    001/*
    002 * Copyright (c) 2007-2016 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
    021package cascading.tuple.collect;
    022
    023import java.io.Closeable;
    024import java.io.File;
    025import java.io.Flushable;
    026import java.io.IOException;
    027import java.util.Collection;
    028import java.util.Collections;
    029import java.util.Iterator;
    030import java.util.LinkedList;
    031import java.util.List;
    032
    033import cascading.flow.FlowProcess;
    034import cascading.tuple.Tuple;
    035import cascading.tuple.TupleException;
    036import cascading.tuple.io.TupleInputStream;
    037import cascading.tuple.io.TupleOutputStream;
    038import cascading.tuple.util.TupleViews;
    039import cascading.util.CloseableIterator;
    040import org.slf4j.Logger;
    041import org.slf4j.LoggerFactory;
    042
    043/**
    044 * Class SpillableTupleList is a simple durable Collection that can spill its contents to disk when the
    045 * {@code threshold} is met.
    046 * <p/>
    047 * Using a {@code threshold } of -1 will disable the spill, all values will remain in memory.
    048 * <p.></p.>
    049 * This class is used by the {@link cascading.pipe.CoGroup} pipe, to set properties specific to a given
    050 * CoGroup instance, see the {@link cascading.pipe.CoGroup#getConfigDef()} method.
    051 * <p/>
    052 * Use the {@link SpillableProps} fluent helper class to set properties.
    053 *
    054 * @see cascading.tuple.hadoop.collect.HadoopSpillableTupleList
    055 */
    056public abstract class SpillableTupleList implements Collection<Tuple>, Spillable
    057  {
    058  /** Field LOG */
    059  private static final Logger LOG = LoggerFactory.getLogger( SpillableTupleList.class );
    060
    061  public static int getThreshold( FlowProcess flowProcess, int defaultValue )
    062    {
    063    String value = (String) flowProcess.getProperty( SpillableProps.LIST_THRESHOLD );
    064
    065    if( value == null || value.length() == 0 )
    066      return defaultValue;
    067
    068    return Integer.parseInt( value );
    069    }
    070
    071  protected static Class getCodecClass( FlowProcess flowProcess, String defaultCodecs, Class subClass )
    072    {
    073    String compress = (String) flowProcess.getProperty( SpillableProps.SPILL_COMPRESS );
    074
    075    if( compress != null && !Boolean.parseBoolean( compress ) )
    076      return null;
    077
    078    String codecs = (String) flowProcess.getProperty( SpillableProps.SPILL_CODECS );
    079
    080    if( codecs == null || codecs.length() == 0 )
    081      codecs = defaultCodecs;
    082
    083    Class codecClass = null;
    084
    085    for( String codec : codecs.split( "[,\\s]+" ) )
    086      {
    087      try
    088        {
    089        LOG.info( "attempting to load codec: {}", codec );
    090        codecClass = Thread.currentThread().getContextClassLoader().loadClass( codec ).asSubclass( subClass );
    091
    092        if( codecClass != null )
    093          {
    094          LOG.info( "found codec: {}", codec );
    095          break;
    096          }
    097        }
    098      catch( ClassNotFoundException exception )
    099        {
    100        // do nothing
    101        }
    102      }
    103
    104    if( codecClass == null )
    105      {
    106      LOG.warn( "codecs set, but unable to load any: {}", codecs );
    107      return null;
    108      }
    109
    110    return codecClass;
    111    }
    112
    113  private SpillStrategy spillStrategy;
    114
    115  /** Field files */
    116  private List<File> files = Collections.EMPTY_LIST; // lazy init if we do a spill
    117  /** Field current */
    118  private final List<Object[]> current = new LinkedList<Object[]>();
    119  /** Field size */
    120  private int size = 0;
    121  /** Fields listener */
    122  private SpillListener spillListener = SpillListener.NULL;
    123
    124  private Tuple group;
    125
    126  protected SpillableTupleList( final int threshold )
    127    {
    128    this( new SpillStrategy()
    129    {
    130
    131    @Override
    132    public boolean doSpill( Spillable spillable, int size )
    133      {
    134      return size >= threshold;
    135      }
    136
    137    @Override
    138    public String getSpillReason( Spillable spillable )
    139      {
    140      return "met threshold: " + threshold;
    141      }
    142    } );
    143    }
    144
    145  protected SpillableTupleList( SpillStrategy spillStrategy )
    146    {
    147    this.spillStrategy = spillStrategy;
    148    }
    149
    150  @Override
    151  public void setGrouping( Tuple group )
    152    {
    153    this.group = group;
    154    }
    155
    156  @Override
    157  public Tuple getGrouping()
    158    {
    159    return group;
    160    }
    161
    162  @Override
    163  public void setSpillStrategy( SpillStrategy spillStrategy )
    164    {
    165    this.spillStrategy = spillStrategy;
    166    }
    167
    168  @Override
    169  public void setSpillListener( SpillListener spillListener )
    170    {
    171    this.spillListener = spillListener;
    172    }
    173
    174  @Override
    175  public int spillCount()
    176    {
    177    return files.size();
    178    }
    179
    180  private class SpilledListIterator implements Iterator<Tuple>
    181    {
    182    int fileIndex = 0;
    183    private Iterator<Tuple> lastIterator;
    184    private Iterator<Tuple> iterator;
    185
    186    private SpilledListIterator()
    187      {
    188      lastIterator = asTupleIterator();
    189      getNextIterator();
    190      }
    191
    192    private void getNextIterator()
    193      {
    194      if( iterator instanceof Closeable )
    195        closeSilent( (Closeable) iterator );
    196
    197      if( fileIndex < files.size() )
    198        iterator = getIteratorFor( files.get( fileIndex++ ) );
    199      else
    200        iterator = lastIterator;
    201      }
    202
    203    private Iterator<Tuple> getIteratorFor( File file )
    204      {
    205      spillListener.notifyReadSpillBegin( SpillableTupleList.this );
    206
    207      return createIterator( createTupleInputStream( file ) );
    208      }
    209
    210    public boolean hasNext()
    211      {
    212      if( isLastCollection() )
    213        return iterator.hasNext();
    214
    215      if( iterator.hasNext() )
    216        return true;
    217
    218      getNextIterator();
    219
    220      return hasNext();
    221      }
    222
    223    public Tuple next()
    224      {
    225      if( isLastCollection() || iterator.hasNext() )
    226        return iterator.next();
    227
    228      getNextIterator();
    229
    230      return next();
    231      }
    232
    233    private boolean isLastCollection()
    234      {
    235      return iterator == lastIterator;
    236      }
    237
    238    public void remove()
    239      {
    240      throw new UnsupportedOperationException( "remove is not supported" );
    241      }
    242    }
    243
    244  /**
    245   * Method add will add the given {@link cascading.tuple.Tuple} to this list.
    246   *
    247   * @param tuple of type Tuple
    248   */
    249  @Override
    250  public boolean add( Tuple tuple )
    251    {
    252    doSpill(); // spill if we break over the threshold
    253
    254    current.add( Tuple.elements( tuple ).toArray( new Object[ tuple.size() ] ) );
    255    size++;
    256
    257    return true;
    258    }
    259
    260  @Override
    261  public int size()
    262    {
    263    return size;
    264    }
    265
    266  @Override
    267  public boolean isEmpty()
    268    {
    269    return files.isEmpty() && current.size() == 0;
    270    }
    271
    272  private final boolean doSpill()
    273    {
    274    if( !spillStrategy.doSpill( this, current.size() ) )
    275      return false;
    276
    277    long start = System.currentTimeMillis();
    278    spillListener.notifyWriteSpillBegin( this, current.size(), spillStrategy.getSpillReason( this ) );
    279
    280    File file = createTempFile();
    281    TupleOutputStream dataOutputStream = createTupleOutputStream( file );
    282
    283    try
    284      {
    285      writeList( dataOutputStream, current );
    286      }
    287    finally
    288      {
    289      flushSilent( dataOutputStream );
    290      closeSilent( dataOutputStream );
    291      }
    292
    293    spillListener.notifyWriteSpillEnd( this, System.currentTimeMillis() - start );
    294
    295    if( files == Collections.EMPTY_LIST )
    296      files = new LinkedList<File>();
    297
    298    files.add( file );
    299    current.clear();
    300
    301    return true;
    302    }
    303
    304  private void flushSilent( Flushable flushable )
    305    {
    306    try
    307      {
    308      flushable.flush();
    309      }
    310    catch( IOException exception )
    311      {
    312      // ignore
    313      }
    314    }
    315
    316  private void closeSilent( Closeable closeable )
    317    {
    318    try
    319      {
    320      closeable.close();
    321      }
    322    catch( IOException exception )
    323      {
    324      // ignore
    325      }
    326    }
    327
    328  private void writeList( TupleOutputStream dataOutputStream, List<Object[]> list )
    329    {
    330    try
    331      {
    332      dataOutputStream.writeLong( list.size() );
    333
    334      for( Object[] elements : list )
    335        dataOutputStream.writeElementArray( elements );
    336      }
    337    catch( IOException exception )
    338      {
    339      throw new TupleException( "unable to write tuple collection to file output stream", exception );
    340      }
    341    }
    342
    343  protected abstract TupleOutputStream createTupleOutputStream( File file );
    344
    345  private Iterator<Tuple> createIterator( final TupleInputStream tupleInputStream )
    346    {
    347    final long size;
    348
    349    try
    350      {
    351      size = tupleInputStream.readLong();
    352      }
    353    catch( IOException exception )
    354      {
    355      throw new TupleException( "unable to read 'size' of collection from file input stream", exception );
    356      }
    357
    358    return new CloseableIterator<Tuple>()
    359    {
    360    Tuple tuple = new Tuple();
    361    long count = 0;
    362
    363    @Override
    364    public boolean hasNext()
    365      {
    366      return count < size;
    367      }
    368
    369    @Override
    370    public Tuple next()
    371      {
    372      try
    373        {
    374        return tupleInputStream.readTuple( tuple );
    375        }
    376      catch( IOException exception )
    377        {
    378        throw new TupleException( "unable to read next tuple from file input stream containing: " + size + " tuples, successfully read tuples: " + count, exception );
    379        }
    380      finally
    381        {
    382        count++;
    383        }
    384      }
    385
    386    @Override
    387    public void remove()
    388      {
    389      throw new UnsupportedOperationException( "remove is not supported" );
    390      }
    391
    392    @Override
    393    public void close() throws IOException
    394      {
    395      tupleInputStream.close();
    396      }
    397    };
    398    }
    399
    400  protected abstract TupleInputStream createTupleInputStream( File file );
    401
    402  private File createTempFile()
    403    {
    404    try
    405      {
    406      File file = File.createTempFile( "cascading-spillover", null );
    407      file.deleteOnExit();
    408
    409      return file;
    410      }
    411    catch( IOException exception )
    412      {
    413      throw new TupleException( "unable to create temporary file", exception );
    414      }
    415    }
    416
    417  @Override
    418  public void clear()
    419    {
    420    files.clear();
    421    current.clear();
    422    size = 0;
    423    }
    424
    425  @Override
    426  public Iterator<Tuple> iterator()
    427    {
    428    if( files.isEmpty() )
    429      return asTupleIterator();
    430
    431    return new SpilledListIterator();
    432    }
    433
    434  private Iterator<Tuple> asTupleIterator()
    435    {
    436    final Tuple tuple = TupleViews.createObjectArray();
    437    final Iterator<Object[]> iterator = current.iterator();
    438
    439    return new Iterator<Tuple>()
    440    {
    441    @Override
    442    public boolean hasNext()
    443      {
    444      return iterator.hasNext();
    445      }
    446
    447    @Override
    448    public Tuple next()
    449      {
    450      return TupleViews.reset( tuple, iterator.next() );
    451      }
    452
    453    @Override
    454    public void remove()
    455      {
    456      }
    457    };
    458    }
    459
    460  // collection methods, this class cannot only be added to, so they aren't implemented
    461  @Override
    462  public boolean contains( Object object )
    463    {
    464    return false;
    465    }
    466
    467  @Override
    468  public Object[] toArray()
    469    {
    470    return new Object[ 0 ];
    471    }
    472
    473  @Override
    474  public <T> T[] toArray( T[] ts )
    475    {
    476    return null;
    477    }
    478
    479  @Override
    480  public boolean remove( Object object )
    481    {
    482    return false;
    483    }
    484
    485  @Override
    486  public boolean containsAll( Collection<?> objects )
    487    {
    488    return false;
    489    }
    490
    491  @Override
    492  public boolean addAll( Collection<? extends Tuple> tuples )
    493    {
    494    return false;
    495    }
    496
    497  @Override
    498  public boolean removeAll( Collection<?> objects )
    499    {
    500    return false;
    501    }
    502
    503  @Override
    504  public boolean retainAll( Collection<?> objects )
    505    {
    506    return false;
    507    }
    508  }