--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/ref/ReferenceEnqueuePending.java Mon Oct 31 17:38:15 2011 -0700
@@ -0,0 +1,201 @@
+/* Copyright (c) 2011, 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
+ * @bug 4243978
+ * @summary Test if Reference.enqueue() works properly with pending references
+ */
+import java.lang.ref.*;
+
+public class ReferenceEnqueuePending {
+ static class NumberedWeakReference extends WeakReference<Integer> {
+ // Add an integer to identify the weak reference object.
+ int number;
+
+ NumberedWeakReference(Integer referent, ReferenceQueue<Integer> q, int i) {
+ super(referent, q);
+ number = i;
+ }
+ }
+
+ final static boolean debug = System.getProperty("test.debug") != null;
+ final static int iterations = 1000;
+ final static int gc_trigger = 99;
+ static int[] a = new int[2 * iterations];
+ // Keep all weak references alive with the following array.
+ static NumberedWeakReference[] b = new NumberedWeakReference[iterations];
+
+ public static void main(String[] argv) throws Exception {
+ if (debug) {
+ System.out.println("Starting the test.");
+ }
+ // Raise thread priority to match the referenceHandler
+ // priority, so that they can race also on a uniprocessor.
+ raisePriority();
+
+ ReferenceQueue<Integer> refQueue = new ReferenceQueue<>();
+
+ // Our objective is to let the mutator enqueue
+ // a Reference object that may already be in the
+ // pending state because of having been identified
+ // as weakly reachable at a previous garbage collection.
+ // To this end, we create many Reference objects, each with a
+ // a unique integer object as its referant.
+ // We let the referents become eligible for collection,
+ // while racing with the garbage collector which may
+ // have pended some of these Reference objects.
+ // Finally we check that all of the Reference objects
+ // end up on the their queue. The test was originally
+ // submitted to show that such races could break the
+ // pending list and/or the reference queue, because of sharing
+ // the same link ("next") for maintaining both lists, thus
+ // losing some of the Reference objects on either queue.
+
+ Integer obj = new Integer(0);
+ NumberedWeakReference weaky = new NumberedWeakReference(obj, refQueue, 0);
+ for (int i = 1; i < iterations; i++) {
+ // Create a new object, dropping the onlY strong reference to
+ // the previous Integer object.
+ obj = new Integer(i);
+ // Trigger gc each gc_trigger iterations.
+ if ((i % gc_trigger) == 0) {
+ forceGc(0);
+ }
+ // Enqueue every other weaky.
+ if ((i % 2) == 0) {
+ weaky.enqueue();
+ }
+ // Remember the Reference objects, for testing later.
+ b[i - 1] = weaky;
+ // Get a new weaky for the Integer object just
+ // created, which may be explicitly enqueued in
+ // our next trip around the loop.
+ weaky = new NumberedWeakReference(obj, refQueue, i);
+ }
+
+ // Do a final collection to discover and process all
+ // Reference objects created above, allowing enough time
+ // for the ReferenceHandler thread to queue the References.
+ forceGc(100);
+ forceGc(100);
+
+ // Verify that all WeakReference objects ended up queued.
+ checkResult(refQueue, obj, iterations-1);
+ System.out.println("Test passed.");
+ }
+
+ private static void checkResult(ReferenceQueue<Integer> queue,
+ Integer obj,
+ int expected) {
+ if (debug) {
+ System.out.println("Reading the queue");
+ }
+
+ // Empty the queue and record numbers into a[];
+ NumberedWeakReference weakRead = (NumberedWeakReference) queue.poll();
+ int length = 0;
+ while (weakRead != null) {
+ a[length++] = weakRead.number;
+ weakRead = (NumberedWeakReference) queue.poll();
+ }
+ if (debug) {
+ System.out.println("Reference Queue had " + length + " elements");
+ }
+ // Use the last Reference object of those created above, so as to keep it "alive".
+ System.out.println("I must write " + obj + " to prevent compiler optimizations.");
+
+
+ // verify the queued references: all but the last Reference object
+ // should have been in the queue.
+ if (debug) {
+ System.out.println("Start of final check");
+ }
+
+ // Sort the first "length" elements in array "a[]".
+ sort(length);
+
+ boolean fail = (length != expected);
+ for (int i = 0; i < length; i++) {
+ if (a[i] != i) {
+ if (debug) {
+ System.out.println("a[" + i + "] is not " + i + " but " + a[i]);
+ }
+ fail = true;
+ }
+ }
+ if (fail) {
+ printMissingElements(length, expected);
+ throw new RuntimeException("TEST FAILED: only " + length
+ + " reference objects have been queued out of "
+ + expected);
+ }
+ }
+
+ private static void printMissingElements(int length, int expected) {
+ System.out.println("The following numbers were not found in the reference queue: ");
+ int missing = 0;
+ int element = 0;
+ for (int i = 0; i < length; i++) {
+ while ((a[i] != element) & (element < expected)) {
+ System.out.print(element + " ");
+ if (missing % 20 == 19) {
+ System.out.println(" ");
+ }
+ missing++;
+ element++;
+ }
+ element++;
+ }
+ System.out.print("\n");
+ }
+
+ private static void forceGc(long millis) throws InterruptedException {
+ Runtime.getRuntime().gc();
+ Thread.sleep(millis);
+ }
+
+ // Bubble sort the first "length" elements in array "a".
+ private static void sort(int length) {
+ int hold;
+ if (debug) {
+ System.out.println("Sorting. Length=" + length);
+ }
+ for (int pass = 1; pass < length; pass++) { // passes over the array
+ for (int i = 0; i < length - pass; i++) { // a single pass
+ if (a[i] > a[i + 1]) { // then swap
+ hold = a[i];
+ a[i] = a[i + 1];
+ a[i + 1] = hold;
+ }
+ } // End of i loop
+ } // End of pass loop
+ }
+
+ // Raise thread priority so as to increase the
+ // probability of the mutator succeeding in enqueueing
+ // an object that is still in the pending state.
+ // This is (probably) only required for a uniprocessor.
+ static void raisePriority() {
+ Thread tr = Thread.currentThread();
+ tr.setPriority(Thread.MAX_PRIORITY);
+ }
+} // End of class ReferenceEnqueuePending