src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/PigDateTimeRawComparator.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.pig.backend.hadoop.executionengine.mapReduceLayer;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.WritableComparator;
import org.apache.pig.backend.hadoop.DateTimeWritable;
import org.apache.pig.impl.io.NullableDateTimeWritable;
import org.apache.pig.impl.util.ObjectSerializer;
import org.joda.time.DateTime;

public class PigDateTimeRawComparator extends WritableComparator implements
        Configurable {

    private final Log mLog = LogFactory.getLog(getClass());
    private boolean[] mAsc;
    private DateTimeWritable.Comparator mWrappedComp;

    public PigDateTimeRawComparator() {
        super(NullableDateTimeWritable.class);
        mWrappedComp = new DateTimeWritable.Comparator();
    }

    @Override
    public void setConf(Configuration conf) {
        try {
            mAsc = (boolean[]) ObjectSerializer.deserialize(conf
                    .get("pig.sortOrder"));
        } catch (IOException ioe) {
            mLog.error("Unable to deserialize pig.sortOrder "
                    + ioe.getMessage());
            throw new RuntimeException(ioe);
        }
        if (mAsc == null) {
            mAsc = new boolean[1];
            mAsc[0] = true;
        }
    }

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

    /**
     * Compare two NullableIntWritables as raw bytes. If neither are null, then
     * IntWritable.compare() is used. If both are null then the indices are
     * compared. Otherwise the null one is defined to be less.
     */
    @Override
    public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        int rc = 0;

        // If either are null, handle differently.
        if (b1[s1] == 0 && b2[s2] == 0) {
            rc = mWrappedComp.compare(b1, s1 + 1, l1 - 2, b2, s2 + 1, l2 - 2);
        } else {
            // Two nulls are equal if indices are same
            if (b1[s1] != 0 && b2[s2] != 0) {
                rc = b1[s1 + 1] - b2[s2 + 1];
            }
            else if (b1[s1] != 0)
                rc = -1;
            else
                rc = 1;
        }
        if (!mAsc[0])
            rc *= -1;
        return rc;
    }

    @Override
    public int compare(Object o1, Object o2) {
        NullableDateTimeWritable ndtw1 = (NullableDateTimeWritable) o1;
        NullableDateTimeWritable ndtw2 = (NullableDateTimeWritable) o2;
        int rc = 0;

        // If either are null, handle differently.
        if (!ndtw1.isNull() && !ndtw2.isNull()) {
            rc = ((DateTime) ndtw1.getValueAsPigType())
                    .compareTo((DateTime) ndtw2.getValueAsPigType());
        } else {
            // Two nulls are equal if indices are same
            if (ndtw1.isNull() && ndtw2.isNull()) {
                rc = ndtw1.getIndex() - ndtw2.getIndex();
            }
            else if (ndtw1.isNull())
                rc = -1;
            else
                rc = 1;
        }
        if (!mAsc[0])
            rc *= -1;
        return rc;
    }

}