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(non-positive) throws IllegalArgumentException
     */
    public void testNextIntBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
            try {
                rnd.nextInt(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextInt(least >= bound) throws IllegalArgumentException
     */
    public void testNextIntBadBounds() {
        int[][] badBoundss = {
            { 17, 2 },
            { -42, -42 },
            { Integer.MAX_VALUE, Integer.MIN_VALUE },
        };
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (int[] badBounds : badBoundss) {
            try {
                rnd.nextInt(badBounds[0], badBounds[1]);
                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(non-positive) throws IllegalArgumentException
     */
    public void testNextLongBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
            try {
                rnd.nextLong(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * nextLong(least >= bound) throws IllegalArgumentException
     */
    public void testNextLongBadBounds() {
        long[][] badBoundss = {
            { 17L, 2L },
            { -42L, -42L },
            { Long.MAX_VALUE, Long.MIN_VALUE },
        };
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        for (long[] badBounds : badBoundss) {
            try {
                rnd.nextLong(badBounds[0], badBounds[1]);
                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(non-positive) throws IllegalArgumentException
     */
    public void testNextDoubleBoundNonPositive() {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        double[] badBounds = {
            0.0d,
            -17.0d,
            -Double.MIN_VALUE,
            Double.NEGATIVE_INFINITY,
            Double.NaN,
        };
        for (double bound : badBounds) {
            try {
                rnd.nextDouble(bound);
                shouldThrow();
            } catch (IllegalArgumentException success) {}
        }
    }

    /**
     * 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;

        Runnable 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:	1.19
Committed:	Fri Sep 27 20:22:26 2013 UTC (10 years, 7 months ago) by jsr166
Branch:	MAIN
Changes since 1.18:	+62 -20 lines
Log Message:	more "bound" tests
#	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	1.19	* nextInt(non-positive) throws IllegalArgumentException
120	dl	1.1	*/
121	jsr166	1.19	public void testNextIntBoundNonPositive() {
122			ThreadLocalRandom rnd = ThreadLocalRandom.current();
123			for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
124			try {
125			rnd.nextInt(bound);
126			shouldThrow();
127			} catch (IllegalArgumentException success) {}
128			}
129	dl	1.1	}
130
131			/**
132	jsr166	1.14	* nextInt(least >= bound) throws IllegalArgumentException
133	dl	1.1	*/
134			public void testNextIntBadBounds() {
135	jsr166	1.19	int[][] badBoundss = {
136			{ 17, 2 },
137			{ -42, -42 },
138			{ Integer.MAX_VALUE, Integer.MIN_VALUE },
139			};
140			ThreadLocalRandom rnd = ThreadLocalRandom.current();
141			for (int[] badBounds : badBoundss) {
142			try {
143			rnd.nextInt(badBounds[0], badBounds[1]);
144			shouldThrow();
145			} catch (IllegalArgumentException success) {}
146			}
147	dl	1.1	}
148
149			/**
150			* nextInt(bound) returns 0 <= value < bound;
151	jsr166	1.14	* repeated calls produce at least two distinct results
152	dl	1.1	*/
153			public void testNextIntBounded() {
154			// sample bound space across prime number increments
155			for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
156			int f = ThreadLocalRandom.current().nextInt(bound);
157			assertTrue(0 <= f && f < bound);
158			int i = 0;
159			int j;
160	jsr166	1.2	while (i < NCALLS &&
161	dl	1.1	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
162			assertTrue(0 <= j && j < bound);
163			++i;
164			}
165			assertTrue(i < NCALLS);
166			}
167			}
168
169			/**
170			* nextInt(least, bound) returns least <= value < bound;
171	jsr166	1.14	* repeated calls produce at least two distinct results
172	dl	1.1	*/
173			public void testNextIntBounded2() {
174			for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
175			for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
176			int f = ThreadLocalRandom.current().nextInt(least, bound);
177			assertTrue(least <= f && f < bound);
178			int i = 0;
179			int j;
180	jsr166	1.2	while (i < NCALLS &&
181	dl	1.1	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
182			assertTrue(least <= j && j < bound);
183			++i;
184			}
185			assertTrue(i < NCALLS);
186			}
187			}
188			}
189
190			/**
191	jsr166	1.19	* nextLong(non-positive) throws IllegalArgumentException
192	dl	1.1	*/
193	jsr166	1.19	public void testNextLongBoundNonPositive() {
194			ThreadLocalRandom rnd = ThreadLocalRandom.current();
195			for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
196			try {
197			rnd.nextLong(bound);
198			shouldThrow();
199			} catch (IllegalArgumentException success) {}
200			}
201	dl	1.1	}
202
203			/**
204	jsr166	1.14	* nextLong(least >= bound) throws IllegalArgumentException
205	dl	1.1	*/
206			public void testNextLongBadBounds() {
207	jsr166	1.19	long[][] badBoundss = {
208			{ 17L, 2L },
209			{ -42L, -42L },
210			{ Long.MAX_VALUE, Long.MIN_VALUE },
211			};
212			ThreadLocalRandom rnd = ThreadLocalRandom.current();
213			for (long[] badBounds : badBoundss) {
214			try {
215			rnd.nextLong(badBounds[0], badBounds[1]);
216			shouldThrow();
217			} catch (IllegalArgumentException success) {}
218			}
219	dl	1.1	}
220
221			/**
222			* nextLong(bound) returns 0 <= value < bound;
223	jsr166	1.14	* repeated calls produce at least two distinct results
224	dl	1.1	*/
225			public void testNextLongBounded() {
226			for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
227			long f = ThreadLocalRandom.current().nextLong(bound);
228			assertTrue(0 <= f && f < bound);
229			int i = 0;
230			long j;
231	jsr166	1.2	while (i < NCALLS &&
232	dl	1.1	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
233			assertTrue(0 <= j && j < bound);
234			++i;
235			}
236			assertTrue(i < NCALLS);
237			}
238			}
239
240			/**
241			* nextLong(least, bound) returns least <= value < bound;
242	jsr166	1.14	* repeated calls produce at least two distinct results
243	dl	1.1	*/
244			public void testNextLongBounded2() {
245			for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
246			for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
247			long f = ThreadLocalRandom.current().nextLong(least, bound);
248			assertTrue(least <= f && f < bound);
249			int i = 0;
250			long j;
251	jsr166	1.2	while (i < NCALLS &&
252	dl	1.1	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
253			assertTrue(least <= j && j < bound);
254			++i;
255			}
256			assertTrue(i < NCALLS);
257			}
258			}
259			}
260
261			/**
262	jsr166	1.19	* nextDouble(non-positive) throws IllegalArgumentException
263			*/
264			public void testNextDoubleBoundNonPositive() {
265			ThreadLocalRandom rnd = ThreadLocalRandom.current();
266			double[] badBounds = {
267			0.0d,
268			-17.0d,
269			-Double.MIN_VALUE,
270			Double.NEGATIVE_INFINITY,
271			Double.NaN,
272			};
273			for (double bound : badBounds) {
274			try {
275			rnd.nextDouble(bound);
276			shouldThrow();
277			} catch (IllegalArgumentException success) {}
278			}
279			}
280
281			/**
282	dl	1.1	* nextDouble(least, bound) returns least <= value < bound;
283	jsr166	1.14	* repeated calls produce at least two distinct results
284	dl	1.1	*/
285			public void testNextDoubleBounded2() {
286			for (double least = 0.0001; least < 1.0e20; least *= 8) {
287			for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
288			double f = ThreadLocalRandom.current().nextDouble(least, bound);
289			assertTrue(least <= f && f < bound);
290			int i = 0;
291			double j;
292	jsr166	1.2	while (i < NCALLS &&
293	dl	1.1	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
294			assertTrue(least <= j && j < bound);
295			++i;
296			}
297			assertTrue(i < NCALLS);
298			}
299			}
300			}
301
302	jsr166	1.11	/**
303			* Different threads produce different pseudo-random sequences
304			*/
305			public void testDifferentSequences() {
306			// Don't use main thread's ThreadLocalRandom - it is likely to
307			// be polluted by previous tests.
308			final AtomicReference<ThreadLocalRandom> threadLocalRandom =
309			new AtomicReference<ThreadLocalRandom>();
310			final AtomicLong rand = new AtomicLong();
311
312			long firstRand = 0;
313			ThreadLocalRandom firstThreadLocalRandom = null;
314
315	jsr166	1.18	Runnable getRandomState = new CheckedRunnable() {
316	jsr166	1.11	public void realRun() {
317			ThreadLocalRandom current = ThreadLocalRandom.current();
318			assertSame(current, ThreadLocalRandom.current());
319	dl	1.12	// test bug: the following is not guaranteed and not true in JDK8
320			// assertNotSame(current, threadLocalRandom.get());
321	jsr166	1.11	rand.set(current.nextLong());
322			threadLocalRandom.set(current);
323			}};
324
325			Thread first = newStartedThread(getRandomState);
326			awaitTermination(first);
327			firstRand = rand.get();
328			firstThreadLocalRandom = threadLocalRandom.get();
329
330			for (int i = 0; i < NCALLS; i++) {
331			Thread t = newStartedThread(getRandomState);
332			awaitTermination(t);
333			if (firstRand != rand.get())
334			return;
335			}
336			fail("all threads generate the same pseudo-random sequence");
337			}
338
339	dl	1.1	}