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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.management; | ||
| 27 | |||
| 28 | import javax.management.ListenerNotFoundException; | ||
| 29 | import javax.management.MBeanNotificationInfo; | ||
| 30 | import javax.management.Notification; | ||
| 31 | import javax.management.NotificationEmitter; | ||
| 32 | import javax.management.NotificationFilter; | ||
| 33 | import javax.management.NotificationListener; | ||
| 34 | |||
| 35 | import java.util.List; | ||
| 36 | import java.util.ArrayList; | ||
| 37 | import java.util.ListIterator; | ||
| 38 | import java.util.Collections; | ||
| 39 | |||
| 40 | /** | ||
| 41 | * Abstract helper class for notification emitter support. | ||
| 42 | */ | ||
| 43 | abstract class NotificationEmitterSupport implements NotificationEmitter { | ||
| 44 | |||
| 45 | protected NotificationEmitterSupport() { | ||
| 46 | } | ||
| 47 | |||
| 48 | private Object listenerLock = new Object(); | ||
| 49 | |||
| 50 | // Implementation of NotificationEmitter interface | ||
| 51 | // Cloned from JMX NotificationBroadcasterSupport class. | ||
| 52 | public void addNotificationListener(NotificationListener listener, | ||
| 53 | NotificationFilter filter, | ||
| 54 | Object handback) { | ||
| 55 | |||
| 56 | if (listener == null) { | ||
| 57 | throw new IllegalArgumentException ("Listener can't be null") ; | ||
| 58 | } | ||
| 59 | |||
| 60 | /* Adding a new listener takes O(n) time where n is the number | ||
| 61 | of existing listeners. If you have a very large number of | ||
| 62 | listeners performance could degrade. That's a fairly | ||
| 63 | surprising configuration, and it is hard to avoid this | ||
| 64 | behaviour while still retaining the property that the | ||
| 65 | listenerList is not synchronized while notifications are | ||
| 66 | being sent through it. If this becomes a problem, a | ||
| 67 | possible solution would be a multiple-readers single-writer | ||
| 68 | setup, so any number of sendNotification() calls could run | ||
| 69 | concurrently but they would exclude an | ||
| 70 | add/removeNotificationListener. A simpler but less | ||
| 71 | efficient solution would be to clone the listener list | ||
| 72 | every time a notification is sent. */ | ||
| 73 | synchronized (listenerLock) { | ||
| 74 | List<ListenerInfo> newList = new ArrayList<ListenerInfo>(listenerList.size() + 1); | ||
| 75 | newList.addAll(listenerList); | ||
| 76 | newList.add(new ListenerInfo(listener, filter, handback)); | ||
| 77 | listenerList = newList; | ||
| 78 | } | ||
| 79 | } | ||
| 80 | |||
| 81 | public void removeNotificationListener(NotificationListener listener) | ||
| 82 | throws ListenerNotFoundException { | ||
| 83 | |||
| 84 | synchronized (listenerLock) { | ||
| 85 | List<ListenerInfo> newList = new ArrayList<ListenerInfo>(listenerList); | ||
| 86 | /* We scan the list of listeners in reverse order because | ||
| 87 | in forward order we would have to repeat the loop with | ||
| 88 | the same index after a remove. */ | ||
| 89 | for (int i=newList.size()-1; i>=0; i--) { | ||
| 90 | ListenerInfo li = (ListenerInfo)newList.get(i); | ||
| 91 | |||
| 92 | if (li.listener == listener) | ||
| 93 | newList.remove(i); | ||
| 94 | } | ||
| 95 | if (newList.size() == listenerList.size()) | ||
| 96 | throw new ListenerNotFoundException("Listener not registered"); | ||
| 97 | listenerList = newList; | ||
| 98 | } | ||
| 99 | } | ||
| 100 | |||
| 101 | public void removeNotificationListener(NotificationListener listener, | ||
| 102 | NotificationFilter filter, | ||
| 103 | Object handback) | ||
| 104 | throws ListenerNotFoundException { | ||
| 105 | |||
| 106 | boolean found = false; | ||
| 107 | |||
| 108 | synchronized (listenerLock) { | ||
| 109 | List<ListenerInfo> newList = new ArrayList<ListenerInfo>(listenerList); | ||
| 110 | final int size = newList.size(); | ||
| 111 | for (int i = 0; i < size; i++) { | ||
| 112 | ListenerInfo li = (ListenerInfo) newList.get(i); | ||
| 113 | |||
| 114 | if (li.listener == listener) { | ||
| 115 | found = true; | ||
| 116 | if (li.filter == filter | ||
| 117 | && li.handback == handback) { | ||
| 118 | newList.remove(i); | ||
| 119 | listenerList = newList; | ||
| 120 | return; | ||
| 121 | } | ||
| 122 | } | ||
| 123 | } | ||
| 124 | } | ||
| 125 | |||
| 126 | if (found) { | ||
| 127 | /* We found this listener, but not with the given filter | ||
| 128 | * and handback. A more informative exception message may | ||
| 129 | * make debugging easier. */ | ||
| 130 | throw new ListenerNotFoundException("Listener not registered " + | ||
| 131 | "with this filter and " + | ||
| 132 | "handback"); | ||
| 133 | } else { | ||
| 134 | throw new ListenerNotFoundException("Listener not registered"); | ||
| 135 | } | ||
| 136 | } | ||
| 137 | |||
| 138 | void sendNotification(Notification notification) { | ||
| 139 | |||
| 140 | if (notification == null) { | ||
| 141 | return; | ||
| 142 | } | ||
| 143 | |||
| 144 | List<ListenerInfo> currentList; | ||
| 145 | synchronized (listenerLock) { | ||
| 146 | currentList = listenerList; | ||
| 147 | } | ||
| 148 | |||
| 149 | final int size = currentList.size(); | ||
| 150 | for (int i = 0; i < size; i++) { | ||
| 151 | ListenerInfo li = (ListenerInfo) currentList.get(i); | ||
| 152 | |||
| 153 | if (li.filter == null | ||
| 154 | || li.filter.isNotificationEnabled(notification)) { | ||
| 155 | try { | ||
| 156 | li.listener.handleNotification(notification, li.handback); | ||
| 157 | } catch (Exception e) { | ||
| 158 | e.printStackTrace(); | ||
| 159 | throw new AssertionError("Error in invoking listener"); | ||
| 160 | } | ||
| 161 | } | ||
| 162 | } | ||
| 163 | } | ||
| 164 | |||
| 165 | boolean hasListeners() { | ||
| 166 | synchronized (listenerLock) { | ||
| 167 | return !listenerList.isEmpty(); | ||
| 168 | } | ||
| 169 | } | ||
| 170 | |||
| 171 | private class ListenerInfo { | ||
| 172 | public NotificationListener listener; | ||
| 173 | NotificationFilter filter; | ||
| 174 | Object handback; | ||
| 175 | |||
| 176 | public ListenerInfo(NotificationListener listener, | ||
| 177 | NotificationFilter filter, | ||
| 178 | Object handback) { | ||
| 179 | this.listener = listener; | ||
| 180 | this.filter = filter; | ||
| 181 | this.handback = handback; | ||
| 182 | } | ||
| 183 | } | ||
| 184 | |||
| 185 | /** | ||
| 186 | * Current list of listeners, a List of ListenerInfo. The object | ||
| 187 | * referenced by this field is never modified. Instead, the field | ||
| 188 | * is set to a new object when a listener is added or removed, | ||
| 189 | * within a synchronized(this). In this way, there is no need to | ||
| 190 | * synchronize when traversing the list to send a notification to | ||
| 191 | * the listeners in it. That avoids potential deadlocks if the | ||
| 192 | * listeners end up depending on other threads that are themselves | ||
| 193 | * accessing this NotificationBroadcasterSupport. | ||
| 194 | */ | ||
| 195 | private List<ListenerInfo> listenerList = Collections.emptyList(); | ||
| 196 | |||
| 197 | abstract public MBeanNotificationInfo[] getNotificationInfo(); | ||
| 198 | } | ||