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* 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 org.apache.flink.graph.streaming.example;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import org.apache.flink.api.common.ProgramDescription;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.common.functions.FoldFunction;
import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.tuple.Tuple;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.tuple.Tuple3;
import org.apache.flink.graph.Edge;
import org.apache.flink.graph.EdgeDirection;
import org.apache.flink.graph.streaming.EdgesApply;
import org.apache.flink.graph.streaming.SimpleEdgeStream;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.AscendingTimestampExtractor;
import org.apache.flink.streaming.api.functions.windowing.WindowFunction;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import org.apache.flink.types.NullValue;
import org.apache.flink.util.Collector;
/**
* Counts exact number of triangles in a graph slice.
*/
public class WindowTriangles implements ProgramDescription {
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
if (!parseParameters(args, env)) {
return;
}
SimpleEdgeStream<Long, NullValue> edges = getGraphStream(env);
DataStream<Tuple2<Integer, Long>> triangleCount =
edges.slice(windowTime, EdgeDirection.ALL)
.applyOnNeighbors(new GenerateCandidateEdges())
.keyBy(0, 1).timeWindow(windowTime)
.apply(new CountTriangles())
.timeWindowAll(windowTime).sum(0);
if (fileOutput) {
triangleCount.writeAsText(outputPath);
}
else {
triangleCount.print();
}
env.execute("Naive window triangle count");
}
// *************************************************************************
// UTIL METHODS
// *************************************************************************
@SuppressWarnings("serial")
public static final class GenerateCandidateEdges implements
EdgesApply<Long, NullValue, Tuple3<Long, Long, Boolean>> {
@Override
public void applyOnEdges(Long vertexID,
Iterable<Tuple2<Long, NullValue>> neighbors,
Collector<Tuple3<Long, Long, Boolean>> out) throws Exception {
Tuple3<Long, Long, Boolean> outT = new Tuple3<>();
outT.setField(vertexID, 0);
outT.setField(false, 2); //isCandidate=false
Set<Long> neighborIdsSet = new HashSet<Long>();
for (Tuple2<Long, NullValue> t: neighbors) {
outT.setField(t.f0, 1);
out.collect(outT);
neighborIdsSet.add(t.f0);
}
Object[] neighborIds = neighborIdsSet.toArray();
neighborIdsSet.clear();
outT.setField(true, 2); //isCandidate=true
for (int i=0; i<neighborIds.length-1; i++) {
for (int j=i; j<neighborIds.length; j++) {
// only emit the candidates
// with IDs larger than the vertex ID
if (((long)neighborIds[i] > vertexID) && ((long)neighborIds[j] > vertexID)) {
outT.setField((long)neighborIds[i], 0);
outT.setField((long)neighborIds[j], 1);
out.collect(outT);
}
}
}
}
}
@SuppressWarnings("serial")
public static final class CountTriangles implements
WindowFunction<Tuple3<Long, Long, Boolean>, Tuple2<Integer, Long>, Tuple, TimeWindow>{
@Override
public void apply(Tuple key, TimeWindow window,
Iterable<Tuple3<Long, Long, Boolean>> values,
Collector<Tuple2<Integer, Long>> out) throws Exception {
int candidates = 0;
int edges = 0;
for (Tuple3<Long, Long, Boolean> t: values) {
if (t.f2) { // candidate
candidates++;
}
else {
edges++;
}
}
if (edges > 0) {
out.collect(new Tuple2<Integer, Long>(candidates, window.maxTimestamp()));
}
}
}
private static boolean fileOutput = false;
private static String edgeInputPath = null;
private static String outputPath = null;
private static Time windowTime = Time.of(300, TimeUnit.MILLISECONDS);
private static boolean parseParameters(String[] args, StreamExecutionEnvironment env) {
if(args.length > 0) {
if(args.length < 3) {
System.err.println("Usage: WindowTriangles <input edges path> <output path>"
+ " <window time (ms)> <parallelism (optional)>");
return false;
}
fileOutput = true;
edgeInputPath = args[0];
outputPath = args[1];
windowTime = Time.of(Long.parseLong(args[2]), TimeUnit.MILLISECONDS);
if (args.length > 3) {
env.setParallelism(Integer.parseInt(args[3]));
}
} else {
System.out.println("Executing WindowTriangles example with default parameters and built-in default data.");
System.out.println(" Provide parameters to read input data from files.");
System.out.println(" See the documentation for the correct format of input files.");
System.out.println(" Usage: WindowTriangles <input edges path> <output path>"
+ " <window time (ms)> <parallelism (optional)>");
}
return true;
}
@SuppressWarnings("serial")
private static SimpleEdgeStream<Long, NullValue> getGraphStream(StreamExecutionEnvironment env) {
if (fileOutput) {
return new SimpleEdgeStream<>(env.readTextFile(edgeInputPath)
.map(new MapFunction<String, Edge<Long, Long>>() {
@Override
public Edge<Long, Long> map(String s) {
String[] fields = s.split("\\s");
long src = Long.parseLong(fields[0]);
long trg = Long.parseLong(fields[1]);
long timestamp = Long.parseLong(fields[2]);
return new Edge<>(src, trg, timestamp);
}
}), new EdgeValueTimestampExtractor(), env).mapEdges(new RemoveEdgeValue());
}
return new SimpleEdgeStream<>(env.generateSequence(1, 10).flatMap(
new FlatMapFunction<Long, Edge<Long, Long>>() {
@Override
public void flatMap(Long key, Collector<Edge<Long, Long>> out) throws Exception {
for (int i = 1; i < 3; i++) {
long target = key + i;
out.collect(new Edge<>(key, target, key*100 + (i-1)*50));
}
}
}), new EdgeValueTimestampExtractor(), env).mapEdges(new RemoveEdgeValue());
}
@SuppressWarnings("serial")
public static final class EdgeValueTimestampExtractor extends AscendingTimestampExtractor<Edge<Long, Long>> {
@Override
public long extractAscendingTimestamp(Edge<Long, Long> element) {
return element.getValue();
}
}
@SuppressWarnings("serial")
public static final class RemoveEdgeValue implements MapFunction<Edge<Long,Long>, NullValue> {
@Override
public NullValue map(Edge<Long, Long> edge) {
return NullValue.getInstance();
}
}
@Override
public String getDescription() {
return "Streaming Connected Components on Global Aggregation";
}
}
