org.apache.hadoop.tools.DistTool.java Source code

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Here is the source code for org.apache.hadoop.tools.DistTool.java

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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.tools;

import java.io.BufferedReader;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.InvalidInputException;
import org.apache.hadoop.mapred.JobConf;

/**
 * An abstract class for distributed tool for file related operations.
 */
abstract class DistTool implements org.apache.hadoop.util.Tool {
    protected static final Log LOG = LogFactory.getLog(DistTool.class);

    protected JobConf jobconf;

    /** {@inheritDoc} */
    public void setConf(Configuration conf) {
        if (jobconf != conf) {
            jobconf = conf instanceof JobConf ? (JobConf) conf : new JobConf(conf);
        }
    }

    /** {@inheritDoc} */
    public JobConf getConf() {
        return jobconf;
    }

    protected DistTool(Configuration conf) {
        setConf(conf);
    }

    private static final Random RANDOM = new Random();

    protected static String getRandomId() {
        return Integer.toString(RANDOM.nextInt(Integer.MAX_VALUE), 36);
    }

    /** Sanity check for source */
    protected static void checkSource(Configuration conf, List<Path> srcs) throws InvalidInputException {
        List<IOException> ioes = new ArrayList<IOException>();
        for (Path p : srcs) {
            try {
                if (!p.getFileSystem(conf).exists(p)) {
                    ioes.add(new FileNotFoundException("Source " + p + " does not exist."));
                }
            } catch (IOException e) {
                ioes.add(e);
            }
        }
        if (!ioes.isEmpty()) {
            throw new InvalidInputException(ioes);
        }
    }

    protected static String readString(DataInput in) throws IOException {
        if (in.readBoolean()) {
            return Text.readString(in);
        }
        return null;
    }

    protected static void writeString(DataOutput out, String s) throws IOException {
        boolean b = s != null;
        out.writeBoolean(b);
        if (b) {
            Text.writeString(out, s);
        }
    }

    protected static List<String> readFile(Configuration conf, Path inputfile) throws IOException {
        List<String> result = new ArrayList<String>();
        FileSystem fs = inputfile.getFileSystem(conf);
        BufferedReader input = null;
        try {
            input = new BufferedReader(new InputStreamReader(fs.open(inputfile)));
            for (String line; (line = input.readLine()) != null;) {
                result.add(line);
            }
        } finally {
            input.close();
        }
        return result;
    }

    /** An exception class for duplicated source files. */
    public static class DuplicationException extends IOException {
        private static final long serialVersionUID = 1L;
        /** Error code for this exception */
        public static final int ERROR_CODE = -2;

        DuplicationException(String message) {
            super(message);
        }
    }
}