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Comparing jsr166/src/jdk7/java/util/concurrent/FutureTask.java (file contents):
Revision 1.2 by jsr166, Fri Oct 3 23:48:09 2014 UTC vs.
Revision 1.5 by jsr166, Mon Mar 23 18:56:40 2015 UTC

# Line 5 | Line 5
5   */
6  
7   package java.util.concurrent;
8 +
9   import java.util.concurrent.locks.LockSupport;
10  
11   /**
# Line 375 | Line 376 | public class FutureTask<V> implements Ru
376          WaitNode q = null;
377          boolean queued = false;
378          for (;;) {
378 –            if (Thread.interrupted()) {
379 –                removeWaiter(q);
380 –                throw new InterruptedException();
381 –            }
382 –
379              int s = state;
380              if (s > COMPLETING) {
381                  if (q != null)
382                      q.thread = null;
383                  return s;
384              }
385 <            else if (s == COMPLETING) // cannot time out yet
385 >            else if (s == COMPLETING)
386 >                // We may have already promised (via isDone) that we are done
387 >                // so never return empty-handed or throw InterruptedException
388                  Thread.yield();
389 +            else if (Thread.interrupted()) {
390 +                removeWaiter(q);
391 +                throw new InterruptedException();
392 +            }
393              else if (q == null) {
394                  if (timed && nanos <= 0L)
395                      return s;
# Line 411 | Line 413 | public class FutureTask<V> implements Ru
413                      }
414                      parkNanos = nanos - elapsed;
415                  }
416 <                LockSupport.parkNanos(this, parkNanos);
416 >                // nanoTime may be slow; recheck before parking
417 >                if (state < COMPLETING)
418 >                    LockSupport.parkNanos(this, parkNanos);
419              }
420              else
421                  LockSupport.park(this);
# Line 451 | Line 455 | public class FutureTask<V> implements Ru
455      }
456  
457      // Unsafe mechanics
458 <    private static final sun.misc.Unsafe U;
458 >    private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe();
459      private static final long STATE;
460      private static final long RUNNER;
461      private static final long WAITERS;
462      static {
463          try {
464 <            U = sun.misc.Unsafe.getUnsafe();
465 <            Class<?> k = FutureTask.class;
466 <            STATE   = U.objectFieldOffset(k.getDeclaredField("state"));
467 <            RUNNER  = U.objectFieldOffset(k.getDeclaredField("runner"));
468 <            WAITERS = U.objectFieldOffset(k.getDeclaredField("waiters"));
464 >            STATE = U.objectFieldOffset
465 >                (FutureTask.class.getDeclaredField("state"));
466 >            RUNNER = U.objectFieldOffset
467 >                (FutureTask.class.getDeclaredField("runner"));
468 >            WAITERS = U.objectFieldOffset
469 >                (FutureTask.class.getDeclaredField("waiters"));
470          } catch (Exception e) {
471              throw new Error(e);
472          }
473 +
474 +        // Reduce the risk of rare disastrous classloading in first call to
475 +        // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
476 +        Class<?> ensureLoaded = LockSupport.class;
477      }
478  
479   }

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