org.apache.hadoop.hdfs.server.diskbalancer.command.HelpCommand Maven / Gradle / Ivy
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* 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.diskbalancer.command;
import com.google.common.base.Preconditions;
import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.HelpFormatter;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.tools.DiskBalancerCLI;
/**
* Help Command prints out detailed help about each command.
*/
public class HelpCommand extends Command {
/**
* Constructs a help command.
*
* @param conf - config
*/
public HelpCommand(Configuration conf) {
super(conf);
addValidCommandParameters(DiskBalancerCLI.HELP, "Help Command");
}
/**
* Executes the Client Calls.
*
* @param cmd - CommandLine
*/
@Override
public void execute(CommandLine cmd) throws Exception {
LOG.debug("Processing help Command.");
if (cmd == null) {
this.printHelp();
return;
}
Preconditions.checkState(cmd.hasOption(DiskBalancerCLI.HELP));
verifyCommandOptions(DiskBalancerCLI.HELP, cmd);
String helpCommand = cmd.getOptionValue(DiskBalancerCLI.HELP);
if (helpCommand == null || helpCommand.isEmpty()) {
this.printHelp();
return;
}
helpCommand = helpCommand.trim();
helpCommand = helpCommand.toLowerCase();
Command command = null;
switch (helpCommand) {
case DiskBalancerCLI.PLAN:
command = new PlanCommand(getConf());
break;
case DiskBalancerCLI.EXECUTE:
command = new ExecuteCommand(getConf());
break;
case DiskBalancerCLI.QUERY:
command = new QueryCommand(getConf());
break;
case DiskBalancerCLI.CANCEL:
command = new CancelCommand(getConf());
break;
case DiskBalancerCLI.REPORT:
command = new ReportCommand(getConf());
break;
default:
command = this;
break;
}
command.printHelp();
}
/**
* Gets extended help for this command.
*/
@Override
public void printHelp() {
String header = "\nDiskBalancer distributes data evenly between " +
"different disks on a datanode. " +
"DiskBalancer operates by generating a plan, that tells datanode " +
"how to move data between disks. Users can execute a plan by " +
"submitting it to the datanode. \nTo get specific help on a " +
"particular command please run \n\n hdfs diskbalancer -help .";
HelpFormatter helpFormatter = new HelpFormatter();
helpFormatter.printHelp("hdfs diskbalancer [command] [options]",
header, DiskBalancerCLI.getHelpOptions(), "");
}
}