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root/jsr166/jsr166/src/test/tck/ThreadLocalRandomTest.java
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Comparing jsr166/src/test/tck/ThreadLocalRandomTest.java (file contents):
Revision 1.8 by jsr166, Tue Mar 15 19:47:07 2011 UTC vs.
Revision 1.13 by jsr166, Sat Feb 16 20:50:29 2013 UTC

# Line 4 | Line 4
4   * http://creativecommons.org/publicdomain/zero/1.0/
5   */
6   import junit.framework.*;
7 – import java.util.concurrent.*;
7   import java.util.*;
8 <
8 > import java.util.concurrent.ThreadLocalRandom;
9 > import java.util.concurrent.atomic.AtomicLong;
10 > import java.util.concurrent.atomic.AtomicReference;
11  
12   public class ThreadLocalRandomTest extends JSR166TestCase {
13  
# Line 17 | Line 18 | public class ThreadLocalRandomTest exten
18          return new TestSuite(ThreadLocalRandomTest.class);
19      }
20  
21 <    /**
21 >    /*
22       * Testing coverage notes:
23       *
24       * We don't test randomness properties, but only that repeated
# Line 67 | Line 68 | public class ThreadLocalRandomTest exten
68          assertTrue(i < NCALLS);
69      }
70  
70 –
71      /**
72       * Repeated calls to nextBoolean produce at least one different result
73       */
# Line 112 | Line 112 | public class ThreadLocalRandomTest exten
112          assertTrue(i < NCALLS);
113      }
114  
115 –
115      /**
116       * nextInt(negative) throws IllegalArgumentException;
117       */
# Line 133 | Line 132 | public class ThreadLocalRandomTest exten
132          } catch (IllegalArgumentException success) {}
133      }
134  
136 –
135      /**
136       * nextInt(bound) returns 0 <= value < bound;
137       * repeated calls produce at least one different result
# Line 154 | Line 152 | public class ThreadLocalRandomTest exten
152          }
153      }
154  
157 –
155      /**
156       * nextInt(least, bound) returns least <= value < bound;
157       * repeated calls produce at least one different result
# Line 236 | Line 233 | public class ThreadLocalRandomTest exten
233          }
234      }
235  
239 –
236      /**
237       * nextDouble(least, bound) returns least <= value < bound;
238       * repeated calls produce at least one different result
# Line 258 | Line 254 | public class ThreadLocalRandomTest exten
254          }
255      }
256  
257 +    /**
258 +     * Different threads produce different pseudo-random sequences
259 +     */
260 +    public void testDifferentSequences() {
261 +        // Don't use main thread's ThreadLocalRandom - it is likely to
262 +        // be polluted by previous tests.
263 +        final AtomicReference<ThreadLocalRandom> threadLocalRandom =
264 +            new AtomicReference<ThreadLocalRandom>();
265 +        final AtomicLong rand = new AtomicLong();
266 +
267 +        long firstRand = 0;
268 +        ThreadLocalRandom firstThreadLocalRandom = null;
269 +
270 +        final CheckedRunnable getRandomState = new CheckedRunnable() {
271 +            public void realRun() {
272 +                ThreadLocalRandom current = ThreadLocalRandom.current();
273 +                assertSame(current, ThreadLocalRandom.current());
274 +                // test bug: the following is not guaranteed and not true in JDK8
275 +                //                assertNotSame(current, threadLocalRandom.get());
276 +                rand.set(current.nextLong());
277 +                threadLocalRandom.set(current);
278 +            }};
279 +
280 +        Thread first = newStartedThread(getRandomState);
281 +        awaitTermination(first);
282 +        firstRand = rand.get();
283 +        firstThreadLocalRandom = threadLocalRandom.get();
284 +
285 +        for (int i = 0; i < NCALLS; i++) {
286 +            Thread t = newStartedThread(getRandomState);
287 +            awaitTermination(t);
288 +            if (firstRand != rand.get())
289 +                return;
290 +        }
291 +        fail("all threads generate the same pseudo-random sequence");
292 +    }
293  
294   }

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