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12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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15   * accompanied this code).
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25  
26  package java.lang.management;
27  
28  import javax.management.openmbean.CompositeData;
29  import java.util.concurrent.locks.*;
30  import 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 name="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
42   * {@link ReentrantReadWriteLock ReentrantReadWriteLock} are
43   * two examples of ownable synchronizers provided by the platform.
44   *
45   * <h3><a name="MappedType">MXBean Mapping</a></h3>
46   * <tt>LockInfo</tt> 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  
56  public class LockInfo {
57  
58      private String className;
59      private int    identityHashCode;
60  
61      /**
62       * Constructs a <tt>LockInfo</tt> 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      * <blockquote>
108      * <table border summary="The attributes and the types the given CompositeData contains">
109      * <tr>
110      *   <th align=left>Attribute Name</th>
111      *   <th align=left>Type</th>
112      * </tr>
113      * <tr>
114      *   <td>className</td>
115      *   <td><tt>java.lang.String</tt></td>
116      * </tr>
117      * <tr>
118      *   <td>identityHashCode</td>
119      *   <td><tt>java.lang.Integer</tt></td>
120      * </tr>
121      * </table>
122      * </blockquote>
123      *
124      * @param cd {@code CompositeData} representing a {@code LockInfo}
125      *
126      * @throws IllegalArgumentException if {@code cd} does not
127      *   represent a {@code LockInfo} with the attributes described
128      *   above.
129      * @return a {@code LockInfo} object represented
130      *         by {@code cd} if {@code cd} is not {@code null};
131      *         {@code null} otherwise.
132      *
133      * @since 1.8
134      */
135     public static LockInfo from(CompositeData cd) {
136         if (cd == null) {
137             return null;
138         }
139 
140         if (cd instanceof LockInfoCompositeData) {
141             return ((LockInfoCompositeData) cd).getLockInfo();
142         } else {
143             return LockInfoCompositeData.toLockInfo(cd);
144         }
145     }
146 
147     /**
148      * Returns a string representation of a lock.  The returned
149      * string representation consists of the name of the class of the
150      * lock object, the at-sign character `@', and the unsigned
151      * hexadecimal representation of the <em>identity</em> hash code
152      * of the object.  This method returns a string equals to the value of:
153      * <blockquote>
154      * <pre>
155      * lock.getClass().getName() + '@' + Integer.toHexString(System.identityHashCode(lock))
156      * </pre></blockquote>
157      * where <tt>lock</tt> is the lock object.
158      *
159      * @return the string representation of a lock.
160      */
161     public String toString() {
162         return className + '@' + Integer.toHexString(identityHashCode);
163     }
164 }