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 | |
| 9 | import junit.framework.*; |
| 10 | import java.util.*; |
| 11 | import java.util.concurrent.ThreadLocalRandom; |
| 12 | import java.util.concurrent.atomic.AtomicLong; |
| 13 | import java.util.concurrent.atomic.AtomicReference; |
| 14 | |
| 15 | public class ThreadLocalRandomTest extends JSR166TestCase { |
| 16 | |
| 17 | /* |
| 18 | * Testing coverage notes: |
| 19 | * |
| 20 | * We don't test randomness properties, but only that repeated |
| 21 | * calls, up to NCALLS tries, produce at least one different |
| 22 | * result. For bounded versions, we sample various intervals |
| 23 | * across multiples of primes. |
| 24 | */ |
| 25 | |
| 26 | // |
| 27 | static final int NCALLS = 10000; |
| 28 | |
| 29 | // max sampled int bound |
| 30 | static final int MAX_INT_BOUND = (1 << 28); |
| 31 | |
| 32 | // Max sampled long bound |
| 33 | static final long MAX_LONG_BOUND = (1L << 42); |
| 34 | |
| 35 | /** |
| 36 | * setSeed throws UnsupportedOperationException |
| 37 | */ |
| 38 | public void testSetSeed() { |
| 39 | try { |
| 40 | ThreadLocalRandom.current().setSeed(17); |
| 41 | shouldThrow(); |
| 42 | } catch (UnsupportedOperationException success) {} |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Repeated calls to nextInt produce at least one different result |
| 47 | */ |
| 48 | public void testNextInt() { |
| 49 | int f = ThreadLocalRandom.current().nextInt(); |
| 50 | int i = 0; |
| 51 | while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f) |
| 52 | ++i; |
| 53 | assertTrue(i < NCALLS); |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * Repeated calls to nextLong produce at least one different result |
| 58 | */ |
| 59 | public void testNextLong() { |
| 60 | long f = ThreadLocalRandom.current().nextLong(); |
| 61 | int i = 0; |
| 62 | while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f) |
| 63 | ++i; |
| 64 | assertTrue(i < NCALLS); |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Repeated calls to nextBoolean produce at least one different result |
| 69 | */ |
| 70 | public void testNextBoolean() { |
| 71 | boolean f = ThreadLocalRandom.current().nextBoolean(); |
| 72 | int i = 0; |
| 73 | while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f) |
| 74 | ++i; |
| 75 | assertTrue(i < NCALLS); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Repeated calls to nextFloat produce at least one different result |
| 80 | */ |
| 81 | public void testNextFloat() { |
| 82 | float f = ThreadLocalRandom.current().nextFloat(); |
| 83 | int i = 0; |
| 84 | while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f) |
| 85 | ++i; |
| 86 | assertTrue(i < NCALLS); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Repeated calls to nextDouble produce at least one different result |
| 91 | */ |
| 92 | public void testNextDouble() { |
| 93 | double f = ThreadLocalRandom.current().nextDouble(); |
| 94 | double i = 0; |
| 95 | while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f) |
| 96 | ++i; |
| 97 | assertTrue(i < NCALLS); |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Repeated calls to nextGaussian produce at least one different result |
| 102 | */ |
| 103 | public void testNextGaussian() { |
| 104 | double f = ThreadLocalRandom.current().nextGaussian(); |
| 105 | int i = 0; |
| 106 | while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f) |
| 107 | ++i; |
| 108 | assertTrue(i < NCALLS); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * nextInt(negative) throws IllegalArgumentException; |
| 113 | */ |
| 114 | public void testNextIntBoundedNeg() { |
| 115 | try { |
| 116 | int f = ThreadLocalRandom.current().nextInt(-17); |
| 117 | shouldThrow(); |
| 118 | } catch (IllegalArgumentException success) {} |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * nextInt(least >= bound) throws IllegalArgumentException; |
| 123 | */ |
| 124 | public void testNextIntBadBounds() { |
| 125 | try { |
| 126 | int f = ThreadLocalRandom.current().nextInt(17, 2); |
| 127 | shouldThrow(); |
| 128 | } catch (IllegalArgumentException success) {} |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * nextInt(bound) returns 0 <= value < bound; |
| 133 | * repeated calls produce at least one different result |
| 134 | */ |
| 135 | public void testNextIntBounded() { |
| 136 | // sample bound space across prime number increments |
| 137 | for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) { |
| 138 | int f = ThreadLocalRandom.current().nextInt(bound); |
| 139 | assertTrue(0 <= f && f < bound); |
| 140 | int i = 0; |
| 141 | int j; |
| 142 | while (i < NCALLS && |
| 143 | (j = ThreadLocalRandom.current().nextInt(bound)) == f) { |
| 144 | assertTrue(0 <= j && j < bound); |
| 145 | ++i; |
| 146 | } |
| 147 | assertTrue(i < NCALLS); |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * nextInt(least, bound) returns least <= value < bound; |
| 153 | * repeated calls produce at least one different result |
| 154 | */ |
| 155 | public void testNextIntBounded2() { |
| 156 | for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) { |
| 157 | for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) { |
| 158 | int f = ThreadLocalRandom.current().nextInt(least, bound); |
| 159 | assertTrue(least <= f && f < bound); |
| 160 | int i = 0; |
| 161 | int j; |
| 162 | while (i < NCALLS && |
| 163 | (j = ThreadLocalRandom.current().nextInt(least, bound)) == f) { |
| 164 | assertTrue(least <= j && j < bound); |
| 165 | ++i; |
| 166 | } |
| 167 | assertTrue(i < NCALLS); |
| 168 | } |
| 169 | } |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * nextLong(negative) throws IllegalArgumentException; |
| 174 | */ |
| 175 | public void testNextLongBoundedNeg() { |
| 176 | try { |
| 177 | long f = ThreadLocalRandom.current().nextLong(-17); |
| 178 | shouldThrow(); |
| 179 | } catch (IllegalArgumentException success) {} |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | * nextLong(least >= bound) throws IllegalArgumentException; |
| 184 | */ |
| 185 | public void testNextLongBadBounds() { |
| 186 | try { |
| 187 | long f = ThreadLocalRandom.current().nextLong(17, 2); |
| 188 | shouldThrow(); |
| 189 | } catch (IllegalArgumentException success) {} |
| 190 | } |
| 191 | |
| 192 | /** |
| 193 | * nextLong(bound) returns 0 <= value < bound; |
| 194 | * repeated calls produce at least one different result |
| 195 | */ |
| 196 | public void testNextLongBounded() { |
| 197 | for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) { |
| 198 | long f = ThreadLocalRandom.current().nextLong(bound); |
| 199 | assertTrue(0 <= f && f < bound); |
| 200 | int i = 0; |
| 201 | long j; |
| 202 | while (i < NCALLS && |
| 203 | (j = ThreadLocalRandom.current().nextLong(bound)) == f) { |
| 204 | assertTrue(0 <= j && j < bound); |
| 205 | ++i; |
| 206 | } |
| 207 | assertTrue(i < NCALLS); |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | /** |
| 212 | * nextLong(least, bound) returns least <= value < bound; |
| 213 | * repeated calls produce at least one different result |
| 214 | */ |
| 215 | public void testNextLongBounded2() { |
| 216 | for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) { |
| 217 | for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) { |
| 218 | long f = ThreadLocalRandom.current().nextLong(least, bound); |
| 219 | assertTrue(least <= f && f < bound); |
| 220 | int i = 0; |
| 221 | long j; |
| 222 | while (i < NCALLS && |
| 223 | (j = ThreadLocalRandom.current().nextLong(least, bound)) == f) { |
| 224 | assertTrue(least <= j && j < bound); |
| 225 | ++i; |
| 226 | } |
| 227 | assertTrue(i < NCALLS); |
| 228 | } |
| 229 | } |
| 230 | } |
| 231 | |
| 232 | /** |
| 233 | * nextDouble(least, bound) returns least <= value < bound; |
| 234 | * repeated calls produce at least one different result |
| 235 | */ |
| 236 | public void testNextDoubleBounded2() { |
| 237 | for (double least = 0.0001; least < 1.0e20; least *= 8) { |
| 238 | for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) { |
| 239 | double f = ThreadLocalRandom.current().nextDouble(least, bound); |
| 240 | assertTrue(least <= f && f < bound); |
| 241 | int i = 0; |
| 242 | double j; |
| 243 | while (i < NCALLS && |
| 244 | (j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) { |
| 245 | assertTrue(least <= j && j < bound); |
| 246 | ++i; |
| 247 | } |
| 248 | assertTrue(i < NCALLS); |
| 249 | } |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * Different threads produce different pseudo-random sequences |
| 255 | */ |
| 256 | public void testDifferentSequences() { |
| 257 | // Don't use main thread's ThreadLocalRandom - it is likely to |
| 258 | // be polluted by previous tests. |
| 259 | final AtomicReference<ThreadLocalRandom> threadLocalRandom = |
| 260 | new AtomicReference<ThreadLocalRandom>(); |
| 261 | final AtomicLong rand = new AtomicLong(); |
| 262 | |
| 263 | long firstRand = 0; |
| 264 | ThreadLocalRandom firstThreadLocalRandom = null; |
| 265 | |
| 266 | final CheckedRunnable getRandomState = new CheckedRunnable() { |
| 267 | public void realRun() { |
| 268 | ThreadLocalRandom current = ThreadLocalRandom.current(); |
| 269 | assertSame(current, ThreadLocalRandom.current()); |
| 270 | // test bug: the following is not guaranteed and not true in JDK8 |
| 271 | // assertNotSame(current, threadLocalRandom.get()); |
| 272 | rand.set(current.nextLong()); |
| 273 | threadLocalRandom.set(current); |
| 274 | }}; |
| 275 | |
| 276 | Thread first = newStartedThread(getRandomState); |
| 277 | awaitTermination(first); |
| 278 | firstRand = rand.get(); |
| 279 | firstThreadLocalRandom = threadLocalRandom.get(); |
| 280 | |
| 281 | for (int i = 0; i < NCALLS; i++) { |
| 282 | Thread t = newStartedThread(getRandomState); |
| 283 | awaitTermination(t); |
| 284 | if (firstRand != rand.get()) |
| 285 | return; |
| 286 | } |
| 287 | fail("all threads generate the same pseudo-random sequence"); |
| 288 | } |
| 289 | |
| 290 | } |