1 /*
   2  * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   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
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /* @test
  25  * @bug 4268317 8132306
  26  * @summary Test if Reference.enqueue() works properly with GC
  27  */
  28 
  29 import java.lang.ref.*;
  30 
  31 public class ReferenceEnqueue {
  32 
  33     public static void main(String args[]) throws Exception {
  34         for (int i=0; i < 5; i++)
  35             new WeakRef().run();
  36         System.out.println("Test passed.");
  37     }
  38 
  39     static class WeakRef {
  40         final ReferenceQueue<Object> queue = new ReferenceQueue<Object>();
  41         final Reference<Object> ref;
  42         final int iterations = 1000;
  43 
  44         WeakRef() {
  45             this.ref = new WeakReference<Object>(new Object(), queue);
  46         }
  47 
  48         void run() throws InterruptedException {
  49             System.gc();
  50             for (int i = 0; i < iterations; i++) {
  51                 System.gc();
  52                 if (ref.isEnqueued()) {
  53                     break;
  54                 }
  55 
  56                 Thread.sleep(100);
  57             }
  58 
  59             if (ref.isEnqueued() == false) {
  60                 // GC have not enqueued refWeak for the timeout period
  61                 System.out.println("Reference not enqueued yet");
  62                 return;
  63             }
  64 
  65             if (ref.enqueue() == true) {
  66                 // enqueue() should return false since
  67                 // ref is already enqueued by the GC
  68                 throw new RuntimeException("Error: enqueue() returned true;"
  69                         + " expected false");
  70             }
  71 
  72             if (queue.poll() == null) {
  73                 // poll() should return ref enqueued by the GC
  74                 throw new RuntimeException("Error: poll() returned null;"
  75                         + " expected ref object");
  76             }
  77         }
  78     }
  79 }