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1
22 package org.jboss.kernel.plugins.event;
23
24 import java.util.Iterator  ;
25 import java.util.List ;
26 import java.util.ListIterator ;
27 import java.util.Map ;
28
29 import org.jboss.kernel.spi.event.KernelEvent;
30 import org.jboss.kernel.spi.event.KernelEventEmitter;
31 import org.jboss.kernel.spi.event.KernelEventFilter;
32 import org.jboss.kernel.spi.event.KernelEventListener;
33 import org.jboss.logging.Logger;
34 import org.jboss.util.collection.CollectionsFactory;
35
36
42 public class AbstractEventEmitter implements KernelEventEmitter
43 {
44
45 private static final Logger log = Logger.getLogger(AbstractEventEmitter.class);
46
47
48 protected static final Object NULL = new Object ();
49
50
51 protected static final KernelEventFilter NULL_FILTER = new KernelEventFilter()
52 {
53 public boolean wantEvent(KernelEvent event, Object handback)
54 {
55 return false;
56 }
57 };
58
59
60 protected Map <KernelEventFilter, Map <Object , List <KernelEventListener>>> eventListenerRegistry = CollectionsFactory.createConcurrentReaderMap();
61
62
63 private long emitterSequence = 0;
64
65
70 public boolean hasListeners()
71 {
72 return eventListenerRegistry.isEmpty() == false;
73 }
74
75
78 public KernelEvent createEvent(String type, Object context)
79 {
80 return new AbstractEvent(this, type, nextEmitterSequence(), System.currentTimeMillis(), context);
81 }
82
83 public void registerListener(KernelEventListener listener, KernelEventFilter filter, Object handback) throws Throwable
84 {
85 KernelEventFilter filterObject = filter == null ? NULL_FILTER : filter;
86 Object handbackObject = handback == null ? NULL : handback;
87
88 synchronized (eventListenerRegistry)
89 {
90 Map <Object , List <KernelEventListener>> handbacks = eventListenerRegistry.get(filterObject);
91 if (handbacks == null)
92 {
93 handbacks = CollectionsFactory.createConcurrentReaderMap();
94 eventListenerRegistry.put(filterObject, handbacks);
95 }
96 List <KernelEventListener> listeners = handbacks.get(handbackObject);
97 if (listeners == null)
98 {
99 listeners = CollectionsFactory.createCopyOnWriteList();
100 handbacks.put(handbackObject, listeners);
101 }
102 listeners.add(listener);
103 if (log.isTraceEnabled())
104 log.trace("Registered listener: " + listener + " with filter=" + filter + " handback=" + handback + " on object " + this);
105
106 }
107 }
108
109 public void unregisterListener(KernelEventListener listener, KernelEventFilter filter, Object handback) throws Throwable
110 {
111 KernelEventFilter filterObject = filter == null ? NULL_FILTER : filter;
112 Object handbackObject = handback == null ? NULL : handback;
113
114 synchronized (eventListenerRegistry)
115 {
116 Map <Object , List <KernelEventListener>> handbacks = eventListenerRegistry.get(filterObject);
117 if (handbacks != null)
118 {
119 List <KernelEventListener> listeners = handbacks.get(handbackObject);
120 if (listeners != null && listeners.remove(listener))
121 {
122 if (log.isTraceEnabled())
123 log.trace("Unregistered listener: " + listener + " with filter=" + filter + " handback=" + handback + " on object " + this);
124 return;
125 }
126 }
127 }
128 throw new IllegalStateException ("Listener not registered.");
129 }
130
131 public void fireKernelEvent(KernelEvent event)
132 {
133 if (log.isTraceEnabled())
134 log.trace("Firing event: " + event + " on object " + this);
135 if (eventListenerRegistry.isEmpty() == false)
136 {
137 for (Iterator i = eventListenerRegistry.entrySet().iterator(); i.hasNext();)
138 {
139 Map.Entry registryEntry = (Map.Entry ) i.next();
140
141 Map handbacks = (Map ) registryEntry.getValue();
142 if (handbacks != null)
143 {
144 KernelEventFilter filter = null;
145 Object filterObject = registryEntry.getKey();
146 if (filterObject != NULL_FILTER)
147 filter = (KernelEventFilter) filterObject;
148
149 for (Iterator j = handbacks.entrySet().iterator(); j.hasNext();)
150 {
151 Map.Entry handbackEntry = (Map.Entry ) j.next();
152 List listeners = (List ) handbackEntry.getValue();
153 if (listeners != null)
154 {
155 Object handback = handbackEntry.getKey();
156 if (handback == NULL)
157 handback = null;
158
159 for (ListIterator k = listeners.listIterator(); k.hasNext();)
160 {
161 KernelEventListener listener = (KernelEventListener) k.next();
162 try
163 {
164 if (filter == null || filter.wantEvent(event, handback))
165 fireKernelEvent(listener, event, handback);
166 }
167 catch (Throwable t)
168 {
169 log.debug("Ignored unhandled throwable: ", t);
170 }
171 }
172 }
173 }
174 }
175 }
176 }
177 }
178
179
186 protected void fireKernelEvent(KernelEventListener listener, KernelEvent event, Object handback)
187 {
188 listener.onEvent(event, handback);
189 }
190
191
196 protected long nextEmitterSequence()
197 {
198 synchronized (eventListenerRegistry)
199 {
200 return emitterSequence++;
201 }
202 }
203 }
204 |
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