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Java > Open Source Codes > org > apache > tomcat > util > modeler > BaseNotificationBroadcaster


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. 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.apache.tomcat.util.modeler;
20
21
22 import java.util.ArrayList JavaDoc;
23 import java.util.Iterator JavaDoc;
24
25 import javax.management.ListenerNotFoundException JavaDoc;
26 import javax.management.MBeanNotificationInfo JavaDoc;
27 import javax.management.Notification JavaDoc;
28 import javax.management.NotificationBroadcaster JavaDoc;
29 import javax.management.NotificationFilter JavaDoc;
30 import javax.management.NotificationListener JavaDoc;
31
32
33 /**
34  * <p>Implementation of <code>NotificationBroadcaster</code> for attribute
35  * change notifications. This class is used by <code>BaseModelMBean</code> to
36  * handle notifications of attribute change events to interested listeners.
37  *</p>
38  *
39  * @author Craig R. McClanahan
40  * @author Costin Manolache
41  */
42
43 public class BaseNotificationBroadcaster implements NotificationBroadcaster JavaDoc {
44
45
46     // ----------------------------------------------------------- Constructors
47
48
49     // ----------------------------------------------------- Instance Variables
50
51
52     /**
53      * The set of registered <code>BaseNotificationBroadcasterEntry</code>
54      * entries.
55      */
56     protected ArrayList JavaDoc entries = new ArrayList JavaDoc();
57
58
59     // --------------------------------------------------------- Public Methods
60
61
62     /**
63      * Add a notification event listener to this MBean.
64      *
65      * @param listener Listener that will receive event notifications
66      * @param filter Filter object used to filter event notifications
67      * actually delivered, or <code>null</code> for no filtering
68      * @param handback Handback object to be sent along with event
69      * notifications
70      *
71      * @exception IllegalArgumentException if the listener parameter is null
72      */
73     public void addNotificationListener(NotificationListener JavaDoc listener,
74                                         NotificationFilter JavaDoc filter,
75                                         Object JavaDoc handback)
76         throws IllegalArgumentException JavaDoc {
77
78         synchronized (entries) {
79
80             // Optimization to coalesce attribute name filters
81 if (filter instanceof BaseAttributeFilter) {
82                 BaseAttributeFilter newFilter = (BaseAttributeFilter) filter;
83                 Iterator JavaDoc items = entries.iterator();
84                 while (items.hasNext()) {
85                     BaseNotificationBroadcasterEntry item =
86                         (BaseNotificationBroadcasterEntry) items.next();
87                     if ((item.listener == listener) &&
88                         (item.filter != null) &&
89                         (item.filter instanceof BaseAttributeFilter) &&
90                         (item.handback == handback)) {
91                         BaseAttributeFilter oldFilter =
92                             (BaseAttributeFilter) item.filter;
93                         String JavaDoc newNames[] = newFilter.getNames();
94                         String JavaDoc oldNames[] = oldFilter.getNames();
95                         if (newNames.length == 0) {
96                             oldFilter.clear();
97                         } else {
98                             if (oldNames.length != 0) {
99                                 for (int i = 0; i < newNames.length; i++)
100                                     oldFilter.addAttribute(newNames[i]);
101                             }
102                         }
103                         return;
104                     }
105                 }
106             }
107
108             // General purpose addition of a new entry
109 entries.add(new BaseNotificationBroadcasterEntry
110                         (listener, filter, handback));
111         }
112
113     }
114
115
116     /**
117      * Return an <code>MBeanNotificationInfo</code> object describing the
118      * notifications sent by this MBean.
119      */
120     public MBeanNotificationInfo JavaDoc[] getNotificationInfo() {
121
122         return (new MBeanNotificationInfo JavaDoc[0]);
123
124     }
125
126
127     /**
128      * Remove a notification event listener from this MBean.
129      *
130      * @param listener The listener to be removed (any and all registrations
131      * for this listener will be eliminated)
132      *
133      * @exception ListenerNotFoundException if this listener is not
134      * registered in the MBean
135      */
136     public void removeNotificationListener(NotificationListener JavaDoc listener)
137         throws ListenerNotFoundException JavaDoc {
138
139         synchronized (entries) {
140             Iterator JavaDoc items = entries.iterator();
141             while (items.hasNext()) {
142                 BaseNotificationBroadcasterEntry item =
143                     (BaseNotificationBroadcasterEntry) items.next();
144                 if (item.listener == listener)
145                     items.remove();
146             }
147         }
148
149     }
150
151
152     /**
153      * Remove a notification event listener from this MBean.
154      *
155      * @param listener The listener to be removed (any and all registrations
156      * for this listener will be eliminated)
157      * @param handback Handback object to be sent along with event
158      * notifications
159      *
160      * @exception ListenerNotFoundException if this listener is not
161      * registered in the MBean
162      */
163     public void removeNotificationListener(NotificationListener JavaDoc listener,
164                                            Object JavaDoc handback)
165         throws ListenerNotFoundException JavaDoc {
166
167         removeNotificationListener(listener);
168
169     }
170
171
172     /**
173      * Remove a notification event listener from this MBean.
174      *
175      * @param listener The listener to be removed (any and all registrations
176      * for this listener will be eliminated)
177      * @param filter Filter object used to filter event notifications
178      * actually delivered, or <code>null</code> for no filtering
179      * @param handback Handback object to be sent along with event
180      * notifications
181      *
182      * @exception ListenerNotFoundException if this listener is not
183      * registered in the MBean
184      */
185     public void removeNotificationListener(NotificationListener JavaDoc listener,
186                                            NotificationFilter JavaDoc filter,
187                                            Object JavaDoc handback)
188         throws ListenerNotFoundException JavaDoc {
189
190         removeNotificationListener(listener);
191
192     }
193
194
195     /**
196      * Send the specified notification to all interested listeners.
197      *
198      * @param notification The notification to be sent
199      */
200     public void sendNotification(Notification JavaDoc notification) {
201
202         synchronized (entries) {
203             Iterator JavaDoc items = entries.iterator();
204             while (items.hasNext()) {
205                 BaseNotificationBroadcasterEntry item =
206                     (BaseNotificationBroadcasterEntry) items.next();
207                 if ((item.filter != null) &&
208                     (!item.filter.isNotificationEnabled(notification)))
209                     continue;
210                 item.listener.handleNotification(notification, item.handback);
211             }
212         }
213
214     }
215
216
217     // -------------------- Internal Extensions --------------------
218
219     // Fast access. First index is the hook type
220 // ( FixedNotificationFilter.getType() ).
221 NotificationListener JavaDoc hooks[][]=new NotificationListener JavaDoc[20][];
222     int hookCount[]=new int[20];
223
224     private synchronized void registerNotifications( FixedNotificationFilter filter ) {
225         String JavaDoc names[]=filter.getNames();
226         Registry reg=Registry.getRegistry();
227         for( int i=0; i<names.length; i++ ) {
228             int code=reg.getId(null, names[i]);
229             if( hooks.length < code ) {
230                 // XXX reallocate
231 throw new RuntimeException JavaDoc( "Too many hooks " + code );
232             }
233             NotificationListener JavaDoc listeners[]=hooks[code];
234             if( listeners== null ) {
235
236             }
237
238
239         }
240     }
241
242 }
243
244
245 /**
246  * Utility class representing a particular registered listener entry.
247  */
248
249 class BaseNotificationBroadcasterEntry {
250
251     public BaseNotificationBroadcasterEntry(NotificationListener JavaDoc listener,
252                                             NotificationFilter JavaDoc filter,
253                                             Object JavaDoc handback) {
254         this.listener = listener;
255         this.filter = filter;
256         this.handback = handback;
257     }
258
259     public NotificationFilter JavaDoc filter = null;
260
261     public Object JavaDoc handback = null;
262
263     public NotificationListener JavaDoc listener = null;
264
265 }
266
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