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

/*
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 * 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
 *
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package org.apache.beam.runners.spark.structuredstreaming.translation.helpers;

import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.KV;
import org.apache.spark.api.java.function.MapFunction;

/** Helper functions for working with {@link org.apache.beam.sdk.values.KV}. */
public final class KVHelpers {

  /** A Spark {@link MapFunction} for extracting the key out of a {@link KV} for GBK for example. */
  public static <K, V> MapFunction<WindowedValue<KV<K, V>>, K> extractKey() {
    return wv -> wv.getValue().getKey();
  }
}