| 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( |
| 64 |
< |
"next", new Class[] { int.class }); |
| 66 |
> |
m = ThreadLocalRandom.class.getDeclaredMethod("next", int.class); |
| 67 |
|
m.setAccessible(true); |
| 68 |
|
} catch (SecurityException acceptable) { |
| 69 |
|
// Security manager may deny access |
| 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<ThreadLocalRandom>(); |
| 357 |
> |
new AtomicReference<>(); |
| 358 |
|
final AtomicLong rand = new AtomicLong(); |
| 359 |
|
|
| 358 |
– |
long firstRand = 0; |
| 359 |
– |
ThreadLocalRandom firstThreadLocalRandom = null; |
| 360 |
– |
|
| 360 |
|
Runnable getRandomState = new CheckedRunnable() { |
| 361 |
|
public void realRun() { |
| 362 |
|
ThreadLocalRandom current = ThreadLocalRandom.current(); |
| 363 |
|
assertSame(current, ThreadLocalRandom.current()); |
| 365 |
– |
// test bug: the following is not guaranteed and not true in JDK8 |
| 366 |
– |
// assertNotSame(current, threadLocalRandom.get()); |
| 364 |
|
rand.set(current.nextLong()); |
| 365 |
|
threadLocalRandom.set(current); |
| 366 |
|
}}; |
| 367 |
|
|
| 368 |
< |
Thread first = newStartedThread(getRandomState); |
| 369 |
< |
awaitTermination(first); |
| 370 |
< |
firstRand = rand.get(); |
| 371 |
< |
firstThreadLocalRandom = threadLocalRandom.get(); |
| 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 |
< |
Thread t = newStartedThread(getRandomState); |
| 375 |
< |
awaitTermination(t); |
| 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 |
|
} |
