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 2001-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
42 *
43 * $Id: MessageQueue.java,v 1.3 2005/12/20 20:31:59 tanderson Exp $
44 */
45 package org.exolab.jms.messagemgr;
46
47 import java.util.HashMap;
48 import java.util.Map;
49 import java.util.SortedMap;
50 import java.util.TreeMap;
51
52
53 /***
54 * <code>MessageQueue</code> implements a synchronized queue of
55 * {@link MessageHandle} instances.
56 * .<p/>
57 * Message handles are ordered using {@link MessageHandleComparator}
58 *
59 * @version $Revision: 1.3 $ $Date: 2005/12/20 20:31:59 $
60 * @author <a href="mailto:jima@comware.com.au">Jim Alateras</a>
61 * @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
62 */
63 class MessageQueue {
64
65 /***
66 * The message handle queue.
67 */
68 private final SortedMap _queue = new TreeMap(new MessageHandleComparator());
69
70 /***
71 * The set of handles, keyed on message identifier.
72 */
73 private final Map _handles = new HashMap();
74
75
76 /***
77 * Add a message handle.
78 *
79 * @param handle the message handle
80 * @return <code>true</code> if queue set did not already contain the handle
81 */
82 public synchronized boolean add(MessageHandle handle) {
83 boolean added = false;
84 if (_queue.put(handle, handle) == null) {
85 _handles.put(handle.getMessageId(), handle);
86 added = true;
87 }
88 return added;
89 }
90
91 /***
92 * Determines if a message handle exists.
93 *
94 * @param handle the message handle
95 * @return <code>true</code> if it exists
96 */
97 public synchronized boolean contains(MessageHandle handle) {
98 return _queue.containsKey(handle);
99 }
100
101 /***
102 * Return all elements in the queue.
103 *
104 * @return a list of message handles
105 */
106 public synchronized MessageHandle[] toArray() {
107 return (MessageHandle[]) _queue.keySet().toArray(new MessageHandle[0]);
108 }
109
110 /***
111 * Removes a message handle from the queue.
112 *
113 * @param handle the message handle to remove
114 * @return the removed handle, or <code>null</code> if it wasn't present
115 */
116 public synchronized MessageHandle remove(MessageHandle handle) {
117 MessageHandle result = (MessageHandle) _queue.remove(handle);
118 if (result != null) {
119 _handles.remove(handle.getMessageId());
120 }
121 return result;
122 }
123
124 /***
125 * Removes a message handle from the queue.
126 *
127 * @param messageId the message identifier of the handle to remove
128 * @return the removed handle, or <code>null</code> if it wasn't present
129 */
130 public synchronized MessageHandle remove(String messageId) {
131 MessageHandle result = (MessageHandle) _handles.remove(messageId);
132 if (result != null) {
133 _queue.remove(result);
134 }
135 return result;
136 }
137
138 /***
139 * Removes all the elements from the queue.
140 */
141 public synchronized void clear() {
142 _queue.clear();
143 _handles.clear();
144 }
145
146 /***
147 * Returns the number of message handles in the queue.
148 *
149 * @return the number message handles in the queue
150 */
151 public synchronized int size() {
152 return _queue.size();
153 }
154
155 /***
156 * Removes and returns the first message handle in the queue.
157 *
158 * @return the first message handle in the queue, or <code>null</code>,
159 * if the queue is empty
160 */
161 public synchronized MessageHandle removeFirst() {
162 MessageHandle first = null;
163 if (_queue.size() > 0) {
164 first = (MessageHandle) _queue.firstKey();
165 _queue.remove(first);
166 _handles.remove(first.getMessageId());
167 }
168 return first;
169 }
170
171 }