import java.util.List;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.TimeUnit;

/** See newDirectExecutorService javadoc for behavioral notes. */
@GwtIncompatible
final class DirectExecutorService extends AbstractListeningExecutorService {

  /** Lock used whenever accessing the state variables (runningTasks, shutdown) of the executor */
  private final Object lock = new Object();

  /*

   *
   * @since 18.0 (present as MoreExecutors.sameThreadExecutor() since 10.0)
   */
  @GwtIncompatible // TODO
  public static ListeningExecutorService newDirectExecutorService() {
    return new DirectExecutorService();
  }

  /**
   * Returns an {@link Executor} that runs each task in the thread that invokes {@link
   * Executor#execute execute}, as in {@link CallerRunsPolicy}.
   *