com.datasalt.pangool.tuplemr.mapred.SerializerComparator.java Source code

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Here is the source code for com.datasalt.pangool.tuplemr.mapred.SerializerComparator.java

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/**
 * Copyright [2012] [Datasalt Systems S.L.]
 *
 * 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.datasalt.pangool.tuplemr.mapred;

import java.io.IOException;
import java.io.Serializable;
import java.util.Comparator;

import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.WritableComparator;
import org.apache.hadoop.io.serializer.Serializer;

import com.datasalt.pangool.serialization.HadoopSerialization;

/**
 * A simple {@link RawComparator} and {@link Serializable} that
 * compares in binary. It also implements Comparator<Object>{@link #compare(Object, Object)}
 * by serializing the objects using {@link HadoopSerialization}, 
 * and then comparing the bytes. That is useful for testing purposes.
 * <br>
 * This class needs to receive a configuration via {@link #setConf(Configuration)} before
 * being ready to use the {@link #compare(Object, Object)} method.  
 */
@SuppressWarnings("serial")
public class SerializerComparator implements Comparator<Object>, Serializable, Configurable {

    protected transient Configuration conf;
    protected transient HadoopSerialization hadoopSer;

    private transient DataOutputBuffer buf1;
    private transient DataOutputBuffer buf2;

    @SuppressWarnings({ "rawtypes", "unchecked" })
    public int compare(Object o1, Serializer ser1, Object o2, Serializer ser2) {
        try {
            if (o1 == null) {
                return (o2 == null) ? 0 : -1;
            } else if (o2 == null) {
                return 1;
            }

            buf1.reset();
            if (ser1 == null) {
                hadoopSer.ser(o1, buf1);
            } else {
                ser1.open(buf1);
                ser1.serialize(o1);
                ser1.close();
            }
            buf2.reset();
            if (ser2 == null) {
                hadoopSer.ser(o2, buf2);
            } else {
                ser2.open(buf2);
                ser2.serialize(o2);
                ser2.close();
            }

            return WritableComparator.compareBytes(buf1.getData(), 0, buf1.getLength(), buf2.getData(), 0,
                    buf2.getLength());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public int compare(Object o1, Object o2) {
        return compare(o1, null, o2, null);
    }

    @Override
    public void setConf(Configuration conf) {
        buf1 = new DataOutputBuffer();
        buf2 = new DataOutputBuffer();

        try {
            hadoopSer = new HadoopSerialization(conf);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public Configuration getConf() {
        return conf;
    }
}