EdgeTargetVertexJoin.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.model.impl.operators.sampling.functions;

import org.apache.flink.api.common.functions.JoinFunction;
import org.apache.flink.api.java.functions.FunctionAnnotation;
import org.apache.flink.api.java.tuple.Tuple3;
import org.gradoop.common.model.api.entities.Edge;
import org.gradoop.common.model.api.entities.Vertex;
import org.gradoop.common.model.impl.id.GradoopId;

/**
 * Joins to get the edge target:<br>
 * {@code (edge,edge.targetId,bool-source),(target) -> (edge,bool-source,(bool)target[propertyKey])}
 *
 * @param <V> The vertex type.
 * @param <E> The edge type.
 */
@FunctionAnnotation.ForwardedFieldsFirst({"f0->f0", "f2->f1"})
@FunctionAnnotation.ReadFieldsSecond("properties")
public class EdgeTargetVertexJoin<V extends Vertex, E extends Edge>
  implements JoinFunction<Tuple3<E, GradoopId, Boolean>, V, Tuple3<E, Boolean, Boolean>> {

  /**
   *  Reduce object instantiations
   */
  private Tuple3<E, Boolean, Boolean> reuse;

  /**
   * Property key of vertex value
   */
  private final String propertyKey;

  /**
   * Creates an instance of this join function
   *
   * @param propertyKey property key of marked vertex value
   */
  public EdgeTargetVertexJoin(String propertyKey) {
    this.reuse = new Tuple3<>();
    this.propertyKey = propertyKey;
  }

  @Override
  public Tuple3<E, Boolean, Boolean> join(Tuple3<E, GradoopId, Boolean> interim, V vertex) {
    reuse.f0 = interim.f0;
    reuse.f1 = interim.f2;
    reuse.f2 = vertex.getPropertyValue(propertyKey).getBoolean();
    return reuse;
  }
}