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 java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

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

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:	1.20
Committed:	Wed Dec 31 19:05:43 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.19:	+4 -2 lines
Log Message:	no wildcard 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	jsr166	1.20
7	jsr166	1.10	import java.util.concurrent.ThreadLocalRandom;
8	jsr166	1.11	import java.util.concurrent.atomic.AtomicLong;
9			import java.util.concurrent.atomic.AtomicReference;
10	dl	1.1
11	jsr166	1.20	import junit.framework.Test;
12			import junit.framework.TestSuite;
13
14	dl	1.1	public class ThreadLocalRandomTest extends JSR166TestCase {
15
16			public static void main(String[] args) {
17	jsr166	1.7	junit.textui.TestRunner.run(suite());
18	dl	1.1	}
19			public static Test suite() {
20	jsr166	1.4	return new TestSuite(ThreadLocalRandomTest.class);
21	dl	1.1	}
22
23	jsr166	1.13	/*
24	dl	1.1	* Testing coverage notes:
25	jsr166	1.2	*
26	dl	1.1	* We don't test randomness properties, but only that repeated
27			* calls, up to NCALLS tries, produce at least one different
28			* result. For bounded versions, we sample various intervals
29			* across multiples of primes.
30			*/
31
32	jsr166	1.14	// max numbers of calls to detect getting stuck on one value
33	dl	1.1	static final int NCALLS = 10000;
34
35			// max sampled int bound
36			static final int MAX_INT_BOUND = (1 << 28);
37
38	jsr166	1.14	// max sampled long bound
39	dl	1.1	static final long MAX_LONG_BOUND = (1L << 42);
40
41	dl	1.15	// Number of replications for other checks
42			static final int REPS = 20;
43
44	dl	1.1	/**
45			* setSeed throws UnsupportedOperationException
46			*/
47			public void testSetSeed() {
48			try {
49			ThreadLocalRandom.current().setSeed(17);
50	jsr166	1.3	shouldThrow();
51	jsr166	1.5	} catch (UnsupportedOperationException success) {}
52	dl	1.1	}
53
54			/**
55	jsr166	1.14	* Repeated calls to nextInt produce at least two distinct results
56	dl	1.1	*/
57			public void testNextInt() {
58			int f = ThreadLocalRandom.current().nextInt();
59			int i = 0;
60			while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
61			++i;
62			assertTrue(i < NCALLS);
63			}
64
65			/**
66	jsr166	1.14	* Repeated calls to nextLong produce at least two distinct results
67	dl	1.1	*/
68			public void testNextLong() {
69			long f = ThreadLocalRandom.current().nextLong();
70			int i = 0;
71			while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
72			++i;
73			assertTrue(i < NCALLS);
74			}
75
76			/**
77	jsr166	1.14	* Repeated calls to nextBoolean produce at least two distinct results
78	dl	1.1	*/
79			public void testNextBoolean() {
80			boolean f = ThreadLocalRandom.current().nextBoolean();
81			int i = 0;
82			while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
83			++i;
84			assertTrue(i < NCALLS);
85			}
86
87			/**
88	jsr166	1.14	* Repeated calls to nextFloat produce at least two distinct results
89	dl	1.1	*/
90			public void testNextFloat() {
91			float f = ThreadLocalRandom.current().nextFloat();
92			int i = 0;
93			while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
94			++i;
95			assertTrue(i < NCALLS);
96			}
97
98			/**
99	jsr166	1.14	* Repeated calls to nextDouble produce at least two distinct results
100	dl	1.1	*/
101			public void testNextDouble() {
102			double f = ThreadLocalRandom.current().nextDouble();
103	jsr166	1.14	int i = 0;
104	dl	1.1	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
105			++i;
106			assertTrue(i < NCALLS);
107			}
108
109			/**
110	jsr166	1.14	* Repeated calls to nextGaussian produce at least two distinct results
111	dl	1.1	*/
112			public void testNextGaussian() {
113			double f = ThreadLocalRandom.current().nextGaussian();
114			int i = 0;
115			while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
116			++i;
117			assertTrue(i < NCALLS);
118			}
119
120			/**
121	jsr166	1.19	* nextInt(non-positive) throws IllegalArgumentException
122	dl	1.1	*/
123	jsr166	1.19	public void testNextIntBoundNonPositive() {
124			ThreadLocalRandom rnd = ThreadLocalRandom.current();
125			for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
126			try {
127			rnd.nextInt(bound);
128			shouldThrow();
129			} catch (IllegalArgumentException success) {}
130			}
131	dl	1.1	}
132
133			/**
134	jsr166	1.14	* nextInt(least >= bound) throws IllegalArgumentException
135	dl	1.1	*/
136			public void testNextIntBadBounds() {
137	jsr166	1.19	int[][] badBoundss = {
138			{ 17, 2 },
139			{ -42, -42 },
140			{ Integer.MAX_VALUE, Integer.MIN_VALUE },
141			};
142			ThreadLocalRandom rnd = ThreadLocalRandom.current();
143			for (int[] badBounds : badBoundss) {
144			try {
145			rnd.nextInt(badBounds[0], badBounds[1]);
146			shouldThrow();
147			} catch (IllegalArgumentException success) {}
148			}
149	dl	1.1	}
150
151			/**
152			* nextInt(bound) returns 0 <= value < bound;
153	jsr166	1.14	* repeated calls produce at least two distinct results
154	dl	1.1	*/
155			public void testNextIntBounded() {
156			// sample bound space across prime number increments
157			for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
158			int f = ThreadLocalRandom.current().nextInt(bound);
159			assertTrue(0 <= f && f < bound);
160			int i = 0;
161			int j;
162	jsr166	1.2	while (i < NCALLS &&
163	dl	1.1	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
164			assertTrue(0 <= j && j < bound);
165			++i;
166			}
167			assertTrue(i < NCALLS);
168			}
169			}
170
171			/**
172			* nextInt(least, bound) returns least <= value < bound;
173	jsr166	1.14	* repeated calls produce at least two distinct results
174	dl	1.1	*/
175			public void testNextIntBounded2() {
176			for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
177			for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
178			int f = ThreadLocalRandom.current().nextInt(least, bound);
179			assertTrue(least <= f && f < bound);
180			int i = 0;
181			int j;
182	jsr166	1.2	while (i < NCALLS &&
183	dl	1.1	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
184			assertTrue(least <= j && j < bound);
185			++i;
186			}
187			assertTrue(i < NCALLS);
188			}
189			}
190			}
191
192			/**
193	jsr166	1.19	* nextLong(non-positive) throws IllegalArgumentException
194	dl	1.1	*/
195	jsr166	1.19	public void testNextLongBoundNonPositive() {
196			ThreadLocalRandom rnd = ThreadLocalRandom.current();
197			for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
198			try {
199			rnd.nextLong(bound);
200			shouldThrow();
201			} catch (IllegalArgumentException success) {}
202			}
203	dl	1.1	}
204
205			/**
206	jsr166	1.14	* nextLong(least >= bound) throws IllegalArgumentException
207	dl	1.1	*/
208			public void testNextLongBadBounds() {
209	jsr166	1.19	long[][] badBoundss = {
210			{ 17L, 2L },
211			{ -42L, -42L },
212			{ Long.MAX_VALUE, Long.MIN_VALUE },
213			};
214			ThreadLocalRandom rnd = ThreadLocalRandom.current();
215			for (long[] badBounds : badBoundss) {
216			try {
217			rnd.nextLong(badBounds[0], badBounds[1]);
218			shouldThrow();
219			} catch (IllegalArgumentException success) {}
220			}
221	dl	1.1	}
222
223			/**
224			* nextLong(bound) returns 0 <= value < bound;
225	jsr166	1.14	* repeated calls produce at least two distinct results
226	dl	1.1	*/
227			public void testNextLongBounded() {
228			for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
229			long f = ThreadLocalRandom.current().nextLong(bound);
230			assertTrue(0 <= f && f < bound);
231			int i = 0;
232			long j;
233	jsr166	1.2	while (i < NCALLS &&
234	dl	1.1	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
235			assertTrue(0 <= j && j < bound);
236			++i;
237			}
238			assertTrue(i < NCALLS);
239			}
240			}
241
242			/**
243			* nextLong(least, bound) returns least <= value < bound;
244	jsr166	1.14	* repeated calls produce at least two distinct results
245	dl	1.1	*/
246			public void testNextLongBounded2() {
247			for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
248			for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
249			long f = ThreadLocalRandom.current().nextLong(least, bound);
250			assertTrue(least <= f && f < bound);
251			int i = 0;
252			long j;
253	jsr166	1.2	while (i < NCALLS &&
254	dl	1.1	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
255			assertTrue(least <= j && j < bound);
256			++i;
257			}
258			assertTrue(i < NCALLS);
259			}
260			}
261			}
262
263			/**
264	jsr166	1.19	* nextDouble(non-positive) throws IllegalArgumentException
265			*/
266			public void testNextDoubleBoundNonPositive() {
267			ThreadLocalRandom rnd = ThreadLocalRandom.current();
268			double[] badBounds = {
269			0.0d,
270			-17.0d,
271			-Double.MIN_VALUE,
272			Double.NEGATIVE_INFINITY,
273			Double.NaN,
274			};
275			for (double bound : badBounds) {
276			try {
277			rnd.nextDouble(bound);
278			shouldThrow();
279			} catch (IllegalArgumentException success) {}
280			}
281			}
282
283			/**
284	dl	1.1	* nextDouble(least, bound) returns least <= value < bound;
285	jsr166	1.14	* repeated calls produce at least two distinct results
286	dl	1.1	*/
287			public void testNextDoubleBounded2() {
288			for (double least = 0.0001; least < 1.0e20; least *= 8) {
289			for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
290			double f = ThreadLocalRandom.current().nextDouble(least, bound);
291			assertTrue(least <= f && f < bound);
292			int i = 0;
293			double j;
294	jsr166	1.2	while (i < NCALLS &&
295	dl	1.1	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
296			assertTrue(least <= j && j < bound);
297			++i;
298			}
299			assertTrue(i < NCALLS);
300			}
301			}
302			}
303
304	jsr166	1.11	/**
305			* Different threads produce different pseudo-random sequences
306			*/
307			public void testDifferentSequences() {
308			// Don't use main thread's ThreadLocalRandom - it is likely to
309			// be polluted by previous tests.
310			final AtomicReference<ThreadLocalRandom> threadLocalRandom =
311			new AtomicReference<ThreadLocalRandom>();
312			final AtomicLong rand = new AtomicLong();
313
314			long firstRand = 0;
315			ThreadLocalRandom firstThreadLocalRandom = null;
316
317	jsr166	1.18	Runnable getRandomState = new CheckedRunnable() {
318	jsr166	1.11	public void realRun() {
319			ThreadLocalRandom current = ThreadLocalRandom.current();
320			assertSame(current, ThreadLocalRandom.current());
321	dl	1.12	// test bug: the following is not guaranteed and not true in JDK8
322			// assertNotSame(current, threadLocalRandom.get());
323	jsr166	1.11	rand.set(current.nextLong());
324			threadLocalRandom.set(current);
325			}};
326
327			Thread first = newStartedThread(getRandomState);
328			awaitTermination(first);
329			firstRand = rand.get();
330			firstThreadLocalRandom = threadLocalRandom.get();
331
332			for (int i = 0; i < NCALLS; i++) {
333			Thread t = newStartedThread(getRandomState);
334			awaitTermination(t);
335			if (firstRand != rand.get())
336			return;
337			}
338			fail("all threads generate the same pseudo-random sequence");
339			}
340
341	dl	1.1	}