final int millis;
    volatile boolean completed;

    public SleepingRunnable(int millis) {
      this.millis = millis;
    }

    @Override
    public void run() {
      try {
        Thread.sleep(millis);
      } catch (InterruptedException wontHappen) {
        throw new AssertionError();
      }
      completed = true;
    }
  }

        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

    }
  }

  /**
   * Delays, via Thread.sleep, for the given millisecond delay, but if the sleep is shorter than
   * specified, may re-sleep or yield until time elapses.
   */
  static void delay(long millis) throws InterruptedException {
    long startTime = System.nanoTime();
    long ns = millis * 1000 * 1000;
    for (; ; ) {
      if (millis > 0L) Thread.sleep(millis);
      else // too short to sleep

    }
  }

  private static void assertAtLeastTimePassed(Stopwatch stopwatch, long expectedMillis) {
    long elapsedMillis = stopwatch.elapsed(MILLISECONDS);
    /*
     * The "+ 5" below is to permit, say, sleep(10) to sleep only 9 milliseconds. We see such
     * behavior sometimes when running these tests publicly as part of Guava. "+ 5" is probably more
     * generous than it needs to be.
     */
    assertTrue(

    }
  }

  private static void assertAtLeastTimePassed(Stopwatch stopwatch, long expectedMillis) {
    long elapsedMillis = stopwatch.elapsed(MILLISECONDS);
    /*
     * The "+ 5" below is to permit, say, sleep(10) to sleep only 9 milliseconds. We see such
     * behavior sometimes when running these tests publicly as part of Guava. "+ 5" is probably more
     * generous than it needs to be.
     */
    assertTrue(

      this.everyMillis = everyMillis;
      this.interruptee = interruptee;
    }

    @Override
    public void run() {
      while (true) {
        try {
          Thread.sleep(everyMillis);
        } catch (InterruptedException e) {
          // ok. just stop sleeping.
        }
        if (shouldStop) {
          break;
        }
        interruptee.interrupt();
      }
    }

        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

    assertEquals(1, service.numIterations.get());
    service.stopAsync();
    service.secondBarrier.await();
    service.awaitTerminated();
    // Sleep for a while just to ensure that our task wasn't called again.
    Thread.sleep(UNIT.toMillis(3 * DELAY));
    assertEquals(1, service.numIterations.get());
  }

  public void testCustomScheduler_deadlock() throws InterruptedException, BrokenBarrierException {

    Interrupter(Thread threadToInterrupt) {
      this.threadToInterrupt = threadToInterrupt;
    }

    @Override
    public void run() {
      try {
        Thread.sleep(100);
      } catch (InterruptedException e) {
        throw new AssertionError();
      } finally {
        threadToInterrupt.interrupt();
      }
    }
  }

    assertEquals(1, service.numIterations.get());
    service.stopAsync();
    service.secondBarrier.await();
    service.awaitTerminated();
    // Sleep for a while just to ensure that our task wasn't called again.
    Thread.sleep(UNIT.toMillis(3 * DELAY));
    assertEquals(1, service.numIterations.get());
  }

  public void testCustomScheduler_deadlock() throws InterruptedException, BrokenBarrierException {