org.apache.giraph.block_app.library.pagerank.PageRankInitializeAndNormalizeEdgesPiece.java Source code

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Here is the source code for org.apache.giraph.block_app.library.pagerank.PageRankInitializeAndNormalizeEdgesPiece.java

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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.giraph.block_app.library.pagerank;

import org.apache.giraph.block_app.framework.api.BlockWorkerReceiveApi;
import org.apache.giraph.block_app.framework.api.BlockWorkerSendApi;
import org.apache.giraph.block_app.framework.piece.Piece;
import org.apache.giraph.block_app.framework.piece.interfaces.VertexReceiver;
import org.apache.giraph.block_app.framework.piece.interfaces.VertexSender;
import org.apache.giraph.combiner.NullMessageCombiner;
import org.apache.giraph.conf.GiraphConfiguration;
import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
import org.apache.giraph.edge.Edge;
import org.apache.giraph.edge.MutableEdge;
import org.apache.giraph.function.vertex.ConsumerWithVertex;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;

/**
 * Normalize outgoing edge weight.
 *
 * @param <I> Vertex id
 * @param <V> Vertex value
 */
public class PageRankInitializeAndNormalizeEdgesPiece<I extends WritableComparable, V extends Writable>
        extends Piece<I, V, DoubleWritable, NullWritable, Object> {
    /** Consumer which sets pagerank value in vertex */
    private final ConsumerWithVertex<I, V, DoubleWritable, DoubleWritable> valueSetter;
    /** Default initial value pagerank value */
    private final DoubleWritable initialValue;

    /**
     * Constructor
     *
     * @param valueSetter Consumer which sets pagerank value in vertex
     * @param conf        Configuration
     */
    public PageRankInitializeAndNormalizeEdgesPiece(
            ConsumerWithVertex<I, V, DoubleWritable, DoubleWritable> valueSetter, GiraphConfiguration conf) {
        this.valueSetter = valueSetter;
        initialValue = new DoubleWritable(PageRankSettings.getInitialValue(conf));
    }

    @Override
    public VertexSender<I, V, DoubleWritable> getVertexSender(
            final BlockWorkerSendApi<I, V, DoubleWritable, NullWritable> workerApi, Object executionStage) {
        final NullWritable reusableMessage = NullWritable.get();
        return vertex -> {
            if (vertex.getNumEdges() > 0) {
                // Normalize edge weights if vertex has out edges
                double weightSum = 0.0;
                for (Edge<I, DoubleWritable> edge : vertex.getEdges()) {
                    weightSum += edge.getValue().get();
                }
                for (MutableEdge<I, DoubleWritable> edge : vertex.getMutableEdges()) {
                    edge.setValue(new DoubleWritable(edge.getValue().get() / weightSum));
                }
                // Make sure all the vertices are created
                workerApi.sendMessageToAllEdges(vertex, reusableMessage);
            }
        };
    }

    @Override
    public VertexReceiver<I, V, DoubleWritable, NullWritable> getVertexReceiver(BlockWorkerReceiveApi<I> workerApi,
            Object executionStage) {
        return (vertex, messages) -> {
            // Set initial pagerank value on all vertices
            valueSetter.apply(vertex, initialValue);
        };
    }

    @Override
    protected NullMessageCombiner getMessageCombiner(ImmutableClassesGiraphConfiguration conf) {
        return new NullMessageCombiner();
    }
}