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.AtomicInteger;
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:	1.16
Committed:	Fri Aug 16 07:07:01 2013 UTC (10 years, 9 months ago) by jsr166
Branch:	MAIN
Changes since 1.15:	+0 -230 lines
Log Message:	introduce ThreadLocalRandom8Test, fixing 4jdk7-test-tck
#	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.AtomicInteger;
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	// Number of replications for other checks
41	static final int REPS = 20;
42
43	/**
44	* setSeed throws UnsupportedOperationException
45	*/
46	public void testSetSeed() {
47	try {
48	ThreadLocalRandom.current().setSeed(17);
49	shouldThrow();
50	} catch (UnsupportedOperationException success) {}
51	}
52
53	/**
54	* Repeated calls to nextInt produce at least two distinct results
55	*/
56	public void testNextInt() {
57	int f = ThreadLocalRandom.current().nextInt();
58	int i = 0;
59	while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
60	++i;
61	assertTrue(i < NCALLS);
62	}
63
64	/**
65	* Repeated calls to nextLong produce at least two distinct results
66	*/
67	public void testNextLong() {
68	long f = ThreadLocalRandom.current().nextLong();
69	int i = 0;
70	while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
71	++i;
72	assertTrue(i < NCALLS);
73	}
74
75	/**
76	* Repeated calls to nextBoolean produce at least two distinct results
77	*/
78	public void testNextBoolean() {
79	boolean f = ThreadLocalRandom.current().nextBoolean();
80	int i = 0;
81	while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
82	++i;
83	assertTrue(i < NCALLS);
84	}
85
86	/**
87	* Repeated calls to nextFloat produce at least two distinct results
88	*/
89	public void testNextFloat() {
90	float f = ThreadLocalRandom.current().nextFloat();
91	int i = 0;
92	while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
93	++i;
94	assertTrue(i < NCALLS);
95	}
96
97	/**
98	* Repeated calls to nextDouble produce at least two distinct results
99	*/
100	public void testNextDouble() {
101	double f = ThreadLocalRandom.current().nextDouble();
102	int i = 0;
103	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
104	++i;
105	assertTrue(i < NCALLS);
106	}
107
108	/**
109	* Repeated calls to nextGaussian produce at least two distinct results
110	*/
111	public void testNextGaussian() {
112	double f = ThreadLocalRandom.current().nextGaussian();
113	int i = 0;
114	while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
115	++i;
116	assertTrue(i < NCALLS);
117	}
118
119	/**
120	* nextInt(negative) throws IllegalArgumentException
121	*/
122	public void testNextIntBoundedNeg() {
123	try {
124	int f = ThreadLocalRandom.current().nextInt(-17);
125	shouldThrow();
126	} catch (IllegalArgumentException success) {}
127	}
128
129	/**
130	* nextInt(least >= bound) throws IllegalArgumentException
131	*/
132	public void testNextIntBadBounds() {
133	try {
134	int f = ThreadLocalRandom.current().nextInt(17, 2);
135	shouldThrow();
136	} catch (IllegalArgumentException success) {}
137	}
138
139	/**
140	* nextInt(bound) returns 0 <= value < bound;
141	* repeated calls produce at least two distinct results
142	*/
143	public void testNextIntBounded() {
144	// sample bound space across prime number increments
145	for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
146	int f = ThreadLocalRandom.current().nextInt(bound);
147	assertTrue(0 <= f && f < bound);
148	int i = 0;
149	int j;
150	while (i < NCALLS &&
151	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
152	assertTrue(0 <= j && j < bound);
153	++i;
154	}
155	assertTrue(i < NCALLS);
156	}
157	}
158
159	/**
160	* nextInt(least, bound) returns least <= value < bound;
161	* repeated calls produce at least two distinct results
162	*/
163	public void testNextIntBounded2() {
164	for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
165	for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
166	int f = ThreadLocalRandom.current().nextInt(least, bound);
167	assertTrue(least <= f && f < bound);
168	int i = 0;
169	int j;
170	while (i < NCALLS &&
171	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
172	assertTrue(least <= j && j < bound);
173	++i;
174	}
175	assertTrue(i < NCALLS);
176	}
177	}
178	}
179
180	/**
181	* nextLong(negative) throws IllegalArgumentException
182	*/
183	public void testNextLongBoundedNeg() {
184	try {
185	long f = ThreadLocalRandom.current().nextLong(-17);
186	shouldThrow();
187	} catch (IllegalArgumentException success) {}
188	}
189
190	/**
191	* nextLong(least >= bound) throws IllegalArgumentException
192	*/
193	public void testNextLongBadBounds() {
194	try {
195	long f = ThreadLocalRandom.current().nextLong(17, 2);
196	shouldThrow();
197	} catch (IllegalArgumentException success) {}
198	}
199
200	/**
201	* nextLong(bound) returns 0 <= value < bound;
202	* repeated calls produce at least two distinct results
203	*/
204	public void testNextLongBounded() {
205	for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
206	long f = ThreadLocalRandom.current().nextLong(bound);
207	assertTrue(0 <= f && f < bound);
208	int i = 0;
209	long j;
210	while (i < NCALLS &&
211	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
212	assertTrue(0 <= j && j < bound);
213	++i;
214	}
215	assertTrue(i < NCALLS);
216	}
217	}
218
219	/**
220	* nextLong(least, bound) returns least <= value < bound;
221	* repeated calls produce at least two distinct results
222	*/
223	public void testNextLongBounded2() {
224	for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
225	for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
226	long f = ThreadLocalRandom.current().nextLong(least, bound);
227	assertTrue(least <= f && f < bound);
228	int i = 0;
229	long j;
230	while (i < NCALLS &&
231	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
232	assertTrue(least <= j && j < bound);
233	++i;
234	}
235	assertTrue(i < NCALLS);
236	}
237	}
238	}
239
240	/**
241	* nextDouble(least, bound) returns least <= value < bound;
242	* repeated calls produce at least two distinct results
243	*/
244	public void testNextDoubleBounded2() {
245	for (double least = 0.0001; least < 1.0e20; least *= 8) {
246	for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
247	double f = ThreadLocalRandom.current().nextDouble(least, bound);
248	assertTrue(least <= f && f < bound);
249	int i = 0;
250	double j;
251	while (i < NCALLS &&
252	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
253	assertTrue(least <= j && j < bound);
254	++i;
255	}
256	assertTrue(i < NCALLS);
257	}
258	}
259	}
260
261	/**
262	* Different threads produce different pseudo-random sequences
263	*/
264	public void testDifferentSequences() {
265	// Don't use main thread's ThreadLocalRandom - it is likely to
266	// be polluted by previous tests.
267	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
268	new AtomicReference<ThreadLocalRandom>();
269	final AtomicLong rand = new AtomicLong();
270
271	long firstRand = 0;
272	ThreadLocalRandom firstThreadLocalRandom = null;
273
274	final CheckedRunnable getRandomState = new CheckedRunnable() {
275	public void realRun() {
276	ThreadLocalRandom current = ThreadLocalRandom.current();
277	assertSame(current, ThreadLocalRandom.current());
278	// test bug: the following is not guaranteed and not true in JDK8
279	// assertNotSame(current, threadLocalRandom.get());
280	rand.set(current.nextLong());
281	threadLocalRandom.set(current);
282	}};
283
284	Thread first = newStartedThread(getRandomState);
285	awaitTermination(first);
286	firstRand = rand.get();
287	firstThreadLocalRandom = threadLocalRandom.get();
288
289	for (int i = 0; i < NCALLS; i++) {
290	Thread t = newStartedThread(getRandomState);
291	awaitTermination(t);
292	if (firstRand != rand.get())
293	return;
294	}
295	fail("all threads generate the same pseudo-random sequence");
296	}
297
298	}