1 /*
2 * Copyright (c) 2014, 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 import java.io.ByteArrayInputStream;
25 import java.io.ByteArrayOutputStream;
26 import java.io.ObjectInputStream;
27 import java.io.ObjectOutputStream;
28 import java.lang.reflect.Field;
29 import java.util.Hashtable;
30
31 /**
32 * @test
33 * @bug 8068427
34 * @summary Hashtable deserialization reconstitutes table with wrong capacity
35 */
36 public class DeserializedLength {
37
38 static boolean testDeserializedLength(int elements, float loadFactor) throws Exception {
39 // construct Hashtable with minimal initial capacity and given loadFactor
40 Hashtable<Integer, Integer> ht1 = new Hashtable<>(1, loadFactor);
41 // add given number of unique elements
42 for (int i = 0; i < elements; i++) {
43 ht1.put(i, i);
44 }
45
46 // serialize it to byte[] array
47 byte[] bytes;
48 try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
49 ObjectOutputStream oos = new ObjectOutputStream(baos)) {
50 oos.writeObject(ht1);
51 oos.flush();
52 bytes = baos.toByteArray();
53 }
54
55 // de-serialize it from byte[] array
56 Hashtable<?, ?> ht2;
57 try (ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
58 ObjectInputStream ois = new ObjectInputStream(bais)) {
59 ht2 = (Hashtable<?, ?>) ois.readObject();
60 }
61
62 // compare lengths of internal tables
63 Object[] table1 = (Object[]) hashtableTableField.get(ht1);
64 Object[] table2 = (Object[]) hashtableTableField.get(ht2);
65 assert table1 != null;
66 assert table2 != null;
67
68 int minLength = (int) (ht1.size() / loadFactor) + 1;
69 int maxLength = minLength * 2;
70
71 boolean ok = (table2.length >= minLength && table2.length <= maxLength);
72
73 System.out.printf(
74 "%7d %5.2f %7d %7d %7d...%7d %s\n",
75 ht1.size(), loadFactor,
76 table1.length, table2.length,
77 minLength, maxLength,
78 (ok ? "OK" : "NOT-OK")
79 );
80
81 return ok;
82 }
83
84 private static final Field hashtableTableField;
85
86 static {
87 try {
88 hashtableTableField = Hashtable.class.getDeclaredField("table");
89 hashtableTableField.setAccessible(true);
90 } catch (NoSuchFieldException e) {
91 throw new Error(e);
92 }
93 }
94
95 public static void main(String[] args) throws Exception {
96 boolean ok = true;
97
98 System.out.printf("Results:\n" +
99 " ser. deser.\n" +
100 " size load lentgh length valid range ok?\n" +
101 "------- ----- ------- ------- ----------------- ------\n"
102 );
103
104 for (int elements : new int[]{10, 50, 500, 5000}) {
105 for (float loadFactor : new float[]{0.15f, 0.5f, 0.75f, 1.0f, 2.5f}) {
106 ok &= testDeserializedLength(elements, loadFactor);
107 }
108 }
109 if (!ok) {
110 throw new AssertionError("Test failed.");
111 }
112 }
113 }