocking worker queue and attahc to the specified 87 * queue worker. Make the thread a deamon thread. 88 * 89 * @param name - the name of the thread 90 * @param worker - the queue worker attached to this queue 91 */ 92 public BlockingWorkerQueue(String name, QueueWorker worker) { 93 super("BWQ:" + name); 94 _worker = worker; 95 this.setDaemon(true); 96 } 97 98 /*** 99 * Add some work to the end of the queue 100 * 101 * @param work - add this piece of work 102 */ 103 public void add(Object object) { 104 synchronized (_queue) { 105 _queue.addLast(object); 106 _queue.notifyAll(); 107 } 108 } 109 110 /*** 111 * This method is called once the thread has started. It basically loops 112 * forever removing work from the queue and passing it to the runnable. 113 * <p> 114 * Calling <code>close</code> on this object will terminate it. 115 */ 116 public void run() { 117 while (!_closed) { 118 Object work = null; 119 120 synchronized (_queue) { 121 // if there are no messages in the queue then block 122 if (_queue.size() == 0) { 123 try { 124 _queue.wait(); 125 } catch (InterruptedException exception) { 126 // ignore the exception; 127 } 128 continue; 129 } 130 131 // if we get this far then there is something in the queue. 132 // Remove it and hand it to the worker 133 work = _queue.removeFirst(); 134 } 135 136 if (work != null) { 137 _worker.execute(work); 138 } 139 } 140 } 141 142 /*** 143 * Return the number of entries still on the queue 144 * 145 * @size int 146 */ 147 public int size() { 148 return _queue.size(); 149 } 150 151 /*** 152 * Close this worker queue 153 */ 154 public void close() { 155 _closed = true; 156 interrupt(); 157 } 158 159 } 160

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