test/tck/DoubleAccumulatorTest.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Phaser;
import java.util.concurrent.atomic.DoubleAccumulator;

import junit.framework.Test;
import junit.framework.TestSuite;

public class DoubleAccumulatorTest extends JSR166TestCase {
    public static void main(String[] args) {
        junit.textui.TestRunner.run(suite());
    }
    public static Test suite() {
        return new TestSuite(DoubleAccumulatorTest.class);
    }

    /**
     * default constructed initializes to zero
     */
    public void testConstructor() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0.0, ai.get());
    }

    /**
     * accumulate accumulates given value to current, and get returns current value
     */
    public void testAccumulateAndGet() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        ai.accumulate(2.0);
        assertEquals(2.0, ai.get());
        ai.accumulate(-4.0);
        assertEquals(2.0, ai.get());
        ai.accumulate(4.0);
        assertEquals(4.0, ai.get());
    }

    /**
     * reset zeroes get
     */
    public void testReset() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        ai.accumulate(2.0);
        assertEquals(2.0, ai.get());
        ai.reset();
        assertEquals(0.0, ai.get());
    }

    /**
     * getThenReset returns get then zeros
     */
    public void testGetThenReset() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        ai.accumulate(2.0);
        assertEquals(2.0, ai.get());
        assertEquals(2.0, ai.getThenReset());
        assertEquals(0.0, ai.get());
    }

    /**
     * toString returns current value.
     */
    public void testToString() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals("0.0", ai.toString());
        ai.accumulate(1.0);
        assertEquals(Double.toString(1.0), ai.toString());
    }

    /**
     * intValue returns current value.
     */
    public void testIntValue() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0, ai.intValue());
        ai.accumulate(1.0);
        assertEquals(1, ai.intValue());
    }

    /**
     * longValue returns current value.
     */
    public void testLongValue() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0, ai.longValue());
        ai.accumulate(1.0);
        assertEquals(1, ai.longValue());
    }

    /**
     * floatValue returns current value.
     */
    public void testFloatValue() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0.0f, ai.floatValue());
        ai.accumulate(1.0);
        assertEquals(1.0f, ai.floatValue());
    }

    /**
     * doubleValue returns current value.
     */
    public void testDoubleValue() {
        DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0.0, ai.doubleValue());
        ai.accumulate(1.0);
        assertEquals(1.0, ai.doubleValue());
    }

    /**
     * accumulates by multiple threads produce correct result
     */
    public void testAccumulateAndGetMT() {
        final int incs = 1000000;
        final int nthreads = 4;
        final ExecutorService pool = Executors.newCachedThreadPool();
        DoubleAccumulator a = new DoubleAccumulator(Double::max, 0.0);
        Phaser phaser = new Phaser(nthreads + 1);
        for (int i = 0; i < nthreads; ++i)
            pool.execute(new AccTask(a, phaser, incs));
        phaser.arriveAndAwaitAdvance();
        phaser.arriveAndAwaitAdvance();
        double expected = incs - 1;
        double result = a.get();
        assertEquals(expected, result);
        pool.shutdown();
    }

    static final class AccTask implements Runnable {
        final DoubleAccumulator acc;
        final Phaser phaser;
        final int incs;
        volatile double result;
        AccTask(DoubleAccumulator acc, Phaser phaser, int incs) {
            this.acc = acc;
            this.phaser = phaser;
            this.incs = incs;
        }

        public void run() {
            phaser.arriveAndAwaitAdvance();
            DoubleAccumulator a = acc;
            for (int i = 0; i < incs; ++i)
                a.accumulate(i);
            result = a.get();
            phaser.arrive();
        }
    }

}
Revision:	1.3
Committed:	Wed Dec 31 19:05:42 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.2:	+6 -2 lines
Log Message:	no wildcard imports
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7	jsr166	1.3	import java.util.concurrent.Executors;
8			import java.util.concurrent.ExecutorService;
9			import java.util.concurrent.Phaser;
10	dl	1.1	import java.util.concurrent.atomic.DoubleAccumulator;
11
12	jsr166	1.3	import junit.framework.Test;
13			import junit.framework.TestSuite;
14
15	dl	1.1	public class DoubleAccumulatorTest extends JSR166TestCase {
16			public static void main(String[] args) {
17			junit.textui.TestRunner.run(suite());
18			}
19			public static Test suite() {
20			return new TestSuite(DoubleAccumulatorTest.class);
21			}
22
23			/**
24			* default constructed initializes to zero
25			*/
26			public void testConstructor() {
27			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
28			assertEquals(0.0, ai.get());
29			}
30
31			/**
32			* accumulate accumulates given value to current, and get returns current value
33			*/
34			public void testAccumulateAndGet() {
35			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
36			ai.accumulate(2.0);
37			assertEquals(2.0, ai.get());
38			ai.accumulate(-4.0);
39			assertEquals(2.0, ai.get());
40			ai.accumulate(4.0);
41			assertEquals(4.0, ai.get());
42			}
43
44			/**
45			* reset zeroes get
46			*/
47			public void testReset() {
48			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
49			ai.accumulate(2.0);
50			assertEquals(2.0, ai.get());
51			ai.reset();
52			assertEquals(0.0, ai.get());
53			}
54
55			/**
56			* getThenReset returns get then zeros
57			*/
58			public void testGetThenReset() {
59			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
60			ai.accumulate(2.0);
61			assertEquals(2.0, ai.get());
62			assertEquals(2.0, ai.getThenReset());
63			assertEquals(0.0, ai.get());
64			}
65
66			/**
67			* toString returns current value.
68			*/
69			public void testToString() {
70			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
71			assertEquals("0.0", ai.toString());
72			ai.accumulate(1.0);
73			assertEquals(Double.toString(1.0), ai.toString());
74			}
75
76			/**
77			* intValue returns current value.
78			*/
79			public void testIntValue() {
80			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
81			assertEquals(0, ai.intValue());
82			ai.accumulate(1.0);
83			assertEquals(1, ai.intValue());
84			}
85
86			/**
87			* longValue returns current value.
88			*/
89			public void testLongValue() {
90			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
91			assertEquals(0, ai.longValue());
92			ai.accumulate(1.0);
93			assertEquals(1, ai.longValue());
94			}
95
96			/**
97			* floatValue returns current value.
98			*/
99			public void testFloatValue() {
100			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
101			assertEquals(0.0f, ai.floatValue());
102			ai.accumulate(1.0);
103			assertEquals(1.0f, ai.floatValue());
104			}
105
106			/**
107			* doubleValue returns current value.
108			*/
109			public void testDoubleValue() {
110			DoubleAccumulator ai = new DoubleAccumulator(Double::max, 0.0);
111			assertEquals(0.0, ai.doubleValue());
112			ai.accumulate(1.0);
113			assertEquals(1.0, ai.doubleValue());
114			}
115
116			/**
117			* accumulates by multiple threads produce correct result
118			*/
119			public void testAccumulateAndGetMT() {
120			final int incs = 1000000;
121			final int nthreads = 4;
122			final ExecutorService pool = Executors.newCachedThreadPool();
123			DoubleAccumulator a = new DoubleAccumulator(Double::max, 0.0);
124			Phaser phaser = new Phaser(nthreads + 1);
125			for (int i = 0; i < nthreads; ++i)
126			pool.execute(new AccTask(a, phaser, incs));
127			phaser.arriveAndAwaitAdvance();
128			phaser.arriveAndAwaitAdvance();
129			double expected = incs - 1;
130			double result = a.get();
131			assertEquals(expected, result);
132			pool.shutdown();
133			}
134
135	jsr166	1.2	static final class AccTask implements Runnable {
136	dl	1.1	final DoubleAccumulator acc;
137			final Phaser phaser;
138			final int incs;
139			volatile double result;
140	jsr166	1.2	AccTask(DoubleAccumulator acc, Phaser phaser, int incs) {
141			this.acc = acc;
142	dl	1.1	this.phaser = phaser;
143			this.incs = incs;
144			}
145
146			public void run() {
147			phaser.arriveAndAwaitAdvance();
148			DoubleAccumulator a = acc;
149			for (int i = 0; i < incs; ++i)
150			a.accumulate(i);
151			result = a.get();
152			phaser.arrive();
153			}
154			}
155
156			}