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 java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

import junit.framework.Test;
import junit.framework.TestSuite;

public class ThreadLocalRandomTest extends JSR166TestCase {

    public static void main(String[] args) {
        main(suite(), args);
    }
    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 next (only accessible via reflection) produce
     * at least two distinct results, and repeated calls produce all
     * possible values.
     */
    public void testNext() throws ReflectiveOperationException {
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        final java.lang.reflect.Method m;
        try {
            m = ThreadLocalRandom.class.getDeclaredMethod(
                    "next", new Class[] { int.class });
            m.setAccessible(true);
        } catch (SecurityException
                 | java.lang.reflect.InaccessibleObjectException acceptable) {
            // Either jdk9 module system or security manager might deny access.
            return;
        }

        int i;
        {
            int val = new java.util.Random().nextInt(4);
            for (i = 0; i < NCALLS; i++) {
                int q = (int) m.invoke(rnd, new Object[] { 2 });
                if (val == q) break;
            }
            assertTrue(i < NCALLS);
        }

        {
            int r = (int) m.invoke(rnd, new Object[] { 3 });
            for (i = 0; i < NCALLS; i++) {
                int q = (int) m.invoke(rnd, new Object[] { 3 });
                assertTrue(q < (1<<3));
                if (r != q) break;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * 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:	1.23
Committed:	Fri Dec 9 06:56:30 2016 UTC (7 years, 5 months ago) by jsr166
Branch:	MAIN
Changes since 1.22:	+23 -19 lines
Log Message:	testNext: tolerate InaccessibleObjectException
#	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 java.util.concurrent.ThreadLocalRandom;
8	import java.util.concurrent.atomic.AtomicLong;
9	import java.util.concurrent.atomic.AtomicReference;
10
11	import junit.framework.Test;
12	import junit.framework.TestSuite;
13
14	public class ThreadLocalRandomTest extends JSR166TestCase {
15
16	public static void main(String[] args) {
17	main(suite(), args);
18	}
19	public static Test suite() {
20	return new TestSuite(ThreadLocalRandomTest.class);
21	}
22
23	/*
24	* Testing coverage notes:
25	*
26	* We don't test randomness properties, but only that repeated
27	* calls, up to NCALLS tries, produce at least one different
28	* result. For bounded versions, we sample various intervals
29	* across multiples of primes.
30	*/
31
32	// max numbers of calls to detect getting stuck on one value
33	static final int NCALLS = 10000;
34
35	// max sampled int bound
36	static final int MAX_INT_BOUND = (1 << 28);
37
38	// max sampled long bound
39	static final long MAX_LONG_BOUND = (1L << 42);
40
41	// Number of replications for other checks
42	static final int REPS = 20;
43
44	/**
45	* setSeed throws UnsupportedOperationException
46	*/
47	public void testSetSeed() {
48	try {
49	ThreadLocalRandom.current().setSeed(17);
50	shouldThrow();
51	} catch (UnsupportedOperationException success) {}
52	}
53
54	/**
55	* Repeated calls to next (only accessible via reflection) produce
56	* at least two distinct results, and repeated calls produce all
57	* possible values.
58	*/
59	public void testNext() throws ReflectiveOperationException {
60	ThreadLocalRandom rnd = ThreadLocalRandom.current();
61	final java.lang.reflect.Method m;
62	try {
63	m = ThreadLocalRandom.class.getDeclaredMethod(
64	"next", new Class[] { int.class });
65	m.setAccessible(true);
66	} catch (SecurityException
67	\| java.lang.reflect.InaccessibleObjectException acceptable) {
68	// Either jdk9 module system or security manager might deny access.
69	return;
70	}
71
72	int i;
73	{
74	int val = new java.util.Random().nextInt(4);
75	for (i = 0; i < NCALLS; i++) {
76	int q = (int) m.invoke(rnd, new Object[] { 2 });
77	if (val == q) break;
78	}
79	assertTrue(i < NCALLS);
80	}
81
82	{
83	int r = (int) m.invoke(rnd, new Object[] { 3 });
84	for (i = 0; i < NCALLS; i++) {
85	int q = (int) m.invoke(rnd, new Object[] { 3 });
86	assertTrue(q < (1<<3));
87	if (r != q) break;
88	}
89	assertTrue(i < NCALLS);
90	}
91	}
92
93	/**
94	* Repeated calls to nextInt produce at least two distinct results
95	*/
96	public void testNextInt() {
97	int f = ThreadLocalRandom.current().nextInt();
98	int i = 0;
99	while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
100	++i;
101	assertTrue(i < NCALLS);
102	}
103
104	/**
105	* Repeated calls to nextLong produce at least two distinct results
106	*/
107	public void testNextLong() {
108	long f = ThreadLocalRandom.current().nextLong();
109	int i = 0;
110	while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
111	++i;
112	assertTrue(i < NCALLS);
113	}
114
115	/**
116	* Repeated calls to nextBoolean produce at least two distinct results
117	*/
118	public void testNextBoolean() {
119	boolean f = ThreadLocalRandom.current().nextBoolean();
120	int i = 0;
121	while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
122	++i;
123	assertTrue(i < NCALLS);
124	}
125
126	/**
127	* Repeated calls to nextFloat produce at least two distinct results
128	*/
129	public void testNextFloat() {
130	float f = ThreadLocalRandom.current().nextFloat();
131	int i = 0;
132	while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
133	++i;
134	assertTrue(i < NCALLS);
135	}
136
137	/**
138	* Repeated calls to nextDouble produce at least two distinct results
139	*/
140	public void testNextDouble() {
141	double f = ThreadLocalRandom.current().nextDouble();
142	int i = 0;
143	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
144	++i;
145	assertTrue(i < NCALLS);
146	}
147
148	/**
149	* Repeated calls to nextGaussian produce at least two distinct results
150	*/
151	public void testNextGaussian() {
152	double f = ThreadLocalRandom.current().nextGaussian();
153	int i = 0;
154	while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
155	++i;
156	assertTrue(i < NCALLS);
157	}
158
159	/**
160	* nextInt(non-positive) throws IllegalArgumentException
161	*/
162	public void testNextIntBoundNonPositive() {
163	ThreadLocalRandom rnd = ThreadLocalRandom.current();
164	for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
165	try {
166	rnd.nextInt(bound);
167	shouldThrow();
168	} catch (IllegalArgumentException success) {}
169	}
170	}
171
172	/**
173	* nextInt(least >= bound) throws IllegalArgumentException
174	*/
175	public void testNextIntBadBounds() {
176	int[][] badBoundss = {
177	{ 17, 2 },
178	{ -42, -42 },
179	{ Integer.MAX_VALUE, Integer.MIN_VALUE },
180	};
181	ThreadLocalRandom rnd = ThreadLocalRandom.current();
182	for (int[] badBounds : badBoundss) {
183	try {
184	rnd.nextInt(badBounds[0], badBounds[1]);
185	shouldThrow();
186	} catch (IllegalArgumentException success) {}
187	}
188	}
189
190	/**
191	* nextInt(bound) returns 0 <= value < bound;
192	* repeated calls produce at least two distinct results
193	*/
194	public void testNextIntBounded() {
195	// sample bound space across prime number increments
196	for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
197	int f = ThreadLocalRandom.current().nextInt(bound);
198	assertTrue(0 <= f && f < bound);
199	int i = 0;
200	int j;
201	while (i < NCALLS &&
202	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
203	assertTrue(0 <= j && j < bound);
204	++i;
205	}
206	assertTrue(i < NCALLS);
207	}
208	}
209
210	/**
211	* nextInt(least, bound) returns least <= value < bound;
212	* repeated calls produce at least two distinct results
213	*/
214	public void testNextIntBounded2() {
215	for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
216	for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
217	int f = ThreadLocalRandom.current().nextInt(least, bound);
218	assertTrue(least <= f && f < bound);
219	int i = 0;
220	int j;
221	while (i < NCALLS &&
222	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
223	assertTrue(least <= j && j < bound);
224	++i;
225	}
226	assertTrue(i < NCALLS);
227	}
228	}
229	}
230
231	/**
232	* nextLong(non-positive) throws IllegalArgumentException
233	*/
234	public void testNextLongBoundNonPositive() {
235	ThreadLocalRandom rnd = ThreadLocalRandom.current();
236	for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
237	try {
238	rnd.nextLong(bound);
239	shouldThrow();
240	} catch (IllegalArgumentException success) {}
241	}
242	}
243
244	/**
245	* nextLong(least >= bound) throws IllegalArgumentException
246	*/
247	public void testNextLongBadBounds() {
248	long[][] badBoundss = {
249	{ 17L, 2L },
250	{ -42L, -42L },
251	{ Long.MAX_VALUE, Long.MIN_VALUE },
252	};
253	ThreadLocalRandom rnd = ThreadLocalRandom.current();
254	for (long[] badBounds : badBoundss) {
255	try {
256	rnd.nextLong(badBounds[0], badBounds[1]);
257	shouldThrow();
258	} catch (IllegalArgumentException success) {}
259	}
260	}
261
262	/**
263	* nextLong(bound) returns 0 <= value < bound;
264	* repeated calls produce at least two distinct results
265	*/
266	public void testNextLongBounded() {
267	for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
268	long f = ThreadLocalRandom.current().nextLong(bound);
269	assertTrue(0 <= f && f < bound);
270	int i = 0;
271	long j;
272	while (i < NCALLS &&
273	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
274	assertTrue(0 <= j && j < bound);
275	++i;
276	}
277	assertTrue(i < NCALLS);
278	}
279	}
280
281	/**
282	* nextLong(least, bound) returns least <= value < bound;
283	* repeated calls produce at least two distinct results
284	*/
285	public void testNextLongBounded2() {
286	for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
287	for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
288	long f = ThreadLocalRandom.current().nextLong(least, bound);
289	assertTrue(least <= f && f < bound);
290	int i = 0;
291	long j;
292	while (i < NCALLS &&
293	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
294	assertTrue(least <= j && j < bound);
295	++i;
296	}
297	assertTrue(i < NCALLS);
298	}
299	}
300	}
301
302	/**
303	* nextDouble(non-positive) throws IllegalArgumentException
304	*/
305	public void testNextDoubleBoundNonPositive() {
306	ThreadLocalRandom rnd = ThreadLocalRandom.current();
307	double[] badBounds = {
308	0.0d,
309	-17.0d,
310	-Double.MIN_VALUE,
311	Double.NEGATIVE_INFINITY,
312	Double.NaN,
313	};
314	for (double bound : badBounds) {
315	try {
316	rnd.nextDouble(bound);
317	shouldThrow();
318	} catch (IllegalArgumentException success) {}
319	}
320	}
321
322	/**
323	* nextDouble(least, bound) returns least <= value < bound;
324	* repeated calls produce at least two distinct results
325	*/
326	public void testNextDoubleBounded2() {
327	for (double least = 0.0001; least < 1.0e20; least *= 8) {
328	for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
329	double f = ThreadLocalRandom.current().nextDouble(least, bound);
330	assertTrue(least <= f && f < bound);
331	int i = 0;
332	double j;
333	while (i < NCALLS &&
334	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
335	assertTrue(least <= j && j < bound);
336	++i;
337	}
338	assertTrue(i < NCALLS);
339	}
340	}
341	}
342
343	/**
344	* Different threads produce different pseudo-random sequences
345	*/
346	public void testDifferentSequences() {
347	// Don't use main thread's ThreadLocalRandom - it is likely to
348	// be polluted by previous tests.
349	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
350	new AtomicReference<ThreadLocalRandom>();
351	final AtomicLong rand = new AtomicLong();
352
353	long firstRand = 0;
354	ThreadLocalRandom firstThreadLocalRandom = null;
355
356	Runnable getRandomState = new CheckedRunnable() {
357	public void realRun() {
358	ThreadLocalRandom current = ThreadLocalRandom.current();
359	assertSame(current, ThreadLocalRandom.current());
360	// test bug: the following is not guaranteed and not true in JDK8
361	// assertNotSame(current, threadLocalRandom.get());
362	rand.set(current.nextLong());
363	threadLocalRandom.set(current);
364	}};
365
366	Thread first = newStartedThread(getRandomState);
367	awaitTermination(first);
368	firstRand = rand.get();
369	firstThreadLocalRandom = threadLocalRandom.get();
370
371	for (int i = 0; i < NCALLS; i++) {
372	Thread t = newStartedThread(getRandomState);
373	awaitTermination(t);
374	if (firstRand != rand.get())
375	return;
376	}
377	fail("all threads generate the same pseudo-random sequence");
378	}
379
380	}