runners/spark/3/src/main/java/org/apache/beam/runners/spark/structuredstreaming/translation/helpers/MultiOutputCoder.java

/*
 * 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.spark.structuredstreaming.translation.helpers;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Map;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.coders.CoderException;
import org.apache.beam.sdk.coders.CustomCoder;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.TupleTag;
import scala.Tuple2;

/**
 * Coder to serialize and deserialize {@code}Tuple2<TupleTag<T>, WindowedValue<T>{/@code} to be used
 * in spark encoders while applying {@link org.apache.beam.sdk.transforms.DoFn}.
 *
 * @param <T> type of the elements in the collection
 */
@SuppressWarnings({
  "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
  "nullness" // TODO(https://github.com/apache/beam/issues/20497)
})
public class MultiOutputCoder<T> extends CustomCoder<Tuple2<TupleTag<T>, WindowedValue<T>>> {
  Coder<TupleTag> tupleTagCoder;
  Map<TupleTag<?>, Coder<?>> coderMap;
  Coder<? extends BoundedWindow> windowCoder;

  public static MultiOutputCoder of(
      Coder<TupleTag> tupleTagCoder,
      Map<TupleTag<?>, Coder<?>> coderMap,
      Coder<? extends BoundedWindow> windowCoder) {
    return new MultiOutputCoder(tupleTagCoder, coderMap, windowCoder);
  }

  private MultiOutputCoder(
      Coder<TupleTag> tupleTagCoder,
      Map<TupleTag<?>, Coder<?>> coderMap,
      Coder<? extends BoundedWindow> windowCoder) {
    this.tupleTagCoder = tupleTagCoder;
    this.coderMap = coderMap;
    this.windowCoder = windowCoder;
  }

  @Override
  public void encode(Tuple2<TupleTag<T>, WindowedValue<T>> tuple2, OutputStream outStream)
      throws IOException {
    TupleTag<T> tupleTag = tuple2._1();
    tupleTagCoder.encode(tupleTag, outStream);
    Coder<T> valueCoder = (Coder<T>) coderMap.get(tupleTag);
    WindowedValue.FullWindowedValueCoder<T> wvCoder =
        WindowedValue.FullWindowedValueCoder.of(valueCoder, windowCoder);
    wvCoder.encode(tuple2._2(), outStream);
  }

  @Override
  public Tuple2<TupleTag<T>, WindowedValue<T>> decode(InputStream inStream)
      throws CoderException, IOException {
    TupleTag<T> tupleTag = (TupleTag<T>) tupleTagCoder.decode(inStream);
    Coder<T> valueCoder = (Coder<T>) coderMap.get(tupleTag);
    WindowedValue.FullWindowedValueCoder<T> wvCoder =
        WindowedValue.FullWindowedValueCoder.of(valueCoder, windowCoder);
    WindowedValue<T> wv = wvCoder.decode(inStream);
    return Tuple2.apply(tupleTag, wv);
  }
}