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 java.util.Map;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.runners.PTransformOverrideFactory;
  import org.apache.beam.sdk.transforms.DoFn.RequiresStableInput;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.Reshuffle;
  import org.apache.beam.sdk.util.construction.PTransformReplacements;
  import org.apache.beam.sdk.util.construction.ReplacementOutputs;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionTuple;
  import org.apache.beam.sdk.values.TupleTag;
  
  /** Transform overrides for supporting {@link RequiresStableInput} in the Dataflow runner. */
  class RequiresStableInputParDoOverrides {
  
    /**
     * Returns a {@link PTransformOverrideFactory} that inserts a {@link Reshuffle.ViaRandomKey}
     * before a {@link ParDo.SingleOutput} that uses the {@link RequiresStableInput} annotation.
     */
    static <InputT, OutputT>
        PTransformOverrideFactory<
                PCollection<InputT>, PCollection<OutputT>, ParDo.SingleOutput<InputT, OutputT>>
            singleOutputOverrideFactory() {
      return new SingleOutputOverrideFactory<>();
    }
  
    /**
     * Returns a {@link PTransformOverrideFactory} that inserts a {@link Reshuffle.ViaRandomKey}
     * before a {@link ParDo.MultiOutput} that uses the {@link RequiresStableInput} annotation.
     */
    static <InputT, OutputT>
        PTransformOverrideFactory<
                PCollection<InputT>, PCollectionTuple, ParDo.MultiOutput<InputT, OutputT>>
            multiOutputOverrideFactory() {
      return new MultiOutputOverrideFactory<>();
    }
  
    private static class SingleOutputOverrideFactory<InputT, OutputT>
        implements PTransformOverrideFactory<
            PCollection<InputT>, PCollection<OutputT>, ParDo.SingleOutput<InputT, OutputT>> {
  
      @Override
      public PTransformReplacement<PCollection<InputT>, PCollection<OutputT>> getReplacementTransform(
          AppliedPTransform<
                  PCollection<InputT>, PCollection<OutputT>, ParDo.SingleOutput<InputT, OutputT>>
              appliedTransform) {
        return PTransformReplacement.of(
            PTransformReplacements.getSingletonMainInput(appliedTransform),
            new PTransform<PCollection<InputT>, PCollection<OutputT>>() {
              @Override
              public PCollection<OutputT> expand(PCollection<InputT> input) {
                return input
                    .apply("Materialize input", Reshuffle.viaRandomKey())
                    .apply("ParDo with stable input", appliedTransform.getTransform());
              }
            });
      }
  
      @Override
      public Map<PCollection<?>, ReplacementOutput> mapOutputs(
          Map<TupleTag<?>, PCollection<?>> outputs, PCollection<OutputT> newOutput) {
        return ReplacementOutputs.singleton(outputs, newOutput);
      }
    }
  
    private static class MultiOutputOverrideFactory<InputT, OutputT>
        implements PTransformOverrideFactory<
            PCollection<InputT>, PCollectionTuple, ParDo.MultiOutput<InputT, OutputT>> {
  
      @Override
      public PTransformReplacement<PCollection<InputT>, PCollectionTuple> getReplacementTransform(
          AppliedPTransform<PCollection<InputT>, PCollectionTuple, ParDo.MultiOutput<InputT, OutputT>>
              appliedTransform) {
        return PTransformReplacement.of(
            PTransformReplacements.getSingletonMainInput(appliedTransform),
            new PTransform<PCollection<InputT>, PCollectionTuple>() {
              @Override
              public PCollectionTuple expand(PCollection<InputT> input) {
                return input
                    .apply("Materialize input", Reshuffle.viaRandomKey())
                    .apply("ParDo with stable input", appliedTransform.getTransform());
              }
            });
      }
  
      @Override
      public Map<PCollection<?>, ReplacementOutput> mapOutputs(
          Map<TupleTag<?>, PCollection<?>> outputs, PCollectionTuple newOutput) {
        return ReplacementOutputs.tagged(outputs, newOutput);
      }
    }
  }
  