1 /*
2 * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * @test
26 * @bug 6503247 6574123
27 * @summary Test resilience to tryAcquire methods that throw
28 * @author Martin Buchholz
29 */
30
31 import java.util.*;
32 import java.util.concurrent.*;
33 import java.util.concurrent.locks.*;
34
35 /**
36 * This uses a variant of the standard Mutex demo, except with a
37 * tryAcquire method that randomly throws various Throwable
38 * subclasses.
39 */
40 @SuppressWarnings({"deprecation", "serial"})
41 public class FlakyMutex implements Lock {
42 static class MyError extends Error {}
43 static class MyException extends Exception {}
44 static class MyRuntimeException extends RuntimeException {}
45
46 static final Random rnd = new Random();
47
48 static void maybeThrow() {
49 switch (rnd.nextInt(10)) {
50 case 0: throw new MyError();
51 case 1: throw new MyRuntimeException();
52 case 2: Thread.currentThread().stop(new MyException()); break;
53 default: /* Do nothing */ break;
54 }
55 }
56
57 static void checkThrowable(Throwable t) {
58 check((t instanceof MyError) ||
59 (t instanceof MyException) ||
60 (t instanceof MyRuntimeException));
61 }
62
63 static void realMain(String[] args) throws Throwable {
64 final int nThreads = 3;
65 final CyclicBarrier barrier = new CyclicBarrier(nThreads + 1);
66 final FlakyMutex m = new FlakyMutex();
67 final ExecutorService es = Executors.newFixedThreadPool(nThreads);
68 for (int i = 0; i < nThreads; i++) {
69 es.submit(new Runnable() { public void run() {
70 try {
71 barrier.await();
72 for (int i = 0; i < 10000; i++) {
73 for (;;) {
74 try { m.lock(); break; }
75 catch (Throwable t) { checkThrowable(t); }
76 }
77
78 try { check(! m.tryLock()); }
79 catch (Throwable t) { checkThrowable(t); }
80
81 try { check(! m.tryLock(1, TimeUnit.MICROSECONDS)); }
82 catch (Throwable t) { checkThrowable(t); }
83
84 m.unlock();
85 }
86 } catch (Throwable t) { unexpected(t); }}});}
87 barrier.await();
88 es.shutdown();
89 check(es.awaitTermination(30, TimeUnit.SECONDS));
90 }
91
92 private static class FlakySync extends AbstractQueuedLongSynchronizer {
93 private static final long serialVersionUID = -1L;
94
95 public boolean isHeldExclusively() { return getState() == 1; }
96
97 public boolean tryAcquire(long acquires) {
98 // Sneak in some tests for queue state
99 if (hasQueuedPredecessors())
100 check(getFirstQueuedThread() != Thread.currentThread());
101 if (getFirstQueuedThread() == Thread.currentThread()) {
102 check(hasQueuedThreads());
103 check(!hasQueuedPredecessors());
104 } else {
105 // Might be true, but only transiently
106 do {} while (hasQueuedPredecessors() != hasQueuedThreads());
107 }
108
109 maybeThrow();
110 return compareAndSetState(0, 1);
111 }
112
113 public boolean tryRelease(long releases) {
114 setState(0);
115 return true;
116 }
117
118 Condition newCondition() { return new ConditionObject(); }
119 }
120
121 private final FlakySync sync = new FlakySync();
122 public void lock() { sync.acquire(1); }
123 public boolean tryLock() { return sync.tryAcquire(1); }
124 public void lockInterruptibly() throws InterruptedException {
125 sync.acquireInterruptibly(1);
126 }
127 public boolean tryLock(long timeout, TimeUnit unit) throws InterruptedException {
128 return sync.tryAcquireNanos(1, unit.toNanos(timeout));
129 }
130 public void unlock() { sync.release(1); }
131 public Condition newCondition() { return sync.newCondition(); }
132 public boolean isLocked() { return sync.isHeldExclusively(); }
133 public boolean hasQueuedThreads() { return sync.hasQueuedThreads(); }
134
135 //--------------------- Infrastructure ---------------------------
136 static volatile int passed = 0, failed = 0;
137 static void pass() {passed++;}
138 static void fail() {failed++; Thread.dumpStack();}
139 static void fail(String msg) {System.out.println(msg); fail();}
140 static void unexpected(Throwable t) {failed++; t.printStackTrace();}
141 static void check(boolean cond) {if (cond) pass(); else fail();}
142 static void equal(Object x, Object y) {
143 if (x == null ? y == null : x.equals(y)) pass();
144 else fail(x + " not equal to " + y);}
145 public static void main(String[] args) throws Throwable {
146 try {realMain(args);} catch (Throwable t) {unexpected(t);}
147 System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
148 if (failed > 0) throw new AssertionError("Some tests failed");}
149 }