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1
19
20 package org.netbeans.modules.retouche.source.util;
21
22 import java.lang.management.ManagementFactory  ;
23 import java.lang.management.MemoryMXBean ;
24 import java.lang.management.MemoryNotificationInfo ;
25 import java.lang.management.MemoryPoolMXBean ;
26 import java.lang.management.MemoryType ;
27 import java.lang.management.MemoryUsage ;
28 import java.util.ArrayList ;
29 import java.util.List ;
30 import javax.management.ListenerNotFoundException ;
31 import javax.management.Notification ;
32 import javax.management.NotificationEmitter ;
33 import javax.management.NotificationListener ;
34 import org.openide.ErrorManager;
35
36
45 public class LowMemoryNotifier {
46
47 private static final float DEFAULT_HEAP_LIMIT = 0.9f;
48
49 private static LowMemoryNotifier instance;
50
51 private final NotificationListener notificationListener = new Listener ();
52 private final List <LowMemoryListener> listeners;
53 private MemoryPoolMXBean pool;
54 private MemoryPoolMXBean cachedPool; private float heapLimit;
56
57
58
59 private LowMemoryNotifier() {
60 this.heapLimit = DEFAULT_HEAP_LIMIT;
61 this.listeners = new ArrayList <LowMemoryListener> ();
62 }
63
64
65 float getHeapLimit () {
66 return this.heapLimit;
67 }
68
69 void setHeapLimit (float heapLimit) {
70 this.heapLimit = heapLimit;
71 synchronized (this) {
72 if (this.pool != null) {
73 MemoryUsage mu = pool.getUsage();
74 this.pool.setUsageThreshold ((long)(mu.getMax() * heapLimit));
75 }
76 }
77 }
78
79
80 public synchronized void addLowMemoryListener (final LowMemoryListener listener) {
81 assert listener != null;
82 if (this.pool == null) {
83 this.pool = initJMX ();
84 }
85 assert this.pool != null;
86 final MemoryUsage usage = this.pool.getUsage();
87 assert usage != null : String.format("Pool %s returned null MemoryUsage, Valid: %s\n",this.pool.getName(),this.pool.isValid() ? Boolean.TRUE : Boolean.FALSE);
88 if (usage != null && usage.getUsed() >= this.pool.getUsageThreshold()) {
89 listener.lowMemory (new LowMemoryEvent (this, this.pool));
90 }
91 this.listeners.add (listener);
92 }
93
94 public synchronized void removeLowMemoryListener (final LowMemoryListener listener) {
95 assert listener != null;
96 this.listeners.remove (listener);
97 if (this.listeners.isEmpty() && this.pool != null) {
98 finishJMX (this.pool);
99 this.pool = null;
100 }
101 }
102
103 private void fireLowMemory () {
104 LowMemoryListener[] _listeners;
105 MemoryPoolMXBean _pool;
106 synchronized (this) {
107 _listeners = this.listeners.toArray(new LowMemoryListener[this.listeners.size()]);
108 _pool = this.pool;
109 }
110 if (_listeners.length > 0) {
111 assert _pool != null;
112 final LowMemoryEvent event = new LowMemoryEvent (this, _pool);
113 for (LowMemoryListener l : _listeners) {
114 l.lowMemory(event);
115 }
116 }
117 }
118
119 private MemoryPoolMXBean initJMX () {
120 List <MemoryPoolMXBean > pools = null;
121 if (this.cachedPool == null || !this.cachedPool.isValid()) {
122 pools = ManagementFactory.getMemoryPoolMXBeans();
123 for (MemoryPoolMXBean pool : pools) {
124 if (pool.getType() == MemoryType.HEAP && pool.isUsageThresholdSupported()) { this.cachedPool = pool;
126 break;
127 }
128 }
129 }
130 assert this.cachedPool != null : dumpMemoryPoolMXBean (pools);
131 if (this.cachedPool != null) {
132 MemoryUsage mu = this.cachedPool.getUsage();
133 this.cachedPool.setUsageThreshold((long)(mu.getMax() * heapLimit));
134 MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
135 ((NotificationEmitter )mbean).addNotificationListener(this.notificationListener,null,null);
136 }
137 return this.cachedPool;
138 }
139
140 private void finishJMX (final MemoryPoolMXBean pool) {
141 assert pool != null;
142 try {
143 MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
144 ((NotificationEmitter )mbean).removeNotificationListener(this.notificationListener);
145 } catch (ListenerNotFoundException e) {
146 ErrorManager.getDefault().notify(e);
147 }
148 pool.setUsageThreshold(0);
149 }
150
151 private class Listener implements NotificationListener {
152 public void handleNotification(Notification notification, Object handback) {
153 final String notificationType = notification.getType();
154 if (notificationType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {
155 fireLowMemory ();
156 }
157 }
158
159 }
160
161 private static String dumpMemoryPoolMXBean (List <MemoryPoolMXBean > pools) {
162 StringBuilder sb = new StringBuilder ();
163 for (MemoryPoolMXBean pool : pools) {
164 sb.append(String.format("Pool: %s Type: %s TresholdSupported: %s\n", pool.getName(), pool.getType(), pool.isUsageThresholdSupported() ? Boolean.TRUE : Boolean.FALSE));
165 }
166 sb.append('\n');
167 return sb.toString();
168 }
169
170 public static synchronized LowMemoryNotifier getDefault () {
171 if (instance == null) {
172 instance = new LowMemoryNotifier ();
173 }
174 return instance;
175 }
176
177 }
178 |
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