org.apache.hadoop.util.ServicePlugin Maven / Gradle / Ivy
/**
* 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.hadoop.util;
import java.io.Closeable;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Service plug-in interface.
*
* Service plug-ins may be used to expose functionality of datanodes or
* namenodes using arbitrary RPC protocols. Plug-ins are instantiated by the
* service instance, and are notified of service life-cycle events using the
* methods defined by this class.
*
* Service plug-ins are started after the service instance is started, and
* stopped before the service instance is stopped.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public interface ServicePlugin extends Closeable {
/**
* This method is invoked when the service instance has been started.
*
* @param service The service instance invoking this method
*/
void start(Object service);
/**
* This method is invoked when the service instance is about to be shut down.
*/
void stop();
}