com.conversantmedia.mapreduce.tool.AnnotatedDelegatingReducer.java Source code

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Here is the source code for com.conversantmedia.mapreduce.tool.AnnotatedDelegatingReducer.java

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package com.conversantmedia.mapreduce.tool;

/*
 * #%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.io.IOException;

import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.ReflectionUtils;

import com.conversantmedia.mapreduce.tool.AnnotatedDelegatingComponent;

/**
 * Extensible base class for reducers with annotations.
 * Mostly for testing until we get AOP working properly.
 *
 * @param <K1>   input key type
 * @param <V1>   input value type
 * @param <K2>   output key type
 * @param <V2>   output value type
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public final class AnnotatedDelegatingReducer<K1, V1, K2, V2> extends Reducer<K1, V1, K2, V2>
        implements AnnotatedDelegatingComponent<Reducer<K1, V1, K2, V2>> {

    public static final String CONFKEY_DELEGATE_REDUCER_CLASS = AnnotatedDelegatingReducer.class.getName()
            + ";delegate";

    private Reducer<K1, V1, K2, V2> reducer;

    @Override
    public void run(Reducer<K1, V1, K2, V2>.Context context) throws IOException, InterruptedException {
        setup(context);
        getDelegate(context).run(context);
        cleanup(context);
    }

    @Override
    public Reducer<K1, V1, K2, V2> getDelegate(TaskAttemptContext context) {
        if (this.reducer == null) {
            Class<? extends Reducer> reducerClass = (Class<? extends Reducer>) context.getConfiguration()
                    .getClass(CONFKEY_DELEGATE_REDUCER_CLASS, Reducer.class);
            reducer = (Reducer<K1, V1, K2, V2>) ReflectionUtils.newInstance(reducerClass,
                    context.getConfiguration());
        }
        return this.reducer;
    }

}