1 /*
2 * Copyright (c) 2014, 2018, 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 package gc.g1.unloading.keepref;
24
25 import java.lang.reflect.*;
26 import java.util.*;
27
28 /**
29 * This holder keeps class from being collected by saving link in static field of class loaded by null classloader.
30 * It uses pool of classes that should reside in bootclasspath.
31 */
32 public class NullClassloaderHolder implements RefHolder {
33
34 private static final int NUMBER_OF_CLASSES = 1000;
35 private static Set<Class<?>> classesPool = Collections.synchronizedSet(new HashSet<Class<?>>());
36
37 static {
38 for (int i = 1; i <= NUMBER_OF_CLASSES; i++) {
39 String className = "gc.g1.unloading.rootSetHelper.classesPool.Class" + i;
40 try {
41 Class<?> clazz = Class.forName(className);
42 if (clazz.getClassLoader() != null) {
43 throw new RuntimeException("Test bug! Classes from pool implied to be loaded by bootclassloader.");
44 }
45 classesPool.add(clazz);
46 } catch (ClassNotFoundException e) {
47 throw new RuntimeException("Test bug", e);
48 }
49 }
50 }
51
52 @Override
53 public Object hold(Object object) {
54 if (classesPool.isEmpty()) {
55 return null;
56 } else {
57 Class<?> clazz = (Class<?>) classesPool.iterator().next();
58 classesPool.remove(clazz);
59 Field f = getRandomField(clazz);
60 try {
61 f.set(null, object);
62 return clazz.newInstance();
63 } catch (IllegalArgumentException | IllegalAccessException | InstantiationException e) {
64 throw new RuntimeException("Test bug", e);
65 }
66 }
67 }
68
69 private static Field getRandomField(Class<?> clazz) {
70 ArrayList<Field> fields = new ArrayList<>();
71 for (Field f : clazz.getFields()) {
72 if (f.getName().startsWith("staticField")) {
73 fields.add(f);
74 }
75 }
76 return fields.get(new Random().nextInt(fields.size()));
77 }
78
79 }
|
1 /*
2 * Copyright (c) 2014, 2020, 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 package gc.g1.unloading.keepref;
24
25 import java.lang.reflect.*;
26 import java.util.*;
27
28 /**
29 * This holder keeps class from being collected by saving link in static field of class loaded by null classloader.
30 * It uses pool of classes that should reside in bootclasspath.
31 */
32 public class NullClassloaderHolder implements RefHolder {
33
34 private static final int NUMBER_OF_CLASSES = 1000;
35 private static Set<Class<?>> classesPool = Collections.synchronizedSet(new HashSet<Class<?>>());
36 private final Random random;
37
38 static {
39 for (int i = 1; i <= NUMBER_OF_CLASSES; i++) {
40 String className = "gc.g1.unloading.rootSetHelper.classesPool.Class" + i;
41 try {
42 Class<?> clazz = Class.forName(className);
43 if (clazz.getClassLoader() != null) {
44 throw new RuntimeException("Test bug! Classes from pool implied to be loaded by bootclassloader.");
45 }
46 classesPool.add(clazz);
47 } catch (ClassNotFoundException e) {
48 throw new RuntimeException("Test bug", e);
49 }
50 }
51 }
52
53 public NullClassloaderHolder(long seed) {
54 random = new Random(seed);
55 }
56
57 @Override
58 public Object hold(Object object) {
59 if (classesPool.isEmpty()) {
60 return null;
61 } else {
62 Class<?> clazz = (Class<?>) classesPool.iterator().next();
63 classesPool.remove(clazz);
64 Field f = getRandomField(clazz);
65 try {
66 f.set(null, object);
67 return clazz.newInstance();
68 } catch (IllegalArgumentException | IllegalAccessException | InstantiationException e) {
69 throw new RuntimeException("Test bug", e);
70 }
71 }
72 }
73
74 private Field getRandomField(Class<?> clazz) {
75 ArrayList<Field> fields = new ArrayList<>();
76 for (Field f : clazz.getFields()) {
77 if (f.getName().startsWith("staticField")) {
78 fields.add(f);
79 }
80 }
81 return fields.get(random.nextInt(fields.size()));
82 }
83
84 }
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