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.worker;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState;
  
  import com.google.api.services.dataflow.model.SideInputInfo;
  import java.util.List;
  import java.util.Map;
  import org.apache.beam.runners.dataflow.util.CloudObject;
  import org.apache.beam.runners.dataflow.util.CloudObjects;
  import org.apache.beam.runners.dataflow.util.PropertyNames;
  import org.apache.beam.runners.dataflow.util.Structs;
  import org.apache.beam.runners.dataflow.worker.util.WorkerPropertyNames;
  import org.apache.beam.runners.dataflow.worker.util.common.worker.ParDoFn;
  import org.apache.beam.runners.dataflow.worker.util.common.worker.Receiver;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.util.CoderUtils;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.TupleTag;
  import org.apache.beam.sdk.values.WindowedValue;
  
  /**
   * A {@link ParDoFnFactory} which returns a {@link ParDoFn} that transforms all {@code
   * WindowedValue<V>} to {@code WindowedValue<KV<K, V>>} for a constant key {@code K}.
   */
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class PairWithConstantKeyDoFnFactory implements ParDoFnFactory {
    @Override
    public ParDoFn create(
        PipelineOptions options,
        CloudObject cloudUserFn,
        List<SideInputInfo> sideInputInfos,
        TupleTag<?> mainOutputTag,
        Map<TupleTag<?>, Integer> outputTupleTagsToReceiverIndices,
        DataflowExecutionContext<?> executionContext,
        DataflowOperationContext operationContext)
        throws Exception {
      Coder<?> coder =
          CloudObjects.coderFromCloudObject(
              CloudObject.fromSpec(Structs.getObject(cloudUserFn, PropertyNames.ENCODING)));
      Object key =
          CoderUtils.decodeFromByteArray(
              coder, Structs.getBytes(cloudUserFn, WorkerPropertyNames.ENCODED_KEY));
      return new PairWithConstantKeyParDoFn(key);
    }
  
    /**
     * A {@link ParDoFn} that transforms all {@code WindowedValue<V>} to {@code WindowedValue<KV<K,
     * V>>} for a constant key {@code K}.
     */
    private static class PairWithConstantKeyParDoFn<K> implements ParDoFn {
  
      private final K key;
      private Receiver receiver;
  
      PairWithConstantKeyParDoFn(K key) {
        this.key = key;
      }
  
      @Override
      public void startBundle(Receiver... receivers) throws Exception {
        checkState(
            receivers.length == 1,
            "%s.startBundle() called with %s receivers, expected exactly 1. "
                + "This is a bug in the Dataflow service",
            getClass().getSimpleName(),
            receivers.length);
        this.receiver = receivers[0];
      }
  
      @Override
      public void processElement(Object untypedElem) throws Exception {
        @SuppressWarnings("unchecked")
        WindowedValue<Object> elem = (WindowedValue) untypedElem;
        receiver.process(elem.withValue(KV.of(key, elem.getValue())));
      }
  
      @Override
      public void processTimers() {}
  
      @Override
      public void finishBundle() {}
  
      @Override
      public void abort() {}
    }
  }
  