diff options
Diffstat (limited to 'jsr166-tests/src/test/java/jsr166/ThreadLocalRandomTest.java')
| -rw-r--r-- | jsr166-tests/src/test/java/jsr166/ThreadLocalRandomTest.java | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/jsr166-tests/src/test/java/jsr166/ThreadLocalRandomTest.java b/jsr166-tests/src/test/java/jsr166/ThreadLocalRandomTest.java new file mode 100644 index 0000000..665a2b7 --- /dev/null +++ b/jsr166-tests/src/test/java/jsr166/ThreadLocalRandomTest.java @@ -0,0 +1,290 @@ +/* + * Written by Doug Lea with assistance from members of JCP JSR-166 + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/publicdomain/zero/1.0/ + */ + +package jsr166; + +import junit.framework.*; +import java.util.*; +import java.util.concurrent.ThreadLocalRandom; +import java.util.concurrent.atomic.AtomicLong; +import java.util.concurrent.atomic.AtomicReference; + +public class ThreadLocalRandomTest extends JSR166TestCase { + + /* + * Testing coverage notes: + * + * We don't test randomness properties, but only that repeated + * calls, up to NCALLS tries, produce at least one different + * result. For bounded versions, we sample various intervals + * across multiples of primes. + */ + + // + static final int NCALLS = 10000; + + // max sampled int bound + static final int MAX_INT_BOUND = (1 << 28); + + // Max sampled long bound + static final long MAX_LONG_BOUND = (1L << 42); + + /** + * setSeed throws UnsupportedOperationException + */ + public void testSetSeed() { + try { + ThreadLocalRandom.current().setSeed(17); + shouldThrow(); + } catch (UnsupportedOperationException success) {} + } + + /** + * Repeated calls to nextInt produce at least one different result + */ + public void testNextInt() { + int f = ThreadLocalRandom.current().nextInt(); + int i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * Repeated calls to nextLong produce at least one different result + */ + public void testNextLong() { + long f = ThreadLocalRandom.current().nextLong(); + int i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * Repeated calls to nextBoolean produce at least one different result + */ + public void testNextBoolean() { + boolean f = ThreadLocalRandom.current().nextBoolean(); + int i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * Repeated calls to nextFloat produce at least one different result + */ + public void testNextFloat() { + float f = ThreadLocalRandom.current().nextFloat(); + int i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * Repeated calls to nextDouble produce at least one different result + */ + public void testNextDouble() { + double f = ThreadLocalRandom.current().nextDouble(); + double i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * Repeated calls to nextGaussian produce at least one different result + */ + public void testNextGaussian() { + double f = ThreadLocalRandom.current().nextGaussian(); + int i = 0; + while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f) + ++i; + assertTrue(i < NCALLS); + } + + /** + * nextInt(negative) throws IllegalArgumentException; + */ + public void testNextIntBoundedNeg() { + try { + int f = ThreadLocalRandom.current().nextInt(-17); + shouldThrow(); + } catch (IllegalArgumentException success) {} + } + + /** + * nextInt(least >= bound) throws IllegalArgumentException; + */ + public void testNextIntBadBounds() { + try { + int f = ThreadLocalRandom.current().nextInt(17, 2); + shouldThrow(); + } catch (IllegalArgumentException success) {} + } + + /** + * nextInt(bound) returns 0 <= value < bound; + * repeated calls produce at least one different result + */ + public void testNextIntBounded() { + // sample bound space across prime number increments + for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) { + int f = ThreadLocalRandom.current().nextInt(bound); + assertTrue(0 <= f && f < bound); + int i = 0; + int j; + while (i < NCALLS && + (j = ThreadLocalRandom.current().nextInt(bound)) == f) { + assertTrue(0 <= j && j < bound); + ++i; + } + assertTrue(i < NCALLS); + } + } + + /** + * nextInt(least, bound) returns least <= value < bound; + * repeated calls produce at least one different result + */ + public void testNextIntBounded2() { + for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) { + for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) { + int f = ThreadLocalRandom.current().nextInt(least, bound); + assertTrue(least <= f && f < bound); + int i = 0; + int j; + while (i < NCALLS && + (j = ThreadLocalRandom.current().nextInt(least, bound)) == f) { + assertTrue(least <= j && j < bound); + ++i; + } + assertTrue(i < NCALLS); + } + } + } + + /** + * nextLong(negative) throws IllegalArgumentException; + */ + public void testNextLongBoundedNeg() { + try { + long f = ThreadLocalRandom.current().nextLong(-17); + shouldThrow(); + } catch (IllegalArgumentException success) {} + } + + /** + * nextLong(least >= bound) throws IllegalArgumentException; + */ + public void testNextLongBadBounds() { + try { + long f = ThreadLocalRandom.current().nextLong(17, 2); + shouldThrow(); + } catch (IllegalArgumentException success) {} + } + + /** + * nextLong(bound) returns 0 <= value < bound; + * repeated calls produce at least one different result + */ + public void testNextLongBounded() { + for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) { + long f = ThreadLocalRandom.current().nextLong(bound); + assertTrue(0 <= f && f < bound); + int i = 0; + long j; + while (i < NCALLS && + (j = ThreadLocalRandom.current().nextLong(bound)) == f) { + assertTrue(0 <= j && j < bound); + ++i; + } + assertTrue(i < NCALLS); + } + } + + /** + * nextLong(least, bound) returns least <= value < bound; + * repeated calls produce at least one different result + */ + public void testNextLongBounded2() { + for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) { + for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) { + long f = ThreadLocalRandom.current().nextLong(least, bound); + assertTrue(least <= f && f < bound); + int i = 0; + long j; + while (i < NCALLS && + (j = ThreadLocalRandom.current().nextLong(least, bound)) == f) { + assertTrue(least <= j && j < bound); + ++i; + } + assertTrue(i < NCALLS); + } + } + } + + /** + * nextDouble(least, bound) returns least <= value < bound; + * repeated calls produce at least one different result + */ + public void testNextDoubleBounded2() { + for (double least = 0.0001; least < 1.0e20; least *= 8) { + for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) { + double f = ThreadLocalRandom.current().nextDouble(least, bound); + assertTrue(least <= f && f < bound); + int i = 0; + double j; + while (i < NCALLS && + (j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) { + assertTrue(least <= j && j < bound); + ++i; + } + assertTrue(i < NCALLS); + } + } + } + + /** + * Different threads produce different pseudo-random sequences + */ + public void testDifferentSequences() { + // Don't use main thread's ThreadLocalRandom - it is likely to + // be polluted by previous tests. + final AtomicReference<ThreadLocalRandom> threadLocalRandom = + new AtomicReference<ThreadLocalRandom>(); + final AtomicLong rand = new AtomicLong(); + + long firstRand = 0; + ThreadLocalRandom firstThreadLocalRandom = null; + + final CheckedRunnable getRandomState = new CheckedRunnable() { + public void realRun() { + ThreadLocalRandom current = ThreadLocalRandom.current(); + assertSame(current, ThreadLocalRandom.current()); + // test bug: the following is not guaranteed and not true in JDK8 + // assertNotSame(current, threadLocalRandom.get()); + rand.set(current.nextLong()); + threadLocalRandom.set(current); + }}; + + Thread first = newStartedThread(getRandomState); + awaitTermination(first); + firstRand = rand.get(); + firstThreadLocalRandom = threadLocalRandom.get(); + + for (int i = 0; i < NCALLS; i++) { + Thread t = newStartedThread(getRandomState); + awaitTermination(t); + if (firstRand != rand.get()) + return; + } + fail("all threads generate the same pseudo-random sequence"); + } + +} |