1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 import java.util.Random;
18 
19 public class Main {
20     private static final int buckets = 16 * 1024;
21     private static final int bufferSize = 1024;
22 
23     static class ByteContainer {
24         public byte[] bytes;
25     }
26 
main(String[] args)27     public static void main(String[] args) throws Exception {
28         ByteContainer[] l = new ByteContainer[buckets];
29 
30         for (int i = 0; i < buckets; ++i) {
31             l[i] = new ByteContainer();
32         }
33 
34         Random rnd = new Random(123456);
35         for (int i = 0; i < buckets / 256; ++i) {
36             int index = rnd.nextInt(buckets);
37             l[index].bytes = new byte[bufferSize];
38 
39             // Try to get GC to run if we can
40             Runtime.getRuntime().gc();
41 
42             // Shuffle the array to try cause the lost object problem:
43             // This problem occurs when an object is white, it may be
44             // only referenced from a white or grey object. If the white
45             // object is moved during a CMS to be a black object's field, it
46             // causes the moved object to not get marked. This can result in
47             // heap corruption. A typical way to address this issue is by
48             // having a card table.
49             // This aspect of the test is meant to ensure that card
50             // dirtying works and that we check the marked cards after
51             // marking.
52             // If these operations are not done, a segfault / failed assert
53             // should occur.
54             for (int j = 0; j < l.length; ++j) {
55                 int a = l.length - i - 1;
56                 int b = rnd.nextInt(a);
57                 byte[] temp = l[a].bytes;
58                 l[a].bytes = l[b].bytes;
59                 l[b].bytes = temp;
60             }
61         }
62         System.out.println("Test complete");
63     }
64 }
65