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 import org.codehaus.activemq.util.LRUCache;
25
26 import javax.jms.Message;
27 import java.util.LinkedHashMap;
28
29 /***
30 * Provides basic audit functions for Messages
31 *
32 * @version $Revision: 1.4 $
33 */
34 public class ActiveMQMessageAudit {
35 private static final int DEFAULT_WINDOW_SIZE = 1024;
36 private static final int MAXIMUM_PRODUCER_COUNT = 128;
37 private int windowSize;
38 private LinkedHashMap map;
39
40 /***
41 * Default Constructor windowSize = 1024, maximumNumberOfProducersToTrack = 128
42 */
43 public ActiveMQMessageAudit() {
44 this(DEFAULT_WINDOW_SIZE, MAXIMUM_PRODUCER_COUNT);
45 }
46
47 /***
48 * Construct a MessageAudit
49 *
50 * @param windowSize range of ids to track
51 * @param maximumNumberOfProducersToTrack
52 * number of producers expected in the system
53 */
54 public ActiveMQMessageAudit(int windowSize, final int maximumNumberOfProducersToTrack) {
55 this.windowSize = windowSize;
56 map = new LRUCache(maximumNumberOfProducersToTrack);
57 }
58
59 /***
60 * Checks if this message has beeb seen before
61 *
62 * @param message
63 * @return true if the message is a duplicate
64 */
65 public boolean isDuplicate(Message message) {
66 if (message instanceof Packet) {
67 return isDuplicate((Packet) message);
68 }
69 return false;
70 }
71
72 /***
73 * checks whether this messageId has been seen before
74 *
75 * @param packet
76 * @return true if the message is a duplicate
77 */
78 public boolean isDuplicate(Packet packet) {
79 return isDuplicate(packet.getId());
80 }
81
82 /***
83 * checks whether this messageId has been seen before and adds this messageId to the list
84 *
85 * @param id
86 * @return true if the message is a duplicate
87 */
88 public boolean isDuplicate(String id) {
89 boolean answer = false;
90 String seed = IdGenerator.getSeedFromId(id);
91 if (seed != null) {
92 BitArrayBin bab = (BitArrayBin) map.get(seed);
93 if (bab == null) {
94 bab = new BitArrayBin(windowSize);
95 map.put(seed, bab);
96 }
97 long index = IdGenerator.getCountFromId(id);
98 if (index >= 0) {
99 answer = bab.setBit(index, true);
100 }
101 }
102 return answer;
103 }
104 }