1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 */
22
23 /*
24 * This file is available under and governed by the GNU General Public
25 * License version 2 only, as published by the Free Software Foundation.
26 * However, the following notice accompanied the original version of this
27 * file:
28 *
29 * Written by Doug Lea with assistance from members of JCP JSR-166
30 * Expert Group and released to the public domain, as explained at
31 * http://creativecommons.org/publicdomain/zero/1.0/
32 */
33
34 import java.util.concurrent.Executors;
35 import java.util.concurrent.ExecutorService;
36 import java.util.concurrent.Phaser;
37 import java.util.concurrent.ThreadLocalRandom;
38 import java.util.concurrent.atomic.DoubleAccumulator;
39
40 import junit.framework.Test;
41 import junit.framework.TestSuite;
42
43 public class DoubleAccumulatorTest extends JSR166TestCase {
44 public static void main(String[] args) {
45 main(suite(), args);
46 }
47 public static Test suite() {
48 return new TestSuite(DoubleAccumulatorTest.class);
49 }
50
51 /**
52 * new instance initialized to supplied identity
53 */
54 public void testConstructor() {
55 for (double identity : new double[] {
56 Double.NEGATIVE_INFINITY,
57 Double.POSITIVE_INFINITY,
58 Double.MIN_VALUE,
59 Double.MAX_VALUE,
60 0.0,
61 })
62 assertEquals(identity,
63 new DoubleAccumulator(Double::max, identity).get());
64 }
65
66 /**
67 * accumulate accumulates given value to current, and get returns current value
68 */
69 public void testAccumulateAndGet() {
70 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
71 acc.accumulate(2.0);
72 assertEquals(2.0, acc.get());
73 acc.accumulate(-4.0);
74 assertEquals(2.0, acc.get());
75 acc.accumulate(4.0);
76 assertEquals(4.0, acc.get());
77 }
78
79 /**
80 * reset() causes subsequent get() to return zero
81 */
82 public void testReset() {
83 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
84 acc.accumulate(2.0);
85 assertEquals(2.0, acc.get());
86 acc.reset();
87 assertEquals(0.0, acc.get());
88 }
89
90 /**
91 * getThenReset() returns current value; subsequent get() returns zero
92 */
93 public void testGetThenReset() {
94 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
95 acc.accumulate(2.0);
96 assertEquals(2.0, acc.get());
97 assertEquals(2.0, acc.getThenReset());
98 assertEquals(0.0, acc.get());
99 }
100
101 /**
102 * toString returns current value.
103 */
104 public void testToString() {
105 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
106 assertEquals("0.0", acc.toString());
107 acc.accumulate(1.0);
108 assertEquals(Double.toString(1.0), acc.toString());
109 }
110
111 /**
112 * intValue returns current value.
113 */
114 public void testIntValue() {
115 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
116 assertEquals(0, acc.intValue());
117 acc.accumulate(1.0);
118 assertEquals(1, acc.intValue());
119 }
120
121 /**
122 * longValue returns current value.
123 */
124 public void testLongValue() {
125 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
126 assertEquals(0, acc.longValue());
127 acc.accumulate(1.0);
128 assertEquals(1, acc.longValue());
129 }
130
131 /**
132 * floatValue returns current value.
133 */
134 public void testFloatValue() {
135 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
136 assertEquals(0.0f, acc.floatValue());
137 acc.accumulate(1.0);
138 assertEquals(1.0f, acc.floatValue());
139 }
140
141 /**
142 * doubleValue returns current value.
143 */
144 public void testDoubleValue() {
145 DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
146 assertEquals(0.0, acc.doubleValue());
147 acc.accumulate(1.0);
148 assertEquals(1.0, acc.doubleValue());
149 }
150
151 /**
152 * accumulates by multiple threads produce correct result
153 */
154 public void testAccumulateAndGetMT() {
155 final DoubleAccumulator acc
156 = new DoubleAccumulator((x, y) -> x + y, 0.0);
157 final int nThreads = ThreadLocalRandom.current().nextInt(1, 5);
158 final Phaser phaser = new Phaser(nThreads + 1);
159 final int incs = expensiveTests ? 1_000_000 : 100_000;
160 final double total = nThreads * incs/2.0 * (incs - 1); // Gauss
161 final Runnable task = () -> {
162 phaser.arriveAndAwaitAdvance();
163 for (int i = 0; i < incs; i++) {
164 acc.accumulate((double) i);
165 assertTrue(acc.get() <= total);
166 }
167 phaser.arrive();
168 };
169 final ExecutorService p = Executors.newCachedThreadPool();
170 try (PoolCleaner cleaner = cleaner(p)) {
171 for (int i = nThreads; i-->0; )
172 p.execute(task);
173 phaser.arriveAndAwaitAdvance();
174 phaser.arriveAndAwaitAdvance();
175 assertEquals(total, acc.get());
176 }
177 }
178
179 }