8085978: LinkedTransferQueue<T>.spliterator can report LTQ.Node object, not T
Reviewed-by: psandoz, martin
diff --git a/src/share/classes/java/util/concurrent/LinkedTransferQueue.java b/src/share/classes/java/util/concurrent/LinkedTransferQueue.java
index 5ebd049..b590426 100644
--- a/src/share/classes/java/util/concurrent/LinkedTransferQueue.java
+++ b/src/share/classes/java/util/concurrent/LinkedTransferQueue.java
@@ -780,7 +780,9 @@
}
/**
- * Version of firstOfMode used by Spliterator
+ * Version of firstOfMode used by Spliterator. Callers must
+ * recheck if the returned node's item field is null or
+ * self-linked before using.
*/
final Node firstDataNode() {
for (Node p = head; p != null;) {
@@ -953,11 +955,12 @@
Object[] a = new Object[n];
int i = 0;
do {
- if ((a[i] = p.item) != null)
+ Object e = p.item;
+ if (e != p && (a[i] = e) != null)
++i;
if (p == (p = p.next))
p = q.firstDataNode();
- } while (p != null && i < n);
+ } while (p != null && i < n && p.isData);
if ((current = p) == null)
exhausted = true;
if (i > 0) {
@@ -980,11 +983,11 @@
exhausted = true;
do {
Object e = p.item;
+ if (e != null && e != p)
+ action.accept((E)e);
if (p == (p = p.next))
p = q.firstDataNode();
- if (e != null)
- action.accept((E)e);
- } while (p != null);
+ } while (p != null && p.isData);
}
}
@@ -997,10 +1000,11 @@
((p = current) != null || (p = q.firstDataNode()) != null)) {
Object e;
do {
- e = p.item;
+ if ((e = p.item) == p)
+ e = null;
if (p == (p = p.next))
p = q.firstDataNode();
- } while (e == null && p != null);
+ } while (e == null && p != null && p.isData);
if ((current = p) == null)
exhausted = true;
if (e != null) {
diff --git a/test/java/util/concurrent/LinkedTransferQueue/SpliteratorTraverseAddRemoveTest.java b/test/java/util/concurrent/LinkedTransferQueue/SpliteratorTraverseAddRemoveTest.java
new file mode 100644
index 0000000..4d288a2
--- /dev/null
+++ b/test/java/util/concurrent/LinkedTransferQueue/SpliteratorTraverseAddRemoveTest.java
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @run testng SpliteratorTraverseAddRemoveTest
+ * @bug 8085978
+ * @summary repeatedly traverse the queue using the spliterator while
+ * concurrently adding and removing an element to test that self-linked
+ * nodes are never erroneously reported on traversal
+ */
+
+import org.testng.Assert;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Queue;
+import java.util.Spliterator;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.LinkedTransferQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Consumer;
+
+@Test
+public class SpliteratorTraverseAddRemoveTest {
+
+ static Object[] of(String desc, Consumer<Queue<?>> c) {
+ return new Object[]{desc, c};
+ }
+
+ static void assertIsString(Object e) {
+ Assert.assertTrue(e instanceof String,
+ String.format("Object instanceof %s (actual: instanceof %s)",
+ String.class.getName(),
+ e.getClass().getName()));
+ }
+
+ @DataProvider()
+ public static Object[][] spliteratorTraversers() {
+ return new Object[][]{
+ of("forEachRemaining", q -> {
+ q.spliterator().forEachRemaining(SpliteratorTraverseAddRemoveTest::assertIsString);
+ }),
+ of("tryAdvance", q -> {
+ Spliterator<?> s = q.spliterator();
+ while (s.tryAdvance(SpliteratorTraverseAddRemoveTest::assertIsString))
+ ;
+ }),
+ of("trySplit then forEachRemaining", q -> {
+ Spliterator<?> r = q.spliterator();
+
+ List<Spliterator<?>> ss = new ArrayList<>();
+ Spliterator<?> l;
+ while ((l = r.trySplit()) != null) {
+ ss.add(l);
+ }
+ ss.add(r);
+
+ ss.forEach(s -> s.forEachRemaining(SpliteratorTraverseAddRemoveTest::assertIsString));
+ }),
+ };
+ }
+
+ @Test(dataProvider = "spliteratorTraversers")
+ public void testQueue(String desc, Consumer<Queue<String>> c)
+ throws InterruptedException {
+ AtomicBoolean done = new AtomicBoolean(false);
+ Queue<String> msgs = new LinkedTransferQueue<>();
+
+ CompletableFuture<Void> traversalTask = CompletableFuture.runAsync(() -> {
+ while (!done.get()) {
+ // Traversal will fail if self-linked nodes of
+ // LinkedTransferQueue are erroneously reported
+ c.accept(msgs);
+ }
+ });
+ CompletableFuture<Void> addAndRemoveTask = CompletableFuture.runAsync(() -> {
+ while (!traversalTask.isDone()) {
+ msgs.add("msg");
+ msgs.remove("msg");
+ }
+ });
+
+ Thread.sleep(TimeUnit.SECONDS.toMillis(1));
+ done.set(true);
+
+ addAndRemoveTask.join();
+ Assert.assertTrue(traversalTask.isDone());
+ traversalTask.join();
+ }
+}