CreateImportEdge.java

/*
 * Copyright © 2014 - 2021 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.io.impl.edgelist.functions;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.functions.FunctionAnnotation;
import org.apache.flink.api.java.tuple.Tuple2;
import org.gradoop.common.model.impl.properties.Properties;
import org.gradoop.flink.io.impl.graph.tuples.ImportEdge;
import org.gradoop.common.util.GradoopConstants;

/**
 * {@code (edgeId, (sourceId, targetId)) => ImportEdge}
 * <p>
 * Forwarded fields:
 * <br>
 * {@code f0}:        {@code edgeId}<br>
 * {@code f1.f0->f1}: {@code sourceId}<br>
 * {@code f1.f1->f2}: {@code targetId}
 *
 * @param <K> id type
 */
@FunctionAnnotation.ForwardedFields("f0; f1.f0->f1; f1.f1->f2")
public class CreateImportEdge<K extends Comparable<K>>
  implements MapFunction<Tuple2<K, Tuple2<K, K>>, ImportEdge<K>> {
  /**
   * Reduce object instantiations
   */
  private ImportEdge<K> reuseEdge;

  /**
   * Constructor
   */
  public CreateImportEdge() {
    this.reuseEdge = new ImportEdge<>();
    reuseEdge.setLabel(GradoopConstants.DEFAULT_EDGE_LABEL);
  }

  /**
   * Method to create ImportEdge
   *
   * @param idTuple    tuple that contains unique line id + source and target ids
   * @return           initialized reuseEdge
   * @throws Exception on failure
   */
  @Override
  public ImportEdge<K> map(Tuple2<K, Tuple2<K, K>> idTuple) throws Exception {
    reuseEdge.setId(idTuple.f0);
    reuseEdge.setProperties(Properties.create());
    reuseEdge.setSourceId(idTuple.f1.f0);
    reuseEdge.setTargetId(idTuple.f1.f1);
    return reuseEdge;
  }
}