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) {
        main(suite(), args);
    }
    public static Test suite() {
        return new TestSuite(DoubleAccumulatorTest.class);
    }

    /**
     * new instance initialized to supplied identity
     */
    public void testConstructor() {
        for (double identity : new double[] {
                 Double.NEGATIVE_INFINITY,
                 Double.POSITIVE_INFINITY,
                 Double.MIN_VALUE,
                 Double.MAX_VALUE,
                 0.0,
             })
            assertEquals(identity,
                         new DoubleAccumulator(Double::max, identity).get());
    }

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

    /**
     * reset() causes subsequent get() to return zero
     */
    public void testReset() {
        DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
        acc.accumulate(2.0);
        assertEquals(2.0, acc.get());
        acc.reset();
        assertEquals(0.0, acc.get());
    }

    /**
     * getThenReset() returns current value; subsequent get() returns zero
     */
    public void testGetThenReset() {
        DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
        acc.accumulate(2.0);
        assertEquals(2.0, acc.get());
        assertEquals(2.0, acc.getThenReset());
        assertEquals(0.0, acc.get());
    }

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

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

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

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

    /**
     * doubleValue returns current value.
     */
    public void testDoubleValue() {
        DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
        assertEquals(0.0, acc.doubleValue());
        acc.accumulate(1.0);
        assertEquals(1.0, acc.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:	1.7
Committed:	Sun Apr 23 03:14:10 2017 UTC (7 years ago) by jsr166
Branch:	MAIN
Changes since 1.6:	+37 -37 lines
Log Message:	rename ai -> acc
#	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	jsr166	1.4	main(suite(), args);
18	dl	1.1	}
19			public static Test suite() {
20			return new TestSuite(DoubleAccumulatorTest.class);
21			}
22
23			/**
24	jsr166	1.6	* new instance initialized to supplied identity
25	dl	1.1	*/
26			public void testConstructor() {
27	jsr166	1.6	for (double identity : new double[] {
28			Double.NEGATIVE_INFINITY,
29			Double.POSITIVE_INFINITY,
30			Double.MIN_VALUE,
31			Double.MAX_VALUE,
32			0.0,
33			})
34			assertEquals(identity,
35			new DoubleAccumulator(Double::max, identity).get());
36	dl	1.1	}
37
38			/**
39			* accumulate accumulates given value to current, and get returns current value
40			*/
41			public void testAccumulateAndGet() {
42	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
43			acc.accumulate(2.0);
44			assertEquals(2.0, acc.get());
45			acc.accumulate(-4.0);
46			assertEquals(2.0, acc.get());
47			acc.accumulate(4.0);
48			assertEquals(4.0, acc.get());
49	dl	1.1	}
50
51			/**
52	jsr166	1.5	* reset() causes subsequent get() to return zero
53	dl	1.1	*/
54			public void testReset() {
55	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
56			acc.accumulate(2.0);
57			assertEquals(2.0, acc.get());
58			acc.reset();
59			assertEquals(0.0, acc.get());
60	dl	1.1	}
61
62			/**
63	jsr166	1.5	* getThenReset() returns current value; subsequent get() returns zero
64	dl	1.1	*/
65			public void testGetThenReset() {
66	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
67			acc.accumulate(2.0);
68			assertEquals(2.0, acc.get());
69			assertEquals(2.0, acc.getThenReset());
70			assertEquals(0.0, acc.get());
71	dl	1.1	}
72
73			/**
74			* toString returns current value.
75			*/
76			public void testToString() {
77	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
78			assertEquals("0.0", acc.toString());
79			acc.accumulate(1.0);
80			assertEquals(Double.toString(1.0), acc.toString());
81	dl	1.1	}
82
83			/**
84			* intValue returns current value.
85			*/
86			public void testIntValue() {
87	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
88			assertEquals(0, acc.intValue());
89			acc.accumulate(1.0);
90			assertEquals(1, acc.intValue());
91	dl	1.1	}
92
93			/**
94			* longValue returns current value.
95			*/
96			public void testLongValue() {
97	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
98			assertEquals(0, acc.longValue());
99			acc.accumulate(1.0);
100			assertEquals(1, acc.longValue());
101	dl	1.1	}
102
103			/**
104			* floatValue returns current value.
105			*/
106			public void testFloatValue() {
107	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
108			assertEquals(0.0f, acc.floatValue());
109			acc.accumulate(1.0);
110			assertEquals(1.0f, acc.floatValue());
111	dl	1.1	}
112
113			/**
114			* doubleValue returns current value.
115			*/
116			public void testDoubleValue() {
117	jsr166	1.7	DoubleAccumulator acc = new DoubleAccumulator(Double::max, 0.0);
118			assertEquals(0.0, acc.doubleValue());
119			acc.accumulate(1.0);
120			assertEquals(1.0, acc.doubleValue());
121	dl	1.1	}
122
123			/**
124			* accumulates by multiple threads produce correct result
125			*/
126			public void testAccumulateAndGetMT() {
127			final int incs = 1000000;
128			final int nthreads = 4;
129			final ExecutorService pool = Executors.newCachedThreadPool();
130			DoubleAccumulator a = new DoubleAccumulator(Double::max, 0.0);
131			Phaser phaser = new Phaser(nthreads + 1);
132			for (int i = 0; i < nthreads; ++i)
133			pool.execute(new AccTask(a, phaser, incs));
134			phaser.arriveAndAwaitAdvance();
135			phaser.arriveAndAwaitAdvance();
136			double expected = incs - 1;
137			double result = a.get();
138			assertEquals(expected, result);
139			pool.shutdown();
140			}
141
142	jsr166	1.2	static final class AccTask implements Runnable {
143	dl	1.1	final DoubleAccumulator acc;
144			final Phaser phaser;
145			final int incs;
146			volatile double result;
147	jsr166	1.2	AccTask(DoubleAccumulator acc, Phaser phaser, int incs) {
148			this.acc = acc;
149	dl	1.1	this.phaser = phaser;
150			this.incs = incs;
151			}
152
153			public void run() {
154			phaser.arriveAndAwaitAdvance();
155			DoubleAccumulator a = acc;
156			for (int i = 0; i < incs; ++i)
157			a.accumulate(i);
158			result = a.get();
159			phaser.arrive();
160			}
161			}
162
163			}