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.ThreadLocalRandom;
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 LongAccumulator acc
            = new LongAccumulator((x, y) -> x + y, 0L);
        final int nThreads = ThreadLocalRandom.current().nextInt(1, 5);
        final Phaser phaser = new Phaser(nThreads + 1);
        final int incs = expensiveTests ? 1_000_000 : 100_000;
        final long total = nThreads * incs/2L * (incs - 1); // Gauss
        final Runnable task = () -> {
            phaser.arriveAndAwaitAdvance();
            for (int i = 0; i < incs; i++) {
                acc.accumulate((long) i);
                assertTrue(acc.get() <= total);
            }
            phaser.arrive();
        };
        final ExecutorService p = Executors.newCachedThreadPool();
        try (PoolCleaner cleaner = cleaner(p)) {
            for (int i = nThreads; i-->0; )
                p.execute(task);
            phaser.arriveAndAwaitAdvance();
            phaser.arriveAndAwaitAdvance();
            assertEquals(total, acc.get());
        }
    }

}
Revision:	1.10
Committed:	Mon Sep 9 01:05:22 2019 UTC (4 years, 8 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.9:	+1 -1 lines
Log Message:	run fewer iterations when !expensiveTests
#	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	jsr166	1.9	import java.util.concurrent.ThreadLocalRandom;
11	dl	1.1	import java.util.concurrent.atomic.LongAccumulator;
12
13	jsr166	1.4	import junit.framework.Test;
14			import junit.framework.TestSuite;
15
16	dl	1.1	public class LongAccumulatorTest extends JSR166TestCase {
17			public static void main(String[] args) {
18	jsr166	1.5	main(suite(), args);
19	dl	1.1	}
20			public static Test suite() {
21			return new TestSuite(LongAccumulatorTest.class);
22			}
23
24			/**
25	jsr166	1.7	* new instance initialized to supplied identity
26	dl	1.1	*/
27			public void testConstructor() {
28	jsr166	1.7	for (long identity : new long[] { Long.MIN_VALUE, 0, Long.MAX_VALUE })
29			assertEquals(identity,
30			new LongAccumulator(Long::max, identity).get());
31	dl	1.1	}
32
33			/**
34			* accumulate accumulates given value to current, and get returns current value
35			*/
36			public void testAccumulateAndGet() {
37	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
38			acc.accumulate(2);
39			assertEquals(2, acc.get());
40			acc.accumulate(-4);
41			assertEquals(2, acc.get());
42			acc.accumulate(4);
43			assertEquals(4, acc.get());
44	dl	1.1	}
45
46			/**
47	jsr166	1.6	* reset() causes subsequent get() to return zero
48	dl	1.1	*/
49			public void testReset() {
50	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
51			acc.accumulate(2);
52			assertEquals(2, acc.get());
53			acc.reset();
54			assertEquals(0, acc.get());
55	dl	1.1	}
56
57			/**
58	jsr166	1.6	* getThenReset() returns current value; subsequent get() returns zero
59	dl	1.1	*/
60			public void testGetThenReset() {
61	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
62			acc.accumulate(2);
63			assertEquals(2, acc.get());
64			assertEquals(2, acc.getThenReset());
65			assertEquals(0, acc.get());
66	dl	1.1	}
67
68			/**
69			* toString returns current value.
70			*/
71			public void testToString() {
72	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
73			assertEquals("0", acc.toString());
74			acc.accumulate(1);
75			assertEquals(Long.toString(1), acc.toString());
76	dl	1.1	}
77
78			/**
79			* intValue returns current value.
80			*/
81			public void testIntValue() {
82	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
83			assertEquals(0, acc.intValue());
84			acc.accumulate(1);
85			assertEquals(1, acc.intValue());
86	dl	1.1	}
87
88			/**
89			* longValue returns current value.
90			*/
91			public void testLongValue() {
92	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
93			assertEquals(0, acc.longValue());
94			acc.accumulate(1);
95			assertEquals(1, acc.longValue());
96	dl	1.1	}
97
98			/**
99			* floatValue returns current value.
100			*/
101			public void testFloatValue() {
102	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
103			assertEquals(0.0f, acc.floatValue());
104			acc.accumulate(1);
105			assertEquals(1.0f, acc.floatValue());
106	dl	1.1	}
107
108			/**
109			* doubleValue returns current value.
110			*/
111			public void testDoubleValue() {
112	jsr166	1.8	LongAccumulator acc = new LongAccumulator(Long::max, 0L);
113			assertEquals(0.0, acc.doubleValue());
114			acc.accumulate(1);
115			assertEquals(1.0, acc.doubleValue());
116	dl	1.1	}
117
118			/**
119			* accumulates by multiple threads produce correct result
120			*/
121			public void testAccumulateAndGetMT() {
122	jsr166	1.9	final LongAccumulator acc
123			= new LongAccumulator((x, y) -> x + y, 0L);
124			final int nThreads = ThreadLocalRandom.current().nextInt(1, 5);
125			final Phaser phaser = new Phaser(nThreads + 1);
126	jsr166	1.10	final int incs = expensiveTests ? 1_000_000 : 100_000;
127	jsr166	1.9	final long total = nThreads * incs/2L * (incs - 1); // Gauss
128			final Runnable task = () -> {
129	dl	1.1	phaser.arriveAndAwaitAdvance();
130	jsr166	1.9	for (int i = 0; i < incs; i++) {
131			acc.accumulate((long) i);
132			assertTrue(acc.get() <= total);
133			}
134	dl	1.1	phaser.arrive();
135	jsr166	1.9	};
136			final ExecutorService p = Executors.newCachedThreadPool();
137			try (PoolCleaner cleaner = cleaner(p)) {
138			for (int i = nThreads; i-->0; )
139			p.execute(task);
140			phaser.arriveAndAwaitAdvance();
141			phaser.arriveAndAwaitAdvance();
142			assertEquals(total, acc.get());
143	dl	1.1	}
144			}
145
146			}