test/tck/LongAccumulatorTest.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.LongAccumulator;

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

public class LongAccumulatorTest extends JSR166TestCase {
    public static void main(String[] args) {
        main(suite(), args);
    }
    public static Test suite() {
        return new TestSuite(LongAccumulatorTest.class);
    }

    /**
     * new instance initialized to supplied identity
     */
    public void testConstructor() {
        for (long identity : new long[] { Long.MIN_VALUE, 0, Long.MAX_VALUE })
            assertEquals(identity,
                         new LongAccumulator(Long::max, identity).get());
    }

    /**
     * accumulate accumulates given value to current, and get returns current value
     */
    public void testAccumulateAndGet() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        acc.accumulate(2);
        assertEquals(2, acc.get());
        acc.accumulate(-4);
        assertEquals(2, acc.get());
        acc.accumulate(4);
        assertEquals(4, acc.get());
    }

    /**
     * reset() causes subsequent get() to return zero
     */
    public void testReset() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        acc.accumulate(2);
        assertEquals(2, acc.get());
        acc.reset();
        assertEquals(0, acc.get());
    }

    /**
     * getThenReset() returns current value; subsequent get() returns zero
     */
    public void testGetThenReset() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        acc.accumulate(2);
        assertEquals(2, acc.get());
        assertEquals(2, acc.getThenReset());
        assertEquals(0, acc.get());
    }

    /**
     * toString returns current value.
     */
    public void testToString() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        assertEquals("0", acc.toString());
        acc.accumulate(1);
        assertEquals(Long.toString(1), acc.toString());
    }

    /**
     * intValue returns current value.
     */
    public void testIntValue() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        assertEquals(0, acc.intValue());
        acc.accumulate(1);
        assertEquals(1, acc.intValue());
    }

    /**
     * longValue returns current value.
     */
    public void testLongValue() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        assertEquals(0, acc.longValue());
        acc.accumulate(1);
        assertEquals(1, acc.longValue());
    }

    /**
     * floatValue returns current value.
     */
    public void testFloatValue() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        assertEquals(0.0f, acc.floatValue());
        acc.accumulate(1);
        assertEquals(1.0f, acc.floatValue());
    }

    /**
     * doubleValue returns current value.
     */
    public void testDoubleValue() {
        LongAccumulator acc = new LongAccumulator(Long::max, 0L);
        assertEquals(0.0, acc.doubleValue());
        acc.accumulate(1);
        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();
        LongAccumulator a = new LongAccumulator(Long::max, 0L);
        Phaser phaser = new Phaser(nthreads + 1);
        for (int i = 0; i < nthreads; ++i)
            pool.execute(new AccTask(a, phaser, incs));
        phaser.arriveAndAwaitAdvance();
        phaser.arriveAndAwaitAdvance();
        long expected = incs - 1;
        long result = a.get();
        assertEquals(expected, result);
        pool.shutdown();
    }

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

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

}
Revision:	1.8
Committed:	Sun Apr 23 03:14:10 2017 UTC (7 years ago) by jsr166
Branch:	MAIN
Changes since 1.7:	+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	1.4	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.LongAccumulator;
11
12	jsr166	1.4	import junit.framework.Test;
13			import junit.framework.TestSuite;
14
15	dl	1.1	public class LongAccumulatorTest extends JSR166TestCase {
16			public static void main(String[] args) {
17	jsr166	1.5	main(suite(), args);
18	dl	1.1	}
19			public static Test suite() {
20			return new TestSuite(LongAccumulatorTest.class);
21			}
22
23			/**
24	jsr166	1.7	* new instance initialized to supplied identity
25	dl	1.1	*/
26			public void testConstructor() {
27	jsr166	1.7	for (long identity : new long[] { Long.MIN_VALUE, 0, Long.MAX_VALUE })
28			assertEquals(identity,
29			new LongAccumulator(Long::max, identity).get());
30	dl	1.1	}
31
32			/**
33			* accumulate accumulates given value to current, and get returns current value
34			*/
35			public void testAccumulateAndGet() {
36	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
37			acc.accumulate(2);
38			assertEquals(2, acc.get());
39			acc.accumulate(-4);
40			assertEquals(2, acc.get());
41			acc.accumulate(4);
42			assertEquals(4, acc.get());
43	dl	1.1	}
44
45			/**
46	jsr166	1.6	* reset() causes subsequent get() to return zero
47	dl	1.1	*/
48			public void testReset() {
49	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
50			acc.accumulate(2);
51			assertEquals(2, acc.get());
52			acc.reset();
53			assertEquals(0, acc.get());
54	dl	1.1	}
55
56			/**
57	jsr166	1.6	* getThenReset() returns current value; subsequent get() returns zero
58	dl	1.1	*/
59			public void testGetThenReset() {
60	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
61			acc.accumulate(2);
62			assertEquals(2, acc.get());
63			assertEquals(2, acc.getThenReset());
64			assertEquals(0, acc.get());
65	dl	1.1	}
66
67			/**
68			* toString returns current value.
69			*/
70			public void testToString() {
71	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
72			assertEquals("0", acc.toString());
73			acc.accumulate(1);
74			assertEquals(Long.toString(1), acc.toString());
75	dl	1.1	}
76
77			/**
78			* intValue returns current value.
79			*/
80			public void testIntValue() {
81	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
82			assertEquals(0, acc.intValue());
83			acc.accumulate(1);
84			assertEquals(1, acc.intValue());
85	dl	1.1	}
86
87			/**
88			* longValue returns current value.
89			*/
90			public void testLongValue() {
91	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
92			assertEquals(0, acc.longValue());
93			acc.accumulate(1);
94			assertEquals(1, acc.longValue());
95	dl	1.1	}
96
97			/**
98			* floatValue returns current value.
99			*/
100			public void testFloatValue() {
101	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
102			assertEquals(0.0f, acc.floatValue());
103			acc.accumulate(1);
104			assertEquals(1.0f, acc.floatValue());
105	dl	1.1	}
106
107			/**
108			* doubleValue returns current value.
109			*/
110			public void testDoubleValue() {
111	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
112			assertEquals(0.0, acc.doubleValue());
113			acc.accumulate(1);
114			assertEquals(1.0, acc.doubleValue());
115	dl	1.1	}
116
117			/**
118			* accumulates by multiple threads produce correct result
119			*/
120			public void testAccumulateAndGetMT() {
121			final int incs = 1000000;
122			final int nthreads = 4;
123			final ExecutorService pool = Executors.newCachedThreadPool();
124			LongAccumulator a = new LongAccumulator(Long::max, 0L);
125			Phaser phaser = new Phaser(nthreads + 1);
126			for (int i = 0; i < nthreads; ++i)
127	dl	1.2	pool.execute(new AccTask(a, phaser, incs));
128	dl	1.1	phaser.arriveAndAwaitAdvance();
129			phaser.arriveAndAwaitAdvance();
130			long expected = incs - 1;
131			long result = a.get();
132			assertEquals(expected, result);
133			pool.shutdown();
134			}
135
136	jsr166	1.3	static final class AccTask implements Runnable {
137	dl	1.2	final LongAccumulator acc;
138	dl	1.1	final Phaser phaser;
139			final int incs;
140			volatile long result;
141	jsr166	1.3	AccTask(LongAccumulator acc, Phaser phaser, int incs) {
142			this.acc = acc;
143	dl	1.1	this.phaser = phaser;
144			this.incs = incs;
145			}
146
147			public void run() {
148			phaser.arriveAndAwaitAdvance();
149	dl	1.2	LongAccumulator a = acc;
150	dl	1.1	for (int i = 0; i < incs; ++i)
151			a.accumulate(i);
152			result = a.get();
153			phaser.arrive();
154			}
155			}
156
157			}