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
#	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(negative) throws IllegalArgumentException
120	*/
121	public void testNextIntBoundedNeg() {
122	try {
123	int f = ThreadLocalRandom.current().nextInt(-17);
124	shouldThrow();
125	} catch (IllegalArgumentException success) {}
126	}
127
128	/**
129	* nextInt(least >= bound) throws IllegalArgumentException
130	*/
131	public void testNextIntBadBounds() {
132	try {
133	int f = ThreadLocalRandom.current().nextInt(17, 2);
134	shouldThrow();
135	} catch (IllegalArgumentException success) {}
136	}
137
138	/**
139	* nextInt(bound) returns 0 <= value < bound;
140	* repeated calls produce at least two distinct results
141	*/
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	while (i < NCALLS &&
150	(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	* repeated calls produce at least two distinct results
161	*/
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	while (i < NCALLS &&
170	(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	* nextLong(negative) throws IllegalArgumentException
181	*/
182	public void testNextLongBoundedNeg() {
183	try {
184	long f = ThreadLocalRandom.current().nextLong(-17);
185	shouldThrow();
186	} catch (IllegalArgumentException success) {}
187	}
188
189	/**
190	* nextLong(least >= bound) throws IllegalArgumentException
191	*/
192	public void testNextLongBadBounds() {
193	try {
194	long f = ThreadLocalRandom.current().nextLong(17, 2);
195	shouldThrow();
196	} catch (IllegalArgumentException success) {}
197	}
198
199	/**
200	* nextLong(bound) returns 0 <= value < bound;
201	* repeated calls produce at least two distinct results
202	*/
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	while (i < NCALLS &&
210	(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	* repeated calls produce at least two distinct results
221	*/
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	while (i < NCALLS &&
230	(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	* repeated calls produce at least two distinct results
242	*/
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	while (i < NCALLS &&
251	(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	/**
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	// test bug: the following is not guaranteed and not true in JDK8
278	// assertNotSame(current, threadLocalRandom.get());
279	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	}