1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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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
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23 
24 /*
25  * @test
26  * @bug 6330307 6355645
27  * @summary Check for race conditions in COWArray classes
28  * @author Martin Buchholz
29  */
30 
31 import java.util.List;
32 import java.util.Set;
33 import java.util.concurrent.CopyOnWriteArrayList;
34 import java.util.concurrent.CopyOnWriteArraySet;
35 
36 public class RacingCows {
realMain(String[] args)37     private static void realMain(String[] args) throws Throwable {
38         final int iterations = 100000;
39         final Integer two = Integer.valueOf(2);
40         final Integer three = Integer.valueOf(3);
41 
42         //------------ CopyOnWriteArraySet -------------------------------
43         final Set<Integer> s1 = new CopyOnWriteArraySet<>();
44         final Set<Integer> s2 = new CopyOnWriteArraySet<>();
45         s1.add(1);
46 
47         final Thread t1 = new CheckedThread() { public void realRun() {
48             for (int i = 0; i < iterations; i++) {
49                 s2.add(two);
50                 s2.remove(two);
51             }}};
52         t1.start();
53 
54         for (int i = 0; i < iterations; i++) {
55             check(! s1.equals(s2));
56             check(! s2.equals(s1));
57         }
58         t1.join();
59 
60         //------------ CopyOnWriteArrayList ------------------------------
61         final List<Integer> l1 = new CopyOnWriteArrayList<>();
62         final List<Integer> l2 = new CopyOnWriteArrayList<>();
63         final List<Integer> l3 = new CopyOnWriteArrayList<>();
64         l1.add(1);
65 
66         final Thread t2 = new CheckedThread() { public void realRun() {
67             for (int i = 0; i < iterations; i++) {
68                 switch (i%2) {
69                 case 0: l2.add(two);    break;
70                 case 1: l2.add(0, two); break;
71                 }
72                 switch (i%3) {
73                 case 0: l2.remove(two); break;
74                 case 1: l2.remove(0);   break;
75                 case 2: l2.clear();     break;
76                 }}}};
77         t2.start();
78 
79         final Thread t3 = new CheckedThread() { public void realRun() {
80             l3.add(three);
81             for (int i = 0; i < iterations; i++) {
82                 switch (i%2) {
83                 case 0: l3.add(two);    break;
84                 case 1: l3.add(0, two); break;
85                 }
86                 switch (i%2) {
87                 case 0: l3.remove(two); break;
88                 case 1: l3.remove(0);   break;
89                 }}}};
90         t3.start();
91 
92         for (int i = 0; i < iterations; i++) {
93             check(! l1.equals(l2));
94             check(! l2.equals(l1));
95 
96             // CopyOnWriteArrayList(mutatingCollection)
97             try { new CopyOnWriteArrayList<Integer>(l2); }
98             catch (Throwable t) { unexpected(t); }
99 
100             // addAllAbsent(mutatingCollection)
101             try { new CopyOnWriteArrayList<Integer>().addAllAbsent(l3); }
102             catch (Throwable t) { unexpected(t); }
103 
104             // addAll(mutatingCollection)
105             try { new CopyOnWriteArrayList<Integer>().addAll(l3); }
106             catch (Throwable t) { unexpected(t); }
107 
108             // addAll(int, mutatingCollection)
109             try { new CopyOnWriteArrayList<Integer>().addAll(0,l3); }
110             catch (Throwable t) { unexpected(t); }
111         }
112         t2.join();
113         t3.join();
114     }
115 
116     //--------------------- Infrastructure ---------------------------
117     static volatile int passed = 0, failed = 0;
pass()118     static void pass() {passed++;}
fail()119     static void fail() {failed++; Thread.dumpStack();}
fail(String msg)120     static void fail(String msg) {System.out.println(msg); fail();}
unexpected(Throwable t)121     static void unexpected(Throwable t) {failed++; t.printStackTrace();}
check(boolean cond)122     static void check(boolean cond) {if (cond) pass(); else fail();}
equal(Object x, Object y)123     static void equal(Object x, Object y) {
124         if (x == null ? y == null : x.equals(y)) pass();
125         else fail(x + " not equal to " + y);}
main(String[] args)126     public static void main(String[] args) throws Throwable {
127         try {realMain(args);} catch (Throwable t) {unexpected(t);}
128         System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
129         if (failed > 0) throw new AssertionError("Some tests failed");}
130     private abstract static class CheckedThread extends Thread {
realRun()131         public abstract void realRun() throws Throwable;
run()132         public void run() {
133             try { realRun(); } catch (Throwable t) { unexpected(t); }}}
134 }
135