1 /***
2 *
3 * Copyright 2004 Protique Ltd
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 **/
18
19 package org.codehaus.activemq;
20
21 import org.codehaus.activemq.message.Packet;
22 import org.codehaus.activemq.util.BitArrayBin;
23 import org.codehaus.activemq.util.IdGenerator;
24
25 import javax.jms.Message;
26 import java.util.LinkedHashMap;
27
28 /***
29 * Provides basic audit functions for Messages
30 *
31 * @version $Revision: 1.3 $
32 */
33 public class ActiveMQMessageAudit {
34 private static final int DEFAULT_WINDOW_SIZE = 1024;
35 private static final int MAXIMUM_PRODUCER_COUNT = 128;
36 private int windowSize;
37 private LinkedHashMap map;
38
39 /***
40 * Default Constructor windowSize = 1024, maximumNumberOfProducersToTrack = 128
41 */
42 public ActiveMQMessageAudit() {
43 this(DEFAULT_WINDOW_SIZE, MAXIMUM_PRODUCER_COUNT);
44 }
45
46 /***
47 * Construct a MessageAudit
48 *
49 * @param windowSize range of ids to track
50 * @param maximumNumberOfProducersToTrack
51 * number of producers expected in the system
52 */
53 public ActiveMQMessageAudit(int windowSize, final int maximumNumberOfProducersToTrack) {
54 this.windowSize = windowSize;
55 map = new LinkedHashMap() {
56 public boolean removeOldestEntry() {
57 return size() > maximumNumberOfProducersToTrack;
58 }
59 };
60 }
61
62 /***
63 * Checks if this message has beeb seen before
64 *
65 * @param message
66 * @return true if the message is a duplicate
67 */
68 public boolean isDuplicate(Message message) {
69 if (message instanceof Packet) {
70 return isDuplicate((Packet) message);
71 }
72 return false;
73 }
74
75 /***
76 * checks whether this messageId has been seen before
77 *
78 * @param packet
79 * @return true if the message is a duplicate
80 */
81 public boolean isDuplicate(Packet packet) {
82 return isDuplicate(packet.getId());
83 }
84
85 /***
86 * checks whether this messageId has been seen before and adds this messageId to the list
87 *
88 * @param id
89 * @return true if the message is a duplicate
90 */
91 public boolean isDuplicate(String id) {
92 boolean answer = false;
93 String seed = IdGenerator.getSeedFromId(id);
94 if (seed != null) {
95 BitArrayBin bab = (BitArrayBin) map.get(seed);
96 if (bab == null) {
97 bab = new BitArrayBin(windowSize);
98 map.put(seed, bab);
99 }
100 long index = IdGenerator.getCountFromId(id);
101 if (index >= 0) {
102 answer = bab.setBit(index, true);
103 }
104 }
105 return answer;
106 }
107 }