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