1 /*

     2  * Copyright (c) 2005, 2013, 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 sun.management.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 1.9

   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 

   245 }