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 ai = new LongAccumulator(Long::max, 0L);
        ai.accumulate(2);
        assertEquals(2, ai.get());
        ai.accumulate(-4);
        assertEquals(2, ai.get());
        ai.accumulate(4);
        assertEquals(4, ai.get());
    }

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

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

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

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

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

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

    /**
     * doubleValue returns current value.
     */
    public void testDoubleValue() {
        LongAccumulator ai = new LongAccumulator(Long::max, 0L);
        assertEquals(0.0, ai.doubleValue());
        ai.accumulate(1);
        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();
        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:	1.7
Committed:	Sun Apr 23 03:03:16 2017 UTC (7 years ago) by jsr166
Branch:	MAIN
Changes since 1.6:	+4 -3 lines
Log Message:	improve testConstructor
#	Content
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	import java.util.concurrent.Executors;
8	import java.util.concurrent.ExecutorService;
9	import java.util.concurrent.Phaser;
10	import java.util.concurrent.atomic.LongAccumulator;
11
12	import junit.framework.Test;
13	import junit.framework.TestSuite;
14
15	public class LongAccumulatorTest extends JSR166TestCase {
16	public static void main(String[] args) {
17	main(suite(), args);
18	}
19	public static Test suite() {
20	return new TestSuite(LongAccumulatorTest.class);
21	}
22
23	/**
24	* new instance initialized to supplied identity
25	*/
26	public void testConstructor() {
27	for (long identity : new long[] { Long.MIN_VALUE, 0, Long.MAX_VALUE })
28	assertEquals(identity,
29	new LongAccumulator(Long::max, identity).get());
30	}
31
32	/**
33	* accumulate accumulates given value to current, and get returns current value
34	*/
35	public void testAccumulateAndGet() {
36	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
37	ai.accumulate(2);
38	assertEquals(2, ai.get());
39	ai.accumulate(-4);
40	assertEquals(2, ai.get());
41	ai.accumulate(4);
42	assertEquals(4, ai.get());
43	}
44
45	/**
46	* reset() causes subsequent get() to return zero
47	*/
48	public void testReset() {
49	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
50	ai.accumulate(2);
51	assertEquals(2, ai.get());
52	ai.reset();
53	assertEquals(0, ai.get());
54	}
55
56	/**
57	* getThenReset() returns current value; subsequent get() returns zero
58	*/
59	public void testGetThenReset() {
60	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
61	ai.accumulate(2);
62	assertEquals(2, ai.get());
63	assertEquals(2, ai.getThenReset());
64	assertEquals(0, ai.get());
65	}
66
67	/**
68	* toString returns current value.
69	*/
70	public void testToString() {
71	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
72	assertEquals("0", ai.toString());
73	ai.accumulate(1);
74	assertEquals(Long.toString(1), ai.toString());
75	}
76
77	/**
78	* intValue returns current value.
79	*/
80	public void testIntValue() {
81	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
82	assertEquals(0, ai.intValue());
83	ai.accumulate(1);
84	assertEquals(1, ai.intValue());
85	}
86
87	/**
88	* longValue returns current value.
89	*/
90	public void testLongValue() {
91	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
92	assertEquals(0, ai.longValue());
93	ai.accumulate(1);
94	assertEquals(1, ai.longValue());
95	}
96
97	/**
98	* floatValue returns current value.
99	*/
100	public void testFloatValue() {
101	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
102	assertEquals(0.0f, ai.floatValue());
103	ai.accumulate(1);
104	assertEquals(1.0f, ai.floatValue());
105	}
106
107	/**
108	* doubleValue returns current value.
109	*/
110	public void testDoubleValue() {
111	LongAccumulator ai = new LongAccumulator(Long::max, 0L);
112	assertEquals(0.0, ai.doubleValue());
113	ai.accumulate(1);
114	assertEquals(1.0, ai.doubleValue());
115	}
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	pool.execute(new AccTask(a, phaser, incs));
128	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	static final class AccTask implements Runnable {
137	final LongAccumulator acc;
138	final Phaser phaser;
139	final int incs;
140	volatile long result;
141	AccTask(LongAccumulator acc, Phaser phaser, int incs) {
142	this.acc = acc;
143	this.phaser = phaser;
144	this.incs = incs;
145	}
146
147	public void run() {
148	phaser.arriveAndAwaitAdvance();
149	LongAccumulator a = acc;
150	for (int i = 0; i < incs; ++i)
151	a.accumulate(i);
152	result = a.get();
153	phaser.arrive();
154	}
155	}
156
157	}