Github user vasia commented on a diff in the pull request:
https://github.com/apache/flink/pull/596#discussion_r28645013
--- Diff:
flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/library/ConnectedComponents.java
---
@@ -0,0 +1,90 @@
+/*
+ * 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.library;
+
+import org.apache.flink.graph.Graph;
+import org.apache.flink.graph.GraphAlgorithm;
+import org.apache.flink.graph.spargel.MessageIterator;
+import org.apache.flink.graph.spargel.MessagingFunction;
+import org.apache.flink.graph.spargel.VertexUpdateFunction;
+import org.apache.flink.types.NullValue;
+
+/**
+ * Connected components algorithm.
+ *
+ * Initially, each vertex will have its own ID as a value(is its own
component). The vertices propagate their
+ * current component ID in iterations, each time adopting a new value from
the received neighbor IDs,
+ * provided that the value is less than the current minimum.
+ *
+ * The algorithm converges when vertices no longer update their value or
when the maximum number of iterations
+ * is reached.
+ */
+@SuppressWarnings("serial")
+public class ConnectedComponents implements GraphAlgorithm<Long, Long,
NullValue>{
+
+ private Integer maxIterations;
+
+ public ConnectedComponents(Integer maxIterations) {
+ this.maxIterations = maxIterations;
+ }
+
+ @Override
+ public Graph<Long, Long, NullValue> run(Graph<Long, Long, NullValue>
graph) throws Exception {
+
+ Graph<Long, Long, NullValue> undirectedGraph =
graph.getUndirected();
+
+ // initialize vertex values and run the Vertex Centric Iteration
+ return undirectedGraph.runVertexCentricIteration(new
CCUpdater(),
+ new CCMessenger(), maxIterations);
+ }
+
+ /**
+ * Updates the value of a vertex by picking the minimum neighbor ID out
of all the incoming messages.
+ */
+ public static final class CCUpdater extends VertexUpdateFunction<Long,
Long, Long> {
+
+ @Override
--- End diff --
This essentially does the same as `CCUpdater` in the Spargel example, but
since you want to use this to show that the `VertexUpdateFunction` and the
`MessagingFunction` remain the same, maybe it's better not to change the code
here? i.e. have the exact same code as in the Spargel example.
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