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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
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package org.apache.flink.test.iterative;
import java.util.ArrayList;
import java.util.List;
import org.apache.flink.api.common.functions.RichCoGroupFunction;
import org.apache.flink.api.common.functions.RichFlatMapFunction;
import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.api.java.functions.FunctionAnnotation.ConstantFieldsFirst;
import org.apache.flink.api.java.functions.FunctionAnnotation.ConstantFieldsSecond;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.test.testdata.ConnectedComponentsData;
import org.apache.flink.test.util.JavaProgramTestBase;
import org.apache.flink.util.Collector;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.operators.DeltaIteration;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.io.LocalCollectionOutputFormat;
import org.apache.flink.examples.java.graph.ConnectedComponents.DuplicateValue;
import org.apache.flink.examples.java.graph.ConnectedComponents.NeighborWithComponentIDJoin;
@SuppressWarnings("serial")
public class CoGroupConnectedComponentsSecondITCase extends JavaProgramTestBase {
private static final long SEED = 0xBADC0FFEEBEEFL;
private static final int NUM_VERTICES = 1000;
private static final int NUM_EDGES = 10000;
@Override
protected void testProgram() throws Exception {
// set up execution environment
ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
// read vertex and edge data
DataSet<Long> vertices = env.fromElements(ConnectedComponentsData.getEnumeratingVertices(NUM_VERTICES).split("\n"))
.map(new VertexParser());
DataSet<Tuple2<Long, Long>> edges = env.fromElements(ConnectedComponentsData.getRandomOddEvenEdges(NUM_EDGES, NUM_VERTICES, SEED).split("\n"))
.flatMap(new EdgeParser());
// assign the initial components (equal to the vertex id)
DataSet<Tuple2<Long, Long>> verticesWithInitialId = vertices.map(new DuplicateValue<Long>());
// open a delta iteration
DeltaIteration<Tuple2<Long, Long>, Tuple2<Long, Long>> iteration =
verticesWithInitialId.iterateDelta(verticesWithInitialId, 100, 0);
// apply the step logic: join with the edges, select the minimum neighbor, update if the component of the candidate is smaller
DataSet<Tuple2<Long, Long>> changes = iteration
.getWorkset().join(edges).where(0).equalTo(0).with(new NeighborWithComponentIDJoin())
.coGroup(iteration.getSolutionSet()).where(0).equalTo(0)
.with(new MinIdAndUpdate());
// close the delta iteration (delta and new workset are identical)
DataSet<Tuple2<Long, Long>> result = iteration.closeWith(changes, changes);
// emit result
List<Tuple2<Long,Long>> resutTuples = new ArrayList<Tuple2<Long,Long>>();
result.output(new LocalCollectionOutputFormat<Tuple2<Long,Long>>(resutTuples));
env.execute();
}
// --------------------------------------------------------------------------------------------
// The test program
// --------------------------------------------------------------------------------------------
public static final class VertexParser extends RichMapFunction<String, Long> {
@Override
public Long map(String value) throws Exception {
return Long.parseLong(value);
}
}
public static final class EdgeParser extends RichFlatMapFunction<String, Tuple2<Long, Long>> {
@Override
public void flatMap(String value, Collector<Tuple2<Long, Long>> out) throws Exception {
String[] parts = value.split(" ");
long v1 = Long.parseLong(parts[0]);
long v2 = Long.parseLong(parts[1]);
out.collect(new Tuple2<Long, Long>(v1, v2));
out.collect(new Tuple2<Long, Long>(v2, v1));
}
}
@ConstantFieldsFirst("0")
@ConstantFieldsSecond("0")
public static final class MinIdAndUpdate extends RichCoGroupFunction<Tuple2<Long, Long>, Tuple2<Long, Long>, Tuple2<Long, Long>> {
@Override
public void coGroup(Iterable<Tuple2<Long, Long>> candidates, Iterable<Tuple2<Long, Long>> current, Collector<Tuple2<Long, Long>> out) {
if (!current.iterator().hasNext()) {
throw new RuntimeException("Error: Id not encountered before.");
}
Tuple2<Long, Long> old = current.iterator().next();
long minimumComponentID = Long.MAX_VALUE;
for (Tuple2<Long, Long> candidate : candidates) {
long candidateComponentID = candidate.f1;
if (candidateComponentID < minimumComponentID) {
minimumComponentID = candidateComponentID;
}
}
if (minimumComponentID < old.f1) {
old.f1 = minimumComponentID;
out.collect(old);
}
}
}
}