org.gradoop.flink.model.impl.operators.grouping.functions.BuildVertexWithSuperVertexBC.java Source code

Introduction

Here is the source code for org.gradoop.flink.model.impl.operators.grouping.functions.BuildVertexWithSuperVertexBC.java

Source

/**
 * Copyright  2014 - 2018 Leipzig University (Database Research Group)
 *
 * Licensed 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.gradoop.flink.model.impl.operators.grouping.functions;

import com.google.common.collect.Maps;
import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.api.java.functions.FunctionAnnotation;
import org.apache.flink.configuration.Configuration;
import org.gradoop.common.model.impl.id.GradoopId;
import org.gradoop.flink.model.impl.operators.grouping.tuples.VertexGroupItem;
import org.gradoop.flink.model.impl.operators.grouping.tuples.VertexWithSuperVertex;
import org.gradoop.flink.model.impl.tuples.IdWithIdSet;

import java.util.List;
import java.util.Map;

/**
 * Maps a {@link VertexGroupItem} to a {@link VertexWithSuperVertex} according
 * the the broadcasted mapping information.
 */
@FunctionAnnotation.ForwardedFields("f0" // vertex id
)
public class BuildVertexWithSuperVertexBC extends RichMapFunction<VertexGroupItem, VertexWithSuperVertex> {
    /**
     * Broadcast variable name
     */
    public static final String BC_MAPPING = "mapping";
    /**
     * Reduce object instantiation
     */
    private final VertexWithSuperVertex reuseTuple;
    /**
     * Map from final super vertex id to a set of super vertex ids representing
     * the same group. The information is used to determine the correct super
     * vertex id for each incoming {@link VertexGroupItem}.
     */
    private List<IdWithIdSet> mapping;
    /**
     * Maps intermediate super vertex ids to their final super vertex id.
     */
    private Map<GradoopId, GradoopId> cache;

    /**
     * Creates the mapper
     */
    public BuildVertexWithSuperVertexBC() {
        this.reuseTuple = new VertexWithSuperVertex();
        this.cache = Maps.newConcurrentMap();
    }

    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);
        mapping = getRuntimeContext().getBroadcastVariable(BC_MAPPING);
    }

    @Override
    public VertexWithSuperVertex map(VertexGroupItem item) throws Exception {
        reuseTuple.setVertexId(item.getVertexId());
        reuseTuple.setSuperVertexId(getFinalGroupRepresentative(item.getSuperVertexId()));
        return reuseTuple;
    }

    /**
     * Determines the final super vertex id for the given id.
     *
     * @param current current super vertex id of a vertex
     * @return final super vertex id
     */
    private GradoopId getFinalGroupRepresentative(GradoopId current) {
        GradoopId result = null;
        if (cache.containsKey(current)) {
            result = cache.get(current);
        } else {
            for (IdWithIdSet group : mapping) {
                if (group.getIdSet().contains(current)) {
                    result = group.f0;
                    cache.put(current, result);
                }
            }
        }
        return result;
    }
}