1 /*
2 * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package com.sun.management;
27
28 import com.sun.management.internal.VMOptionCompositeData;
29 import javax.management.openmbean.CompositeData;
30
31 /**
32 * Information about a VM option including its value and
33 * where the value came from which is referred as its
34 * {@link VMOption.Origin <i>origin</i>}.
35 * <p>
36 * Each VM option has a default value. A VM option can
37 * be set at VM creation time typically as a command line
38 * argument to the launcher or an argument passed to the
39 * VM created using the JNI invocation interface.
40 * In addition, a VM option may be set via an environment
41 * variable or a configuration file. A VM option can also
42 * be set dynamically via a management interface after
43 * the VM was started.
44 *
45 * A {@code VMOption} contains the value of a VM option
46 * and the origin of that value at the time this {@code VMOption}
47 * object was constructed. The value of the VM option
48 * may be changed after the {@code VMOption} object was constructed,
49 *
50 * @see <a href="{@docRoot}/../../../../technotes/guides/vm/index.html">
51 * Java Virtual Machine</a>
52 * @author Mandy Chung
53 * @since 1.6
54 */
55 @jdk.Exported
56 public class VMOption {
57 private String name;
58 private String value;
59 private boolean writeable;
60 private Origin origin;
61
62 /**
63 * Origin of the value of a VM option. It tells where the
64 * value of a VM option came from.
65 *
66 * @since 1.6
67 */
68 @jdk.Exported
69 public enum Origin {
70 /**
71 * The VM option has not been set and its value
72 * is the default value.
73 */
74 DEFAULT,
75 /**
76 * The VM option was set at VM creation time typically
77 * as a command line argument to the launcher or
78 * an argument passed to the VM created using the
79 * JNI invocation interface.
80 */
81 VM_CREATION,
82 /**
83 * The VM option was set via an environment variable.
84 */
85 ENVIRON_VAR,
86 /**
87 * The VM option was set via a configuration file.
88 */
89 CONFIG_FILE,
90 /**
91 * The VM option was set via the management interface after the VM
92 * was started.
93 */
94 MANAGEMENT,
95 /**
96 * The VM option was set via the VM ergonomic support.
97 */
98 ERGONOMIC,
99 /**
100 * The VM option was set using the attach framework.
101 * @since 9
102 */
103 ATTACH_ON_DEMAND,
104 /**
105 * The VM option was set via some other mechanism.
106 */
107 OTHER
108 }
109
110 /**
111 * Constructs a {@code VMOption}.
112 *
113 * @param name Name of a VM option.
114 * @param value Value of a VM option.
115 * @param writeable {@code true} if a VM option can be set dynamically,
116 * or {@code false} otherwise.
117 * @param origin where the value of a VM option came from.
118 *
119 * @throws NullPointerException if the name or value is {@code null}
120 */
121 public VMOption(String name, String value, boolean writeable, Origin origin) {
122 this.name = name;
123 this.value = value;
124 this.writeable = writeable;
125 this.origin = origin;
126 }
127
128 /**
129 * Constructs a {@code VMOption} object from a
130 * {@link CompositeData CompositeData}.
131 */
132 private VMOption(CompositeData cd) {
133 // validate the input composite data
134 VMOptionCompositeData.validateCompositeData(cd);
135
136 this.name = VMOptionCompositeData.getName(cd);
137 this.value = VMOptionCompositeData.getValue(cd);
138 this.writeable = VMOptionCompositeData.isWriteable(cd);
139 this.origin = VMOptionCompositeData.getOrigin(cd);
140 }
141
142 /**
143 * Returns the name of this VM option.
144 *
145 * @return the name of this VM option.
146 */
147 public String getName() {
148 return name;
149 }
150
151 /**
152 * Returns the value of this VM option at the time when
153 * this {@code VMOption} was created. The value could have been changed.
154 *
155 * @return the value of the VM option at the time when
156 * this {@code VMOption} was created.
157 */
158 public String getValue() {
159 return value;
160 }
161
162 /**
163 * Returns the origin of the value of this VM option. That is,
164 * where the value of this VM option came from.
165 *
166 * @return where the value of this VM option came from.
167 */
168 public Origin getOrigin() {
169 return origin;
170 }
171
172 /**
173 * Tests if this VM option is writeable. If this VM option is writeable,
174 * it can be set by the {@link HotSpotDiagnosticMXBean#setVMOption
175 * HotSpotDiagnosticMXBean.setVMOption} method.
176 *
177 * @return {@code true} if this VM option is writeable; {@code false}
178 * otherwise.
179 */
180 public boolean isWriteable() {
181 return writeable;
182 }
183
184 public String toString() {
185 return "VM option: " + getName() +
186 " value: " + value + " " +
187 " origin: " + origin + " " +
188 (writeable ? "(read-write)" : "(read-only)");
189 }
190
191 /**
192 * Returns a {@code VMOption} object represented by the
193 * given {@code CompositeData}. The given {@code CompositeData}
194 * must contain the following attributes:
195 *
196 * <blockquote>
197 * <table border>
198 * <tr>
199 * <th align=left>Attribute Name</th>
200 * <th align=left>Type</th>
201 * </tr>
202 * <tr>
203 * <td>name</td>
204 * <td>{@code java.lang.String}</td>
205 * </tr>
206 * <tr>
207 * <td>value</td>
208 * <td>{@code java.lang.String}</td>
209 * </tr>
210 * <tr>
211 * <td>origin</td>
212 * <td>{@code java.lang.String}</td>
213 * </tr>
214 * <tr>
215 * <td>writeable</td>
216 * <td>{@code java.lang.Boolean}</td>
217 * </tr>
218 * </table>
219 * </blockquote>
220 *
221 * @param cd {@code CompositeData} representing a {@code VMOption}
222 *
223 * @throws IllegalArgumentException if {@code cd} does not
224 * represent a {@code VMOption} with the attributes described
225 * above.
226 *
227 * @return a {@code VMOption} object represented by {@code cd}
228 * if {@code cd} is not {@code null};
229 * {@code null} otherwise.
230 */
231 public static VMOption from(CompositeData cd) {
232 if (cd == null) {
233 return null;
234 }
235
236 if (cd instanceof VMOptionCompositeData) {
237 return ((VMOptionCompositeData) cd).getVMOption();
238 } else {
239 return new VMOption(cd);
240 }
241
242 }
243
244 // for sun.management.MappedMXBeanType
245 static CompositeData toCompositeData(VMOption option) {
246 return VMOptionCompositeData.toCompositeData(option);
247 }
248 }