org.apache.hadoop.util.ToolRunner 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.IOException;
import java.io.PrintStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.CallerContext;
/**
* A utility to help run {@link Tool}s.
*
* ToolRunner can be used to run classes implementing
* Tool interface. It works in conjunction with
* {@link GenericOptionsParser} to parse the
*
* generic hadoop command line arguments and modifies the
* Configuration of the Tool. The
* application-specific options are passed along without being modified.
*
*
* @see Tool
* @see GenericOptionsParser
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class ToolRunner {
/**
* Runs the given Tool by {@link Tool#run(String[])}, after
* parsing with the given generic arguments. Uses the given
* Configuration, or builds one if null.
*
* Sets the Tool's configuration with the possibly modified
* version of the conf.
*
* @param conf Configuration for the Tool.
* @param tool Tool to run.
* @param args command-line arguments to the tool.
* @return exit code of the {@link Tool#run(String[])} method.
*/
public static int run(Configuration conf, Tool tool, String[] args)
throws Exception{
if (CallerContext.getCurrent() == null) {
CallerContext ctx = new CallerContext.Builder("CLI").build();
CallerContext.setCurrent(ctx);
}
if(conf == null) {
conf = new Configuration();
}
GenericOptionsParser parser = new GenericOptionsParser(conf, args);
//set the configuration back, so that Tool can configure itself
tool.setConf(conf);
//get the args w/o generic hadoop args
String[] toolArgs = parser.getRemainingArgs();
return tool.run(toolArgs);
}
/**
* Runs the Tool with its Configuration.
*
* Equivalent to run(tool.getConf(), tool, args).
*
* @param tool Tool to run.
* @param args command-line arguments to the tool.
* @return exit code of the {@link Tool#run(String[])} method.
*/
public static int run(Tool tool, String[] args)
throws Exception{
return run(tool.getConf(), tool, args);
}
/**
* Prints generic command-line argurments and usage information.
*
* @param out stream to write usage information to.
*/
public static void printGenericCommandUsage(PrintStream out) {
GenericOptionsParser.printGenericCommandUsage(out);
}
/**
* Print out a prompt to the user, and return true if the user
* responds with "y" or "yes". (case insensitive)
*/
public static boolean confirmPrompt(String prompt) throws IOException {
while (true) {
System.err.print(prompt + " (Y or N) ");
StringBuilder responseBuilder = new StringBuilder();
while (true) {
int c = System.in.read();
if (c == -1 || c == '\r' || c == '\n') {
break;
}
responseBuilder.append((char)c);
}
String response = responseBuilder.toString();
if (response.equalsIgnoreCase("y") ||
response.equalsIgnoreCase("yes")) {
return true;
} else if (response.equalsIgnoreCase("n") ||
response.equalsIgnoreCase("no")) {
return false;
}
System.err.println("Invalid input: " + response);
// else ask them again
}
}
}