1 /*
   2  * Copyright (c) 2005, 2012, 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 /*
  25  * @test
  26  * @bug 6215625 7161229
  27  * @summary Check correct behavior when last element is removed.
  28  * @author Martin Buchholz
  29  */
  30 
  31 import java.util.*;
  32 import java.util.concurrent.*;
  33 
  34 public class LastElement {
  35     void test(String[] args) throws Throwable {
  36         testQueue(new LinkedBlockingQueue<Integer>());
  37         testQueue(new LinkedBlockingDeque<Integer>());
  38         testQueue(new ArrayBlockingQueue<Integer>(10, true));
  39         testQueue(new ArrayBlockingQueue<Integer>(10, false));
  40         testQueue(new LinkedTransferQueue<Integer>());
  41         testQueue(new PriorityBlockingQueue<Integer>());
  42     }
  43 
  44     void testQueue(BlockingQueue<Integer> q) throws Throwable {
  45         Integer one = 1;
  46         Integer two = 2;
  47         Integer three = 3;
  48 
  49         // remove(Object)
  50         q.put(one);
  51         q.put(two);
  52         check(! q.isEmpty() && q.size() == 2);
  53         check(q.remove(one));
  54         check(q.remove(two));
  55         check(q.isEmpty() && q.size() == 0);
  56         q.put(three);
  57         try {check(q.take() == three);}
  58         catch (Throwable t) {unexpected(t);}
  59         check(q.isEmpty() && q.size() == 0);
  60         check(noRetention(q));
  61 
  62         // iterator().remove()
  63         q.clear();
  64         q.put(one);
  65         check(q.offer(two));
  66         check(! q.isEmpty() && q.size() == 2);
  67         Iterator<Integer> i = q.iterator();
  68         check(i.next() == one);
  69         i.remove();
  70         check(i.next() == two);
  71         i.remove();
  72         check(q.isEmpty() && q.size() == 0);
  73         q.put(three);
  74         try {check(q.take() == three);}
  75         catch (Throwable t) {unexpected(t);}
  76         check(q.isEmpty() && q.size() == 0);
  77     }
  78 
  79     boolean noRetention(BlockingQueue<?> q) {
  80         if (q instanceof PriorityBlockingQueue) {
  81             PriorityBlockingQueue<?> pbq = (PriorityBlockingQueue) q;
  82             try {
  83                 java.lang.reflect.Field queue =
  84                     PriorityBlockingQueue.class.getDeclaredField("queue");
  85                 queue.setAccessible(true);
  86                 Object[] a = (Object[]) queue.get(pbq);
  87                 return a[0] == null;
  88             }
  89             catch (NoSuchFieldException e) {
  90                 unexpected(e);
  91             }
  92             catch (IllegalAccessException e) {
  93                 // ignore - security manager must be installed
  94             }
  95         }
  96         return true;
  97     }
  98 
  99     //--------------------- Infrastructure ---------------------------
 100     volatile int passed = 0, failed = 0;
 101     void pass() {passed++;}
 102     void fail() {failed++; Thread.dumpStack();}
 103     void fail(String msg) {System.err.println(msg); fail();}
 104     void unexpected(Throwable t) {failed++; t.printStackTrace();}
 105     void check(boolean cond) {if (cond) pass(); else fail();}
 106     void equal(Object x, Object y) {
 107         if (x == null ? y == null : x.equals(y)) pass();
 108         else fail(x + " not equal to " + y);}
 109     public static void main(String[] args) throws Throwable {
 110         new LastElement().instanceMain(args);}
 111     public void instanceMain(String[] args) throws Throwable {
 112         try {test(args);} catch (Throwable t) {unexpected(t);}
 113         System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
 114         if (failed > 0) throw new AssertionError("Some tests failed");}
 115 }