    001/*
    002 * Copyright (c) 2007-2017 Xplenty, 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
    021package cascading.tuple.io;
    022
    023import java.io.DataInputStream;
    024import java.io.IOException;
    025import java.io.InputStream;
    026import java.util.Comparator;
    027import java.util.List;
    028
    029import cascading.tuple.Tuple;
    030import org.slf4j.Logger;
    031import org.slf4j.LoggerFactory;
    032
    033/** Class TupleInputStream is used internally to read Tuples from storage. */
    034public abstract class TupleInputStream extends DataInputStream
    035  {
    036  /** Field LOG */
    037  private static final Logger LOG = LoggerFactory.getLogger( TupleInputStream.class );
    038
    039  /** Field inputStream */
    040  protected final InputStream inputStream;
    041  /** Field elementReader */
    042  protected final ElementReader elementReader;
    043
    044  public interface TupleElementReader<T extends TupleInputStream>
    045    {
    046    Object read( T stream ) throws IOException;
    047    }
    048
    049  public interface ElementReader
    050    {
    051    Object read( int token, DataInputStream inputStream ) throws IOException;
    052
    053    Object read( Class type, DataInputStream inputStream ) throws IOException;
    054
    055    Comparator getComparatorFor( int type, DataInputStream inputStream ) throws IOException;
    056
    057    void close();
    058    }
    059
    060  public TupleInputStream( InputStream inputStream, ElementReader elementReader )
    061    {
    062    super( inputStream );
    063    this.inputStream = inputStream;
    064    this.elementReader = elementReader;
    065    }
    066
    067  public InputStream getInputStream()
    068    {
    069    return inputStream;
    070    }
    071
    072  public Tuple readTuple() throws IOException
    073    {
    074    Tuple tuple = new Tuple();
    075
    076    return readTuple( tuple );
    077    }
    078
    079  public <T extends Tuple> T readWith( TupleElementReader[] readers, T tuple ) throws IOException
    080    {
    081    List<Object> elements = Tuple.elements( tuple );
    082
    083    elements.clear();
    084
    085    for( int i = 0; i < readers.length; i++ )
    086      {
    087      Object element = readers[ i ].read( this );
    088
    089      elements.add( element );
    090      }
    091
    092    return tuple;
    093    }
    094
    095  public <T extends Tuple> T readTuple( T tuple ) throws IOException
    096    {
    097    return readUnTyped( tuple );
    098    }
    099
    100  public <T extends Tuple> T readTyped( Class[] classes, T tuple ) throws IOException
    101    {
    102    List<Object> elements = Tuple.elements( tuple );
    103
    104    elements.clear();
    105
    106    for( int i = 0; i < classes.length; i++ )
    107      {
    108      Class type = classes[ i ];
    109
    110      elements.add( readType( type ) );
    111      }
    112
    113    return tuple;
    114    }
    115
    116  public <T extends Tuple> T readUnTyped( T tuple ) throws IOException
    117    {
    118    List<Object> elements = Tuple.elements( tuple );
    119
    120    elements.clear();
    121    int len = getNumElements();
    122
    123    for( int i = 0; i < len; i++ )
    124      elements.add( getNextElement() );
    125
    126    return tuple;
    127    }
    128
    129  public abstract int getNumElements() throws IOException;
    130
    131  public abstract int readToken() throws IOException;
    132
    133  public abstract Object getNextElement() throws IOException;
    134
    135  public TuplePair readTuplePair() throws IOException
    136    {
    137    return readTuplePair( new TuplePair() );
    138    }
    139
    140  public TuplePair readTuplePair( TuplePair tuplePair ) throws IOException
    141    {
    142    Tuple[] tuples = TuplePair.tuples( tuplePair );
    143
    144    readTuple( tuples[ 0 ] ); // guaranteed to not be null
    145    readTuple( tuples[ 1 ] ); // guaranteed to not be null
    146
    147    return tuplePair;
    148    }
    149
    150  public IndexTuple readIndexTuple() throws IOException
    151    {
    152    return readIndexTuple( new IndexTuple() );
    153    }
    154
    155  public abstract IndexTuple readIndexTuple( IndexTuple tuple ) throws IOException;
    156
    157  protected abstract Object readType( int type ) throws IOException;
    158
    159  public abstract Object readType( Class type ) throws IOException;
    160
    161  public Comparator getComparatorFor( int type ) throws IOException
    162    {
    163    if( type >= 0 && type <= 10 )
    164      return null;
    165
    166    return elementReader.getComparatorFor( type, this );
    167    }
    168
    169  @Override
    170  public void close() throws IOException
    171    {
    172    LOG.debug( "closing tuple input stream" );
    173
    174    try
    175      {
    176      super.close();
    177      }
    178    finally
    179      {
    180      if( elementReader != null )
    181        elementReader.close();
    182      }
    183    }
    184  }