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11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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13  * accompanied this code).
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23 
24 /*
25  * @test
26  * @run testng SpliteratorTraverseAddRemoveTest
27  * @bug 8085978
28  * @summary repeatedly traverse the queue using the spliterator while
29  *          concurrently adding and removing an element to test that self-linked
30  *          nodes are never erroneously reported on traversal
31  */
32 
33 import org.testng.Assert;
34 import org.testng.annotations.DataProvider;
35 import org.testng.annotations.Test;
36 
37 import java.util.ArrayList;
38 import java.util.List;
39 import java.util.Queue;
40 import java.util.Spliterator;
41 import java.util.concurrent.CompletableFuture;
42 import java.util.concurrent.LinkedTransferQueue;
43 import java.util.concurrent.TimeUnit;
44 import java.util.concurrent.atomic.AtomicBoolean;
45 import java.util.function.Consumer;
46 
47 @Test
48 public class SpliteratorTraverseAddRemoveTest {
49 
of(String desc, Consumer<Queue<?>> c)50     static Object[] of(String desc, Consumer<Queue<?>> c) {
51         return new Object[]{desc, c};
52     }
53 
assertIsString(Object e)54     static void assertIsString(Object e) {
55         Assert.assertTrue(e instanceof String,
56                           String.format("Object instanceof %s (actual: instanceof %s)",
57                                         String.class.getName(),
58                                         e.getClass().getName()));
59     }
60 
61     @DataProvider()
spliteratorTraversers()62     public static Object[][] spliteratorTraversers() {
63         return new Object[][]{
64                 of("forEachRemaining", q -> {
65                     q.spliterator().forEachRemaining(SpliteratorTraverseAddRemoveTest::assertIsString);
66                 }),
67                 of("tryAdvance", q -> {
68                     Spliterator<?> s = q.spliterator();
69                     while (s.tryAdvance(SpliteratorTraverseAddRemoveTest::assertIsString))
70                         ;
71                 }),
72                 of("trySplit then forEachRemaining", q -> {
73                     Spliterator<?> r = q.spliterator();
74 
75                     List<Spliterator<?>> ss = new ArrayList<>();
76                     Spliterator<?> l;
77                     while ((l = r.trySplit()) != null) {
78                         ss.add(l);
79                     }
80                     ss.add(r);
81 
82                     ss.forEach(s -> s.forEachRemaining(SpliteratorTraverseAddRemoveTest::assertIsString));
83                 }),
84         };
85     }
86 
87     @Test(dataProvider = "spliteratorTraversers")
88     public void testQueue(String desc, Consumer<Queue<String>> c)
89             throws InterruptedException {
90         AtomicBoolean done = new AtomicBoolean(false);
91         Queue<String> msgs = new LinkedTransferQueue<>();
92 
93         CompletableFuture<Void> traversalTask = CompletableFuture.runAsync(() -> {
94             while (!done.get()) {
95                 // Traversal will fail if self-linked nodes of
96                 // LinkedTransferQueue are erroneously reported
97                 c.accept(msgs);
98             }
99         });
100         CompletableFuture<Void> addAndRemoveTask = CompletableFuture.runAsync(() -> {
101             while (!traversalTask.isDone()) {
102                 msgs.add("msg");
103                 msgs.remove("msg");
104             }
105         });
106 
107         Thread.sleep(TimeUnit.SECONDS.toMillis(1));
108         done.set(true);
109 
110         addAndRemoveTask.join();
111         Assert.assertTrue(traversalTask.isDone());
112         traversalTask.join();
113     }
114 }
115