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/* * @(#)MemoryNotificationInfo.java 1.8 06/03/08 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.lang.management; import javax.management.openmbean.CompositeData; import sun.management.MemoryNotifInfoCompositeData; /** * The information about a memory notification. * * <p> * A memory notification is emitted by {@link MemoryMXBean} * when the Java virtual machine detects that the memory usage * of a memory pool is exceeding a threshold value. * The notification emitted will contain the memory notification * information about the detected condition: * <ul> * <li>The name of the memory pool.</li> * <li>The memory usage of the memory pool when the notification * was constructed.</li> * <li>The number of times that the memory usage has crossed * a threshold when the notification was constructed. * For usage threshold notifications, this count will be the * {@link MemoryPoolMXBean#getUsageThresholdCount usage threshold * count}. For collection threshold notifications, * this count will be the * {@link MemoryPoolMXBean#getCollectionUsageThresholdCount * collection usage threshold count}. * </li> * </ul> * * <p> * A {@link CompositeData CompositeData} representing * the <tt>MemoryNotificationInfo</tt> object * is stored in the * {@link javax.management.Notification#setUserData user data} * of a {@link javax.management.Notification notification}. * The {@link #from from} method is provided to convert from * a <tt>CompositeData</tt> to a <tt>MemoryNotificationInfo</tt> * object. For example: * * <blockquote><pre> * Notification notif; * * // receive the notification emitted by MemoryMXBean and set to notif * ... * * String notifType = notif.getType(); * if (notifType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED) || * notifType.equals(MemoryNotificationInfo.MEMORY_COLLECTION_THRESHOLD_EXCEEDED)) { * // retrieve the memory notification information * CompositeData cd = (CompositeData) notif.getUserData(); * MemoryNotificationInfo info = MemoryNotificationInfo.from(cd); * .... * } * </pre></blockquote> * * <p> * The types of notifications emitted by <tt>MemoryMXBean</tt> are: * <ul> * <li>A {@link #MEMORY_THRESHOLD_EXCEEDED * usage threshold exceeded notification}. * <br>This notification will be emitted when * the memory usage of a memory pool is increased and has reached * or exceeded its * <a href="MemoryPoolMXBean.html#UsageThreshold"> usage threshold</a> value. * Subsequent crossing of the usage threshold value does not cause * further notification until the memory usage has returned * to become less than the usage threshold value. * <p></li> * <li>A {@link #MEMORY_COLLECTION_THRESHOLD_EXCEEDED * collection usage threshold exceeded notification}. * <br>This notification will be emitted when * the memory usage of a memory pool is greater than or equal to its * <a href="MemoryPoolMXBean.html#CollectionThreshold"> * collection usage threshold</a> after the Java virtual machine * has expended effort in recycling unused objects in that * memory pool.</li> * </ul> * * @author Mandy Chung * @version 1.8, 03/08/06 * @since 1.5 * */ public class MemoryNotificationInfo { private final String poolName; private final MemoryUsage usage; private final long count; /** * Notification type denoting that * the memory usage of a memory pool has * reached or exceeded its * <a href="MemoryPoolMXBean.html#UsageThreshold"> usage threshold</a> value. * This notification is emitted by {@link MemoryMXBean}. * Subsequent crossing of the usage threshold value does not cause * further notification until the memory usage has returned * to become less than the usage threshold value. * The value of this notification type is * <tt>java.management.memory.threshold.exceeded</tt>. */ public static final String MEMORY_THRESHOLD_EXCEEDED = "java.management.memory.threshold.exceeded"; /** * Notification type denoting that * the memory usage of a memory pool is greater than or equal to its * <a href="MemoryPoolMXBean.html#CollectionThreshold"> * collection usage threshold</a> after the Java virtual machine * has expended effort in recycling unused objects in that * memory pool. * This notification is emitted by {@link MemoryMXBean}. * The value of this notification type is * <tt>java.management.memory.collection.threshold.exceeded</tt>. */ public static final String MEMORY_COLLECTION_THRESHOLD_EXCEEDED = "java.management.memory.collection.threshold.exceeded"; /** * Constructs a <tt>MemoryNotificationInfo</tt> object. * * @param poolName The name of the memory pool which triggers this notification. * @param usage Memory usage of the memory pool. * @param count The threshold crossing count. */ public MemoryNotificationInfo(String poolName, MemoryUsage usage, long count) { if (poolName == null) { throw new NullPointerException("Null poolName"); } if (usage == null) { throw new NullPointerException("Null usage"); } this.poolName = poolName; this.usage = usage; this.count = count; } MemoryNotificationInfo(CompositeData cd) { MemoryNotifInfoCompositeData.validateCompositeData(cd); this.poolName = MemoryNotifInfoCompositeData.getPoolName(cd); this.usage = MemoryNotifInfoCompositeData.getUsage(cd); this.count = MemoryNotifInfoCompositeData.getCount(cd); } /** * Returns the name of the memory pool that triggers this notification. * The memory pool usage has crossed a threshold. * * @return the name of the memory pool that triggers this notification. */ public String getPoolName() { return poolName; } /** * Returns the memory usage of the memory pool * when this notification was constructed. * * @return the memory usage of the memory pool * when this notification was constructed. */ public MemoryUsage getUsage() { return usage; } /** * Returns the number of times that the memory usage has crossed * a threshold when the notification was constructed. * For usage threshold notifications, this count will be the * {@link MemoryPoolMXBean#getUsageThresholdCount threshold * count}. For collection threshold notifications, * this count will be the * {@link MemoryPoolMXBean#getCollectionUsageThresholdCount * collection usage threshold count}. * * @return the number of times that the memory usage has crossed * a threshold when the notification was constructed. */ public long getCount() { return count; } /** * Returns a <tt>MemoryNotificationInfo</tt> object represented by the * given <tt>CompositeData</tt>. * The given <tt>CompositeData</tt> must contain * the following attributes: * <blockquote> * <table border> * <tr> * <th align=left>Attribute Name</th> * <th align=left>Type</th> * </tr> * <tr> * <td>poolName</td> * <td><tt>java.lang.String</tt></td> * </tr> * <tr> * <td>usage</td> * <td><tt>javax.management.openmbean.CompositeData</tt></td> * </tr> * <tr> * <td>count</td> * <td><tt>java.lang.Long</tt></td> * </tr> * </table> * </blockquote> * * @param cd <tt>CompositeData</tt> representing a * <tt>MemoryNotificationInfo</tt> * * @throws IllegalArgumentException if <tt>cd</tt> does not * represent a <tt>MemoryNotificationInfo</tt> object. * * @return a <tt>MemoryNotificationInfo</tt> object represented * by <tt>cd</tt> if <tt>cd</tt> is not <tt>null</tt>; * <tt>null</tt> otherwise. */ public static MemoryNotificationInfo from(CompositeData cd) { if (cd == null) { return null; } if (cd instanceof MemoryNotifInfoCompositeData) { return ((MemoryNotifInfoCompositeData) cd).getMemoryNotifInfo(); } else { return new MemoryNotificationInfo(cd); } } }