test/tck/ThreadLocalRandomTest.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 junit.framework.*;
import java.util.*;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

public class ThreadLocalRandomTest extends JSR166TestCase {

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

    /*
     * Testing coverage notes:
     *
     * We don't test randomness properties, but only that repeated
     * calls, up to NCALLS tries, produce at least one different
     * result.  For bounded versions, we sample various intervals
     * across multiples of primes.
     */

    // max numbers of calls to detect getting stuck on one value
    static final int NCALLS = 10000;

    // max sampled int bound
    static final int MAX_INT_BOUND = (1 << 28);

    // max sampled long bound
    static final long MAX_LONG_BOUND = (1L << 42);

    // Number of replications for other checks
    static final int REPS = 20;

    /**
     * setSeed throws UnsupportedOperationException
     */
    public void testSetSeed() {
        try {
            ThreadLocalRandom.current().setSeed(17);
            shouldThrow();
        } catch (UnsupportedOperationException success) {}
    }

    /**
     * Repeated calls to nextInt produce at least two distinct results
     */
    public void testNextInt() {
        int f = ThreadLocalRandom.current().nextInt();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextLong produce at least two distinct results
     */
    public void testNextLong() {
        long f = ThreadLocalRandom.current().nextLong();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextBoolean produce at least two distinct results
     */
    public void testNextBoolean() {
        boolean f = ThreadLocalRandom.current().nextBoolean();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextFloat produce at least two distinct results
     */
    public void testNextFloat() {
        float f = ThreadLocalRandom.current().nextFloat();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextDouble produce at least two distinct results
     */
    public void testNextDouble() {
        double f = ThreadLocalRandom.current().nextDouble();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextGaussian produce at least two distinct results
     */
    public void testNextGaussian() {
        double f = ThreadLocalRandom.current().nextGaussian();
        int i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * nextInt(negative) throws IllegalArgumentException
     */
    public void testNextIntBoundedNeg() {
        try {
            int f = ThreadLocalRandom.current().nextInt(-17);
            shouldThrow();
        } catch (IllegalArgumentException success) {}
    }

    /**
     * nextInt(least >= bound) throws IllegalArgumentException
     */
    public void testNextIntBadBounds() {
        try {
            int f = ThreadLocalRandom.current().nextInt(17, 2);
            shouldThrow();
        } catch (IllegalArgumentException success) {}
    }

    /**
     * nextInt(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded() {
        // sample bound space across prime number increments
        for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
            int f = ThreadLocalRandom.current().nextInt(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            int j;
            while (i < NCALLS &&
                   (j = ThreadLocalRandom.current().nextInt(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextInt(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded2() {
        for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
            for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
                int f = ThreadLocalRandom.current().nextInt(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                int j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextLong(negative) throws IllegalArgumentException
     */
    public void testNextLongBoundedNeg() {
        try {
            long f = ThreadLocalRandom.current().nextLong(-17);
            shouldThrow();
        } catch (IllegalArgumentException success) {}
    }

    /**
     * nextLong(least >= bound) throws IllegalArgumentException
     */
    public void testNextLongBadBounds() {
        try {
            long f = ThreadLocalRandom.current().nextLong(17, 2);
            shouldThrow();
        } catch (IllegalArgumentException success) {}
    }

    /**
     * nextLong(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded() {
        for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
            long f = ThreadLocalRandom.current().nextLong(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            long j;
            while (i < NCALLS &&
                   (j = ThreadLocalRandom.current().nextLong(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextLong(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded2() {
        for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
            for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
                long f = ThreadLocalRandom.current().nextLong(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                long j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextDouble(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextDoubleBounded2() {
        for (double least = 0.0001; least < 1.0e20; least *= 8) {
            for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
                double f = ThreadLocalRandom.current().nextDouble(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                double j;
                while (i < NCALLS &&
                       (j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * Different threads produce different pseudo-random sequences
     */
    public void testDifferentSequences() {
        // Don't use main thread's ThreadLocalRandom - it is likely to
        // be polluted by previous tests.
        final AtomicReference<ThreadLocalRandom> threadLocalRandom =
            new AtomicReference<ThreadLocalRandom>();
        final AtomicLong rand = new AtomicLong();

        long firstRand = 0;
        ThreadLocalRandom firstThreadLocalRandom = null;

        final CheckedRunnable getRandomState = new CheckedRunnable() {
            public void realRun() {
                ThreadLocalRandom current = ThreadLocalRandom.current();
                assertSame(current, ThreadLocalRandom.current());
                // test bug: the following is not guaranteed and not true in JDK8
                //                assertNotSame(current, threadLocalRandom.get());
                rand.set(current.nextLong());
                threadLocalRandom.set(current);
            }};

        Thread first = newStartedThread(getRandomState);
        awaitTermination(first);
        firstRand = rand.get();
        firstThreadLocalRandom = threadLocalRandom.get();

        for (int i = 0; i < NCALLS; i++) {
            Thread t = newStartedThread(getRandomState);
            awaitTermination(t);
            if (firstRand != rand.get())
                return;
        }
        fail("all threads generate the same pseudo-random sequence");
    }

}
Revision:	1.17
Committed:	Fri Aug 16 07:10:20 2013 UTC (10 years, 9 months ago) by jsr166
Branch:	MAIN
Changes since 1.16:	+0 -1 lines
Log Message:	remove unused 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	jsr166	1.8	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6			import junit.framework.*;
7			import java.util.*;
8	jsr166	1.10	import java.util.concurrent.ThreadLocalRandom;
9	jsr166	1.11	import java.util.concurrent.atomic.AtomicLong;
10			import java.util.concurrent.atomic.AtomicReference;
11	dl	1.1
12			public class ThreadLocalRandomTest extends JSR166TestCase {
13
14			public static void main(String[] args) {
15	jsr166	1.7	junit.textui.TestRunner.run(suite());
16	dl	1.1	}
17			public static Test suite() {
18	jsr166	1.4	return new TestSuite(ThreadLocalRandomTest.class);
19	dl	1.1	}
20
21	jsr166	1.13	/*
22	dl	1.1	* Testing coverage notes:
23	jsr166	1.2	*
24	dl	1.1	* We don't test randomness properties, but only that repeated
25			* calls, up to NCALLS tries, produce at least one different
26			* result. For bounded versions, we sample various intervals
27			* across multiples of primes.
28			*/
29
30	jsr166	1.14	// max numbers of calls to detect getting stuck on one value
31	dl	1.1	static final int NCALLS = 10000;
32
33			// max sampled int bound
34			static final int MAX_INT_BOUND = (1 << 28);
35
36	jsr166	1.14	// max sampled long bound
37	dl	1.1	static final long MAX_LONG_BOUND = (1L << 42);
38
39	dl	1.15	// Number of replications for other checks
40			static final int REPS = 20;
41
42	dl	1.1	/**
43			* setSeed throws UnsupportedOperationException
44			*/
45			public void testSetSeed() {
46			try {
47			ThreadLocalRandom.current().setSeed(17);
48	jsr166	1.3	shouldThrow();
49	jsr166	1.5	} catch (UnsupportedOperationException success) {}
50	dl	1.1	}
51
52			/**
53	jsr166	1.14	* Repeated calls to nextInt produce at least two distinct results
54	dl	1.1	*/
55			public void testNextInt() {
56			int f = ThreadLocalRandom.current().nextInt();
57			int i = 0;
58			while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
59			++i;
60			assertTrue(i < NCALLS);
61			}
62
63			/**
64	jsr166	1.14	* Repeated calls to nextLong produce at least two distinct results
65	dl	1.1	*/
66			public void testNextLong() {
67			long f = ThreadLocalRandom.current().nextLong();
68			int i = 0;
69			while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
70			++i;
71			assertTrue(i < NCALLS);
72			}
73
74			/**
75	jsr166	1.14	* Repeated calls to nextBoolean produce at least two distinct results
76	dl	1.1	*/
77			public void testNextBoolean() {
78			boolean f = ThreadLocalRandom.current().nextBoolean();
79			int i = 0;
80			while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
81			++i;
82			assertTrue(i < NCALLS);
83			}
84
85			/**
86	jsr166	1.14	* Repeated calls to nextFloat produce at least two distinct results
87	dl	1.1	*/
88			public void testNextFloat() {
89			float f = ThreadLocalRandom.current().nextFloat();
90			int i = 0;
91			while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
92			++i;
93			assertTrue(i < NCALLS);
94			}
95
96			/**
97	jsr166	1.14	* Repeated calls to nextDouble produce at least two distinct results
98	dl	1.1	*/
99			public void testNextDouble() {
100			double f = ThreadLocalRandom.current().nextDouble();
101	jsr166	1.14	int i = 0;
102	dl	1.1	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
103			++i;
104			assertTrue(i < NCALLS);
105			}
106
107			/**
108	jsr166	1.14	* Repeated calls to nextGaussian produce at least two distinct results
109	dl	1.1	*/
110			public void testNextGaussian() {
111			double f = ThreadLocalRandom.current().nextGaussian();
112			int i = 0;
113			while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
114			++i;
115			assertTrue(i < NCALLS);
116			}
117
118			/**
119	jsr166	1.14	* nextInt(negative) throws IllegalArgumentException
120	dl	1.1	*/
121			public void testNextIntBoundedNeg() {
122			try {
123	jsr166	1.6	int f = ThreadLocalRandom.current().nextInt(-17);
124	jsr166	1.3	shouldThrow();
125	jsr166	1.5	} catch (IllegalArgumentException success) {}
126	dl	1.1	}
127
128			/**
129	jsr166	1.14	* nextInt(least >= bound) throws IllegalArgumentException
130	dl	1.1	*/
131			public void testNextIntBadBounds() {
132			try {
133	jsr166	1.6	int f = ThreadLocalRandom.current().nextInt(17, 2);
134	jsr166	1.3	shouldThrow();
135	jsr166	1.5	} catch (IllegalArgumentException success) {}
136	dl	1.1	}
137
138			/**
139			* nextInt(bound) returns 0 <= value < bound;
140	jsr166	1.14	* repeated calls produce at least two distinct results
141	dl	1.1	*/
142			public void testNextIntBounded() {
143			// sample bound space across prime number increments
144			for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
145			int f = ThreadLocalRandom.current().nextInt(bound);
146			assertTrue(0 <= f && f < bound);
147			int i = 0;
148			int j;
149	jsr166	1.2	while (i < NCALLS &&
150	dl	1.1	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
151			assertTrue(0 <= j && j < bound);
152			++i;
153			}
154			assertTrue(i < NCALLS);
155			}
156			}
157
158			/**
159			* nextInt(least, bound) returns least <= value < bound;
160	jsr166	1.14	* repeated calls produce at least two distinct results
161	dl	1.1	*/
162			public void testNextIntBounded2() {
163			for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
164			for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
165			int f = ThreadLocalRandom.current().nextInt(least, bound);
166			assertTrue(least <= f && f < bound);
167			int i = 0;
168			int j;
169	jsr166	1.2	while (i < NCALLS &&
170	dl	1.1	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
171			assertTrue(least <= j && j < bound);
172			++i;
173			}
174			assertTrue(i < NCALLS);
175			}
176			}
177			}
178
179			/**
180	jsr166	1.14	* nextLong(negative) throws IllegalArgumentException
181	dl	1.1	*/
182			public void testNextLongBoundedNeg() {
183			try {
184	jsr166	1.6	long f = ThreadLocalRandom.current().nextLong(-17);
185	jsr166	1.3	shouldThrow();
186	jsr166	1.5	} catch (IllegalArgumentException success) {}
187	dl	1.1	}
188
189			/**
190	jsr166	1.14	* nextLong(least >= bound) throws IllegalArgumentException
191	dl	1.1	*/
192			public void testNextLongBadBounds() {
193			try {
194	jsr166	1.6	long f = ThreadLocalRandom.current().nextLong(17, 2);
195	jsr166	1.3	shouldThrow();
196	jsr166	1.5	} catch (IllegalArgumentException success) {}
197	dl	1.1	}
198
199			/**
200			* nextLong(bound) returns 0 <= value < bound;
201	jsr166	1.14	* repeated calls produce at least two distinct results
202	dl	1.1	*/
203			public void testNextLongBounded() {
204			for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
205			long f = ThreadLocalRandom.current().nextLong(bound);
206			assertTrue(0 <= f && f < bound);
207			int i = 0;
208			long j;
209	jsr166	1.2	while (i < NCALLS &&
210	dl	1.1	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
211			assertTrue(0 <= j && j < bound);
212			++i;
213			}
214			assertTrue(i < NCALLS);
215			}
216			}
217
218			/**
219			* nextLong(least, bound) returns least <= value < bound;
220	jsr166	1.14	* repeated calls produce at least two distinct results
221	dl	1.1	*/
222			public void testNextLongBounded2() {
223			for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
224			for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
225			long f = ThreadLocalRandom.current().nextLong(least, bound);
226			assertTrue(least <= f && f < bound);
227			int i = 0;
228			long j;
229	jsr166	1.2	while (i < NCALLS &&
230	dl	1.1	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
231			assertTrue(least <= j && j < bound);
232			++i;
233			}
234			assertTrue(i < NCALLS);
235			}
236			}
237			}
238
239			/**
240			* nextDouble(least, bound) returns least <= value < bound;
241	jsr166	1.14	* repeated calls produce at least two distinct results
242	dl	1.1	*/
243			public void testNextDoubleBounded2() {
244			for (double least = 0.0001; least < 1.0e20; least *= 8) {
245			for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
246			double f = ThreadLocalRandom.current().nextDouble(least, bound);
247			assertTrue(least <= f && f < bound);
248			int i = 0;
249			double j;
250	jsr166	1.2	while (i < NCALLS &&
251	dl	1.1	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
252			assertTrue(least <= j && j < bound);
253			++i;
254			}
255			assertTrue(i < NCALLS);
256			}
257			}
258			}
259
260	jsr166	1.11	/**
261			* Different threads produce different pseudo-random sequences
262			*/
263			public void testDifferentSequences() {
264			// Don't use main thread's ThreadLocalRandom - it is likely to
265			// be polluted by previous tests.
266			final AtomicReference<ThreadLocalRandom> threadLocalRandom =
267			new AtomicReference<ThreadLocalRandom>();
268			final AtomicLong rand = new AtomicLong();
269
270			long firstRand = 0;
271			ThreadLocalRandom firstThreadLocalRandom = null;
272
273			final CheckedRunnable getRandomState = new CheckedRunnable() {
274			public void realRun() {
275			ThreadLocalRandom current = ThreadLocalRandom.current();
276			assertSame(current, ThreadLocalRandom.current());
277	dl	1.12	// test bug: the following is not guaranteed and not true in JDK8
278			// assertNotSame(current, threadLocalRandom.get());
279	jsr166	1.11	rand.set(current.nextLong());
280			threadLocalRandom.set(current);
281			}};
282
283			Thread first = newStartedThread(getRandomState);
284			awaitTermination(first);
285			firstRand = rand.get();
286			firstThreadLocalRandom = threadLocalRandom.get();
287
288			for (int i = 0; i < NCALLS; i++) {
289			Thread t = newStartedThread(getRandomState);
290			awaitTermination(t);
291			if (firstRand != rand.get())
292			return;
293			}
294			fail("all threads generate the same pseudo-random sequence");
295			}
296
297	dl	1.1	}