6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage

6815766: LinkedBlockingQueue's iterator can return null if drainTo(c) executes concurrently
Summary: Faster, more correct. Use self-linking trick to avoid gc retention
Reviewed-by: martin, dholmes

jdk/test/java/util/Collection/MOAT.java

@@ -426,6 +426,36 @@ public class MOAT {
         q.poll();
         equal(q.size(), 4);
         checkFunctionalInvariants(q);
+        if ((q instanceof LinkedBlockingQueue) ||
+            (q instanceof LinkedBlockingDeque) ||
+            (q instanceof ConcurrentLinkedQueue)) {
+            testQueueIteratorRemove(q);
+        }
+    }
+
+    private static void testQueueIteratorRemove(Queue<Integer> q) {
+        System.err.printf("testQueueIteratorRemove %s%n",
+                          q.getClass().getSimpleName());
+        q.clear();
+        for (int i = 0; i < 5; i++)
+            q.add(i);
+        Iterator<Integer> it = q.iterator();
+        check(it.hasNext());
+        for (int i = 3; i >= 0; i--)
+            q.remove(i);
+        equal(it.next(), 0);
+        equal(it.next(), 4);
+
+        q.clear();
+        for (int i = 0; i < 5; i++)
+            q.add(i);
+        it = q.iterator();
+        equal(it.next(), 0);
+        check(it.hasNext());
+        for (int i = 1; i < 4; i++)
+            q.remove(i);
+        equal(it.next(), 1);
+        equal(it.next(), 4);
     }
 
     private static void testList(final List<Integer> l) {
@@ -451,6 +481,11 @@ public class MOAT {
     }
 
     private static void testCollection(Collection<Integer> c) {
+        try { testCollection1(c); }
+        catch (Throwable t) { unexpected(t); }
+    }
+
+    private static void testCollection1(Collection<Integer> c) {
 
         System.out.println("\n==> " + c.getClass().getName());
 

jdk/test/java/util/concurrent/BlockingQueue/OfferDrainToLoops.java

+/*
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+/*
+ * @test
+ * @bug 6805775 6815766
+ * @summary Test concurrent offer vs. drainTo
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+
+@SuppressWarnings({"unchecked", "rawtypes"})
+public class OfferDrainToLoops {
+    void checkNotContainsNull(Iterable it) {
+        for (Object x : it)
+            check(x != null);
+    }
+
+    abstract class CheckedThread extends Thread {
+        abstract protected void realRun();
+        public void run() {
+            try { realRun(); } catch (Throwable t) { unexpected(t); }
+        }
+        {
+            setDaemon(true);
+            start();
+        }
+    }
+
+    void test(String[] args) throws Throwable {
+        test(new LinkedBlockingQueue());
+        test(new LinkedBlockingQueue(2000));
+        test(new LinkedBlockingDeque());
+        test(new LinkedBlockingDeque(2000));
+        test(new ArrayBlockingQueue(2000));
+    }
+
+    void test(final BlockingQueue q) throws Throwable {
+        System.out.println(q.getClass().getSimpleName());
+        final long testDurationSeconds = 1L;
+        final long testDurationMillis = testDurationSeconds * 1000L;
+        final long quittingTimeNanos
+            = System.nanoTime() + testDurationSeconds * 1000L * 1000L * 1000L;
+
+        Thread offerer = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if ((i % 1024) == 0 &&
+                        System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    while (! q.offer(i))
+                        Thread.yield();
+                }}};
+
+        Thread drainer = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if (System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    List list = new ArrayList();
+                    int n = q.drainTo(list);
+                    equal(list.size(), n);
+                    for (int j = 0; j < n - 1; j++)
+                        equal((Long) list.get(j) + 1L, list.get(j + 1));
+                    Thread.yield();
+                }}};
+
+        Thread scanner = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if (System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    checkNotContainsNull(q);
+                    Thread.yield();
+                }}};
+
+        offerer.join(10 * testDurationMillis);
+        drainer.join(10 * testDurationMillis);
+        check(! offerer.isAlive());
+        check(! drainer.isAlive());
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new OfferDrainToLoops().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}

jdk/test/java/util/concurrent/ConcurrentQueues/IteratorWeakConsistency.java

+/*
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+
+/*
+ * @test
+ * @bug 6805775 6815766
+ * @summary Check weak consistency of concurrent queue iterators
+ */
+
+@SuppressWarnings({"unchecked", "rawtypes"})
+public class IteratorWeakConsistency {
+
+    void test(String[] args) throws Throwable {
+        test(new LinkedBlockingQueue());
+        test(new LinkedBlockingQueue(20));
+        test(new LinkedBlockingDeque());
+        test(new LinkedBlockingDeque(20));
+        test(new ConcurrentLinkedQueue());
+        // Other concurrent queues (e.g. ArrayBlockingQueue) do not
+        // currently have weakly consistent iterators.
+        // test(new ArrayBlockingQueue(20));
+    }
+
+    void test(Queue q) throws Throwable {
+        // TODO: make this more general
+        for (int i = 0; i < 10; i++)
+            q.add(i);
+        Iterator it = q.iterator();
+        q.poll();
+        q.poll();
+        q.poll();
+        q.remove(7);
+        List list = new ArrayList();
+        while (it.hasNext())
+            list.add(it.next());
+        equal(list, Arrays.asList(0, 3, 4, 5, 6, 8, 9));
+        check(! list.contains(null));
+        System.out.printf("%s: %s%n",
+                          q.getClass().getSimpleName(),
+                          list);
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    static Class<?> thisClass = new Object(){}.getClass().getEnclosingClass();
+    public static void main(String[] args) throws Throwable {
+        new IteratorWeakConsistency().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}