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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 tma@netspace.net.au. 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 2003-2004 (C) Exoffice Technologies Inc. All Rights Reserved. 42 * 43 * $Id: CountingListener.java,v 1.3 2004/01/31 13:44:24 tanderson Exp $ 44 */ 45 package org.exolab.jmscts.core; 46 47 import javax.jms.Message; 48 import javax.jms.MessageListener; 49 50 import EDU.oswego.cs.dl.util.concurrent.Semaphore; 51 52 53 /*** 54 * Helper class for counting the number of messages received. 55 * Clients waiting on this will be notified when the expected number of 56 * messages are received. 57 * 58 * @version $Revision: 1.3 $ $Date: 2004/01/31 13:44:24 $ 59 * @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a> 60 */ 61 public class CountingListener implements MessageListener { 62 63 /*** 64 * The number of expected messages 65 */ 66 private final int _expected; 67 68 /*** 69 * The actual number of messages received 70 */ 71 private volatile int _count = 0; 72 73 /*** 74 * Semaphore used to synchronize process completion 75 */ 76 private Semaphore _completedLock = new Semaphore(0); 77 78 79 /*** 80 * Construct an instance of the listener, with the number of messages 81 * expected to be received. When this count is reached, the listener 82 * notifies the waiting client (if any) 83 * 84 * @param expected the number of messages expected 85 */ 86 public CountingListener(int expected) { 87 _expected = expected; 88 } 89 90 /*** 91 * This method is asynchronously invoked by the message consumer when 92 * a message becomes available. 93 * If the number of expected messages are received, it notifies 94 * the waiting client (if any) 95 * 96 * @param message the received message 97 */ 98 public void onMessage(Message message) { 99 if (++_count >= _expected) { 100 _completedLock.release(); 101 } 102 } 103 104 /*** 105 * Returns the no. of messages expected 106 * 107 * @return the no. of messages expected 108 */ 109 public int getExpected() { 110 return _expected; 111 } 112 113 /*** 114 * Returns the count of received messages 115 * 116 * @return the number of messages received 117 */ 118 public int getReceived() { 119 return _count; 120 } 121 122 /*** 123 * Wait for the listener to complete processing 124 * 125 * @param timeout the number of milleseconds to wait. An argument less 126 * than or equal to zero means not to wait at all 127 * @throws InterruptedException if interrupted while waiting 128 * @return <code>true</code> if the listener completed in the given time 129 * frame 130 */ 131 public boolean waitForCompletion(long timeout) 132 throws InterruptedException { 133 boolean completed = _completedLock.attempt(timeout); 134 if (completed) { 135 _completedLock.release(); 136 } 137 return completed; 138 } 139 140 /*** 141 * Wait indefinitely for the listener to complete processing 142 * 143 * @throws InterruptedException if interrupted while waiting 144 */ 145 public void waitForCompletion() throws InterruptedException { 146 _completedLock.acquire(); 147 _completedLock.release(); 148 } 149 150 }

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