/*
* @(#)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);
}
}
}
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