ManagedResourceWithTask.java

/*
 * Copyright (C) 2012 Google Inc.
 *
 * Licensed 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 interactivespaces.util.resource;

import interactivespaces.system.InteractiveSpacesEnvironment;

import java.util.concurrent.Future;

/**
 * A {@link ManagedResource} paired with a {@link Runnable} task.
 *
 * The resource is started first then the task. When shutting down, the task is shut down first, then the resource.
 *
 * @author Keith M. Hughes
 */
public class ManagedResourceWithTask implements ManagedResource {

  /**
   * The resource being managed.
   */
  private ManagedResource resource;

  /**
   * The task to be run.
   */
  private Runnable task;

  /**
   * The space environment being run under.
   */
  private InteractiveSpacesEnvironment spaceEnvironment;

  /**
   * The future for the task.
   */
  private Future<?> future;

  /**
   * Construct a new resource.
   *
   * @param resource
   *          the resource
   * @param task
   *          the task that uses the resource
   * @param spaceEnvironment
   *          the space environment being run under
   */
  public ManagedResourceWithTask(ManagedResource resource, Runnable task, InteractiveSpacesEnvironment spaceEnvironment) {
    this.resource = resource;
    this.task = task;
    this.spaceEnvironment = spaceEnvironment;
  }

  @Override
  public void startup() {
    resource.startup();

    future = spaceEnvironment.getExecutorService().submit(task);
  }

  @Override
  public void shutdown() {
    if (future != null) {
      future.cancel(true);
      future = null;
    }

    resource.shutdown();
    resource = null;
  }
}