com.marklogic.mapreduce.ValueReader.java Source code

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Here is the source code for com.marklogic.mapreduce.ValueReader.java

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/*
 * Copyright 2003-2016 MarkLogic Corporation
 *
 * 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.
 */
package com.marklogic.mapreduce;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.util.ReflectionUtils;

import com.marklogic.mapreduce.utilities.InternalUtilities;
import com.marklogic.xcc.ResultItem;

/**
 * <p>A RecordReader that fetches data from MarkLogic server and generates 
 * an integer key for each value fetched.</p>
 * 
 * @author jchen
 * 
 * @param <VALUEIN>
 */
public class ValueReader<VALUEIN> extends MarkLogicRecordReader<LongWritable, VALUEIN>
        implements MarkLogicConstants {

    static final float VALUE_TO_FRAGMENT_RATIO = 100;

    public static final Log LOG = LogFactory.getLog(ValueReader.class);
    private LongWritable key;
    private VALUEIN value;
    private Class<? extends Writable> valueClass;

    public ValueReader(Configuration conf) {
        super(conf);
        valueClass = conf.getClass(INPUT_VALUE_CLASS, Text.class, Writable.class);
    }

    @Override
    public LongWritable getCurrentKey() throws IOException, InterruptedException {
        return key;
    }

    @Override
    public VALUEIN getCurrentValue() throws IOException, InterruptedException {
        return value;
    }

    @Override
    protected void endOfResult() {
        key = null;
        value = null;
    }

    @SuppressWarnings("unchecked")
    @Override
    protected boolean nextResult(ResultItem result) {
        if (key == null) {
            key = new LongWritable(getCount());
        } else {
            key.set(getCount());
        }
        if (value == null) {
            value = (VALUEIN) ReflectionUtils.newInstance(valueClass, getConf());
        }
        InternalUtilities.assignResultValue(valueClass, result, value);

        return true;
    }

    @Override
    protected float getDefaultRatio() {
        return VALUE_TO_FRAGMENT_RATIO;
    }

}