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1
19
20 package org.netbeans.modules.java.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
40 public class LowMemoryNotifier {
41
42 private static final float DEFAULT_HEAP_LIMIT = 0.9f;
43
44 private static LowMemoryNotifier instance;
45
46 private final NotificationListener notificationListener = new Listener ();
47 private final List <LowMemoryListener> listeners;
48 private MemoryPoolMXBean pool;
49 private MemoryPoolMXBean cachedPool; private float heapLimit;
51
52
53
54 private LowMemoryNotifier() {
55 this.heapLimit = DEFAULT_HEAP_LIMIT;
56 this.listeners = new ArrayList <LowMemoryListener> ();
57 }
58
59
60 float getHeapLimit () {
61 return this.heapLimit;
62 }
63
64 void setHeapLimit (float heapLimit) {
65 this.heapLimit = heapLimit;
66 synchronized (this) {
67 if (this.pool != null) {
68 MemoryUsage mu = pool.getUsage();
69 this.pool.setUsageThreshold ((long)(mu.getMax() * heapLimit));
70 }
71 }
72 }
73
74
75 public synchronized void addLowMemoryListener (final LowMemoryListener listener) {
76 assert listener != null;
77 if (this.pool == null) {
78 this.pool = initJMX ();
79 }
80 assert this.pool != null;
81 final MemoryUsage usage = this.pool.getUsage();
82 assert usage != null : String.format("Pool %s returned null MemoryUsage, Valid: %s\n",this.pool.getName(),this.pool.isValid() ? Boolean.TRUE : Boolean.FALSE);
83 if (usage != null && usage.getUsed() >= this.pool.getUsageThreshold()) {
84 listener.lowMemory (new LowMemoryEvent (this, this.pool));
85 }
86 this.listeners.add (listener);
87 }
88
89 public synchronized void removeLowMemoryListener (final LowMemoryListener listener) {
90 assert listener != null;
91 this.listeners.remove (listener);
92 if (this.listeners.isEmpty() && this.pool != null) {
93 finishJMX (this.pool);
94 this.pool = null;
95 }
96 }
97
98 private void fireLowMemory () {
99 LowMemoryListener[] _listeners;
100 MemoryPoolMXBean _pool;
101 synchronized (this) {
102 _listeners = this.listeners.toArray(new LowMemoryListener[this.listeners.size()]);
103 _pool = this.pool;
104 }
105 if (_listeners.length > 0) {
106 assert _pool != null;
107 final LowMemoryEvent event = new LowMemoryEvent (this, _pool);
108 for (LowMemoryListener l : _listeners) {
109 l.lowMemory(event);
110 }
111 }
112 }
113
114 private MemoryPoolMXBean initJMX () {
115 List <MemoryPoolMXBean > pools = null;
116 if (this.cachedPool == null || !this.cachedPool.isValid()) {
117 pools = ManagementFactory.getMemoryPoolMXBeans();
118 for (MemoryPoolMXBean pool : pools) {
119 if (pool.getType() == MemoryType.HEAP && pool.isUsageThresholdSupported()) { this.cachedPool = pool;
121 break;
122 }
123 }
124 }
125 assert this.cachedPool != null : dumpMemoryPoolMXBean (pools);
126 if (this.cachedPool != null) {
127 MemoryUsage mu = this.cachedPool.getUsage();
128 this.cachedPool.setUsageThreshold((long)(mu.getMax() * heapLimit));
129 MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
130 ((NotificationEmitter )mbean).addNotificationListener(this.notificationListener,null,null);
131 }
132 return this.cachedPool;
133 }
134
135 private void finishJMX (final MemoryPoolMXBean pool) {
136 assert pool != null;
137 try {
138 MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
139 ((NotificationEmitter )mbean).removeNotificationListener(this.notificationListener);
140 } catch (ListenerNotFoundException e) {
141 ErrorManager.getDefault().notify(e);
142 }
143 pool.setUsageThreshold(0);
144 }
145
146 private class Listener implements NotificationListener {
147 public void handleNotification(Notification notification, Object handback) {
148 final String notificationType = notification.getType();
149 if (notificationType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {
150 fireLowMemory ();
151 }
152 }
153
154 }
155
156 private static String dumpMemoryPoolMXBean (List <MemoryPoolMXBean > pools) {
157 StringBuilder sb = new StringBuilder ();
158 for (MemoryPoolMXBean pool : pools) {
159 sb.append(String.format("Pool: %s Type: %s TresholdSupported: %s\n", pool.getName(), pool.getType(), pool.isUsageThresholdSupported() ? Boolean.TRUE : Boolean.FALSE));
160 }
161 sb.append('\n');
162 return sb.toString();
163 }
164
165 public static synchronized LowMemoryNotifier getDefault () {
166 if (instance == null) {
167 instance = new LowMemoryNotifier ();
168 }
169 return instance;
170 }
171
172 }
173 |
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