    001    /*
    002     * Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
    003     *
    004     * Project and contact information: http://www.cascading.org/
    005     *
    006     * This file is part of the Cascading project.
    007     *
    008     * Licensed under the Apache License, Version 2.0 (the "License");
    009     * you may not use this file except in compliance with the License.
    010     * You may obtain a copy of the License at
    011     *
    012     *     http://www.apache.org/licenses/LICENSE-2.0
    013     *
    014     * Unless required by applicable law or agreed to in writing, software
    015     * distributed under the License is distributed on an "AS IS" BASIS,
    016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    017     * See the License for the specific language governing permissions and
    018     * limitations under the License.
    019     */
    020
    021    package cascading.tuple.hadoop.util;
    022
    023    import java.io.Serializable;
    024    import java.util.Arrays;
    025    import java.util.Comparator;
    026
    027    import cascading.tuple.Hasher;
    028    import cascading.tuple.StreamComparator;
    029    import cascading.tuple.hadoop.io.BufferedInputStream;
    030    import org.apache.hadoop.io.WritableComparator;
    031
    032    /**
    033     * Class BytesComparator is used to compare arrays of bytes.
    034     * <p/>
    035     * Note that BytesComparator implements {@link Hasher}, but for the Hasher interface to be applied during grouping,
    036     * sorting or joining, it must be set on a {@link cascading.tuple.Fields} instance via
    037     * {@link cascading.tuple.Fields#setComparator(Comparable, java.util.Comparator)}.
    038     */
    039    public class BytesComparator implements StreamComparator<BufferedInputStream>, Hasher<byte[]>, Comparator<byte[]>, Serializable
    040      {
    041      @Override
    042      public int compare( byte[] lhs, byte[] rhs )
    043        {
    044        if( lhs == rhs )
    045          return 0;
    046
    047        return WritableComparator.compareBytes( lhs, 0, lhs.length, rhs, 0, rhs.length );
    048        }
    049
    050      @Override
    051      public int compare( BufferedInputStream lhsStream, BufferedInputStream rhsStream )
    052        {
    053        byte[] lhs = lhsStream.getBuffer();
    054        int lhsPos = lhsStream.getPosition();
    055        int lhsLen = readLen( lhs, lhsPos );
    056
    057        lhsStream.skip( lhsLen + 4 );
    058
    059        byte[] rhs = rhsStream.getBuffer();
    060        int rhsPos = rhsStream.getPosition();
    061        int rhsLen = readLen( rhs, rhsPos );
    062
    063        rhsStream.skip( rhsLen + 4 );
    064
    065        return WritableComparator.compareBytes( lhs, lhsPos + 4, lhsLen, rhs, rhsPos + 4, rhsLen );
    066        }
    067
    068      private int readLen( byte[] buffer, int off )
    069        {
    070        return ( ( buffer[ off ] & 0xff ) << 24 ) +
    071          ( ( buffer[ off + 1 ] & 0xff ) << 16 ) +
    072          ( ( buffer[ off + 2 ] & 0xff ) << 8 ) +
    073          ( buffer[ off + 3 ] & 0xff );
    074        }
    075
    076      @Override
    077      public int hashCode( byte[] value )
    078        {
    079        return Arrays.hashCode( value );
    080        }
    081      }