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root/jsr166/jsr166/src/test/tck/ThreadLocalRandomTest.java

Comparing jsr166/src/test/tck/ThreadLocalRandomTest.java (file contents):
Revision 1.7 by jsr166, Wed Aug 25 00:07:03 2010 UTC vs.
Revision 1.28 by jsr166, Sun Jan 7 22:59:18 2018 UTC

#	Line 1 | Line 1
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/licenses/publicdomain
4	>	* http://creativecommons.org/publicdomain/zero/1.0/
5		*/
6	–	import junit.framework.*;
7	–	import java.util.concurrent.*;
8	–	import java.util.*;
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	<	junit.textui.TestRunner.run(suite());
17	>	main(suite(), args);
18		}
19		public static Test suite() {
20		return new TestSuite(ThreadLocalRandomTest.class);
21		}
22
23	<	/**
23	>	/*
24		* Testing coverage notes:
25		*
26		* We don't test randomness properties, but only that repeated
#	Line 26 | Line 29 | public class ThreadLocalRandomTest exten
29		* across multiples of primes.
30		*/
31
32	<	//
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
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		*/
#	Line 46 | Line 52 | public class ThreadLocalRandomTest exten
52		}
53
54		/**
55	<	* Repeated calls to nextInt produce at least one different result
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	>	// Inhibit "An illegal reflective access operation has occurred"
61	>	if (!testImplementationDetails) return;
62	>
63	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
64	>	final java.lang.reflect.Method m;
65	>	try {
66	>	m = ThreadLocalRandom.class.getDeclaredMethod(
67	>	"next", new Class[] { int.class });
68	>	m.setAccessible(true);
69	>	} catch (SecurityException acceptable) {
70	>	// Security manager may deny access
71	>	return;
72	>	} catch (Exception ex) {
73	>	// jdk9 module system may deny access
74	>	if (ex.getClass().getSimpleName()
75	>	.equals("InaccessibleObjectException"))
76	>	return;
77	>	throw ex;
78	>	}
79	>
80	>	int i;
81	>	{
82	>	int val = new java.util.Random().nextInt(4);
83	>	for (i = 0; i < NCALLS; i++) {
84	>	int q = (int) m.invoke(rnd, new Object[] { 2 });
85	>	if (val == q) break;
86	>	}
87	>	assertTrue(i < NCALLS);
88	>	}
89	>
90	>	{
91	>	int r = (int) m.invoke(rnd, new Object[] { 3 });
92	>	for (i = 0; i < NCALLS; i++) {
93	>	int q = (int) m.invoke(rnd, new Object[] { 3 });
94	>	assertTrue(q < (1<<3));
95	>	if (r != q) break;
96	>	}
97	>	assertTrue(i < NCALLS);
98	>	}
99	>	}
100	>
101	>	/**
102	>	* Repeated calls to nextInt produce at least two distinct results
103		*/
104		public void testNextInt() {
105		int f = ThreadLocalRandom.current().nextInt();
#	Line 57 | Line 110 | public class ThreadLocalRandomTest exten
110		}
111
112		/**
113	<	* Repeated calls to nextLong produce at least one different result
113	>	* Repeated calls to nextLong produce at least two distinct results
114		*/
115		public void testNextLong() {
116		long f = ThreadLocalRandom.current().nextLong();
#	Line 67 | Line 120 | public class ThreadLocalRandomTest exten
120		assertTrue(i < NCALLS);
121		}
122
70	–
123		/**
124	<	* Repeated calls to nextBoolean produce at least one different result
124	>	* Repeated calls to nextBoolean produce at least two distinct results
125		*/
126		public void testNextBoolean() {
127		boolean f = ThreadLocalRandom.current().nextBoolean();
#	Line 80 | Line 132 | public class ThreadLocalRandomTest exten
132		}
133
134		/**
135	<	* Repeated calls to nextFloat produce at least one different result
135	>	* Repeated calls to nextFloat produce at least two distinct results
136		*/
137		public void testNextFloat() {
138		float f = ThreadLocalRandom.current().nextFloat();
#	Line 91 | Line 143 | public class ThreadLocalRandomTest exten
143		}
144
145		/**
146	<	* Repeated calls to nextDouble produce at least one different result
146	>	* Repeated calls to nextDouble produce at least two distinct results
147		*/
148		public void testNextDouble() {
149		double f = ThreadLocalRandom.current().nextDouble();
150	<	double i = 0;
150	>	int i = 0;
151		while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
152		++i;
153		assertTrue(i < NCALLS);
154		}
155
156		/**
157	<	* Repeated calls to nextGaussian produce at least one different result
157	>	* Repeated calls to nextGaussian produce at least two distinct results
158		*/
159		public void testNextGaussian() {
160		double f = ThreadLocalRandom.current().nextGaussian();
#	Line 112 | Line 164 | public class ThreadLocalRandomTest exten
164		assertTrue(i < NCALLS);
165		}
166
115	–
167		/**
168	<	* nextInt(negative) throws IllegalArgumentException;
168	>	* nextInt(non-positive) throws IllegalArgumentException
169		*/
170	<	public void testNextIntBoundedNeg() {
171	<	try {
172	<	int f = ThreadLocalRandom.current().nextInt(-17);
173	<	shouldThrow();
174	<	} catch (IllegalArgumentException success) {}
170	>	public void testNextIntBoundNonPositive() {
171	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
172	>	for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
173	>	try {
174	>	rnd.nextInt(bound);
175	>	shouldThrow();
176	>	} catch (IllegalArgumentException success) {}
177	>	}
178		}
179
180		/**
181	<	* nextInt(least >= bound) throws IllegalArgumentException;
181	>	* nextInt(least >= bound) throws IllegalArgumentException
182		*/
183		public void testNextIntBadBounds() {
184	<	try {
185	<	int f = ThreadLocalRandom.current().nextInt(17, 2);
186	<	shouldThrow();
187	<	} catch (IllegalArgumentException success) {}
184	>	int[][] badBoundss = {
185	>	{ 17, 2 },
186	>	{ -42, -42 },
187	>	{ Integer.MAX_VALUE, Integer.MIN_VALUE },
188	>	};
189	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
190	>	for (int[] badBounds : badBoundss) {
191	>	try {
192	>	rnd.nextInt(badBounds[0], badBounds[1]);
193	>	shouldThrow();
194	>	} catch (IllegalArgumentException success) {}
195	>	}
196		}
197
136	–
198		/**
199		* nextInt(bound) returns 0 <= value < bound;
200	<	* repeated calls produce at least one different result
200	>	* repeated calls produce at least two distinct results
201		*/
202		public void testNextIntBounded() {
203		// sample bound space across prime number increments
#	Line 154 | Line 215 | public class ThreadLocalRandomTest exten
215		}
216		}
217
157	–
218		/**
219		* nextInt(least, bound) returns least <= value < bound;
220	<	* repeated calls produce at least one different result
220	>	* repeated calls produce at least two distinct results
221		*/
222		public void testNextIntBounded2() {
223		for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
#	Line 177 | Line 237 | public class ThreadLocalRandomTest exten
237		}
238
239		/**
240	<	* nextLong(negative) throws IllegalArgumentException;
240	>	* nextLong(non-positive) throws IllegalArgumentException
241		*/
242	<	public void testNextLongBoundedNeg() {
243	<	try {
244	<	long f = ThreadLocalRandom.current().nextLong(-17);
245	<	shouldThrow();
246	<	} catch (IllegalArgumentException success) {}
242	>	public void testNextLongBoundNonPositive() {
243	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
244	>	for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
245	>	try {
246	>	rnd.nextLong(bound);
247	>	shouldThrow();
248	>	} catch (IllegalArgumentException success) {}
249	>	}
250		}
251
252		/**
253	<	* nextLong(least >= bound) throws IllegalArgumentException;
253	>	* nextLong(least >= bound) throws IllegalArgumentException
254		*/
255		public void testNextLongBadBounds() {
256	<	try {
257	<	long f = ThreadLocalRandom.current().nextLong(17, 2);
258	<	shouldThrow();
259	<	} catch (IllegalArgumentException success) {}
256	>	long[][] badBoundss = {
257	>	{ 17L, 2L },
258	>	{ -42L, -42L },
259	>	{ Long.MAX_VALUE, Long.MIN_VALUE },
260	>	};
261	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
262	>	for (long[] badBounds : badBoundss) {
263	>	try {
264	>	rnd.nextLong(badBounds[0], badBounds[1]);
265	>	shouldThrow();
266	>	} catch (IllegalArgumentException success) {}
267	>	}
268		}
269
270		/**
271		* nextLong(bound) returns 0 <= value < bound;
272	<	* repeated calls produce at least one different result
272	>	* repeated calls produce at least two distinct results
273		*/
274		public void testNextLongBounded() {
275		for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
#	Line 217 | Line 288 | public class ThreadLocalRandomTest exten
288
289		/**
290		* nextLong(least, bound) returns least <= value < bound;
291	<	* repeated calls produce at least one different result
291	>	* repeated calls produce at least two distinct results
292		*/
293		public void testNextLongBounded2() {
294		for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
#	Line 236 | Line 307 | public class ThreadLocalRandomTest exten
307		}
308		}
309
310	+	/**
311	+	* nextDouble(non-positive) throws IllegalArgumentException
312	+	*/
313	+	public void testNextDoubleBoundNonPositive() {
314	+	ThreadLocalRandom rnd = ThreadLocalRandom.current();
315	+	double[] badBounds = {
316	+	0.0d,
317	+	-17.0d,
318	+	-Double.MIN_VALUE,
319	+	Double.NEGATIVE_INFINITY,
320	+	Double.NaN,
321	+	};
322	+	for (double bound : badBounds) {
323	+	try {
324	+	rnd.nextDouble(bound);
325	+	shouldThrow();
326	+	} catch (IllegalArgumentException success) {}
327	+	}
328	+	}
329
330		/**
331		* nextDouble(least, bound) returns least <= value < bound;
332	<	* repeated calls produce at least one different result
332	>	* repeated calls produce at least two distinct results
333		*/
334		public void testNextDoubleBounded2() {
335		for (double least = 0.0001; least < 1.0e20; least *= 8) {
#	Line 258 | Line 348 | public class ThreadLocalRandomTest exten
348		}
349		}
350
351	+	/**
352	+	* Different threads produce different pseudo-random sequences
353	+	*/
354	+	public void testDifferentSequences() {
355	+	// Don't use main thread's ThreadLocalRandom - it is likely to
356	+	// be polluted by previous tests.
357	+	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
358	+	new AtomicReference<>();
359	+	final AtomicLong rand = new AtomicLong();
360	+
361	+	long firstRand = 0;
362	+	ThreadLocalRandom firstThreadLocalRandom = null;
363	+
364	+	Runnable getRandomState = new CheckedRunnable() {
365	+	public void realRun() {
366	+	ThreadLocalRandom current = ThreadLocalRandom.current();
367	+	assertSame(current, ThreadLocalRandom.current());
368	+	// test bug: the following is not guaranteed and not true in JDK8
369	+	//                assertNotSame(current, threadLocalRandom.get());
370	+	rand.set(current.nextLong());
371	+	threadLocalRandom.set(current);
372	+	}};
373	+
374	+	Thread first = newStartedThread(getRandomState);
375	+	awaitTermination(first);
376	+	firstRand = rand.get();
377	+	firstThreadLocalRandom = threadLocalRandom.get();
378	+
379	+	for (int i = 0; i < NCALLS; i++) {
380	+	Thread t = newStartedThread(getRandomState);
381	+	awaitTermination(t);
382	+	if (firstRand != rand.get())
383	+	return;
384	+	}
385	+	fail("all threads generate the same pseudo-random sequence");
386	+	}
387	+
388	+	/**
389	+	* Repeated calls to nextBytes produce at least values of different signs for every byte
390	+	*/
391	+	public void testNextBytes() {
392	+	ThreadLocalRandom rnd = ThreadLocalRandom.current();
393	+	int n = rnd.nextInt(1, 20);
394	+	byte[] bytes = new byte[n];
395	+	outer:
396	+	for (int i = 0; i < n; i++) {
397	+	for (int tries = NCALLS; tries-->0; ) {
398	+	byte before = bytes[i];
399	+	rnd.nextBytes(bytes);
400	+	byte after = bytes[i];
401	+	if (after * before < 0)
402	+	continue outer;
403	+	}
404	+	fail("not enough variation in random bytes");
405	+	}
406	+	}
407	+
408	+	/**
409	+	* Filling an empty array with random bytes succeeds without effect.
410	+	*/
411	+	public void testNextBytes_emptyArray() {
412	+	ThreadLocalRandom.current().nextBytes(new byte[0]);
413	+	}
414	+
415	+	public void testNextBytes_nullArray() {
416	+	try {
417	+	ThreadLocalRandom.current().nextBytes(null);
418	+	shouldThrow();
419	+	} catch (NullPointerException success) {}
420	+	}
421
422		}

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