    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.collect;
    022
    023    import java.util.Collection;
    024
    025    import cascading.flow.FlowProcess;
    026    import cascading.provider.FactoryLoader;
    027    import cascading.tuple.Tuple;
    028    import cascading.tuple.collect.Spillable;
    029    import cascading.tuple.collect.SpillableTupleList;
    030    import cascading.tuple.collect.SpillableTupleMap;
    031    import cascading.tuple.collect.TupleCollectionFactory;
    032    import cascading.tuple.collect.TupleMapFactory;
    033    import org.apache.hadoop.mapred.JobConf;
    034
    035    /**
    036     * HadoopSpillableTupleMap is responsible for spilling values to disk if the map threshold is reached.
    037     *
    038     * @see SpillableTupleMap
    039     * @see SpillableTupleList
    040     */
    041    public class HadoopSpillableTupleMap extends SpillableTupleMap
    042      {
    043      private final FlowProcess<JobConf> flowProcess;
    044      private final Spillable.SpillStrategy spillStrategy;
    045      private final TupleCollectionFactory<JobConf> tupleCollectionFactory;
    046
    047      public HadoopSpillableTupleMap( int initialCapacity, float loadFactor, int mapThreshold, int listThreshold, FlowProcess<JobConf> flowProcess )
    048        {
    049        super( initialCapacity, loadFactor, mapThreshold, listThreshold );
    050        this.flowProcess = flowProcess;
    051        this.spillStrategy = getSpillStrategy();
    052
    053        FactoryLoader loader = FactoryLoader.getInstance();
    054
    055        this.tupleCollectionFactory = loader.loadFactoryFrom( flowProcess, TupleMapFactory.TUPLE_MAP_FACTORY, HadoopTupleCollectionFactory.class );
    056        }
    057
    058      @Override
    059      protected Collection<Tuple> createTupleCollection( Tuple tuple )
    060        {
    061        Collection<Tuple> collection = tupleCollectionFactory.create( flowProcess );
    062
    063        if( collection instanceof Spillable )
    064          {
    065          ( (Spillable) collection ).setGrouping( tuple );
    066          ( (Spillable) collection ).setSpillListener( getSpillListener() );
    067          ( (Spillable) collection ).setSpillStrategy( spillStrategy );
    068          }
    069
    070        return collection;
    071        }
    072
    073      /**
    074       * Method getSpillStrategy returns a SpillStrategy instance that is passed to the underlying Spillable
    075       * tuple collection.
    076       *
    077       * @return of type Spillable#SpillStrategy
    078       */
    079      protected Spillable.SpillStrategy getSpillStrategy()
    080        {
    081        return new Spillable.SpillStrategy()
    082        {
    083        int minThreshold = (int) ( getMapThreshold() * .05 );
    084
    085        int current()
    086          {
    087          return Math.max( minThreshold, Math.min( getInitListThreshold(), getMapThreshold() / size() ) );
    088          }
    089
    090        @Override
    091        public boolean doSpill( Spillable spillable, int size )
    092          {
    093          return current() <= size;
    094          }
    095
    096        @Override
    097        public String getSpillReason( Spillable spillable )
    098          {
    099          return "met current threshold: " + current();
    100          }
    101        };
    102        }
    103      }