1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 */
22
23/*
24 * This file is available under and governed by the GNU General Public
25 * License version 2 only, as published by the Free Software Foundation.
26 * However, the following notice accompanied the original version of this
27 * file:
28 *
29 * Written by Doug Lea with assistance from members of JCP JSR-166
30 * Expert Group and released to the public domain, as explained at
31 * http://creativecommons.org/publicdomain/zero/1.0/
32 */
33
34/*
35 * @test
36 * @bug 6801020 6803402
37 * @summary Try to tickle race conditions in
38 * AbstractQueuedSynchronizer "shared" code
39 */
40
41import java.util.concurrent.Semaphore;
42
43public class RacingReleases {
44
45    /** Increase this for better chance of tickling races */
46    static final int iterations = 1000;
47
48    public static void test(final boolean fair,
49                            final boolean interruptibly)
50        throws Throwable {
51        for (int i = 0; i < iterations; i++) {
52            final Semaphore sem = new Semaphore(0, fair);
53            final Throwable[] badness = new Throwable[1];
54            Runnable blocker = interruptibly ?
55                new Runnable() {
56                    public void run() {
57                        try {
58                            sem.acquire();
59                        } catch (Throwable t) {
60                            badness[0] = t;
61                            throw new Error(t);
62                        }}}
63                :
64                new Runnable() {
65                    public void run() {
66                        try {
67                            sem.acquireUninterruptibly();
68                        } catch (Throwable t) {
69                            badness[0] = t;
70                            throw new Error(t);
71                        }}};
72
73            Thread b1 = new Thread(blocker);
74            Thread b2 = new Thread(blocker);
75            Runnable signaller = new Runnable() {
76                public void run() {
77                    try {
78                        sem.release();
79                    } catch (Throwable t) {
80                        badness[0] = t;
81                        throw new Error(t);
82                    }}};
83            Thread s1 = new Thread(signaller);
84            Thread s2 = new Thread(signaller);
85            Thread[] threads = { b1, b2, s1, s2 };
86            java.util.Collections.shuffle(java.util.Arrays.asList(threads));
87            for (Thread thread : threads)
88                thread.start();
89            for (Thread thread : threads) {
90                thread.join(60 * 1000);
91                if (thread.isAlive())
92                    throw new Error
93                        (String.format
94                         ("Semaphore stuck: permits %d, thread waiting %s%n",
95                          sem.availablePermits(),
96                          sem.hasQueuedThreads() ? "true" : "false"));
97            }
98            if (badness[0] != null)
99                throw new Error(badness[0]);
100            if (sem.availablePermits() != 0)
101              throw new Error(String.valueOf(sem.availablePermits()));
102            if (sem.hasQueuedThreads())
103              throw new Error(String.valueOf(sem.hasQueuedThreads()));
104            if (sem.getQueueLength() != 0)
105              throw new Error(String.valueOf(sem.getQueueLength()));
106            if (sem.isFair() != fair)
107              throw new Error(String.valueOf(sem.isFair()));
108        }
109    }
110
111    public static void main(String[] args) throws Throwable {
112        for (boolean fair : new boolean[] { true, false })
113            for (boolean interruptibly : new boolean[] { true, false })
114                test(fair, interruptibly);
115    }
116}
117