PackageConverter.java

package org.apache.pig.backend.hadoop.executionengine.spark.converter;

import java.io.IOException;
import java.io.Serializable;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.POStatus;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POPackage;
import org.apache.pig.backend.hadoop.executionengine.spark.ScalaUtil;
import org.apache.pig.backend.hadoop.executionengine.spark.SparkUtil;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.io.NullableTuple;
import org.apache.pig.impl.io.PigNullableWritable;
import org.apache.spark.rdd.RDD;

import scala.runtime.AbstractFunction1;

/**
 * Package will generate the group from the result of the global rearrange
 * @author zhangbaofeng
 *
 */
@SuppressWarnings({ "serial" })
public class PackageConverter implements POConverter<Tuple, Tuple, POPackage> {
    private static final Log LOG = LogFactory.getLog(PackageConverter.class);

    @Override
    public RDD<Tuple> convert(List<RDD<Tuple>> predecessors, POPackage physicalOperator)
            throws IOException {
        SparkUtil.assertPredecessorSize(predecessors, physicalOperator, 1);
        RDD<Tuple> rdd = predecessors.get(0);
        return rdd.map(new PackageFunction(physicalOperator), ScalaUtil.getClassTag(Tuple.class));
    }

    private static class PackageFunction extends AbstractFunction1<Tuple, Tuple> implements Serializable {

        private final POPackage physicalOperator;

        public PackageFunction(POPackage physicalOperator) {
            this.physicalOperator = physicalOperator;
        }

        @SuppressWarnings("unchecked")
		@Override
        public Tuple apply(final Tuple t) {
            // (key, Seq<Tuple>:{(index, key, value without key)})
            if (LOG.isDebugEnabled()) {
            	LOG.debug("PackageFunction in " + t);
            }
            
            Result result;
            try {
                PigNullableWritable key = new PigNullableWritable() { // Key
                    public Object getValueAsPigType() {
                        try {
                            Object keyTuple = t.get(0);
                            return keyTuple;
                        } catch (ExecException e) {
                           throw new RuntimeException(e);
                        }
                    }
                };
                
                final Iterator<Tuple> bagIterator = (Iterator<Tuple>) t.get(1); // Seq<Tuple>:{(index, key, value without key)}
                Iterator<NullableTuple> iterator = new Iterator<NullableTuple>() {
                    public boolean hasNext() {
                        return bagIterator.hasNext();
                    }
                    
                    public NullableTuple next() {
                        try {
                            // we want the value and index only
                            Tuple next = bagIterator.next();
                            NullableTuple nullableTuple = new NullableTuple((Tuple) next.get(2)); // value
                            nullableTuple.setIndex(((Number) next.get(0)).byteValue());           // index
                            return nullableTuple;
                        } catch (ExecException e) {
                            throw new RuntimeException(e);
                        }
                    }
                    
                    public void remove() {
                        throw new UnsupportedOperationException();
                    }
                };
                
                physicalOperator.setInputs(null);
                physicalOperator.attachInput(key, iterator);
                result = physicalOperator.getNextTuple();
            } catch (ExecException e) {
                throw new RuntimeException("Couldn't do Package on tuple: " + t, e);
            }

            if (result == null) {
                throw new RuntimeException("Null response found for Package on tuple: " + t);
            }
            
            Tuple out;
            switch (result.returnStatus) {
                case POStatus.STATUS_OK: {
                	// (key, {(value)...})
                	if (LOG.isDebugEnabled()) {
                		LOG.debug("PackageFunction out " + result.result);
                	}
                	out = (Tuple) result.result;
                	break;
                }
                case POStatus.STATUS_NULL: {
                	out = null;
                	break;                	
                }
                default: {
                	throw new RuntimeException("Unexpected response code from operator " + physicalOperator 
                			+ " : " + result + " " + result.returnStatus);                	
                }
            }
            if (LOG.isDebugEnabled()) {
            	LOG.debug("PackageFunction out " + out);
            }
            return out;
        }

    }

}