edu.stolaf.cs.wmrserver.streaming.PipeMapper.java Source code

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Here is the source code for edu.stolaf.cs.wmrserver.streaming.PipeMapper.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.
 * 
 * Modified by the WebMapReduce developers.
 */

package edu.stolaf.cs.wmrserver.streaming;

import java.io.*;
import java.net.URLDecoder;

import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.SkipBadRecords;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.util.StringUtils;

/** A generic Mapper bridge.
 *  It delegates operations to an external program via stdin and stdout.
 */
public class PipeMapper extends PipeMapRed implements Mapper {

    private boolean ignoreKey = false;
    private boolean skipping = false;

    private byte[] mapOutputFieldSeparator;
    private byte[] mapInputFieldSeparator;
    private int numOfMapOutputKeyFields = 1;

    String getPipeCommand(JobConf job) {
        String str = job.get("stream.map.streamprocessor");
        if (str == null) {
            return str;
        }
        try {
            return URLDecoder.decode(str, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            System.err.println("stream.map.streamprocessor in jobconf not found");
            return null;
        }
    }

    boolean getDoPipe() {
        return true;
    }

    public void configure(JobConf job) {
        super.configure(job);
        //disable the auto increment of the counter. For streaming, no of 
        //processed records could be different(equal or less) than the no of 
        //records input.
        SkipBadRecords.setAutoIncrMapperProcCount(job, false);
        skipping = job.getBoolean("mapred.skip.on", false);
        String inputFormatClassName = job.getClass("mapred.input.format.class", TextInputFormat.class)
                .getCanonicalName();
        ignoreKey = inputFormatClassName.equals(TextInputFormat.class.getCanonicalName());

        try {
            mapOutputFieldSeparator = job.get("stream.map.output.field.separator", "\t").getBytes("UTF-8");
            mapInputFieldSeparator = job.get("stream.map.input.field.separator", "\t").getBytes("UTF-8");
            numOfMapOutputKeyFields = job.getInt("stream.num.map.output.key.fields", 1);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("The current system does not support UTF-8 encoding!", e);
        }
    }

    // Do NOT declare default constructor
    // (MapRed creates it reflectively)

    public void map(Object key, Object value, OutputCollector output, Reporter reporter) throws IOException {
        if (outerrThreadsThrowable != null) {
            mapRedFinished();
            throw new IOException(
                    "MROutput/MRErrThread failed:" + StringUtils.stringifyException(outerrThreadsThrowable));
        }
        try {
            // 1/4 Hadoop in
            numRecRead_++;
            maybeLogRecord();
            if (debugFailDuring_ && numRecRead_ == 3) {
                throw new IOException("debugFailDuring_");
            }

            // 2/4 Hadoop to Tool
            if (numExceptions_ == 0) {
                if (!this.ignoreKey) {
                    write(key);
                    clientOut_.write(getInputSeparator());
                }
                write(value);
                clientOut_.write('\n');
                if (skipping) {
                    //flush the streams on every record input if running in skip mode
                    //so that we don't buffer other records surrounding a bad record. 
                    clientOut_.flush();
                }
            } else {
                numRecSkipped_++;
            }
        } catch (IOException io) {
            numExceptions_++;
            if (numExceptions_ > 1 || numRecWritten_ < minRecWrittenToEnableSkip_) {
                // terminate with failure
                String msg = logFailure(io);
                appendLogToJobLog("failure");
                mapRedFinished();
                throw new IOException(msg);
            } else {
                // terminate with success:
                // swallow input records although the stream processor failed/closed
            }
        }
    }

    public void close() {
        appendLogToJobLog("success");
        mapRedFinished();
    }

    byte[] getInputSeparator() {
        return mapInputFieldSeparator;
    }

    @Override
    byte[] getFieldSeparator() {
        return mapOutputFieldSeparator;
    }

    @Override
    int getNumOfKeyFields() {
        return numOfMapOutputKeyFields;
    }

}