bundles/org.simantics/src/org/simantics/MemoryWarningSystem.java

   1 package org.simantics;\r
   2 \r
   3 import java.lang.management.ManagementFactory;\r
   4 import java.lang.management.MemoryPoolMXBean;\r
   5 import java.lang.management.MemoryType;\r
   6 import java.util.Collection;\r
   7 import java.util.concurrent.CopyOnWriteArrayList;\r
   8 import java.util.concurrent.ScheduledFuture;\r
   9 import java.util.concurrent.TimeUnit;\r
  10 \r
  11 /**\r
  12  * This memory warning system will call the listener when we exceed the\r
  13  * percentage of available memory specified. There should only be one instance\r
  14  * of this object created, since the usage threshold can only be set to one\r
  15  * number.\r
  16  * \r
  17  * ( adapted from http://www.javaspecialists.eu/archive/Issue092.html )\r
  18  * \r
  19  * @author Antti Villberg\r
  20  */\r
  21 public class MemoryWarningSystem {\r
  22 \r
  23     public interface MemoryWarningListener {\r
  24         void memoryLow(long usedMemory);\r
  25     }\r
  26 \r
  27     private final Collection<MemoryWarningListener> listeners = new CopyOnWriteArrayList<MemoryWarningListener>();\r
  28 \r
  29     private static final MemoryPoolMXBean tenuredGenPool = findTenuredGenPool();\r
  30 \r
  31     private double percentage = 1.0;\r
  32 \r
  33     private ScheduledFuture<?> future;\r
  34 \r
  35     private boolean disposed = false;\r
  36 \r
  37     public MemoryWarningSystem(int amount, TimeUnit unit) {\r
  38 //        MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();\r
  39 //        NotificationEmitter emitter = (NotificationEmitter) mbean;\r
  40 //        emitter.addNotificationListener(new NotificationListener() {\r
  41 //            @Override\r
  42 //            public void handleNotification(Notification n, Object hb) {\r
  43 //                if (n.getType().equals(\r
  44 //                        MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {\r
  45 //                      if(!check()) {\r
  46 //                              long used = getUsed();\r
  47 //                              for (MemoryWarningListener listener : listeners) {\r
  48 //                                      listener.memoryLow(used);\r
  49 //                              }\r
  50 //                      }\r
  51 //                      setPercentageUsageThreshold(percentage);\r
  52 //                }\r
  53 //            }\r
  54 //        }, null, null);\r
  55 \r
  56         future = Simantics.scheduleAtFixedRate(new Runnable() {\r
  57 \r
  58                 @Override\r
  59                 public void run() {\r
  60                         if(!disposed && !check()) {\r
  61                                 long bytes = get();\r
  62                                 for (MemoryWarningListener listener : listeners) {\r
  63                                         listener.memoryLow(bytes);\r
  64                                 }\r
  65                         }\r
  66                 }\r
  67 \r
  68         }, 0, amount, unit);\r
  69 \r
  70     }\r
  71     \r
  72     public long get() {\r
  73         return tenuredGenPool.getUsage().getUsed();\r
  74     }\r
  75     \r
  76     public boolean check() {\r
  77         long max = Runtime.getRuntime().maxMemory();\r
  78         long usedMemory = get();\r
  79         long threshold = (long)(max * percentage);\r
  80         return usedMemory < threshold;\r
  81     }\r
  82     \r
  83     public long getUsed() {\r
  84         return tenuredGenPool.getUsage().getUsed();\r
  85     }\r
  86 \r
  87     public boolean addListener(MemoryWarningListener listener) {\r
  88         return listeners.add(listener);\r
  89     }\r
  90 \r
  91     public boolean removeListener(MemoryWarningListener listener) {\r
  92         return listeners.remove(listener);\r
  93     }\r
  94 \r
  95     public void setPercentageUsageThreshold(double percentage) {\r
  96         if (percentage <= 0.0 || percentage > 1.0) {\r
  97             throw new IllegalArgumentException("Percentage not in range");\r
  98         }\r
  99         this.percentage = percentage;\r
 100 //        long maxMemory = Runtime.getRuntime().maxMemory();\r
 101 //        long warningThreshold = (long) (maxMemory * percentage);\r
 102 //        tenuredGenPool.setUsageThreshold(0);\r
 103 //        tenuredGenPool.setUsageThreshold(warningThreshold);\r
 104     }\r
 105 \r
 106     /**\r
 107      * Tenured Space Pool can be determined by it being of type HEAP and by it\r
 108      * being possible to set the usage threshold.\r
 109      */\r
 110     private static MemoryPoolMXBean findTenuredGenPool() {\r
 111         for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {\r
 112             // I don't know whether this approach is better, or whether\r
 113             // we should rather check for the pool name "Tenured Gen"?\r
 114             if (pool.getType() == MemoryType.HEAP\r
 115                     && pool.isUsageThresholdSupported()) {\r
 116                 return pool;\r
 117             }\r
 118         }\r
 119         throw new IllegalStateException("Could not find tenured space");\r
 120     }\r
 121 \r
 122     public void dispose() {\r
 123         if (!disposed) {\r
 124             disposed = true;\r
 125             future.cancel(false);\r
 126             listeners.clear();\r
 127        }\r
 128     }\r
 129 \r
 130 }