Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 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 | package jsr166; |
| 8 | |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 9 | import java.util.concurrent.ThreadLocalRandom; |
| 10 | import java.util.concurrent.atomic.AtomicLong; |
| 11 | import java.util.concurrent.atomic.AtomicReference; |
| 12 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 13 | import junit.framework.Test; |
| 14 | import junit.framework.TestSuite; |
| 15 | |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 16 | public class ThreadLocalRandomTest extends JSR166TestCase { |
| 17 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 18 | // android-note: Removed because the CTS runner does a bad job of |
| 19 | // retrying tests that have suite() declarations. |
| 20 | // |
| 21 | // public static void main(String[] args) { |
| 22 | // main(suite(), args); |
| 23 | // } |
| 24 | // public static Test suite() { |
Przemyslaw Szczepaniak | b8b7511 | 2016-03-11 15:59:10 +0000 | [diff] [blame] | 25 | // return new TestSuite(ThreadLocalRandomTest.class); |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 26 | // } |
| 27 | |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 28 | /* |
| 29 | * Testing coverage notes: |
| 30 | * |
| 31 | * We don't test randomness properties, but only that repeated |
| 32 | * calls, up to NCALLS tries, produce at least one different |
| 33 | * result. For bounded versions, we sample various intervals |
| 34 | * across multiples of primes. |
| 35 | */ |
| 36 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 37 | // max numbers of calls to detect getting stuck on one value |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 38 | static final int NCALLS = 10000; |
| 39 | |
| 40 | // max sampled int bound |
| 41 | static final int MAX_INT_BOUND = (1 << 28); |
| 42 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 43 | // max sampled long bound |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 44 | static final long MAX_LONG_BOUND = (1L << 42); |
| 45 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 46 | // Number of replications for other checks |
| 47 | static final int REPS = 20; |
| 48 | |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 49 | /** |
| 50 | * setSeed throws UnsupportedOperationException |
| 51 | */ |
| 52 | public void testSetSeed() { |
| 53 | try { |
| 54 | ThreadLocalRandom.current().setSeed(17); |
| 55 | shouldThrow(); |
| 56 | } catch (UnsupportedOperationException success) {} |
| 57 | } |
| 58 | |
| 59 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 60 | * Repeated calls to nextInt produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 61 | */ |
| 62 | public void testNextInt() { |
| 63 | int f = ThreadLocalRandom.current().nextInt(); |
| 64 | int i = 0; |
| 65 | while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f) |
| 66 | ++i; |
| 67 | assertTrue(i < NCALLS); |
| 68 | } |
| 69 | |
| 70 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 71 | * Repeated calls to nextLong produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 72 | */ |
| 73 | public void testNextLong() { |
| 74 | long f = ThreadLocalRandom.current().nextLong(); |
| 75 | int i = 0; |
| 76 | while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f) |
| 77 | ++i; |
| 78 | assertTrue(i < NCALLS); |
| 79 | } |
| 80 | |
| 81 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 82 | * Repeated calls to nextBoolean produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 83 | */ |
| 84 | public void testNextBoolean() { |
| 85 | boolean f = ThreadLocalRandom.current().nextBoolean(); |
| 86 | int i = 0; |
| 87 | while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f) |
| 88 | ++i; |
| 89 | assertTrue(i < NCALLS); |
| 90 | } |
| 91 | |
| 92 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 93 | * Repeated calls to nextFloat produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 94 | */ |
| 95 | public void testNextFloat() { |
| 96 | float f = ThreadLocalRandom.current().nextFloat(); |
| 97 | int i = 0; |
| 98 | while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f) |
| 99 | ++i; |
| 100 | assertTrue(i < NCALLS); |
| 101 | } |
| 102 | |
| 103 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 104 | * Repeated calls to nextDouble produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 105 | */ |
| 106 | public void testNextDouble() { |
| 107 | double f = ThreadLocalRandom.current().nextDouble(); |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 108 | int i = 0; |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 109 | while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f) |
| 110 | ++i; |
| 111 | assertTrue(i < NCALLS); |
| 112 | } |
| 113 | |
| 114 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 115 | * Repeated calls to nextGaussian produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 116 | */ |
| 117 | public void testNextGaussian() { |
| 118 | double f = ThreadLocalRandom.current().nextGaussian(); |
| 119 | int i = 0; |
| 120 | while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f) |
| 121 | ++i; |
| 122 | assertTrue(i < NCALLS); |
| 123 | } |
| 124 | |
| 125 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 126 | * nextInt(non-positive) throws IllegalArgumentException |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 127 | */ |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 128 | public void testNextIntBoundNonPositive() { |
| 129 | ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| 130 | for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) { |
| 131 | try { |
| 132 | rnd.nextInt(bound); |
| 133 | shouldThrow(); |
| 134 | } catch (IllegalArgumentException success) {} |
| 135 | } |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 136 | } |
| 137 | |
| 138 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 139 | * nextInt(least >= bound) throws IllegalArgumentException |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 140 | */ |
| 141 | public void testNextIntBadBounds() { |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 142 | int[][] badBoundss = { |
| 143 | { 17, 2 }, |
| 144 | { -42, -42 }, |
| 145 | { Integer.MAX_VALUE, Integer.MIN_VALUE }, |
| 146 | }; |
| 147 | ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| 148 | for (int[] badBounds : badBoundss) { |
| 149 | try { |
| 150 | rnd.nextInt(badBounds[0], badBounds[1]); |
| 151 | shouldThrow(); |
| 152 | } catch (IllegalArgumentException success) {} |
| 153 | } |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 154 | } |
| 155 | |
| 156 | /** |
| 157 | * nextInt(bound) returns 0 <= value < bound; |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 158 | * repeated calls produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 159 | */ |
| 160 | public void testNextIntBounded() { |
| 161 | // sample bound space across prime number increments |
| 162 | for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) { |
| 163 | int f = ThreadLocalRandom.current().nextInt(bound); |
| 164 | assertTrue(0 <= f && f < bound); |
| 165 | int i = 0; |
| 166 | int j; |
| 167 | while (i < NCALLS && |
| 168 | (j = ThreadLocalRandom.current().nextInt(bound)) == f) { |
| 169 | assertTrue(0 <= j && j < bound); |
| 170 | ++i; |
| 171 | } |
| 172 | assertTrue(i < NCALLS); |
| 173 | } |
| 174 | } |
| 175 | |
| 176 | /** |
| 177 | * nextInt(least, bound) returns least <= value < bound; |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 178 | * repeated calls produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 179 | */ |
| 180 | public void testNextIntBounded2() { |
| 181 | for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) { |
| 182 | for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) { |
| 183 | int f = ThreadLocalRandom.current().nextInt(least, bound); |
| 184 | assertTrue(least <= f && f < bound); |
| 185 | int i = 0; |
| 186 | int j; |
| 187 | while (i < NCALLS && |
| 188 | (j = ThreadLocalRandom.current().nextInt(least, bound)) == f) { |
| 189 | assertTrue(least <= j && j < bound); |
| 190 | ++i; |
| 191 | } |
| 192 | assertTrue(i < NCALLS); |
| 193 | } |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 198 | * nextLong(non-positive) throws IllegalArgumentException |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 199 | */ |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 200 | public void testNextLongBoundNonPositive() { |
| 201 | ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| 202 | for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) { |
| 203 | try { |
| 204 | rnd.nextLong(bound); |
| 205 | shouldThrow(); |
| 206 | } catch (IllegalArgumentException success) {} |
| 207 | } |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 208 | } |
| 209 | |
| 210 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 211 | * nextLong(least >= bound) throws IllegalArgumentException |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 212 | */ |
| 213 | public void testNextLongBadBounds() { |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 214 | long[][] badBoundss = { |
| 215 | { 17L, 2L }, |
| 216 | { -42L, -42L }, |
| 217 | { Long.MAX_VALUE, Long.MIN_VALUE }, |
| 218 | }; |
| 219 | ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| 220 | for (long[] badBounds : badBoundss) { |
| 221 | try { |
| 222 | rnd.nextLong(badBounds[0], badBounds[1]); |
| 223 | shouldThrow(); |
| 224 | } catch (IllegalArgumentException success) {} |
| 225 | } |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 226 | } |
| 227 | |
| 228 | /** |
| 229 | * nextLong(bound) returns 0 <= value < bound; |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 230 | * repeated calls produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 231 | */ |
| 232 | public void testNextLongBounded() { |
| 233 | for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) { |
| 234 | long f = ThreadLocalRandom.current().nextLong(bound); |
| 235 | assertTrue(0 <= f && f < bound); |
| 236 | int i = 0; |
| 237 | long j; |
| 238 | while (i < NCALLS && |
| 239 | (j = ThreadLocalRandom.current().nextLong(bound)) == f) { |
| 240 | assertTrue(0 <= j && j < bound); |
| 241 | ++i; |
| 242 | } |
| 243 | assertTrue(i < NCALLS); |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * nextLong(least, bound) returns least <= value < bound; |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 249 | * repeated calls produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 250 | */ |
| 251 | public void testNextLongBounded2() { |
| 252 | for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) { |
| 253 | for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) { |
| 254 | long f = ThreadLocalRandom.current().nextLong(least, bound); |
| 255 | assertTrue(least <= f && f < bound); |
| 256 | int i = 0; |
| 257 | long j; |
| 258 | while (i < NCALLS && |
| 259 | (j = ThreadLocalRandom.current().nextLong(least, bound)) == f) { |
| 260 | assertTrue(least <= j && j < bound); |
| 261 | ++i; |
| 262 | } |
| 263 | assertTrue(i < NCALLS); |
| 264 | } |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | /** |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 269 | * nextDouble(non-positive) throws IllegalArgumentException |
| 270 | */ |
| 271 | public void testNextDoubleBoundNonPositive() { |
| 272 | ThreadLocalRandom rnd = ThreadLocalRandom.current(); |
| 273 | double[] badBounds = { |
| 274 | 0.0d, |
| 275 | -17.0d, |
| 276 | -Double.MIN_VALUE, |
| 277 | Double.NEGATIVE_INFINITY, |
| 278 | Double.NaN, |
| 279 | }; |
| 280 | for (double bound : badBounds) { |
| 281 | try { |
| 282 | rnd.nextDouble(bound); |
| 283 | shouldThrow(); |
| 284 | } catch (IllegalArgumentException success) {} |
| 285 | } |
| 286 | } |
| 287 | |
| 288 | /** |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 289 | * nextDouble(least, bound) returns least <= value < bound; |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 290 | * repeated calls produce at least two distinct results |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 291 | */ |
| 292 | public void testNextDoubleBounded2() { |
| 293 | for (double least = 0.0001; least < 1.0e20; least *= 8) { |
| 294 | for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) { |
| 295 | double f = ThreadLocalRandom.current().nextDouble(least, bound); |
| 296 | assertTrue(least <= f && f < bound); |
| 297 | int i = 0; |
| 298 | double j; |
| 299 | while (i < NCALLS && |
| 300 | (j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) { |
| 301 | assertTrue(least <= j && j < bound); |
| 302 | ++i; |
| 303 | } |
| 304 | assertTrue(i < NCALLS); |
| 305 | } |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | /** |
| 310 | * Different threads produce different pseudo-random sequences |
| 311 | */ |
| 312 | public void testDifferentSequences() { |
| 313 | // Don't use main thread's ThreadLocalRandom - it is likely to |
| 314 | // be polluted by previous tests. |
| 315 | final AtomicReference<ThreadLocalRandom> threadLocalRandom = |
| 316 | new AtomicReference<ThreadLocalRandom>(); |
| 317 | final AtomicLong rand = new AtomicLong(); |
| 318 | |
| 319 | long firstRand = 0; |
| 320 | ThreadLocalRandom firstThreadLocalRandom = null; |
| 321 | |
Narayan Kamath | 8e9a0e9 | 2015-04-28 11:40:00 +0100 | [diff] [blame] | 322 | Runnable getRandomState = new CheckedRunnable() { |
Calin Juravle | 8f0d92b | 2013-08-01 17:26:00 +0100 | [diff] [blame] | 323 | public void realRun() { |
| 324 | ThreadLocalRandom current = ThreadLocalRandom.current(); |
| 325 | assertSame(current, ThreadLocalRandom.current()); |
| 326 | // test bug: the following is not guaranteed and not true in JDK8 |
| 327 | // assertNotSame(current, threadLocalRandom.get()); |
| 328 | rand.set(current.nextLong()); |
| 329 | threadLocalRandom.set(current); |
| 330 | }}; |
| 331 | |
| 332 | Thread first = newStartedThread(getRandomState); |
| 333 | awaitTermination(first); |
| 334 | firstRand = rand.get(); |
| 335 | firstThreadLocalRandom = threadLocalRandom.get(); |
| 336 | |
| 337 | for (int i = 0; i < NCALLS; i++) { |
| 338 | Thread t = newStartedThread(getRandomState); |
| 339 | awaitTermination(t); |
| 340 | if (firstRand != rand.get()) |
| 341 | return; |
| 342 | } |
| 343 | fail("all threads generate the same pseudo-random sequence"); |
| 344 | } |
| 345 | |
| 346 | } |