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
#	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	import junit.framework.*;
7	import java.util.*;
8	import java.util.concurrent.ThreadLocalRandom;
9	import java.util.concurrent.atomic.AtomicLong;
10	import java.util.concurrent.atomic.AtomicReference;
11
12	public class ThreadLocalRandomTest extends JSR166TestCase {
13
14	public static void main(String[] args) {
15	junit.textui.TestRunner.run(suite());
16	}
17	public static Test suite() {
18	return new TestSuite(ThreadLocalRandomTest.class);
19	}
20
21	/*
22	* Testing coverage notes:
23	*
24	* 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	// max numbers of calls to detect getting stuck on one value
31	static final int NCALLS = 10000;
32
33	// max sampled int bound
34	static final int MAX_INT_BOUND = (1 << 28);
35
36	// max sampled long bound
37	static final long MAX_LONG_BOUND = (1L << 42);
38
39	// Number of replications for other checks
40	static final int REPS = 20;
41
42	/**
43	* setSeed throws UnsupportedOperationException
44	*/
45	public void testSetSeed() {
46	try {
47	ThreadLocalRandom.current().setSeed(17);
48	shouldThrow();
49	} catch (UnsupportedOperationException success) {}
50	}
51
52	/**
53	* Repeated calls to nextInt produce at least two distinct results
54	*/
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	* Repeated calls to nextLong produce at least two distinct results
65	*/
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	* Repeated calls to nextBoolean produce at least two distinct results
76	*/
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	* Repeated calls to nextFloat produce at least two distinct results
87	*/
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	* Repeated calls to nextDouble produce at least two distinct results
98	*/
99	public void testNextDouble() {
100	double f = ThreadLocalRandom.current().nextDouble();
101	int i = 0;
102	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
103	++i;
104	assertTrue(i < NCALLS);
105	}
106
107	/**
108	* Repeated calls to nextGaussian produce at least two distinct results
109	*/
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	* nextInt(non-positive) throws IllegalArgumentException
120	*/
121	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	}
130
131	/**
132	* nextInt(least >= bound) throws IllegalArgumentException
133	*/
134	public void testNextIntBadBounds() {
135	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	}
148
149	/**
150	* nextInt(bound) returns 0 <= value < bound;
151	* repeated calls produce at least two distinct results
152	*/
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	while (i < NCALLS &&
161	(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	* repeated calls produce at least two distinct results
172	*/
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	while (i < NCALLS &&
181	(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	* nextLong(non-positive) throws IllegalArgumentException
192	*/
193	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	}
202
203	/**
204	* nextLong(least >= bound) throws IllegalArgumentException
205	*/
206	public void testNextLongBadBounds() {
207	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	}
220
221	/**
222	* nextLong(bound) returns 0 <= value < bound;
223	* repeated calls produce at least two distinct results
224	*/
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	while (i < NCALLS &&
232	(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	* repeated calls produce at least two distinct results
243	*/
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	while (i < NCALLS &&
252	(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	* 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	* nextDouble(least, bound) returns least <= value < bound;
283	* repeated calls produce at least two distinct results
284	*/
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	while (i < NCALLS &&
293	(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	/**
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	Runnable getRandomState = new CheckedRunnable() {
316	public void realRun() {
317	ThreadLocalRandom current = ThreadLocalRandom.current();
318	assertSame(current, ThreadLocalRandom.current());
319	// test bug: the following is not guaranteed and not true in JDK8
320	// assertNotSame(current, threadLocalRandom.get());
321	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	}