package com.thinkaurelius.faunus.mapreduce.util;
import com.thinkaurelius.faunus.FaunusEdge;
import com.thinkaurelius.faunus.FaunusVertex;
import com.thinkaurelius.faunus.Tokens;
import com.tinkerpop.blueprints.Direction;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.Element;
import com.tinkerpop.blueprints.Vertex;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public class CountMapReduce {
public static final String CLASS = Tokens.makeNamespace(CountMapReduce.class) + ".class";
public enum Counters {
VERTICES_COUNTED,
EDGES_COUNTED
}
public static Configuration createConfiguration(final Class<? extends Element> klass) {
final Configuration configuration = new EmptyConfiguration();
configuration.setClass(CLASS, klass, Element.class);
return configuration;
}
public static class Map extends Mapper<NullWritable, FaunusVertex, NullWritable, LongWritable> {
private boolean isVertex;
private final LongWritable longWritable = new LongWritable();
private SafeMapperOutputs outputs;
@Override
public void setup(final Mapper.Context context) throws IOException, InterruptedException {
this.isVertex = context.getConfiguration().getClass(CLASS, Element.class, Element.class).equals(Vertex.class);
this.outputs = new SafeMapperOutputs(context);
}
@Override
public void map(final NullWritable key, final FaunusVertex value, final Mapper<NullWritable, FaunusVertex, NullWritable, LongWritable>.Context context) throws IOException, InterruptedException {
if (this.isVertex) {
final long pathCount = value.pathCount();
this.longWritable.set(pathCount);
context.write(NullWritable.get(), this.longWritable);
context.getCounter(Counters.VERTICES_COUNTED).increment(pathCount > 0 ? 1 : 0);
} else {
long edgesCounted = 0;
long pathCount = 0;
for (final Edge e : value.getEdges(Direction.OUT)) {
final FaunusEdge edge = (FaunusEdge) e;
if (edge.hasPaths()) {
edgesCounted++;
pathCount = pathCount + edge.pathCount();
}
}
this.longWritable.set(pathCount);
context.write(NullWritable.get(), this.longWritable);
context.getCounter(Counters.EDGES_COUNTED).increment(edgesCounted);
}
this.outputs.write(Tokens.GRAPH, NullWritable.get(), value);
}
@Override
public void cleanup(final Mapper<NullWritable, FaunusVertex, NullWritable, LongWritable>.Context context) throws IOException, InterruptedException {
this.outputs.close();
}
}
public static class Combiner extends Reducer<NullWritable, LongWritable, NullWritable, LongWritable> {
private final LongWritable longWritable = new LongWritable();
@Override
public void reduce(final NullWritable key, final Iterable<LongWritable> values, final Reducer<NullWritable, LongWritable, NullWritable, LongWritable>.Context context) throws IOException, InterruptedException {
long totalCount = 0;
for (final LongWritable temp : values) {
totalCount = totalCount + temp.get();
}
this.longWritable.set(totalCount);
context.write(key, this.longWritable);
}
}
public static class Reduce extends Reducer<NullWritable, LongWritable, NullWritable, LongWritable> {
private SafeReducerOutputs outputs;
private LongWritable longWritable = new LongWritable();
@Override
public void setup(final Reducer<NullWritable, LongWritable, NullWritable, LongWritable>.Context context) {
this.outputs = new SafeReducerOutputs(context);
}
@Override
public void reduce(final NullWritable key, final Iterable<LongWritable> values, final Reducer<NullWritable, LongWritable, NullWritable, LongWritable>.Context context) throws IOException, InterruptedException {
long totalCount = 0;
for (final LongWritable temp : values) {
totalCount = totalCount + temp.get();
}
this.longWritable.set(totalCount);
this.outputs.write(Tokens.SIDEEFFECT, NullWritable.get(), this.longWritable);
}
@Override
public void cleanup(final Reducer<NullWritable, LongWritable, NullWritable, LongWritable>.Context context) throws IOException, InterruptedException {
this.outputs.close();
}
}
}