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.
     */

    //
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    public void testNextDouble() {
        double f = ThreadLocalRandom.current().nextDouble();
        double i = 0;
        while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextGaussian produce at least one different result
     */
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    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 one different result
     */
    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:	1.13
Committed:	Sat Feb 16 20:50:29 2013 UTC (11 years, 2 months ago) by jsr166
Branch:	MAIN
Changes since 1.12:	+1 -1 lines
Log Message:	javadoc comment correctness
#	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	//
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	/**
40	* setSeed throws UnsupportedOperationException
41	*/
42	public void testSetSeed() {
43	try {
44	ThreadLocalRandom.current().setSeed(17);
45	shouldThrow();
46	} catch (UnsupportedOperationException success) {}
47	}
48
49	/**
50	* Repeated calls to nextInt produce at least one different result
51	*/
52	public void testNextInt() {
53	int f = ThreadLocalRandom.current().nextInt();
54	int i = 0;
55	while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
56	++i;
57	assertTrue(i < NCALLS);
58	}
59
60	/**
61	* Repeated calls to nextLong produce at least one different result
62	*/
63	public void testNextLong() {
64	long f = ThreadLocalRandom.current().nextLong();
65	int i = 0;
66	while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
67	++i;
68	assertTrue(i < NCALLS);
69	}
70
71	/**
72	* Repeated calls to nextBoolean produce at least one different result
73	*/
74	public void testNextBoolean() {
75	boolean f = ThreadLocalRandom.current().nextBoolean();
76	int i = 0;
77	while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
78	++i;
79	assertTrue(i < NCALLS);
80	}
81
82	/**
83	* Repeated calls to nextFloat produce at least one different result
84	*/
85	public void testNextFloat() {
86	float f = ThreadLocalRandom.current().nextFloat();
87	int i = 0;
88	while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
89	++i;
90	assertTrue(i < NCALLS);
91	}
92
93	/**
94	* Repeated calls to nextDouble produce at least one different result
95	*/
96	public void testNextDouble() {
97	double f = ThreadLocalRandom.current().nextDouble();
98	double i = 0;
99	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
100	++i;
101	assertTrue(i < NCALLS);
102	}
103
104	/**
105	* Repeated calls to nextGaussian produce at least one different result
106	*/
107	public void testNextGaussian() {
108	double f = ThreadLocalRandom.current().nextGaussian();
109	int i = 0;
110	while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
111	++i;
112	assertTrue(i < NCALLS);
113	}
114
115	/**
116	* nextInt(negative) throws IllegalArgumentException;
117	*/
118	public void testNextIntBoundedNeg() {
119	try {
120	int f = ThreadLocalRandom.current().nextInt(-17);
121	shouldThrow();
122	} catch (IllegalArgumentException success) {}
123	}
124
125	/**
126	* nextInt(least >= bound) throws IllegalArgumentException;
127	*/
128	public void testNextIntBadBounds() {
129	try {
130	int f = ThreadLocalRandom.current().nextInt(17, 2);
131	shouldThrow();
132	} catch (IllegalArgumentException success) {}
133	}
134
135	/**
136	* nextInt(bound) returns 0 <= value < bound;
137	* repeated calls produce at least one different result
138	*/
139	public void testNextIntBounded() {
140	// sample bound space across prime number increments
141	for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
142	int f = ThreadLocalRandom.current().nextInt(bound);
143	assertTrue(0 <= f && f < bound);
144	int i = 0;
145	int j;
146	while (i < NCALLS &&
147	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
148	assertTrue(0 <= j && j < bound);
149	++i;
150	}
151	assertTrue(i < NCALLS);
152	}
153	}
154
155	/**
156	* nextInt(least, bound) returns least <= value < bound;
157	* repeated calls produce at least one different result
158	*/
159	public void testNextIntBounded2() {
160	for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
161	for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
162	int f = ThreadLocalRandom.current().nextInt(least, bound);
163	assertTrue(least <= f && f < bound);
164	int i = 0;
165	int j;
166	while (i < NCALLS &&
167	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
168	assertTrue(least <= j && j < bound);
169	++i;
170	}
171	assertTrue(i < NCALLS);
172	}
173	}
174	}
175
176	/**
177	* nextLong(negative) throws IllegalArgumentException;
178	*/
179	public void testNextLongBoundedNeg() {
180	try {
181	long f = ThreadLocalRandom.current().nextLong(-17);
182	shouldThrow();
183	} catch (IllegalArgumentException success) {}
184	}
185
186	/**
187	* nextLong(least >= bound) throws IllegalArgumentException;
188	*/
189	public void testNextLongBadBounds() {
190	try {
191	long f = ThreadLocalRandom.current().nextLong(17, 2);
192	shouldThrow();
193	} catch (IllegalArgumentException success) {}
194	}
195
196	/**
197	* nextLong(bound) returns 0 <= value < bound;
198	* repeated calls produce at least one different result
199	*/
200	public void testNextLongBounded() {
201	for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
202	long f = ThreadLocalRandom.current().nextLong(bound);
203	assertTrue(0 <= f && f < bound);
204	int i = 0;
205	long j;
206	while (i < NCALLS &&
207	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
208	assertTrue(0 <= j && j < bound);
209	++i;
210	}
211	assertTrue(i < NCALLS);
212	}
213	}
214
215	/**
216	* nextLong(least, bound) returns least <= value < bound;
217	* repeated calls produce at least one different result
218	*/
219	public void testNextLongBounded2() {
220	for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
221	for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
222	long f = ThreadLocalRandom.current().nextLong(least, bound);
223	assertTrue(least <= f && f < bound);
224	int i = 0;
225	long j;
226	while (i < NCALLS &&
227	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
228	assertTrue(least <= j && j < bound);
229	++i;
230	}
231	assertTrue(i < NCALLS);
232	}
233	}
234	}
235
236	/**
237	* nextDouble(least, bound) returns least <= value < bound;
238	* repeated calls produce at least one different result
239	*/
240	public void testNextDoubleBounded2() {
241	for (double least = 0.0001; least < 1.0e20; least *= 8) {
242	for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
243	double f = ThreadLocalRandom.current().nextDouble(least, bound);
244	assertTrue(least <= f && f < bound);
245	int i = 0;
246	double j;
247	while (i < NCALLS &&
248	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
249	assertTrue(least <= j && j < bound);
250	++i;
251	}
252	assertTrue(i < NCALLS);
253	}
254	}
255	}
256
257	/**
258	* Different threads produce different pseudo-random sequences
259	*/
260	public void testDifferentSequences() {
261	// Don't use main thread's ThreadLocalRandom - it is likely to
262	// be polluted by previous tests.
263	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
264	new AtomicReference<ThreadLocalRandom>();
265	final AtomicLong rand = new AtomicLong();
266
267	long firstRand = 0;
268	ThreadLocalRandom firstThreadLocalRandom = null;
269
270	final CheckedRunnable getRandomState = new CheckedRunnable() {
271	public void realRun() {
272	ThreadLocalRandom current = ThreadLocalRandom.current();
273	assertSame(current, ThreadLocalRandom.current());
274	// test bug: the following is not guaranteed and not true in JDK8
275	// assertNotSame(current, threadLocalRandom.get());
276	rand.set(current.nextLong());
277	threadLocalRandom.set(current);
278	}};
279
280	Thread first = newStartedThread(getRandomState);
281	awaitTermination(first);
282	firstRand = rand.get();
283	firstThreadLocalRandom = threadLocalRandom.get();
284
285	for (int i = 0; i < NCALLS; i++) {
286	Thread t = newStartedThread(getRandomState);
287	awaitTermination(t);
288	if (firstRand != rand.get())
289	return;
290	}
291	fail("all threads generate the same pseudo-random sequence");
292	}
293
294	}