* found in any textbook.
   */

  /** Monitor guarding all access */
  final Monitor monitor;

  /** Guard for waiting takes */
  private final Monitor.Guard notEmpty;

  /** Guard for waiting puts */
  private final Monitor.Guard notFull;

  // Internal helper methods

  /** Circularly increment i. */
  final int inc(int i) {
    return (++i == items.length) ? 0 : i;
  }

  /**

  // http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/main/java/util/concurrent/

  private static final long serialVersionUID = 5595510919245408276L;

  final PriorityQueue<E> q;
  final Monitor monitor = new Monitor(true);
  private final Monitor.Guard notEmpty =
      new Monitor.Guard(monitor) {
        @Override
        public boolean isSatisfied() {
          return !q.isEmpty();

        notifyFailed(shutdownFailure);
      } finally {
        monitor.leave();
        dispatchListenerEvents();
      }
    }
    return this;
  }

  @Override
  public final void awaitRunning() {
    monitor.enterWhenUninterruptibly(hasReachedRunning);
    try {
      checkCurrentState(RUNNING);
    } finally {
      monitor.leave();
    }
  }

  @Override

    public void unlock() {
      try {
        super.unlock();
      } finally {
        lockStateChanged(readWriteLock);
      }
    }
  }

  private final class CycleDetectingReentrantWriteLock extends ReentrantReadWriteLock.WriteLock {

    @Weak final CycleDetectingReentrantReadWriteLock readWriteLock;

    CycleDetectingReentrantWriteLock(CycleDetectingReentrantReadWriteLock readWriteLock) {

    try {
      while (true) {
        try {
          latch.await();
          return;
        } catch (InterruptedException e) {
          interrupted = true;
        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /**
   * Invokes {@code latch.}{@link CountDownLatch#await(long, TimeUnit) await(timeout, unit)}

    private final List<Suppression> suppressions = new ArrayList<>();

    @Override
    public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
      suppressions.add(new Suppression(closeable, thrown, suppressed));
    }
  }

  /** Record of a call to suppress. */
  private static class Suppression {
    private final Closeable closeable;

    public void unlock() {
      try {
        super.unlock();
      } finally {
        lockStateChanged(readWriteLock);
      }
    }
  }

  private final class CycleDetectingReentrantWriteLock extends ReentrantReadWriteLock.WriteLock {

    @Weak final CycleDetectingReentrantReadWriteLock readWriteLock;

    CycleDetectingReentrantWriteLock(CycleDetectingReentrantReadWriteLock readWriteLock) {

        notifyFailed(shutdownFailure);
      } finally {
        monitor.leave();
        dispatchListenerEvents();
      }
    }
    return this;
  }

  @Override
  public final void awaitRunning() {
    monitor.enterWhenUninterruptibly(hasReachedRunning);
    try {
      checkCurrentState(RUNNING);
    } finally {
      monitor.leave();
    }
  }

  /**

        return seq.length();
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    }
  }

  private static final class EmptyCharSource extends StringCharSource {

    private static final EmptyCharSource INSTANCE = new EmptyCharSource();

    private EmptyCharSource() {
      super("");
    }

    @Override

        return seq.length();
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    }
  }

  private static final class EmptyCharSource extends StringCharSource {

    private static final EmptyCharSource INSTANCE = new EmptyCharSource();

    private EmptyCharSource() {
      super("");
    }

    @Override