/**
 * (C) Copyright IBM Corp. 2010, 2015
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */


package com.ibm.bi.dml.runtime.matrix.mapred;

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

import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;

import com.ibm.bi.dml.runtime.matrix.data.MatrixCell;
import com.ibm.bi.dml.runtime.matrix.data.MatrixIndexes;
import com.ibm.bi.dml.runtime.matrix.data.MatrixPackedCell;
import com.ibm.bi.dml.runtime.matrix.data.TaggedMatrixValue;


public class GMRCombiner extends ReduceBase
implements Reducer<MatrixIndexes, TaggedMatrixValue, MatrixIndexes, TaggedMatrixValue>
{
	
	//temporary variable
	private TaggedMatrixValue taggedbuffer=null;
	
	public void reduce(MatrixIndexes indexes, Iterator<TaggedMatrixValue> values,
			OutputCollector<MatrixIndexes, TaggedMatrixValue> out, Reporter report) 
	throws IOException 
	{
		long start=System.currentTimeMillis();
		
		cachedValues.reset();
		
		processAggregateInstructions(indexes, values, true);
		
		//output the matrices needed by the reducer
		outputInCombinerFromCachedValues(indexes, taggedbuffer, out);
		
		report.incrCounter(Counters.COMBINE_OR_REDUCE_TIME, System.currentTimeMillis()-start);
	}

	public void configure(JobConf job)
	{
		super.configure(job);
		if(valueClass.equals(MatrixCell.class))
			valueClass=MatrixPackedCell.class;
		taggedbuffer=TaggedMatrixValue.createObject(valueClass);//new TaggedMatrixValue(valueClass);
	}
}