001 /* MemoryNotificationInfo.java - Emitted memory notification info.
002 Copyright (C) 2006 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.lang.management;
039
040 import gnu.java.lang.management.MemoryMXBeanImpl;
041
042 import javax.management.openmbean.CompositeData;
043 import javax.management.openmbean.CompositeType;
044 import javax.management.openmbean.SimpleType;
045
046 /**
047 * <p>
048 * Represents the content of a notification emitted by the
049 * {@link MemoryMXBean}. Such notifications are emitted when
050 * one of the memory pools exceeds its usage or collection
051 * usage threshold. This object contains the following information,
052 * representing the state of the pool at the time of the
053 * notification:
054 * </p>
055 * <ul>
056 * <li>The name of the pool.</li>
057 * <li>The memory usage of the pool at the time of notification.</li>
058 * <li>The number of times the pool has exceeded this particular
059 * threshold in the past.</li>
060 * </ul>
061 * <p>
062 * Two types of notification are emitted by the {@link MemoryMXBean}:
063 * one for exceeding the usage threshold and one for exceeding the
064 * collection usage threshold. The value returned by {@link #getCount()}
065 * is dependent on this type; if the threshold exceeded is the usage
066 * threshold, then the usage threshold count is returned. If, instead,
067 * the collection usage threshold is exceeded, then the collection usage
068 * threshold count is returned.
069 * </p>
070 * <p>
071 * This data is held in the user data part of the notification (returned
072 * by {@link javax.management.Notification#getUserData()}) encapsulated in
073 * a {@link javax.management.openmbean.CompositeData} object. The
074 * {@link #from(javax.management.openmbean.CompositeData)} method may be
075 * used to unwrap the value and obtain an instance of this class.
076 * </p>
077 *
078 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
079 * @since 1.5
080 */
081 public class MemoryNotificationInfo
082 {
083
084 /**
085 * The type of notification emitted when the usage threshold is exceeded.
086 * After a notification is emitted, the usage level must drop below the
087 * threshold again before another notification is emitted. The value is
088 * <code>java.management.memory.threshold.exceeded</code>.
089 */
090 public static final String MEMORY_THRESHOLD_EXCEEDED =
091 "java.management.memory.threshold.exceeded";
092
093 /**
094 * The type of notification emitted when the collection usage threshold
095 * is exceeded, following a garbage collection cycle. The value is
096 * <code>java.management.memory.collection.threshold.exceeded</code>.
097 */
098 public static final String MEMORY_COLLECTION_THRESHOLD_EXCEEDED =
099 "java.management.memory.collection.threshold.exceeded";
100
101 /**
102 * The name of the memory pool which exceeded the threshold.
103 */
104 private String poolName;
105
106 /**
107 * The usage level of the memory pool at the time of notification.
108 */
109 private MemoryUsage usage;
110
111 /**
112 * The number of times the threshold has been crossed.
113 */
114 private long count;
115
116 /**
117 * Constructs a new {@link MemoryNotificationInfo} object using the
118 * specified pool name, usage level and threshold crossing count.
119 *
120 * @param poolName the name of the pool which has exceeded a threshold.
121 * @param usage the usage level of the pool at the time of notification.
122 * @param count the number of times the threshold has been crossed.
123 */
124 public MemoryNotificationInfo(String poolName, MemoryUsage usage, long count)
125 {
126 this.poolName = poolName;
127 this.usage = usage;
128 this.count = count;
129 }
130
131 /**
132 * <p>
133 * Returns a {@link MemoryNotificationInfo} instance using the values
134 * given in the supplied
135 * {@link javax.management.openmbean.CompositeData} object.
136 * The composite data instance should contain the following
137 * attributes with the specified types:
138 * </p>
139 * <table>
140 * <th><td>Name</td><td>Type</td></th>
141 * <tr><td>poolName</td><td>java.lang.String</td></tr>
142 * <tr><td>usage</td><td>javax.management.openmbean.CompositeData
143 * </td></tr>
144 * <tr><td>count</td><td>java.lang.Long</td></tr>
145 * </table>
146 * <p>
147 * The usage level is further described as:
148 * </p>
149 * <table>
150 * <th><td>Name</td><td>Type</td></th>
151 * <tr><td>init</td><td>java.lang.Long</td></tr>
152 * <tr><td>used</td><td>java.lang.Long</td></tr>
153 * <tr><td>committed</td><td>java.lang.Long</td></tr>
154 * <tr><td>max</td><td>java.lang.Long</td></tr>
155 * </table>
156 *
157 * @param data the composite data structure to take values from.
158 * @return a new instance containing the values from the
159 * composite data structure, or <code>null</code>
160 * if the data structure was also <code>null</code>.
161 * @throws IllegalArgumentException if the composite data structure
162 * does not match the structure
163 * outlined above.
164 */
165 public static MemoryNotificationInfo from(CompositeData data)
166 {
167 if (data == null)
168 return null;
169 CompositeType type = data.getCompositeType();
170 ThreadInfo.checkAttribute(type, "poolName", SimpleType.STRING);
171 ThreadInfo.checkAttribute(type, "usage", MemoryMXBeanImpl.usageType);
172 ThreadInfo.checkAttribute(type, "count", SimpleType.LONG);
173 MemoryUsage usage = MemoryUsage.from((CompositeData) data.get("usage"));
174 return new MemoryNotificationInfo(((String) data.get("poolName")),
175 usage,
176 ((Long) data.get("count")).longValue());
177 }
178
179 /**
180 * Returns the number of times the memory pool has crossed the usage
181 * threshold, as of the time of notification. If this is the notification
182 * represented by the type {@link #MEMORY_THRESHOLD_EXCEEDED}, then the
183 * count is the usage threshold count. If this is the notification
184 * represented by the type {@link #MEMORY_COLLECTION_THRESHOLD_EXCEEDED},
185 * then the count is the collection usage threshold count.
186 *
187 * @return the number of times the appropriate threshold has been crossed.
188 */
189 public long getCount()
190 {
191 return count;
192 }
193
194 /**
195 * Returns the name of the pool which has crossed a threshold.
196 *
197 * @return the name of the pool.
198 */
199 public String getPoolName()
200 {
201 return poolName;
202 }
203
204 /**
205 * Returns the usage levels at the time of notification.
206 *
207 * @return the usage levels.
208 */
209 public MemoryUsage getUsage()
210 {
211 return usage;
212 }
213
214 }