/**
* Copyright [2012] [Datasalt Systems S.L.]
*
* 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.datasalt.pangool.tuplemr.mapred;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.ReduceContext;
import org.apache.hadoop.mapreduce.Reducer;
import com.datasalt.pangool.io.DatumWrapper;
import com.datasalt.pangool.io.ITuple;
import com.datasalt.pangool.io.ViewTuple;
import com.datasalt.pangool.tuplemr.SerializationInfo;
import com.datasalt.pangool.tuplemr.TupleMRBuilder;
import com.datasalt.pangool.tuplemr.TupleMRConfig;
import com.datasalt.pangool.tuplemr.TupleMRException;
import com.datasalt.pangool.tuplemr.TupleReducer;
import com.datasalt.pangool.tuplemr.TupleReducer.TupleMRContext;
import com.datasalt.pangool.utils.DCUtils;
/**
* This is a proxy {@link Reducer} implementation that delegates its
* funcionality to a {@link TupleReducer} instance configured by
* {@link TupleMRBuilder#setTupleReducer(TupleReducer)}
*
*/
public class SimpleReducer<OUTPUT_KEY, OUTPUT_VALUE> extends
Reducer<DatumWrapper<ITuple>, NullWritable, OUTPUT_KEY, OUTPUT_VALUE> {
public final static String CONF_REDUCER_HANDLER = SimpleReducer.class.getName()
+ ".reducer.handler";
// Following variables protected to be shared by Combiners
private TupleMRConfig tupleMRConfig;
private SerializationInfo serInfo;
private boolean isMultipleSources;
private TupleReducer<OUTPUT_KEY, OUTPUT_VALUE>.Collector collector;
private TupleIterator<OUTPUT_KEY, OUTPUT_VALUE> tupleIterator;
private ViewTuple groupTuple; // Tuple view over the group
private TupleMRContext context;
private TupleReducer<OUTPUT_KEY, OUTPUT_VALUE> handler;
@SuppressWarnings("unchecked")
public void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
try {
this.tupleMRConfig = TupleMRConfig.get(context.getConfiguration());
this.isMultipleSources = tupleMRConfig.getNumIntermediateSchemas() >= 2;
this.serInfo = tupleMRConfig.getSerializationInfo();
if(!isMultipleSources) {
this.groupTuple = new ViewTuple(serInfo.getGroupSchema(),
this.serInfo.getGroupSchemaIndexTranslation(0)); // by default
// translation for
// 0
} else {
this.groupTuple = new ViewTuple(serInfo.getGroupSchema());
}
this.tupleIterator = new TupleIterator<OUTPUT_KEY, OUTPUT_VALUE>(context);
// setting handler
String fileName = context.getConfiguration()
.get(SimpleReducer.CONF_REDUCER_HANDLER);
handler = DCUtils.loadSerializedObjectInDC(context.getConfiguration(),
TupleReducer.class, fileName, true);
this.collector = handler.new Collector(
(ReduceContext<DatumWrapper<ITuple>, NullWritable, Object, Object>) context);
this.context = new TupleMRContext(
(ReduceContext<DatumWrapper<ITuple>, NullWritable, Object, Object>) context,
tupleMRConfig);
handler.setup(this.context, collector);
} catch(TupleMRException e) {
throw new RuntimeException(e);
}
}
@Override
public void cleanup(Context context) throws IOException, InterruptedException {
try {
handler.cleanup(this.context, collector);
collector.close();
super.cleanup(context);
} catch(TupleMRException e) {
throw new RuntimeException(e);
}
}
@Override
public final void reduce(DatumWrapper<ITuple> key, Iterable<NullWritable> values,
Context context) throws IOException, InterruptedException {
try {
Iterator<NullWritable> iterator = values.iterator();
tupleIterator.setIterator(iterator);
// We get the firts tuple, to create the groupTuple view
ITuple firstTupleGroup = key.datum();
// A view is created over the first tuple to give the user the group
// fields
if(isMultipleSources) {
int schemaId = tupleMRConfig.getSchemaIdByName(firstTupleGroup.getSchema()
.getName());
int[] indexTranslation = serInfo.getGroupSchemaIndexTranslation(schemaId);
groupTuple.setContained(firstTupleGroup, indexTranslation);
} else {
groupTuple.setContained(firstTupleGroup);
}
handler.reduce(groupTuple, tupleIterator, this.context, collector);
} catch(TupleMRException e) {
throw new RuntimeException(e);
}
}
}