test/tck-jsr166e/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 jsr166e.*;
import junit.framework.*;
import java.util.*;
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);

    /**
     * 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:	1.1
Committed:	Sun Jul 14 19:55:05 2013 UTC (10 years, 10 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Log Message:	backport jsr166e to run on jdk6; backport all applicable tck tests from tck to tck-jsr166e
#	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
7	import jsr166e.*;
8	import junit.framework.*;
9	import java.util.*;
10	import java.util.concurrent.atomic.AtomicLong;
11	import java.util.concurrent.atomic.AtomicReference;
12
13	public class ThreadLocalRandomTest extends JSR166TestCase {
14
15	public static void main(String[] args) {
16	junit.textui.TestRunner.run(suite());
17	}
18	public static Test suite() {
19	return new TestSuite(ThreadLocalRandomTest.class);
20	}
21
22	/*
23	* Testing coverage notes:
24	*
25	* We don't test randomness properties, but only that repeated
26	* calls, up to NCALLS tries, produce at least one different
27	* result. For bounded versions, we sample various intervals
28	* across multiples of primes.
29	*/
30
31	// max numbers of calls to detect getting stuck on one value
32	static final int NCALLS = 10000;
33
34	// max sampled int bound
35	static final int MAX_INT_BOUND = (1 << 28);
36
37	// max sampled long bound
38	static final long MAX_LONG_BOUND = (1L << 42);
39
40	/**
41	* setSeed throws UnsupportedOperationException
42	*/
43	public void testSetSeed() {
44	try {
45	ThreadLocalRandom.current().setSeed(17);
46	shouldThrow();
47	} catch (UnsupportedOperationException success) {}
48	}
49
50	/**
51	* Repeated calls to nextInt produce at least two distinct results
52	*/
53	public void testNextInt() {
54	int f = ThreadLocalRandom.current().nextInt();
55	int i = 0;
56	while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
57	++i;
58	assertTrue(i < NCALLS);
59	}
60
61	/**
62	* Repeated calls to nextLong produce at least two distinct results
63	*/
64	public void testNextLong() {
65	long f = ThreadLocalRandom.current().nextLong();
66	int i = 0;
67	while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
68	++i;
69	assertTrue(i < NCALLS);
70	}
71
72	/**
73	* Repeated calls to nextBoolean produce at least two distinct results
74	*/
75	public void testNextBoolean() {
76	boolean f = ThreadLocalRandom.current().nextBoolean();
77	int i = 0;
78	while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
79	++i;
80	assertTrue(i < NCALLS);
81	}
82
83	/**
84	* Repeated calls to nextFloat produce at least two distinct results
85	*/
86	public void testNextFloat() {
87	float f = ThreadLocalRandom.current().nextFloat();
88	int i = 0;
89	while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
90	++i;
91	assertTrue(i < NCALLS);
92	}
93
94	/**
95	* Repeated calls to nextDouble produce at least two distinct results
96	*/
97	public void testNextDouble() {
98	double f = ThreadLocalRandom.current().nextDouble();
99	int i = 0;
100	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
101	++i;
102	assertTrue(i < NCALLS);
103	}
104
105	/**
106	* Repeated calls to nextGaussian produce at least two distinct results
107	*/
108	public void testNextGaussian() {
109	double f = ThreadLocalRandom.current().nextGaussian();
110	int i = 0;
111	while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
112	++i;
113	assertTrue(i < NCALLS);
114	}
115
116	/**
117	* nextInt(negative) throws IllegalArgumentException
118	*/
119	public void testNextIntBoundedNeg() {
120	try {
121	int f = ThreadLocalRandom.current().nextInt(-17);
122	shouldThrow();
123	} catch (IllegalArgumentException success) {}
124	}
125
126	/**
127	* nextInt(least >= bound) throws IllegalArgumentException
128	*/
129	public void testNextIntBadBounds() {
130	try {
131	int f = ThreadLocalRandom.current().nextInt(17, 2);
132	shouldThrow();
133	} catch (IllegalArgumentException success) {}
134	}
135
136	/**
137	* nextInt(bound) returns 0 <= value < bound;
138	* repeated calls produce at least two distinct results
139	*/
140	public void testNextIntBounded() {
141	// sample bound space across prime number increments
142	for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
143	int f = ThreadLocalRandom.current().nextInt(bound);
144	assertTrue(0 <= f && f < bound);
145	int i = 0;
146	int j;
147	while (i < NCALLS &&
148	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
149	assertTrue(0 <= j && j < bound);
150	++i;
151	}
152	assertTrue(i < NCALLS);
153	}
154	}
155
156	/**
157	* nextInt(least, bound) returns least <= value < bound;
158	* repeated calls produce at least two distinct results
159	*/
160	public void testNextIntBounded2() {
161	for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
162	for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
163	int f = ThreadLocalRandom.current().nextInt(least, bound);
164	assertTrue(least <= f && f < bound);
165	int i = 0;
166	int j;
167	while (i < NCALLS &&
168	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
169	assertTrue(least <= j && j < bound);
170	++i;
171	}
172	assertTrue(i < NCALLS);
173	}
174	}
175	}
176
177	/**
178	* nextLong(negative) throws IllegalArgumentException
179	*/
180	public void testNextLongBoundedNeg() {
181	try {
182	long f = ThreadLocalRandom.current().nextLong(-17);
183	shouldThrow();
184	} catch (IllegalArgumentException success) {}
185	}
186
187	/**
188	* nextLong(least >= bound) throws IllegalArgumentException
189	*/
190	public void testNextLongBadBounds() {
191	try {
192	long f = ThreadLocalRandom.current().nextLong(17, 2);
193	shouldThrow();
194	} catch (IllegalArgumentException success) {}
195	}
196
197	/**
198	* nextLong(bound) returns 0 <= value < bound;
199	* repeated calls produce at least two distinct results
200	*/
201	public void testNextLongBounded() {
202	for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
203	long f = ThreadLocalRandom.current().nextLong(bound);
204	assertTrue(0 <= f && f < bound);
205	int i = 0;
206	long j;
207	while (i < NCALLS &&
208	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
209	assertTrue(0 <= j && j < bound);
210	++i;
211	}
212	assertTrue(i < NCALLS);
213	}
214	}
215
216	/**
217	* nextLong(least, bound) returns least <= value < bound;
218	* repeated calls produce at least two distinct results
219	*/
220	public void testNextLongBounded2() {
221	for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
222	for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
223	long f = ThreadLocalRandom.current().nextLong(least, bound);
224	assertTrue(least <= f && f < bound);
225	int i = 0;
226	long j;
227	while (i < NCALLS &&
228	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
229	assertTrue(least <= j && j < bound);
230	++i;
231	}
232	assertTrue(i < NCALLS);
233	}
234	}
235	}
236
237	/**
238	* nextDouble(least, bound) returns least <= value < bound;
239	* repeated calls produce at least two distinct results
240	*/
241	public void testNextDoubleBounded2() {
242	for (double least = 0.0001; least < 1.0e20; least *= 8) {
243	for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
244	double f = ThreadLocalRandom.current().nextDouble(least, bound);
245	assertTrue(least <= f && f < bound);
246	int i = 0;
247	double j;
248	while (i < NCALLS &&
249	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
250	assertTrue(least <= j && j < bound);
251	++i;
252	}
253	assertTrue(i < NCALLS);
254	}
255	}
256	}
257
258	/**
259	* Different threads produce different pseudo-random sequences
260	*/
261	public void testDifferentSequences() {
262	// Don't use main thread's ThreadLocalRandom - it is likely to
263	// be polluted by previous tests.
264	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
265	new AtomicReference<ThreadLocalRandom>();
266	final AtomicLong rand = new AtomicLong();
267
268	long firstRand = 0;
269	ThreadLocalRandom firstThreadLocalRandom = null;
270
271	final CheckedRunnable getRandomState = new CheckedRunnable() {
272	public void realRun() {
273	ThreadLocalRandom current = ThreadLocalRandom.current();
274	assertSame(current, ThreadLocalRandom.current());
275	// test bug: the following is not guaranteed and not true in JDK8
276	// assertNotSame(current, threadLocalRandom.get());
277	rand.set(current.nextLong());
278	threadLocalRandom.set(current);
279	}};
280
281	Thread first = newStartedThread(getRandomState);
282	awaitTermination(first);
283	firstRand = rand.get();
284	firstThreadLocalRandom = threadLocalRandom.get();
285
286	for (int i = 0; i < NCALLS; i++) {
287	Thread t = newStartedThread(getRandomState);
288	awaitTermination(t);
289	if (firstRand != rand.get())
290	return;
291	}
292	fail("all threads generate the same pseudo-random sequence");
293	}
294
295	}