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.lang.reflect.Field;
25 import java.util.ArrayList;
26 import java.util.Collections;
27 import java.util.IdentityHashMap;
28 import java.util.List;
29 import java.util.Random;
30
31 import org.testng.annotations.DataProvider;
32 import org.testng.annotations.Test;
33
34 import static org.testng.Assert.*;
35
36 /*
37 * @test
38 * @bug 6904367
39 * @summary IdentityHashMap reallocates storage when inserting expected
40 * number of elements
41 * @run testng Capacity
42 */
43
44 @Test
45 public class Capacity {
46 static final Field tableField;
47 static final Random random = new Random();
48 static final Object[][] sizesData;
49
50 @DataProvider(name="sizes", parallel = true)
51 public Object[][] sizesToTest() { return sizesData; }
52
53 static {
54 try {
55 tableField = IdentityHashMap.class.getDeclaredField("table");
56 tableField.setAccessible(true);
57 } catch (NoSuchFieldException e) {
58 throw new LinkageError("table", e);
59 }
60
61 ArrayList<Object[]> sizes = new ArrayList<>();
62 for (int size = 0; size < 200; size++)
63 sizes.add(new Object[] { size });
64
65 // some numbers known to demonstrate bug 6904367
66 for (int size : new int[] {682, 683, 1365, 2730, 2731, 5461})
67 sizes.add(new Object[] { size });
68
69 // a few more random sizes to try
70 for (int i = 0; i != 128; i++)
71 sizes.add(new Object[] { random.nextInt(5000) });
72
73 sizesData = sizes.toArray(new Object[0][]);
74 }
75
76 static int capacity(IdentityHashMap<?,?> map) {
77 try {
78 return ((Object[]) tableField.get(map)).length / 2;
79 } catch (Throwable t) {
80 throw new LinkageError("table", t);
81 }
82 }
83
84 static void assertCapacity(IdentityHashMap<?,?> map,
85 int expectedCapacity) {
86 assertEquals(capacity(map), expectedCapacity);
87 }
88
89 static void growUsingPut(IdentityHashMap<Object,Object> map,
90 int elementsToAdd) {
91 for (int i = 0; i < elementsToAdd; i++)
92 map.put(new Object(), new Object());
93 }
94
95 static void growUsingPutAll(IdentityHashMap<Object,Object> map,
96 int elementsToAdd) {
97 IdentityHashMap<Object,Object> other = new IdentityHashMap<>();
98 growUsingPut(other, elementsToAdd);
99 map.putAll(other);
100 }
101
102 static void growUsingRepeatedPutAll(IdentityHashMap<Object,Object> map,
103 int elementsToAdd) {
104 for (int i = 0; i < elementsToAdd; i++)
105 map.putAll(Collections.singletonMap(new Object(),
106 new Object()));
107 }
108
109 /**
110 * Checks that expected number of items can be inserted into
111 * the map without resizing of the internal storage
112 */
113 @Test(dataProvider = "sizes")
114 public void canInsertExpectedItemsWithoutResizing(int size)
115 throws Throwable {
116 // First try growing using put()
117 IdentityHashMap<Object,Object> m = new IdentityHashMap<>(size);
118 int initialCapacity = capacity(m);
119 growUsingPut(m, size);
120 assertCapacity(m, initialCapacity);
121
122 // Doubling from the expected size will cause exactly one
123 // resize, except near minimum capacity.
124 if (size > 1) {
125 growUsingPut(m, size);
126 assertCapacity(m, 2 * initialCapacity);
127 }
128
129 // Try again, growing with putAll()
130 m = new IdentityHashMap<>(size);
131 initialCapacity = capacity(m);
132 growUsingPutAll(m, size);
133 assertCapacity(m, initialCapacity);
134
135 // Doubling from the expected size will cause exactly one
136 // resize, except near minimum capacity.
137 if (size > 1) {
138 growUsingPutAll(m, size);
139 assertCapacity(m, 2 * initialCapacity);
140 }
141 }
142
143 /**
144 * Given the expected size, computes such a number N of items that
145 * inserting (N+1) items will trigger resizing of the internal storage
146 */
147 static int threshold(int size) throws Throwable {
148 IdentityHashMap<Object,Object> m = new IdentityHashMap<>(size);
149 int initialCapacity = capacity(m);
150 while (capacity(m) == initialCapacity)
151 growUsingPut(m, 1);
152 return m.size() - 1;
153 }
154
155 /**
156 * Checks that inserting (threshold+1) item causes resizing
157 * of the internal storage
158 */
159 @Test(dataProvider = "sizes")
160 public void passingThresholdCausesResize(int size) throws Throwable {
161 final int threshold = threshold(size);
162 IdentityHashMap<Object,Object> m = new IdentityHashMap<>(threshold);
163 int initialCapacity = capacity(m);
164
165 growUsingPut(m, threshold);
166 assertCapacity(m, initialCapacity);
167
168 growUsingPut(m, 1);
169 assertCapacity(m, 2 * initialCapacity);
170 }
171
172 /**
173 * Checks that 4 methods of requiring capacity lead to the same
174 * internal capacity, unless sized below default capacity.
175 */
176 @Test(dataProvider = "sizes")
177 public void differentGrowthPatternsResultInSameCapacity(int size)
178 throws Throwable {
179 if (size < 21) // 21 is default maxExpectedSize
180 return;
181
182 IdentityHashMap<Object,Object> m;
183 m = new IdentityHashMap<Object,Object>(size);
184 int capacity1 = capacity(m);
185
186 m = new IdentityHashMap<>();
187 growUsingPut(m, size);
188 int capacity2 = capacity(m);
189
190 m = new IdentityHashMap<>();
191 growUsingPutAll(m, size);
192 int capacity3 = capacity(m);
193
194 m = new IdentityHashMap<>();
195 growUsingRepeatedPutAll(m, size);
196 int capacity4 = capacity(m);
197
198 if (capacity1 != capacity2 ||
199 capacity2 != capacity3 ||
200 capacity3 != capacity4)
201 throw new AssertionError("Capacities not equal: "
202 + capacity1 + " "
203 + capacity2 + " "
204 + capacity3 + " "
205 + capacity4);
206 }
207
208 public void defaultExpectedMaxSizeIs21() {
209 assertCapacity(new IdentityHashMap<Long,Long>(), 32);
210 assertCapacity(new IdentityHashMap<Long,Long>(21), 32);
211 }
212
213 public void minimumCapacityIs4() {
214 assertCapacity(new IdentityHashMap<Long,Long>(0), 4);
215 assertCapacity(new IdentityHashMap<Long,Long>(1), 4);
216 assertCapacity(new IdentityHashMap<Long,Long>(2), 4);
217 assertCapacity(new IdentityHashMap<Long,Long>(3), 8);
218 }
219
220 @Test(enabled = false)
221 /** needs too much memory to run normally */
222 public void maximumCapacityIs2ToThe29() {
223 assertCapacity(new IdentityHashMap<Long,Long>(Integer.MAX_VALUE),
224 1 << 29);
225 }
226 }