content: /*
   * 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.beam.runners.flink.translation.utils;
  
  import java.util.HashMap;
  import java.util.Map;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.runners.TransformHierarchy;
  import org.apache.beam.sdk.values.PValue;
  
  /** Pipeline visitors that fills a lookup table of {@link PValue} to number of consumers. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class CountingPipelineVisitor extends Pipeline.PipelineVisitor.Defaults {
  
    private final Map<PValue, Integer> numConsumers = new HashMap<>();
  
    @Override
    public void visitPrimitiveTransform(TransformHierarchy.Node node) {
      for (PValue input : node.getInputs().values()) {
        numConsumers.merge(input, 1, Integer::sum);
      }
    }
  
    /**
     * Calculate number of consumers of a given {@link PValue}.
     *
     * @param value PValue to perform calculation for.
     * @return Number of consumers.
     */
    public int getNumConsumers(PValue value) {
      return numConsumers.get(value);
    }
  }
  