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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

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 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

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 {@code MemoryNotificationInfo} 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 {@code CompositeData} to a {@code MemoryNotificationInfo}

 * 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 {@code MemoryMXBean} 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.

 *       </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

 * @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

     * {@code java.management.memory.threshold.exceeded}.

     */

    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

     * {@code java.management.memory.collection.threshold.exceeded}.

     */

    public static final String MEMORY_COLLECTION_THRESHOLD_EXCEEDED =

        "java.management.memory.collection.threshold.exceeded";

    /**

     * Constructs a {@code MemoryNotificationInfo} 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 {@code MemoryNotificationInfo} object represented by the

     * given {@code CompositeData}.

     * The given {@code CompositeData} must contain

     * the following attributes:

     * <table class="striped" style="margin-left:2em">

     * <caption style="display:none">The attributes and the types the given CompositeData contains</caption>

     * <thead>

     * <tr>

     *   <th scope="col">Attribute Name</th>

     *   <th scope="col">Type</th>

     * </tr>

     * </thead>

     * <tbody style="text-align:left">

     * <tr>

     *   <th scope="row">poolName</th>

     *   <td>{@code java.lang.String}</td>

     * </tr>

     * <tr>

     *   <th scope="row">usage</th>

     *   <td>{@code javax.management.openmbean.CompositeData}</td>

     * </tr>

     * <tr>

     *   <th scope="row">count</th>

     *   <td>{@code java.lang.Long}</td>

     * </tr>

     * </tbody>

     * </table>

     *

     * @param cd {@code CompositeData} representing a

     *           {@code MemoryNotificationInfo}

     *

     * @throws IllegalArgumentException if {@code cd} does not

     *   represent a {@code MemoryNotificationInfo} object.

     *

     * @return a {@code MemoryNotificationInfo} object represented

     *         by {@code cd} if {@code cd} is not {@code null};

     *         {@code null} 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);

        }

    }

}