/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.tdunning.plume.local.lazy;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.output.MultipleOutputs;
import com.google.common.collect.Lists;
import com.tdunning.plume.DoFn;
import com.tdunning.plume.EmitFn;
import com.tdunning.plume.PCollection;
import com.tdunning.plume.PTable;
import com.tdunning.plume.Pair;
import com.tdunning.plume.local.lazy.MSCR.OutputChannel;
import com.tdunning.plume.local.lazy.MapRedExecutor.PlumeObject;
import com.tdunning.plume.local.lazy.op.ParallelDo;
/**
* Reducer that is used to execute MSCR in MapReds
*/
public class MSCRReducer extends Reducer<PlumeObject, PlumeObject, NullWritable, NullWritable> {
MultipleOutputs mos;
MSCR mscr; // Current MSCR being executed
protected void setup(Reducer<PlumeObject, PlumeObject, NullWritable, NullWritable>.Context context)
throws IOException, InterruptedException {
this.mos = new MultipleOutputs(context);
this.mscr = MapRedExecutor.readMSCR(context.getConfiguration());
}
protected void cleanup(Reducer<PlumeObject, PlumeObject, NullWritable, NullWritable>.Context context)
throws IOException ,InterruptedException {
mos.close();
}
@SuppressWarnings("unchecked")
protected void reduce(final PlumeObject arg0, java.lang.Iterable<PlumeObject> values,
Reducer<PlumeObject,PlumeObject,NullWritable,NullWritable>.Context arg2)
throws IOException, InterruptedException {
PCollection col = mscr.getChannelByNumber().get(arg0.sourceId);
OutputChannel oC = mscr.getOutputChannels().get(col);
if(oC.reducer != null) {
// apply reducer
ParallelDo pDo = oC.reducer;
DoFn reducer = pDo.getFunction(); // TODO how to check / report this
List<WritableComparable> vals = Lists.newArrayList();
for(PlumeObject val: values) {
vals.add(val.obj);
}
reducer.process(Pair.create(arg0.obj, vals), new EmitFn() {
@Override
public void emit(Object v) {
try {
if(v instanceof Pair) {
Pair p = (Pair)v;
mos.write(arg0.sourceId+"", p.getKey(), p.getValue());
} else {
mos.write(arg0.sourceId+"", NullWritable.get(), (WritableComparable)v);
}
} catch (Exception e) {
e.printStackTrace(); // TODO How to report this
}
}
});
} else {
// direct writing - write all key, value pairs
for(PlumeObject val: values) {
if(oC.output instanceof PTable) {
mos.write(arg0.sourceId+"", arg0.obj, val.obj);
} else {
mos.write(arg0.sourceId+"", NullWritable.get(), val.obj);
}
}
}
}
}