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.dataflow;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.MoreObjects.toStringHelper;
  
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  import java.util.ArrayDeque;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.runners.PTransformMatcher;
  import org.apache.beam.sdk.runners.TransformHierarchy;
  import org.apache.beam.sdk.transforms.Combine;
  import org.apache.beam.sdk.transforms.PTransform;
  
  /**
   * A set of {@link PTransformMatcher PTransformMatchers} that are used in the Dataflow Runner and
   * not general enough to be shared between runners.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class DataflowPTransformMatchers {
    private DataflowPTransformMatchers() {}
  
    /**
     * Matches {@link PTransform}s of class {@link Combine.GroupedValues} that have no side inputs.
     */
    static class CombineValuesWithoutSideInputsPTransformMatcher implements PTransformMatcher {
  
      @Override
      public boolean matches(AppliedPTransform<?, ?, ?> application) {
        return application.getTransform().getClass().equals(Combine.GroupedValues.class)
            && ((Combine.GroupedValues<?, ?, ?>) application.getTransform())
                .getSideInputs()
                .isEmpty();
      }
  
      @Override
      public String toString() {
        return toStringHelper(CombineValuesWithoutSideInputsPTransformMatcher.class).toString();
      }
    }
  
    /**
     * Matches {@link PTransform}s of class {@link Combine.GroupedValues} that have no side inputs and
     * are direct subtransforms of a {@link Combine.PerKey}.
     */
    static class CombineValuesWithParentCheckPTransformMatcher implements PTransformMatcher {
  
      @Override
      public boolean matches(AppliedPTransform<?, ?, ?> application) {
        return application.getTransform().getClass().equals(Combine.GroupedValues.class)
            && ((Combine.GroupedValues<?, ?, ?>) application.getTransform()).getSideInputs().isEmpty()
            && parentIsCombinePerKey(application);
      }
  
      @SuppressFBWarnings("DCN_NULLPOINTER_EXCEPTION") // TODO(#35312)
      private boolean parentIsCombinePerKey(AppliedPTransform<?, ?, ?> application) {
        // We want the PipelineVisitor below to change the parent, but the parent must be final to
        // be captured in there. To work around this issue, wrap the parent in a one element array.
        final TransformHierarchy.Node[] parent = new TransformHierarchy.Node[1];
  
        // Traverse the pipeline to find the parent transform to application. Do this by maintaining
        // a stack of each composite transform being entered, and grabbing the top transform of the
        // stack once the target node is visited.
        Pipeline pipeline = application.getPipeline();
        pipeline.traverseTopologically(
            new Pipeline.PipelineVisitor.Defaults() {
              private ArrayDeque<TransformHierarchy.Node> parents = new ArrayDeque<>();
  
              @Override
              public CompositeBehavior enterCompositeTransform(TransformHierarchy.Node node) {
                CompositeBehavior behavior = CompositeBehavior.ENTER_TRANSFORM;
  
                // Combine.GroupedValues is a composite transform in the hierarchy, so when entering
                // a composite first we check if we found our target node.
                if (!node.isRootNode()
                    && node.toAppliedPTransform(getPipeline()).equals(application)) {
                  // If we found the target node grab the node's parent.
                  if (parents.isEmpty()) {
                    parent[0] = null;
                  } else {
                    parent[0] = parents.peekFirst();
                  }
                  behavior = CompositeBehavior.DO_NOT_ENTER_TRANSFORM;
                }
  
                // Even if we found the target node we must add it to the list to maintain parity
                // with the number of removeFirst calls.
                parents.addFirst(node);
                return behavior;
              }
  
              @Override
              public void leaveCompositeTransform(TransformHierarchy.Node node) {
                if (!node.isRootNode()) {
                  parents.removeFirst();
                }
              }
            });
  
        if (parent[0] == null) {
          return false;
        }
  
        // If the parent transform cannot be converted to an appliedPTransform it's definitely not
        // a CombinePerKey.
        AppliedPTransform<?, ?, ?> appliedParent;
        try {
          appliedParent = parent[0].toAppliedPTransform(pipeline);
        } catch (NullPointerException e) {
          return false;
        }
  
        return appliedParent.getTransform().getClass().equals(Combine.PerKey.class);
      }
  
      @Override
      public String toString() {
        return toStringHelper(CombineValuesWithParentCheckPTransformMatcher.class).toString();
      }
    }
  }
  