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 public class VMOption {
56 private String name;
57 private String value;
58 private boolean writeable;
59 private Origin origin;
60
61 /**
62 * Origin of the value of a VM option. It tells where the
63 * value of a VM option came from.
64 *
65 * @since 1.6
66 */
67 public enum Origin {
68 /**
69 * The VM option has not been set and its value
70 * is the default value.
71 */
72 DEFAULT,
73 /**
74 * The VM option was set at VM creation time typically
75 * as a command line argument to the launcher or
76 * an argument passed to the VM created using the
77 * JNI invocation interface.
78 */
79 VM_CREATION,
80 /**
81 * The VM option was set via an environment variable.
82 */
83 ENVIRON_VAR,
84 /**
85 * The VM option was set via a configuration file.
86 */
87 CONFIG_FILE,
88 /**
89 * The VM option was set via the management interface after the VM
90 * was started.
91 */
92 MANAGEMENT,
93 /**
94 * The VM option was set via the VM ergonomic support.
95 */
96 ERGONOMIC,
97 /**
98 * The VM option was set using the attach framework.
99 * @since 1.9
100 */
101 ATTACH_ON_DEMAND,
102 /**
103 * The VM option was set via some other mechanism.
104 */
105 OTHER
106 }
107
108 /**
109 * Constructs a {@code VMOption}.
110 *
111 * @param name Name of a VM option.
112 * @param value Value of a VM option.
113 * @param writeable {@code true} if a VM option can be set dynamically,
114 * or {@code false} otherwise.
115 * @param origin where the value of a VM option came from.
116 *
117 * @throws NullPointerException if the name or value is {@code null}
118 */
119 public VMOption(String name, String value, boolean writeable, Origin origin) {
120 this.name = name;
121 this.value = value;
122 this.writeable = writeable;
123 this.origin = origin;
124 }
125
126 /**
127 * Constructs a {@code VMOption} object from a
128 * {@link CompositeData CompositeData}.
129 */
130 private VMOption(CompositeData cd) {
131 // validate the input composite data
132 VMOptionCompositeData.validateCompositeData(cd);
133
134 this.name = VMOptionCompositeData.getName(cd);
135 this.value = VMOptionCompositeData.getValue(cd);
136 this.writeable = VMOptionCompositeData.isWriteable(cd);
137 this.origin = VMOptionCompositeData.getOrigin(cd);
138 }
139
140 /**
141 * Returns the name of this VM option.
142 *
143 * @return the name of this VM option.
144 */
145 public String getName() {
146 return name;
147 }
148
149 /**
150 * Returns the value of this VM option at the time when
151 * this {@code VMOption} was created. The value could have been changed.
152 *
153 * @return the value of the VM option at the time when
154 * this {@code VMOption} was created.
155 */
156 public String getValue() {
157 return value;
158 }
159
160 /**
161 * Returns the origin of the value of this VM option. That is,
162 * where the value of this VM option came from.
163 *
164 * @return where the value of this VM option came from.
165 */
166 public Origin getOrigin() {
167 return origin;
168 }
169
170 /**
171 * Tests if this VM option is writeable. If this VM option is writeable,
172 * it can be set by the {@link HotSpotDiagnosticMXBean#setVMOption
173 * HotSpotDiagnosticMXBean.setVMOption} method.
174 *
175 * @return {@code true} if this VM option is writeable; {@code false}
176 * otherwise.
177 */
178 public boolean isWriteable() {
179 return writeable;
180 }
181
182 public String toString() {
183 return "VM option: " + getName() +
184 " value: " + value + " " +
185 " origin: " + origin + " " +
186 (writeable ? "(read-write)" : "(read-only)");
187 }
188
189 /**
190 * Returns a {@code VMOption} object represented by the
191 * given {@code CompositeData}. The given {@code CompositeData}
192 * must contain the following attributes:
193 *
194 * <blockquote>
195 * <table border>
196 * <tr>
197 * <th align=left>Attribute Name</th>
198 * <th align=left>Type</th>
199 * </tr>
200 * <tr>
201 * <td>name</td>
202 * <td>{@code java.lang.String}</td>
203 * </tr>
204 * <tr>
205 * <td>value</td>
206 * <td>{@code java.lang.String}</td>
207 * </tr>
208 * <tr>
209 * <td>origin</td>
210 * <td>{@code java.lang.String}</td>
211 * </tr>
212 * <tr>
213 * <td>writeable</td>
214 * <td>{@code java.lang.Boolean}</td>
215 * </tr>
216 * </table>
217 * </blockquote>
218 *
219 * @param cd {@code CompositeData} representing a {@code VMOption}
220 *
221 * @throws IllegalArgumentException if {@code cd} does not
222 * represent a {@code VMOption} with the attributes described
223 * above.
224 *
225 * @return a {@code VMOption} object represented by {@code cd}
226 * if {@code cd} is not {@code null};
227 * {@code null} otherwise.
228 */
229 public static VMOption from(CompositeData cd) {
230 if (cd == null) {
231 return null;
232 }
233
234 if (cd instanceof VMOptionCompositeData) {
235 return ((VMOptionCompositeData) cd).getVMOption();
236 } else {
237 return new VMOption(cd);
238 }
239
240 }
241
242 // for sun.management.MappedMXBeanType
243 static CompositeData toCompositeData(VMOption option) {
244 return VMOptionCompositeData.toCompositeData(option);
245 }
246 }