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.runners.dataflow.util.Structs.getBytes;
  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.Collection;
  import java.util.List;
  import java.util.Map;
  import org.apache.beam.runners.dataflow.util.CloudObject;
  import org.apache.beam.runners.dataflow.util.PropertyNames;
  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.options.PipelineOptions;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.WindowFn;
  import org.apache.beam.sdk.values.TupleTag;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.beam.sdk.values.WindowingStrategy;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  import org.checkerframework.checker.nullness.qual.Nullable;
  import org.joda.time.Instant;
  
  /**
   * A {@link ParDoFnFactory} to create instances of AssignWindowsDoFn according to specifications
   * from the Dataflow service.
   */
  class AssignWindowsParDoFnFactory 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 {
  
      byte[] encodedWindowingStrategy = getBytes(cloudUserFn, PropertyNames.SERIALIZED_FN);
  
      WindowingStrategy<?, ?> deserializedWindowingStrategy =
          GroupAlsoByWindowParDoFnFactory.deserializeWindowingStrategy(encodedWindowingStrategy);
  
      @SuppressWarnings("unchecked")
      WindowingStrategy<Object, BoundedWindow> windowingStrategy =
          (WindowingStrategy<Object, BoundedWindow>) deserializedWindowingStrategy;
  
      return new AssignWindowsParDoFn<>(windowingStrategy.getWindowFn());
    }
  
    private static class AssignWindowsParDoFn<T, W extends BoundedWindow> implements ParDoFn {
      private final WindowFn<T, W> windowFn;
  
      private @Nullable Receiver receiver;
  
      AssignWindowsParDoFn(WindowFn<T, W> windowFn) {
        this.windowFn = windowFn;
      }
  
      @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);
        receiver = receivers[0];
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public void processElement(Object untypedElem) throws Exception {
        WindowedValue<T> elem = (WindowedValue<T>) untypedElem;
  
        Collection<W> windows =
            windowFn.assignWindows(
                windowFn.new AssignContext() {
                  @Override
                  public T element() {
                    return elem.getValue();
                  }
  
                  @Override
                  public Instant timestamp() {
                    return elem.getTimestamp();
                  }
  
                  @Override
                  public BoundedWindow window() {
                    return Iterables.getOnlyElement(elem.getWindows());
                  }
                });
  
        WindowedValues.builder(elem).setWindows(windows).setReceiver(receiver::process).output();
      }
  
      @Override
      public void processTimers() throws Exception {
        // Nothing.
      }
  
      @Override
      public void finishBundle() throws Exception {
        receiver = null;
      }
  
      @Override
      public void abort() throws Exception {
        receiver = null;
      }
    }
  }
  