| 1 |
/* |
| 2 |
* Copyright (c) 2007, 2017, 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 |
* @library /test/lib |
| 28 |
* @build jdk.test.lib.RandomFactory |
| 29 |
* @run main GCDuringIteration |
| 30 |
* @summary Check that iterators work properly in the presence of |
| 31 |
* concurrent finalization and removal of elements. |
| 32 |
* @key randomness |
| 33 |
*/ |
| 34 |
|
| 35 |
import jdk.test.lib.RandomFactory; |
| 36 |
|
| 37 |
import java.lang.ref.ReferenceQueue; |
| 38 |
import java.lang.ref.WeakReference; |
| 39 |
import java.util.Arrays; |
| 40 |
import java.util.Iterator; |
| 41 |
import java.util.Map; |
| 42 |
import java.util.NoSuchElementException; |
| 43 |
import java.util.Random; |
| 44 |
import java.util.WeakHashMap; |
| 45 |
import java.util.concurrent.CountDownLatch; |
| 46 |
import java.util.function.BooleanSupplier; |
| 47 |
|
| 48 |
import static java.util.concurrent.TimeUnit.MILLISECONDS; |
| 49 |
|
| 50 |
public class GCDuringIteration { |
| 51 |
|
| 52 |
/** No guarantees, but effective in practice. */ |
| 53 |
static void forceFullGc() { |
| 54 |
long timeoutMillis = 1000L; |
| 55 |
CountDownLatch finalized = new CountDownLatch(1); |
| 56 |
ReferenceQueue<Object> queue = new ReferenceQueue<>(); |
| 57 |
WeakReference<Object> ref = new WeakReference<>( |
| 58 |
new Object() { protected void finalize() { finalized.countDown(); }}, |
| 59 |
queue); |
| 60 |
try { |
| 61 |
for (int tries = 3; tries--> 0; ) { |
| 62 |
System.gc(); |
| 63 |
if (finalized.await(timeoutMillis, MILLISECONDS) |
| 64 |
&& queue.remove(timeoutMillis) != null |
| 65 |
&& ref.get() == null) { |
| 66 |
System.runFinalization(); // try to pick up stragglers |
| 67 |
return; |
| 68 |
} |
| 69 |
timeoutMillis *= 4; |
| 70 |
} |
| 71 |
} catch (InterruptedException unexpected) { |
| 72 |
throw new AssertionError("unexpected InterruptedException"); |
| 73 |
} |
| 74 |
throw new AssertionError("failed to do a \"full\" gc"); |
| 75 |
} |
| 76 |
|
| 77 |
static void gcAwait(BooleanSupplier s) { |
| 78 |
for (int i = 0; i < 10; i++) { |
| 79 |
if (s.getAsBoolean()) |
| 80 |
return; |
| 81 |
forceFullGc(); |
| 82 |
} |
| 83 |
throw new AssertionError("failed to satisfy condition"); |
| 84 |
} |
| 85 |
|
| 86 |
// A class with the traditional pessimal hashCode implementation, |
| 87 |
// to ensure that all instances end up in the same bucket. |
| 88 |
static class Foo { public int hashCode() { return 42; }} |
| 89 |
|
| 90 |
<K,V> void put(Map<K,V> map, K k, V v) { |
| 91 |
check(! map.containsKey(k)); |
| 92 |
equal(map.get(k), null); |
| 93 |
equal(map.put(k, v), null); |
| 94 |
equal(map.get(k), v); |
| 95 |
check(map.containsKey(k)); |
| 96 |
equal(map.put(k, v), v); |
| 97 |
equal(map.get(k), v); |
| 98 |
check(map.containsKey(k)); |
| 99 |
check(! map.isEmpty()); |
| 100 |
equal(map.keySet().iterator().next(), k); |
| 101 |
equal(map.values().iterator().next(), v); |
| 102 |
} |
| 103 |
|
| 104 |
static final Random rnd = RandomFactory.getRandom(); |
| 105 |
|
| 106 |
void checkIterator(final Iterator<Map.Entry<Foo, Integer>> it, int first) { |
| 107 |
for (int i = first; i >= 0; --i) { |
| 108 |
if (rnd.nextBoolean()) check(it.hasNext()); |
| 109 |
equal(it.next().getValue(), i); |
| 110 |
} |
| 111 |
if (rnd.nextBoolean()) { |
| 112 |
try { |
| 113 |
it.next(); |
| 114 |
throw new AssertionError("should throw"); |
| 115 |
} catch (NoSuchElementException success) {} |
| 116 |
} |
| 117 |
|
| 118 |
if (rnd.nextBoolean()) |
| 119 |
check(! it.hasNext()); |
| 120 |
} |
| 121 |
|
| 122 |
<K,V> V firstValue(Map<K,V> map) { |
| 123 |
return map.values().iterator().next(); |
| 124 |
} |
| 125 |
|
| 126 |
void test(String[] args) throws Throwable { |
| 127 |
final int n = 10; |
| 128 |
// Create array of strong refs |
| 129 |
final Foo[] foos = new Foo[2*n]; |
| 130 |
final Map<Foo,Integer> map = new WeakHashMap<>(foos.length); |
| 131 |
check(map.isEmpty()); |
| 132 |
equal(map.size(), 0); |
| 133 |
|
| 134 |
for (int i = 0; i < foos.length; i++) { |
| 135 |
Foo foo = new Foo(); |
| 136 |
foos[i] = foo; |
| 137 |
put(map, foo, i); |
| 138 |
} |
| 139 |
equal(map.size(), foos.length); |
| 140 |
|
| 141 |
{ |
| 142 |
int first = firstValue(map); |
| 143 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 144 |
foos[first] = null; |
| 145 |
gcAwait(() -> map.size() == first); |
| 146 |
checkIterator(it, first-1); |
| 147 |
equal(map.size(), first); |
| 148 |
equal(firstValue(map), first-1); |
| 149 |
} |
| 150 |
|
| 151 |
{ |
| 152 |
int first = firstValue(map); |
| 153 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 154 |
it.next(); // protects first entry |
| 155 |
System.out.println(map.values()); |
| 156 |
int oldSize = map.size(); |
| 157 |
foos[first] = null; |
| 158 |
forceFullGc(); |
| 159 |
equal(map.size(), oldSize); |
| 160 |
System.out.println(map.values()); |
| 161 |
checkIterator(it, first-1); |
| 162 |
// first entry no longer protected |
| 163 |
gcAwait(() -> map.size() == first); |
| 164 |
equal(firstValue(map), first-1); |
| 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 |
gcAwait(() -> map.size() == first); |
| 174 |
equal(firstValue(map), first); |
| 175 |
System.out.println(map.values()); |
| 176 |
checkIterator(it, first-2); |
| 177 |
// first entry no longer protected |
| 178 |
gcAwait(() -> map.size() == first-1); |
| 179 |
equal(firstValue(map), first-2); |
| 180 |
} |
| 181 |
|
| 182 |
{ |
| 183 |
int first = firstValue(map); |
| 184 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 185 |
it.next(); // protects first entry |
| 186 |
it.hasNext(); // protects second entry |
| 187 |
System.out.println(map.values()); |
| 188 |
int oldSize = map.size(); |
| 189 |
foos[first] = foos[first-1] = null; |
| 190 |
forceFullGc(); |
| 191 |
equal(map.size(), oldSize); |
| 192 |
equal(firstValue(map), first); |
| 193 |
System.out.println(map.values()); |
| 194 |
checkIterator(it, first-1); |
| 195 |
// first entry no longer protected |
| 196 |
gcAwait(() -> map.size() == first-1); |
| 197 |
equal(firstValue(map), first-2); |
| 198 |
} |
| 199 |
|
| 200 |
{ |
| 201 |
int first = firstValue(map); |
| 202 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 203 |
it.next(); // protects first entry |
| 204 |
System.out.println(map.values()); |
| 205 |
equal(map.size(), first+1); |
| 206 |
foos[first] = foos[first-1] = null; |
| 207 |
gcAwait(() -> map.size() == first); |
| 208 |
it.remove(); |
| 209 |
equal(firstValue(map), first-2); |
| 210 |
equal(map.size(), first-1); |
| 211 |
System.out.println(map.values()); |
| 212 |
checkIterator(it, first-2); |
| 213 |
// first entry no longer protected |
| 214 |
gcAwait(() -> map.size() == first-1); |
| 215 |
equal(firstValue(map), first-2); |
| 216 |
} |
| 217 |
|
| 218 |
{ |
| 219 |
int first = firstValue(map); |
| 220 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 221 |
it.next(); // protects first entry |
| 222 |
it.remove(); |
| 223 |
it.hasNext(); // protects second entry |
| 224 |
System.out.println(map.values()); |
| 225 |
equal(map.size(), first); |
| 226 |
foos[first] = foos[first-1] = null; |
| 227 |
forceFullGc(); |
| 228 |
equal(firstValue(map), first-1); |
| 229 |
equal(map.size(), first); |
| 230 |
System.out.println(map.values()); |
| 231 |
checkIterator(it, first-1); |
| 232 |
gcAwait(() -> map.size() == first-1); |
| 233 |
equal(firstValue(map), first-2); |
| 234 |
} |
| 235 |
|
| 236 |
{ |
| 237 |
int first = firstValue(map); |
| 238 |
final Iterator<Map.Entry<Foo,Integer>> it = map.entrySet().iterator(); |
| 239 |
it.hasNext(); // protects first entry |
| 240 |
Arrays.fill(foos, null); |
| 241 |
gcAwait(() -> map.size() == 1); |
| 242 |
System.out.println(map.values()); |
| 243 |
equal(it.next().getValue(), first); |
| 244 |
check(! it.hasNext()); |
| 245 |
gcAwait(() -> map.size() == 0); |
| 246 |
check(map.isEmpty()); |
| 247 |
} |
| 248 |
} |
| 249 |
|
| 250 |
//--------------------- Infrastructure --------------------------- |
| 251 |
volatile int passed = 0, failed = 0; |
| 252 |
void pass() {passed++;} |
| 253 |
void fail() {failed++; Thread.dumpStack();} |
| 254 |
void fail(String msg) {System.err.println(msg); fail();} |
| 255 |
void unexpected(Throwable t) {failed++; t.printStackTrace();} |
| 256 |
void check(boolean cond) {if (cond) pass(); else fail();} |
| 257 |
void equal(Object x, Object y) { |
| 258 |
if (x == null ? y == null : x.equals(y)) pass(); |
| 259 |
else fail(x + " not equal to " + y);} |
| 260 |
public static void main(String[] args) throws Throwable { |
| 261 |
new GCDuringIteration().instanceMain(args);} |
| 262 |
void instanceMain(String[] args) throws Throwable { |
| 263 |
try {test(args);} catch (Throwable t) {unexpected(t);} |
| 264 |
System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed); |
| 265 |
if (failed > 0) throw new AssertionError("Some tests failed");} |
| 266 |
} |
