NullService service = new NullService();
    service.startAsync().awaitRunning();
    assertFalse(future.isDone());
    service.stopAsync().awaitTerminated();
    assertTrue(future.isCancelled());
  }

  private class NullService extends AbstractScheduledService {
    @Override
    protected void runOneIteration() throws Exception {}

    @Override
    protected Scheduler scheduler() {

            // future that eventually came from immediateVoidFuture(), this doesn't leak throwables
            // or completion values.
            newFuture.setFuture(oldFuture);
          } else if (outputFuture.isCancelled() && taskExecutor.trySetCancelled()) {
            // If this CAS succeeds, we know that the provided callable will never be invoked,
            // so when oldFuture completes it is safe to allow the next submitted task to

  tensorflow::unwrap(cancellation_manager)->StartCancel();
}

bool TFE_CancellationManagerIsCancelled(
    TFE_CancellationManager* cancellation_manager) {
  return tensorflow::unwrap(cancellation_manager)->IsCancelled();
}

bool TFE_CancellationManagerIsCancelling(
    TFE_CancellationManager* cancellation_manager) {
  return tensorflow::unwrap(cancellation_manager)->IsCancelling();
}