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1
21 package net.sf.hajdbc.distributable;
22
23 import java.util.concurrent.TimeUnit  ;
24 import java.util.concurrent.locks.Condition ;
25 import java.util.concurrent.locks.Lock ;
26
27 import org.jgroups.Channel;
28 import org.jgroups.ChannelException;
29 import org.jgroups.JChannel;
30 import org.jgroups.blocks.DistributedLockManager;
31 import org.jgroups.blocks.LockManager;
32 import org.jgroups.blocks.LockNotGrantedException;
33 import org.jgroups.blocks.LockNotReleasedException;
34 import org.jgroups.blocks.TwoPhaseVotingAdapter;
35 import org.jgroups.blocks.TwoPhaseVotingListener;
36 import org.jgroups.blocks.VotingAdapter;
37
38
42 public class DistributableLock implements Lock , TwoPhaseVotingListener
43 {
44 private LockManager lockManager;
45 private Channel channel;
46 private int timeout;
47 private Lock lock;
48
49
57 public DistributableLock(String name, String protocol, int timeout, Lock lock) throws Exception
58 {
59 this.timeout = timeout;
60 this.lock = lock;
61 this.channel = new JChannel(protocol);
62 this.channel.connect(name);
63
64 TwoPhaseVotingAdapter adapter = new TwoPhaseVotingAdapter(new VotingAdapter(this.channel));
65
66 adapter.addListener(this);
67
68 this.lockManager = new DistributedLockManager(adapter, name);
69 }
70
71
74 public Channel getChannel()
75 {
76 return this.channel;
77 }
78
79
82 public void lock()
83 {
84 while (!this.tryLock());
85 }
86
87
90 public void lockInterruptibly() throws InterruptedException
91 {
92 while (!this.tryLock())
93 {
94 if (Thread.currentThread().isInterrupted())
95 {
96 throw new InterruptedException ();
97 }
98 }
99 }
100
101
104 public boolean tryLock()
105 {
106 try
107 {
108 this.lockManager.lock(this.getObject(), this.getOwner(), this.timeout);
109
110 return true;
111 }
112 catch (LockNotGrantedException e)
113 {
114 return false;
115 }
116 catch (ClassCastException e)
117 {
118 throw new IllegalStateException (e);
119 }
120 catch (ChannelException e)
121 {
122 throw new IllegalStateException (e);
123 }
124 }
125
126
129 public boolean tryLock(long timeout, TimeUnit unit)
130 {
131 long stopTime = System.currentTimeMillis() + unit.toMillis(timeout);
132
133 while (!this.tryLock())
134 {
135 if (System.currentTimeMillis() >= stopTime)
136 {
137 return false;
138 }
139 }
140
141 return true;
142 }
143
144
147 public void unlock()
148 {
149 try
150 {
151 this.lockManager.unlock(this.getObject(), this.getOwner());
152 }
153 catch (ClassCastException e)
154 {
155 throw new IllegalStateException (e);
156 }
157 catch (ChannelException e)
158 {
159 throw new IllegalStateException (e);
160 }
161 catch (LockNotReleasedException e)
162 {
163 throw new IllegalStateException (e);
164 }
165 }
166
167
170 public Condition newCondition()
171 {
172 return this.lock.newCondition();
173 }
174
175
178 public boolean prepare(Object decree)
179 {
180 if (DistributedLockManager.AcquireLockDecree.class.isInstance(decree))
181 {
182 return this.lock.tryLock();
183 }
184
185 return true;
186 }
187
188
191 public boolean commit(Object decree)
192 {
193 if (DistributedLockManager.ReleaseLockDecree.class.isInstance(decree))
194 {
195 this.lock.unlock();
196 }
197
198 return true;
199 }
200
201
204 public void abort(Object decree)
205 {
206 if (DistributedLockManager.AcquireLockDecree.class.isInstance(decree))
207 {
208 this.lock.unlock();
209 }
210 }
211
212
215 public void stop()
216 {
217 this.channel.close();
218 }
219
220 private Object getObject()
221 {
222 return "";
223 }
224
225 private Object getOwner()
226 {
227 return Thread.currentThread().getId();
228 }
229 }
230 |
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