org.apache.hadoop.hdfs.server.protocol.ServerCommand 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.hdfs.server.protocol;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Base class for a server command.
* Issued by the name-node to notify other servers what should be done.
* Commands are defined by actions defined in respective protocols.
*
* @see DatanodeProtocol
* @see NamenodeProtocol
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public abstract class ServerCommand {
private final int action;
/**
* Create a command for the specified action.
* Actions are protocol specific.
*
* @see DatanodeProtocol
* @see NamenodeProtocol
* @param action protocol specific action
*/
public ServerCommand(int action) {
this.action = action;
}
/**
* Get server command action.
* @return action code.
*/
public int getAction() {
return this.action;
}
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append(getClass().getSimpleName())
.append("/")
.append(action);
return sb.toString();
}
}