slider-core/src/main/java/org/apache/slider/server/services/utility/ClosingService.java

/*
 * 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.slider.server.services.utility;

import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.service.AbstractService;

import java.io.Closeable;

/**
 * Service that closes the closeable supplied during shutdown, if not null.
 */
public class ClosingService<C extends Closeable> extends AbstractService {

  private volatile C closeable;


  public ClosingService(String name,
                        C closeable) {
    super(name);
    this.closeable = closeable;
  }


  public Closeable getCloseable() {
    return closeable;
  }

  public void setCloseable(C closeable) {
    this.closeable = closeable;
  }

  /**
   * Stop routine will close the closeable -if not null - and set the
   * reference to null afterwards
   * @throws Exception
   */
  @Override
  protected void serviceStop() throws Exception {
    IOUtils.closeStream(closeable);
    closeable = null;
  }
}