content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.runners.local;
  
  /** Drives the execution of a {@code Pipeline} by scheduling work. */
  public interface ExecutionDriver {
    DriverState drive();
  
    /** The state of the driver. If the state is terminal, the driver can no longer make progress. */
    enum DriverState {
      CONTINUE(false),
      FAILED(true),
      SHUTDOWN(true);
  
      private final boolean terminal;
  
      DriverState(boolean terminal) {
        this.terminal = terminal;
      }
  
      public boolean isTerminal() {
        return terminal;
      }
    }
  }
  