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

Introduction

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

Source

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 org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.DelegatingMapper;
import org.apache.hadoop.mapreduce.lib.input.MultipleInputs;
import org.springframework.stereotype.Service;

import com.conversantmedia.mapreduce.tool.ToolException;
import com.conversantmedia.mapreduce.tool.annotation.Input;
import com.conversantmedia.mapreduce.tool.annotation.MultiInput;

/**
 * Configures job with the @MultiInput annotation.
 *
 * <code>
 * {@literal @}MultiInput({
 *      {@literal @}Input(mapper=BuildDeleteMapper.class),
 *      {@literal @}Input(path="${context.previous}", mapper=BuildDeletePrevMapper.class),
 *   })
 * </code>
 *
 */
@Service
public class MultiInputAnnotationHandler extends AnnotationHandlerBase {

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

    @Override
    public void process(Annotation annotation, Job job, Object target) throws ToolException {
        for (Input input : ((MultiInput) annotation).value()) {
            Path path = getInputAsPath(input.path());
            if (input.mapper() == Mapper.class) {
                MultipleInputs.addInputPath(job, path, input.format());
            } else {
                MultipleInputs.addInputPath(job, path, input.format(), input.mapper());
                // Need to call again here so the call is captured by our aspect which
                // will replace it with the annotated delegating mapper class for resource
                // injection if required.
                job.setMapperClass(DelegatingMapper.class);
            }
        }
    }

    /**
     *
     * @param expressionOrValue   the path or expression that when evaluated produces
     *             a path to be used as the input.
     * @return               the evaluated path
     * @throws ToolException   if the expression evaluation fails or the result isn't
     *             a legal path type of String or Path.
     */
    protected Path getInputAsPath(String expressionOrValue) throws ToolException {
        Object value = this.evaluateExpression(expressionOrValue);
        if (value == null) {
            throw new ToolException("Input path property is null.");
        }

        Path path = null;
        if (value instanceof Path) {
            path = (Path) value;
        } else if (value instanceof String) {
            path = new Path((String) value);
        } else {
            throw new ToolException(
                    "Illegal Path property. Path must be one of type [" + Path.class + " or java.lang.String]");
        }
        return path;
    }

}