1 /*
   2  * Copyright (c) 2011, 2015, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.javafx.util;
  27 
  28 import static org.junit.Assert.assertEquals;
  29 import static org.junit.Assert.assertFalse;
  30 import static org.junit.Assert.assertTrue;
  31 
  32 import java.util.Iterator;
  33 
  34 import org.junit.Test;
  35 
  36 public class WeakReferenceQueueTest {
  37     @Test
  38     public void testAdd() {
  39         WeakReferenceQueue q = new WeakReferenceQueue();
  40         String s = new String("Wow!");
  41         q.add(s);
  42         assertEquals(1, q.size);
  43     }
  44     
  45     @Test
  46     public void testRemove() {
  47         WeakReferenceQueue q = new WeakReferenceQueue();
  48         String a = new String("a");
  49         q.add(a);
  50         String b = new String("b");
  51         q.add(b);
  52         String c = new String("c");
  53         q.add(c);
  54         
  55         assertEquals(3, q.size);
  56         q.remove(a);
  57         q.remove(c);
  58         assertEquals(1, q.size);
  59     }
  60     
  61     @Test
  62     public void testCleanup() {
  63         WeakReferenceQueue q = new WeakReferenceQueue();
  64         String a = new String("a");
  65         q.add(a);
  66         String b = new String("b");
  67         q.add(b);
  68         String c = new String("c");
  69         q.add(c);
  70         
  71         assertEquals(3, q.size);
  72         a = null;
  73         c = null;
  74         tryGCReallyHard();
  75         q.cleanup();
  76         assertEquals(1, q.size);
  77     }
  78     
  79     @Test
  80     public void testIterator() {
  81         WeakReferenceQueue q = new WeakReferenceQueue();
  82         String a = new String("a");
  83         q.add(a);
  84         String b = new String("b");
  85         q.add(b);
  86         String c = new String("c");
  87         q.add(c);
  88         
  89         // This part of the test requires knowledge that iteration
  90         // is from last to first
  91         Iterator itr = q.iterator();
  92         assertTrue(itr.hasNext());
  93         assertEquals(c, itr.next());
  94         assertTrue(itr.hasNext());
  95         assertEquals(b, itr.next());
  96         assertTrue(itr.hasNext());
  97         assertEquals(a, itr.next());
  98         assertFalse(itr.hasNext());
  99         
 100         // and for good measure do it again without calling hasNext just
 101         // to make sure calling hasNext isn't a requirement
 102         itr = q.iterator();
 103         assertEquals(c, itr.next());
 104         assertEquals(b, itr.next());
 105         assertEquals(a, itr.next());
 106     }
 107     
 108     @Test
 109     public void testEmptyIterator() {
 110         WeakReferenceQueue q = new WeakReferenceQueue();
 111         Iterator itr = q.iterator();
 112         assertFalse(itr.hasNext());
 113     }
 114     
 115     @Test
 116     public void testIteratorRemove() {
 117         WeakReferenceQueue q = new WeakReferenceQueue();
 118         String a = new String("a");
 119         q.add(a);
 120         String b = new String("b");
 121         q.add(b);
 122         String c = new String("c");
 123         q.add(c);
 124         
 125         Iterator itr = q.iterator();
 126         itr.next(); // gives me "c"
 127         itr.remove();
 128         assertEquals(2, q.size);
 129         itr.next(); // gives me "b"
 130         itr.remove();
 131         assertEquals(1, q.size);
 132         itr.next(); // gives me "a"
 133         itr.remove();
 134         assertEquals(0, q.size);
 135         
 136         q.add(a);
 137         q.add(b);
 138         q.add(c);
 139         itr = q.iterator();
 140         itr.next();
 141         itr.next(); // gives me "b"
 142         itr.remove();
 143         
 144         itr = q.iterator();
 145         assertEquals(c, itr.next());
 146         assertEquals(a, itr.next());
 147     }
 148     
 149     @Test
 150     public void testIteratingOverSparseQueue() {
 151         WeakReferenceQueue q = new WeakReferenceQueue();
 152         String a = new String("a");
 153         q.add(a);
 154         String b = new String("b");
 155         q.add(b);
 156         String c = new String("c");
 157         q.add(c);
 158         
 159         assertEquals(3, q.size);
 160         a = null;
 161         c = null;
 162         tryGCReallyHard();
 163         q.cleanup();
 164 
 165         Iterator itr = q.iterator();
 166         assertEquals(b, itr.next());
 167         assertFalse(itr.hasNext());
 168     }
 169 
 170     @Test
 171     public void testIteratingOverSparseQueueWithoutCleanup() {
 172         WeakReferenceQueue q = new WeakReferenceQueue();
 173         String a = new String("a");
 174         q.add(a);
 175         String b = new String("b");
 176         q.add(b);
 177         String c = new String("c");
 178         q.add(c);
 179 
 180         assertEquals(3, q.size);
 181         a = null;
 182         c = null;
 183         tryGCReallyHard();
 184 
 185         Iterator itr = q.iterator();
 186         assertEquals(b, itr.next());
 187         assertFalse(itr.hasNext());
 188     }
 189 
 190     private void tryGCReallyHard() {
 191         // produce some garbage to increase the need of performing gc
 192         for (int i = 0; i < 100000; i++) {
 193             String s = new String("GARBAGE");
 194         }
 195 
 196         // now, yell at the VM to run gc
 197         for (int i = 0; i < 10; i++) {
 198             System.gc();
 199             System.gc();
 200             System.gc();
 201         }
 202 
 203         // finally, give the VM some idle time to perform gc
 204         try { Thread.sleep(100); } catch (InterruptedException e) {}
 205 
 206         // hope that worked!
 207     }
 208 }