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1
7 package org.jboss.cache.lock;
8
9 import junit.framework.Test;
10 import junit.framework.TestCase;
11 import junit.framework.TestSuite;
12
13 import java.util.concurrent.locks.ReentrantReadWriteLock  ;
14 import java.util.concurrent.TimeUnit ;
15
16
21 public class ReentrantWriterPreference2Readers1WriterLockTest extends TestCase {
22 ReentrantReadWriteLock lock;
23 ReentrantReadWriteLock.ReadLock rl;
24 ReentrantReadWriteLock.WriteLock wl;
25 Exception thread_ex=null;
26
27 protected void setUp() throws Exception {
28 super.setUp();
29 lock=new ReentrantReadWriteLock ();
30 rl=lock.readLock();
31 wl=lock.writeLock();
32 thread_ex=null;
33 }
34
35 protected void tearDown() throws Exception {
36 super.tearDown();
37 lock=null;
38 if(thread_ex != null)
39 throw thread_ex;
40 }
41
42
43 private void log(String msg) {
44 System.out.println(System.currentTimeMillis() + " " + Thread.currentThread() +
45 " [" + Thread.currentThread().getName() + "]: " + msg);
46 }
47
48
49 public void testSimpleUpgradeFromReadLockToWriteLock() {
50 int readers, writers;
51 try {
52 rl.lock();
53 readers=lock.getReadLockCount();
54 assertEquals(1, readers);
55 boolean wl_acquired=wl.tryLock(500, TimeUnit.MILLISECONDS);
56 if(!wl_acquired) {
57 fail("write lock could not be acquired");
58 return;
59 }
60 readers=lock.getReadLockCount();
61 assertEquals(1, readers);
62 writers=lock.getWriteHoldCount();
63 assertEquals(1, writers);
64 }
65 catch(InterruptedException e) {
66
67 }
68 finally {
69 rl.unlock();
70 if(lock.getWriteHoldCount() > 0)
71 wl.unlock();
72 }
73 }
74
75 public void test2ReadersAnd1Writer() throws InterruptedException {
76 int readers, writers;
77 Upgrader upgrader=new Upgrader("Upgrader");
78 Reader reader=new Reader("Reader");
79 reader.start();
80 sleepThread(500);
81
82 readers=lock.getReadLockCount();
83 assertEquals(1, readers);
84
85 upgrader.start();
86 sleepThread(500);
87
88 readers=lock.getReadLockCount();
89 assertEquals(2, readers);
90
91 synchronized(upgrader) { upgrader.notify();
93 }
94 sleepThread(500);
95
96 readers=lock.getReadLockCount();
97 assertEquals(2, readers);
98 writers=lock.getWriteHoldCount();
99 assertEquals(0, writers);
100
101 synchronized(reader) { reader.notify();
103 }
104 reader.join();
105
106 readers=lock.getReadLockCount();
107 assertEquals(1, readers);
108 writers=lock.getWriteHoldCount();
109 assertEquals(1, writers);
110
111 synchronized(upgrader) { upgrader.notify();
113 }
114 sleepThread(500);
115 readers=lock.getReadLockCount();
116 assertEquals(0, readers);
117 writers=lock.getWriteHoldCount();
118 assertEquals(0, writers);
119
120 upgrader.join(3000);
121 assertTrue("Known failure. See JBCACHE-461; This is due to a potential bug in ReentrantWriterPreferenceReadWriteLock !",
122 upgrader.wasUpgradeSuccessful());
123 }
124
125
126 private class Reader extends Thread {
127
128 public Reader(String name) {
129 super(name);
130 }
131
132 public void run() {
133 try {
134 log("acquiring RL");
135 rl.lock();
136 log("acquired RL");
137 synchronized(this) {
138 this.wait();
139 }
140 }
141 catch(InterruptedException e) {
142 }
143 finally {
144 log("releasing RL");
145 rl.unlock();
146 log("released RL");
147 }
148 }
149 }
150
151
152 private class Upgrader extends Thread {
153 boolean upgradeSuccessful=false;
154
155 public Upgrader(String name) {
156 super(name);
157 }
158
159 public boolean wasUpgradeSuccessful() {
160 return upgradeSuccessful;
161 }
162
163
164 public void run() {
165 try {
166 log("acquiring RL");
167 rl.lock();
168 log("acquired RL");
169 synchronized(this) {
170 this.wait();
171 }
172 log("attempting to acquire WL");
173 wl.lock();
174 upgradeSuccessful=true;
175 log("acquired WL");
176
177
178 synchronized(this) {
179 this.wait();
180 }
181 log("releasing WL");
182 rl.unlock();
183 log("released WL");
184 }
185 catch(InterruptedException e) {
186 ;
187 }
188 finally {
189 wl.unlock();
190 rl.unlock();
191 }
192 }
193 }
194
195
196 static void sleepThread(long timeout) {
197 try {
198 Thread.sleep(timeout);
199 }
200 catch(InterruptedException e) {
201 }
202 }
203
204 public static Test suite() {
205 return new TestSuite(ReentrantWriterPreference2Readers1WriterLockTest.class);
206 }
207
208 public static void main(String [] args) {
209 junit.textui.TestRunner.run(ReentrantWriterPreference2Readers1WriterLockTest.suite());
210 }
211
212 }
213 |
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