1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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17 * You should have received a copy of the GNU General Public License version
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24 */
25
26package java.lang.management;
27
28import javax.management.openmbean.CompositeData;
29import java.util.concurrent.locks.*;
30import sun.management.LockInfoCompositeData;
31
32/**
33 * Information about a <em>lock</em>.  A lock can be a built-in object monitor,
34 * an <em>ownable synchronizer</em>, or the {@link Condition Condition}
35 * object associated with synchronizers.
36 * <p>
37 * <a id="OwnableSynchronizer">An ownable synchronizer</a> is
38 * a synchronizer that may be exclusively owned by a thread and uses
39 * {@link AbstractOwnableSynchronizer AbstractOwnableSynchronizer}
40 * (or its subclass) to implement its synchronization property.
41 * {@link ReentrantLock ReentrantLock} and the write-lock (but not
42 * the read-lock) of {@link ReentrantReadWriteLock ReentrantReadWriteLock} are
43 * two examples of ownable synchronizers provided by the platform.
44 *
45 * <h3><a id="MappedType">MXBean Mapping</a></h3>
46 * {@code LockInfo} is mapped to a {@link CompositeData CompositeData}
47 * as specified in the {@link #from from} method.
48 *
49 * @see java.util.concurrent.locks.AbstractOwnableSynchronizer
50 * @see java.util.concurrent.locks.Condition
51 *
52 * @author  Mandy Chung
53 * @since   1.6
54 */
55
56public class LockInfo {
57
58    private String className;
59    private int    identityHashCode;
60
61    /**
62     * Constructs a {@code LockInfo} object.
63     *
64     * @param className the fully qualified name of the class of the lock object.
65     * @param identityHashCode the {@link System#identityHashCode
66     *                         identity hash code} of the lock object.
67     */
68    public LockInfo(String className, int identityHashCode) {
69        if (className == null) {
70            throw new NullPointerException("Parameter className cannot be null");
71        }
72        this.className = className;
73        this.identityHashCode = identityHashCode;
74    }
75
76    /**
77     * package-private constructors
78     */
79    LockInfo(Object lock) {
80        this.className = lock.getClass().getName();
81        this.identityHashCode = System.identityHashCode(lock);
82    }
83
84    /**
85     * Returns the fully qualified name of the class of the lock object.
86     *
87     * @return the fully qualified name of the class of the lock object.
88     */
89    public String getClassName() {
90        return className;
91    }
92
93    /**
94     * Returns the identity hash code of the lock object
95     * returned from the {@link System#identityHashCode} method.
96     *
97     * @return the identity hash code of the lock object.
98     */
99    public int getIdentityHashCode() {
100        return identityHashCode;
101    }
102
103    /**
104     * Returns a {@code LockInfo} object represented by the
105     * given {@code CompositeData}.
106     * The given {@code CompositeData} must contain the following attributes:
107     * <table class="striped" style="margin-left:2em;">
108     * <caption style="display:none">The attributes and the types the given CompositeData contains</caption>
109     * <thead style="text-align:left">
110     * <tr>
111     *   <th scope="col">Attribute Name</th>
112     *   <th scope="col">Type</th>
113     * </tr>
114     * </thead>
115     * <tbody style="text-align:left">
116     * <tr>
117     *   <th scope="row">className</th>
118     *   <td>{@code java.lang.String}</td>
119     * </tr>
120     * <tr>
121     *   <th scope="row">identityHashCode</th>
122     *   <td>{@code java.lang.Integer}</td>
123     * </tr>
124     * </tbody>
125     * </table>
126     *
127     * @param cd {@code CompositeData} representing a {@code LockInfo}
128     *
129     * @throws IllegalArgumentException if {@code cd} does not
130     *   represent a {@code LockInfo} with the attributes described
131     *   above.
132     * @return a {@code LockInfo} object represented
133     *         by {@code cd} if {@code cd} is not {@code null};
134     *         {@code null} otherwise.
135     *
136     * @since 1.8
137     */
138    public static LockInfo from(CompositeData cd) {
139        if (cd == null) {
140            return null;
141        }
142
143        if (cd instanceof LockInfoCompositeData) {
144            return ((LockInfoCompositeData) cd).getLockInfo();
145        } else {
146            return LockInfoCompositeData.toLockInfo(cd);
147        }
148    }
149
150    /**
151     * Returns a string representation of a lock.  The returned
152     * string representation consists of the name of the class of the
153     * lock object, the at-sign character `@', and the unsigned
154     * hexadecimal representation of the <em>identity</em> hash code
155     * of the object.  This method returns a string equals to the value of:
156     * <blockquote>
157     * <pre>
158     * lock.getClass().getName() + '@' + Integer.toHexString(System.identityHashCode(lock))
159     * </pre></blockquote>
160     * where {@code lock} is the lock object.
161     *
162     * @return the string representation of a lock.
163     */
164    public String toString() {
165        return className + '@' + Integer.toHexString(identityHashCode);
166    }
167}
168