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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 1.10 by jsr166, Tue May 31 16:16:24 2011 UTC vs.
Revision 1.11 by jsr166, Fri Jun 3 21:36:55 2011 UTC

# Line 6 | Line 6
6   import junit.framework.*;
7   import java.util.*;
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 252 | 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 +                assertNotSame(current, threadLocalRandom.get());
275 +                rand.set(current.nextLong());
276 +                threadLocalRandom.set(current);
277 +            }};
278 +
279 +        Thread first = newStartedThread(getRandomState);
280 +        awaitTermination(first);
281 +        firstRand = rand.get();
282 +        firstThreadLocalRandom = threadLocalRandom.get();
283 +
284 +        for (int i = 0; i < NCALLS; i++) {
285 +            Thread t = newStartedThread(getRandomState);
286 +            awaitTermination(t);
287 +            if (firstRand != rand.get())
288 +                return;
289 +        }
290 +        fail("all threads generate the same pseudo-random sequence");
291 +    }
292 +
293   }

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