com.conversantmedia.mapreduce.tool.annotation.handler.MapperInfoHandler.java Source code

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Here is the source code for com.conversantmedia.mapreduce.tool.annotation.handler.MapperInfoHandler.java

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package com.conversantmedia.mapreduce.tool.annotation.handler;

/*
 * #%L
 * Mara Core framework
 * ~~
 * Copyright (C) 2015 Conversant
 * ~~
 * Licensed 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.
 * #L%
 */

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Type;

import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.springframework.stereotype.Service;

import com.conversantmedia.mapreduce.tool.annotation.MapperInfo;
import com.conversantmedia.mapreduce.tool.annotation.ReducerInfo;

@Service
public class MapperInfoHandler extends AnnotationHandlerBase {

    @Override
    public boolean accept(Annotation annotation) {
        return annotation.annotationType() == MapperInfo.class;
    }

    @Override
    @SuppressWarnings("rawtypes")
    public void process(Annotation annotation, Job job, Object target) {
        MapperInfo map = (MapperInfo) annotation;
        if (map.value() != org.apache.hadoop.mapreduce.Mapper.class) {
            Class<? extends Mapper> mapperClass = map.value();
            job.setMapperClass(mapperClass);

            // Is this a map-only job?
            Field jobField = (Field) target;
            boolean isMapOnly = isMapOnlyJob(job, jobField);

            configureOutputKeyValue(job, mapperClass, map, isMapOnly);
        }
    }

    /**
     * Is this a map-only job?
     * 
     * @param job      the job
     * @param jobField   the field to reflect for annotations
     * @return         <code>true</code> if map only, <code>false</code> otherwise.
     */
    protected boolean isMapOnlyJob(Job job, Field jobField) {
        if (job.getNumReduceTasks() > 0) {
            return false;
        }

        // See if we have a ReducerInfo annotation - otherwise 
        // we'll consider this a "map only" job
        return !jobField.isAnnotationPresent(ReducerInfo.class);
    }

    @SuppressWarnings("rawtypes")
    public void configureOutputKeyValue(Job job, Class<? extends Mapper> mapperClass, MapperInfo map,
            boolean isMapOnly) {
        MaraAnnotationUtil util = MaraAnnotationUtil.INSTANCE;
        // Try and work it out from the generics
        Type[] params = util.getGenericTypeParams(mapperClass, Mapper.class);

        int length = 4;
        int keyIdx = 2;
        int valueIdx = 3;

        // Special case for TableMapper - assume if there are only two, they are the output key/value
        // TODO resolve this hack - force explicit?
        if (params != null && params.length == 2) {
            length = 2;
            keyIdx = 0;
            valueIdx = 1;
        }

        if (map != null && map.output().key() != void.class) {
            job.setMapOutputKeyClass(map.output().key());
            if (isMapOnly) {
                job.setOutputKeyClass(map.output().key());
            }
        } else if (params != null && params.length == length) {
            job.setMapOutputKeyClass((Class<?>) params[keyIdx]);
            if (isMapOnly) {
                job.setOutputKeyClass((Class<?>) params[keyIdx]);
            }
        }

        if (map != null && map.output().value() != void.class) {
            job.setMapOutputValueClass(map.output().value());
            if (isMapOnly) {
                job.setOutputValueClass(map.output().value());
            }
        } else if (params != null && params.length == length) {
            job.setMapOutputValueClass((Class<?>) params[valueIdx]);
            if (isMapOnly) {
                job.setOutputValueClass((Class<?>) params[valueIdx]);
            }
        }
    }

}