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 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.coders.IterableCoder;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.values.TupleTag;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  
  /**
   * A {@link ParDoFn} that writes side input data using {@link
   * StreamingModeExecutionContext.StreamingModeStepContext#writePCollectionViewData}.
   */
  @SuppressWarnings({"keyfor", "nullness"}) // TODO(https://github.com/apache/beam/issues/20497)
  public class StreamingPCollectionViewWriterParDoFn implements ParDoFn {
  
    private final StreamingModeExecutionContext.StreamingModeStepContext stepContext;
    private final TupleTag<?> viewTag;
    private final Coder<Object> elemCoder;
    private final Coder<BoundedWindow> windowCoder;
  
    public StreamingPCollectionViewWriterParDoFn(
        StreamingModeExecutionContext.StreamingModeStepContext stepContext,
        TupleTag<?> viewTag,
        Coder<Object> elemCoder,
        Coder<BoundedWindow> windowCoder) {
      this.stepContext = stepContext;
      this.viewTag = viewTag;
      this.elemCoder = elemCoder;
      this.windowCoder = windowCoder;
    }
  
    @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);
    }
  
    @Override
    public void processElement(Object element) throws Exception {
      WindowedValue<Iterable<Object>> elemsToWrite = (WindowedValue<Iterable<Object>>) element;
      BoundedWindow window = Iterables.getOnlyElement(elemsToWrite.getWindows());
  
      stepContext.writePCollectionViewData(
          viewTag, elemsToWrite.getValue(), IterableCoder.of(elemCoder), window, windowCoder);
    }
  
    @Override
    public void processTimers() {}
  
    @Override
    public void finishBundle() throws Exception {}
  
    @Override
    public void abort() throws Exception {
      // no-op as long as it remains stateless
    }
  }
  