NodeLock


1   package org.jboss.cache.lock;
2   
3   import java.util.Set  ;
4   
5   
6   /**
7    * Interface for a lock for nodes. 
8    */
9   public interface NodeLock
10  {
11  
12     public enum LockType
13     {
14        NONE, READ, WRITE
15     }
16  
17     /**
18      * Returns a copy of the reader lock owner in List. 
19      * Size is zero is not available. Note that this list
20      * is synchronized.
21      *
22      * @return Set of readers
23      */
24     Set   getReaderOwners();
25  
26     /**
27      * Returns the writer lock owner object. Null if not available.
28      *
29      * @return Object owner
30      */
31     Object   getWriterOwner();
32  
33     /**
34      * Acquires a write lock with a timeout of <code>timeout</code> milliseconds.
35      * Note that if the current owner owns a read lock, it will be upgraded
36      * automatically. However, if upgrade fails, i.e., timeout, the read lock will
37      * be released automatically.
38      *
39      * @param caller  Can't be null.
40      * @param timeout
41      * @return boolean True if lock was acquired and was not held before, false if lock was held
42      * @throws LockingException
43      * @throws TimeoutException
44      */
45     boolean acquireWriteLock(Object   caller, long timeout) throws LockingException, TimeoutException,
46           InterruptedException  ;
47  
48     /**
49      * Acquires a read lock with a timeout period of <code>timeout</code> milliseconds.
50      *
51      * @param caller  Can't be null.
52      * @param timeout
53      * @return boolean True if lock was acquired and was not held before, false if lock was held
54      * @throws LockingException
55      * @throws TimeoutException
56      */
57     boolean acquireReadLock(Object   caller, long timeout) throws LockingException, TimeoutException, InterruptedException  ;
58  
59     /**
60      * Releases the lock held by the owner.
61      *
62      * @param caller Can't be null.
63      */
64     void release(Object   caller);
65  
66     /**
67      * Releases all locks associated with this instance.
68      */
69     void releaseAll();
70  
71     /**
72      * Releases all locks with this owner.
73      */
74     void releaseAll(Object   owner);
75  
76     /**
77      * Check if there is a read lock.
78      */
79     boolean isReadLocked();
80  
81     /**
82      * Check if there is a write lock.
83      */
84     boolean isWriteLocked();
85  
86     /**
87      * Check if there is a read or write lock
88      */
89     boolean isLocked();
90  
91     /**
92      * Returns true if the object is the lock owner.
93      */
94     boolean isOwner(Object   o);
95  
96     boolean acquire(Object   caller, long timeout, NodeLock.LockType lock_type) throws LockingException, TimeoutException,
97           InterruptedException  ;
98  
99     Set   acquireAll(Object   caller, long timeout, NodeLock.LockType lock_type) throws LockingException, TimeoutException,
100          InterruptedException  ;
101 
102    void printLockInfo(StringBuffer   sb, int indent);
103 
104 }
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