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Java > Open Source Codes > org > jboss > messaging > channel > plugins > handler > AbstractChannelHandler


1 /*
2  * JBoss, the OpenSource J2EE webOS
3  *
4  * Distributable under LGPL license.
5  * See terms of license at gnu.org.
6  */
7 package org.jboss.messaging.channel.plugins.handler;
8
9 import org.jboss.messaging.interfaces.*;
10 import org.jboss.messaging.interfaces.Consumer;
11 import org.jboss.messaging.interfaces.MessageReference;
12
13 /**
14  * An abstract channel handler
15  *
16  * @author <a HREF="mailto:adrian@jboss.org">Adrian Brock</a>
17  * @version $Revision: 1.1 $
18  */
19 public abstract class AbstractChannelHandler implements ChannelHandler
20 {
21    // Constants -----------------------------------------------------
22
23    // Attributes ----------------------------------------------------
24
25    /** The message set */
26    protected MessageSet messages;
27    
28    // Static --------------------------------------------------------
29
30    // Constructors --------------------------------------------------
31
32    /**
33     * Create a new AbstractChannelHandler.
34     *
35     * @param messages the messages
36     */
37    public AbstractChannelHandler(MessageSet messages)
38    {
39       this.messages = messages;
40       messages.setConsumer(this);
41    }
42    
43    // Public --------------------------------------------------------
44
45    // Consumer implementation ---------------------------------------
46
47    public boolean accepts(MessageReference reference, boolean active)
48    {
49       // We accept all messages
50 return true;
51    }
52    
53    public void onMessage(MessageReference reference)
54    {
55       Consumer consumer;
56       messages.lock();
57       try
58       {
59          consumer = findConsumer(reference);
60       }
61       finally
62       {
63          messages.unlock();
64       }
65
66       if (consumer != null)
67          consumer.onMessage(reference);
68    }
69    
70    // ChannelHandler implementation ---------------------------------
71
72    public void addMessage(MessageReference reference)
73    {
74       Consumer consumer;
75       messages.lock();
76       try
77       {
78          consumer = findConsumer(reference);
79          if (consumer == null)
80             messages.add(reference);
81       }
82       finally
83       {
84          messages.unlock();
85       }
86
87       if (consumer != null)
88          consumer.onMessage(reference);
89    }
90    
91    public MessageReference removeMessage(Consumer consumer)
92    {
93       messages.lock();
94       try
95       {
96          return messages.remove(consumer);
97       }
98       finally
99       {
100          messages.unlock();
101       }
102    }
103
104    public void waitMessage(Consumer consumer, long wait)
105    {
106       MessageReference message;
107       messages.lock();
108       try
109       {
110          message = messages.remove(consumer);
111          // Nothing found, wait
112 if (message == null)
113             addConsumer(consumer, wait);
114       }
115       finally
116       {
117          messages.unlock();
118       }
119       
120       // We found a message, deliver it
121 if (message != null)
122          consumer.onMessage(message);
123    }
124    
125    public void stopWaitMessage(Consumer consumer)
126    {
127       messages.lock();
128       try
129       {
130          removeConsumer(consumer);
131       }
132       finally
133       {
134          messages.unlock();
135       }
136    }
137    
138    // Protected -----------------------------------------------------
139
140    /**
141     * Add a consumer
142     *
143     * @param consumer the consumer to wait for a message
144     * @param wait the length of time to wait
145     */
146    protected abstract void addConsumer(Consumer consumer, long wait);
147    
148    /**
149     * Remove a consumer
150     *
151     * @param consumer the consumer to remove
152     */
153    protected abstract void removeConsumer(Consumer consumer);
154    
155    /**
156     * Find a consumer for a message
157     *
158     * @param reference the message
159     * @return the consumer or null if there are none for the message
160     */
161    protected abstract Consumer findConsumer(MessageReference reference);
162    
163    // Package Private -----------------------------------------------
164
165    // Private -------------------------------------------------------
166
167    // Inner Classes -------------------------------------------------
168 }
169
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