1 /*
   2  * Copyright (c) 2007, 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 /*
  25  * @test
  26  * @bug 6499848
  27  * @ignore until 6842353 is resolved
  28  * @summary Check that iterators work properly in the presence of
  29  *          concurrent finalization and removal of elements.
  30  * @key randomness
  31  */
  32 
  33 import java.util.*;
  34 import java.util.concurrent.CountDownLatch;
  35 
  36 public class GCDuringIteration {
  37     private static void waitForFinalizersToRun() {
  38         for (int i = 0; i < 2; i++)
  39             tryWaitForFinalizersToRun();
  40     }
  41 
  42     private static void tryWaitForFinalizersToRun() {
  43         System.gc();
  44         final CountDownLatch fin = new CountDownLatch(1);
  45         new Object() { protected void finalize() { fin.countDown(); }};
  46         System.gc();
  47         try { fin.await(); }
  48         catch (InterruptedException ie) { throw new Error(ie); }
  49     }
  50 
  51     // A class with the traditional pessimal hashCode implementation,
  52     // to ensure that all instances end up in the same bucket.
  53     static class Foo { public int hashCode() { return 42; }}
  54 
  55     <K,V> void put(Map<K,V> map, K k, V v) {
  56         check(! map.containsKey(k));
  57         equal(map.get(k), null);
  58         equal(map.put(k, v), null);
  59         equal(map.get(k), v);
  60         check(map.containsKey(k));
  61         equal(map.put(k, v), v);
  62         equal(map.get(k), v);
  63         check(map.containsKey(k));
  64         check(! map.isEmpty());
  65         equal(map.keySet().iterator().next(), k);
  66         equal(map.values().iterator().next(), v);
  67     }
  68 
  69     void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) {
  70         final Random rnd = new Random();
  71         for (int i = first; i >= 0; --i) {
  72             if (rnd.nextBoolean()) check(it.hasNext());
  73             equal(it.next().getValue(), i);
  74         }
  75         if (rnd.nextBoolean())
  76             THROWS(NoSuchElementException.class,
  77                    new F(){void f(){it.next();}});
  78         if (rnd.nextBoolean())
  79             check(! it.hasNext());
  80     }
  81 
  82     <K,V> V firstValue(Map<K,V> map) {
  83         return map.values().iterator().next();
  84     }
  85 
  86     void test(String[] args) throws Throwable {
  87         final int n = 10;
  88         // Create array of strong refs
  89         final Foo[] foos = new Foo[2*n];
  90         final Map<Foo,Integer> map = new WeakHashMap<Foo,Integer>(foos.length);
  91         check(map.isEmpty());
  92         equal(map.size(), 0);
  93 
  94         for (int i = 0; i < foos.length; i++) {
  95             Foo foo = new Foo();
  96             foos[i] = foo;
  97             put(map, foo, i);
  98         }
  99         equal(map.size(), foos.length);
 100 
 101         {
 102             int first = firstValue(map);
 103             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 104             foos[first] = null;
 105             for (int i = 0; i < 10 && map.size() != first; i++)
 106                 tryWaitForFinalizersToRun();
 107             equal(map.size(), first);
 108             checkIterator(it, first-1);
 109             equal(map.size(), first);
 110             equal(firstValue(map), first-1);
 111         }
 112 
 113         {
 114             int first = firstValue(map);
 115             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 116             it.next();          // protects first entry
 117             System.out.println(map.values());
 118             foos[first] = null;
 119             tryWaitForFinalizersToRun()
 120             equal(map.size(), first+1);
 121             System.out.println(map.values());
 122             checkIterator(it, first-1);
 123             // first entry no longer protected
 124             for (int i = 0; i < 10 && map.size() != first; i++)
 125                 tryWaitForFinalizersToRun();
 126             equal(map.size(), first);
 127             equal(firstValue(map), first-1);
 128         }
 129 
 130         {
 131             int first = firstValue(map);
 132             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 133             it.next();          // protects first entry
 134             System.out.println(map.values());
 135             foos[first] = foos[first-1] = null;
 136             tryWaitForFinalizersToRun();
 137             equal(map.size(), first);
 138             equal(firstValue(map), first);
 139             System.out.println(map.values());
 140             checkIterator(it, first-2);
 141             // first entry no longer protected
 142             for (int i = 0; i < 10 && map.size() != first-1; i++)
 143                 tryWaitForFinalizersToRun();
 144             equal(map.size(), first-1);
 145             equal(firstValue(map), first-2);
 146         }
 147 
 148         {
 149             int first = firstValue(map);
 150             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 151             it.next();          // protects first entry
 152             it.hasNext();       // protects second entry
 153             System.out.println(map.values());
 154             foos[first] = foos[first-1] = null;
 155             tryWaitForFinalizersToRun();
 156             equal(firstValue(map), first);
 157             equal(map.size(), first+1);
 158             System.out.println(map.values());
 159             checkIterator(it, first-1);
 160             // first entry no longer protected
 161             for (int i = 0; i < 10 && map.size() != first-1; i++)
 162                 tryWaitForFinalizersToRun();
 163             equal(map.size(), first-1);
 164             equal(firstValue(map), first-2);
 165         }
 166 
 167         {
 168             int first = firstValue(map);
 169             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 170             it.next();          // protects first entry
 171             System.out.println(map.values());
 172             foos[first] = foos[first-1] = null;
 173             tryWaitForFinalizersToRun();
 174             it.remove();
 175             equal(firstValue(map), first-2);
 176             equal(map.size(), first-1);
 177             System.out.println(map.values());
 178             checkIterator(it, first-2);
 179             // first entry no longer protected
 180             for (int i = 0; i < 10 && map.size() != first-1; i++)
 181                 tryWaitForFinalizersToRun();
 182             equal(map.size(), first-1);
 183             equal(firstValue(map), first-2);
 184         }
 185 
 186         {
 187             int first = firstValue(map);
 188             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 189             it.next();          // protects first entry
 190             it.remove();
 191             it.hasNext();       // protects second entry
 192             System.out.println(map.values());
 193             foos[first] = foos[first-1] = null;
 194             tryWaitForFinalizersToRun();
 195             equal(firstValue(map), first-1);
 196             equal(map.size(), first);
 197             System.out.println(map.values());
 198             checkIterator(it, first-1);
 199             for (int i = 0; i < 10 && map.size() != first-1; i++)
 200                 tryWaitForFinalizersToRun();
 201             equal(map.size(), first-1);
 202             equal(firstValue(map), first-2);
 203         }
 204 
 205         {
 206             int first = firstValue(map);
 207             final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator();
 208             it.hasNext();       // protects first entry
 209             Arrays.fill(foos, null);
 210             tryWaitForFinalizersToRun();
 211             equal(map.size(), 1);
 212             System.out.println(map.values());
 213             equal(it.next().getValue(), first);
 214             check(! it.hasNext());
 215             for (int i = 0; i < 10 && map.size() != 0; i++)
 216                 tryWaitForFinalizersToRun();
 217             equal(map.size(), 0);
 218             check(map.isEmpty());
 219         }
 220     }
 221 
 222     //--------------------- Infrastructure ---------------------------
 223     volatile int passed = 0, failed = 0;
 224     void pass() {passed++;}
 225     void fail() {failed++; Thread.dumpStack();}
 226     void fail(String msg) {System.err.println(msg); fail();}
 227     void unexpected(Throwable t) {failed++; t.printStackTrace();}
 228     void check(boolean cond) {if (cond) pass(); else fail();}
 229     void equal(Object x, Object y) {
 230         if (x == null ? y == null : x.equals(y)) pass();
 231         else fail(x + " not equal to " + y);}
 232     public static void main(String[] args) throws Throwable {
 233         new GCDuringIteration().instanceMain(args);}
 234     void instanceMain(String[] args) throws Throwable {
 235         try {test(args);} catch (Throwable t) {unexpected(t);}
 236         System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
 237         if (failed > 0) throw new AssertionError("Some tests failed");}
 238     abstract class F {abstract void f() throws Throwable;}
 239     void THROWS(Class<? extends Throwable> k, F... fs) {
 240         for (F f : fs)
 241             try {f.f(); fail("Expected " + k.getName() + " not thrown");}
 242             catch (Throwable t) {
 243                 if (k.isAssignableFrom(t.getClass())) pass();
 244                 else unexpected(t);}}
 245 }
--- EOF ---