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

Comparing jsr166/src/test/tck/ThreadLocalRandomTest.java (file contents):
Revision 1.8 by jsr166, Tue Mar 15 19:47:07 2011 UTC vs.
Revision 1.30 by jsr166, Wed Aug 12 17:39:43 2020 UTC

#	Line 3 | Line 3
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.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("next", int.class);
67	>	m.setAccessible(true);
68	>	} catch (SecurityException acceptable) {
69	>	// Security manager may deny access
70	>	return;
71	>	} catch (Exception ex) {
72	>	// jdk9 module system may deny access
73	>	if (ex.getClass().getSimpleName()
74	>	.equals("InaccessibleObjectException"))
75	>	return;
76	>	throw ex;
77	>	}
78	>
79	>	int i;
80	>	{
81	>	int val = new java.util.Random().nextInt(4);
82	>	for (i = 0; i < NCALLS; i++) {
83	>	int q = (int) m.invoke(rnd, new Object[] { 2 });
84	>	if (val == q) break;
85	>	}
86	>	assertTrue(i < NCALLS);
87	>	}
88	>
89	>	{
90	>	int r = (int) m.invoke(rnd, new Object[] { 3 });
91	>	for (i = 0; i < NCALLS; i++) {
92	>	int q = (int) m.invoke(rnd, new Object[] { 3 });
93	>	assertTrue(q < (1<<3));
94	>	if (r != q) break;
95	>	}
96	>	assertTrue(i < NCALLS);
97	>	}
98	>	}
99	>
100	>	/**
101	>	* Repeated calls to nextInt produce at least two distinct results
102		*/
103		public void testNextInt() {
104		int f = ThreadLocalRandom.current().nextInt();
#	Line 57 | Line 109 | public class ThreadLocalRandomTest exten
109		}
110
111		/**
112	<	* Repeated calls to nextLong produce at least one different result
112	>	* Repeated calls to nextLong produce at least two distinct results
113		*/
114		public void testNextLong() {
115		long f = ThreadLocalRandom.current().nextLong();
#	Line 67 | Line 119 | public class ThreadLocalRandomTest exten
119		assertTrue(i < NCALLS);
120		}
121
70	–
122		/**
123	<	* Repeated calls to nextBoolean produce at least one different result
123	>	* Repeated calls to nextBoolean produce at least two distinct results
124		*/
125		public void testNextBoolean() {
126		boolean f = ThreadLocalRandom.current().nextBoolean();
#	Line 80 | Line 131 | public class ThreadLocalRandomTest exten
131		}
132
133		/**
134	<	* Repeated calls to nextFloat produce at least one different result
134	>	* Repeated calls to nextFloat produce at least two distinct results
135		*/
136		public void testNextFloat() {
137		float f = ThreadLocalRandom.current().nextFloat();
#	Line 91 | Line 142 | public class ThreadLocalRandomTest exten
142		}
143
144		/**
145	<	* Repeated calls to nextDouble produce at least one different result
145	>	* Repeated calls to nextDouble produce at least two distinct results
146		*/
147		public void testNextDouble() {
148		double f = ThreadLocalRandom.current().nextDouble();
149	<	double i = 0;
149	>	int i = 0;
150		while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
151		++i;
152		assertTrue(i < NCALLS);
153		}
154
155		/**
156	<	* Repeated calls to nextGaussian produce at least one different result
156	>	* Repeated calls to nextGaussian produce at least two distinct results
157		*/
158		public void testNextGaussian() {
159		double f = ThreadLocalRandom.current().nextGaussian();
#	Line 112 | Line 163 | public class ThreadLocalRandomTest exten
163		assertTrue(i < NCALLS);
164		}
165
115	–
166		/**
167	<	* nextInt(negative) throws IllegalArgumentException;
167	>	* nextInt(non-positive) throws IllegalArgumentException
168		*/
169	<	public void testNextIntBoundedNeg() {
170	<	try {
171	<	int f = ThreadLocalRandom.current().nextInt(-17);
172	<	shouldThrow();
173	<	} catch (IllegalArgumentException success) {}
169	>	public void testNextIntBoundNonPositive() {
170	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
171	>	for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
172	>	try {
173	>	rnd.nextInt(bound);
174	>	shouldThrow();
175	>	} catch (IllegalArgumentException success) {}
176	>	}
177		}
178
179		/**
180	<	* nextInt(least >= bound) throws IllegalArgumentException;
180	>	* nextInt(least >= bound) throws IllegalArgumentException
181		*/
182		public void testNextIntBadBounds() {
183	<	try {
184	<	int f = ThreadLocalRandom.current().nextInt(17, 2);
185	<	shouldThrow();
186	<	} catch (IllegalArgumentException success) {}
183	>	int[][] badBoundss = {
184	>	{ 17, 2 },
185	>	{ -42, -42 },
186	>	{ Integer.MAX_VALUE, Integer.MIN_VALUE },
187	>	};
188	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
189	>	for (int[] badBounds : badBoundss) {
190	>	try {
191	>	rnd.nextInt(badBounds[0], badBounds[1]);
192	>	shouldThrow();
193	>	} catch (IllegalArgumentException success) {}
194	>	}
195		}
196
136	–
197		/**
198		* nextInt(bound) returns 0 <= value < bound;
199	<	* repeated calls produce at least one different result
199	>	* repeated calls produce at least two distinct results
200		*/
201		public void testNextIntBounded() {
202		// sample bound space across prime number increments
#	Line 154 | Line 214 | public class ThreadLocalRandomTest exten
214		}
215		}
216
157	–
217		/**
218		* nextInt(least, bound) returns least <= value < bound;
219	<	* repeated calls produce at least one different result
219	>	* repeated calls produce at least two distinct results
220		*/
221		public void testNextIntBounded2() {
222		for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
#	Line 177 | Line 236 | public class ThreadLocalRandomTest exten
236		}
237
238		/**
239	<	* nextLong(negative) throws IllegalArgumentException;
239	>	* nextLong(non-positive) throws IllegalArgumentException
240		*/
241	<	public void testNextLongBoundedNeg() {
242	<	try {
243	<	long f = ThreadLocalRandom.current().nextLong(-17);
244	<	shouldThrow();
245	<	} catch (IllegalArgumentException success) {}
241	>	public void testNextLongBoundNonPositive() {
242	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
243	>	for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
244	>	try {
245	>	rnd.nextLong(bound);
246	>	shouldThrow();
247	>	} catch (IllegalArgumentException success) {}
248	>	}
249		}
250
251		/**
252	<	* nextLong(least >= bound) throws IllegalArgumentException;
252	>	* nextLong(least >= bound) throws IllegalArgumentException
253		*/
254		public void testNextLongBadBounds() {
255	<	try {
256	<	long f = ThreadLocalRandom.current().nextLong(17, 2);
257	<	shouldThrow();
258	<	} catch (IllegalArgumentException success) {}
255	>	long[][] badBoundss = {
256	>	{ 17L, 2L },
257	>	{ -42L, -42L },
258	>	{ Long.MAX_VALUE, Long.MIN_VALUE },
259	>	};
260	>	ThreadLocalRandom rnd = ThreadLocalRandom.current();
261	>	for (long[] badBounds : badBoundss) {
262	>	try {
263	>	rnd.nextLong(badBounds[0], badBounds[1]);
264	>	shouldThrow();
265	>	} catch (IllegalArgumentException success) {}
266	>	}
267		}
268
269		/**
270		* nextLong(bound) returns 0 <= value < bound;
271	<	* repeated calls produce at least one different result
271	>	* repeated calls produce at least two distinct results
272		*/
273		public void testNextLongBounded() {
274		for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
#	Line 217 | Line 287 | public class ThreadLocalRandomTest exten
287
288		/**
289		* nextLong(least, bound) returns least <= value < bound;
290	<	* repeated calls produce at least one different result
290	>	* repeated calls produce at least two distinct results
291		*/
292		public void testNextLongBounded2() {
293		for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
#	Line 236 | Line 306 | public class ThreadLocalRandomTest exten
306		}
307		}
308
309	+	/**
310	+	* nextDouble(non-positive) throws IllegalArgumentException
311	+	*/
312	+	public void testNextDoubleBoundNonPositive() {
313	+	ThreadLocalRandom rnd = ThreadLocalRandom.current();
314	+	double[] badBounds = {
315	+	0.0d,
316	+	-17.0d,
317	+	-Double.MIN_VALUE,
318	+	Double.NEGATIVE_INFINITY,
319	+	Double.NaN,
320	+	};
321	+	for (double bound : badBounds) {
322	+	try {
323	+	rnd.nextDouble(bound);
324	+	shouldThrow();
325	+	} catch (IllegalArgumentException success) {}
326	+	}
327	+	}
328
329		/**
330		* nextDouble(least, bound) returns least <= value < bound;
331	<	* repeated calls produce at least one different result
331	>	* repeated calls produce at least two distinct results
332		*/
333		public void testNextDoubleBounded2() {
334		for (double least = 0.0001; least < 1.0e20; least *= 8) {
#	Line 258 | Line 347 | public class ThreadLocalRandomTest exten
347		}
348		}
349
350	+	/**
351	+	* Different threads produce different pseudo-random sequences
352	+	*/
353	+	public void testDifferentSequences() {
354	+	// Don't use main thread's ThreadLocalRandom - it is likely to
355	+	// be polluted by previous tests.
356	+	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
357	+	new AtomicReference<>();
358	+	final AtomicLong rand = new AtomicLong();
359	+
360	+	Runnable getRandomState = new CheckedRunnable() {
361	+	public void realRun() {
362	+	ThreadLocalRandom current = ThreadLocalRandom.current();
363	+	assertSame(current, ThreadLocalRandom.current());
364	+	rand.set(current.nextLong());
365	+	threadLocalRandom.set(current);
366	+	}};
367	+
368	+	awaitTermination(newStartedThread(getRandomState));
369	+	long firstRand = rand.get();
370	+	ThreadLocalRandom firstThreadLocalRandom = threadLocalRandom.get();
371	+	assertNotNull(firstThreadLocalRandom);
372	+
373	+	for (int i = 0; i < NCALLS; i++) {
374	+	awaitTermination(newStartedThread(getRandomState));
375	+	if (testImplementationDetails)
376	+	// ThreadLocalRandom has been a singleton since jdk8.
377	+	assertSame(firstThreadLocalRandom, threadLocalRandom.get());
378	+	if (firstRand != rand.get())
379	+	return;
380	+	}
381	+	fail("all threads generate the same pseudo-random sequence");
382	+	}
383	+
384	+	/**
385	+	* Repeated calls to nextBytes produce at least values of different signs for every byte
386	+	*/
387	+	public void testNextBytes() {
388	+	ThreadLocalRandom rnd = ThreadLocalRandom.current();
389	+	int n = rnd.nextInt(1, 20);
390	+	byte[] bytes = new byte[n];
391	+	outer:
392	+	for (int i = 0; i < n; i++) {
393	+	for (int tries = NCALLS; tries-->0; ) {
394	+	byte before = bytes[i];
395	+	rnd.nextBytes(bytes);
396	+	byte after = bytes[i];
397	+	if (after * before < 0)
398	+	continue outer;
399	+	}
400	+	fail("not enough variation in random bytes");
401	+	}
402	+	}
403	+
404	+	/**
405	+	* Filling an empty array with random bytes succeeds without effect.
406	+	*/
407	+	public void testNextBytes_emptyArray() {
408	+	ThreadLocalRandom.current().nextBytes(new byte[0]);
409	+	}
410	+
411	+	public void testNextBytes_nullArray() {
412	+	try {
413	+	ThreadLocalRandom.current().nextBytes(null);
414	+	shouldThrow();
415	+	} catch (NullPointerException success) {}
416	+	}
417
418		}

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