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   * Licensed to the Apache Software Foundation (ASF) under one
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   * distributed with this work for additional information
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   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
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   *
   *     http://www.apache.org/licenses/LICENSE-2.0
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  package org.apache.beam.sdk.nexmark.queries;
  
  import org.apache.beam.sdk.nexmark.NexmarkConfiguration;
  import org.apache.beam.sdk.nexmark.model.Bid;
  import org.apache.beam.sdk.nexmark.model.BidsPerSession;
  import org.apache.beam.sdk.nexmark.model.Event;
  import org.apache.beam.sdk.transforms.Count;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.windowing.AfterProcessingTime;
  import org.apache.beam.sdk.transforms.windowing.GlobalWindows;
  import org.apache.beam.sdk.transforms.windowing.Repeatedly;
  import org.apache.beam.sdk.transforms.windowing.Window;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.joda.time.Duration;
  
  /**
   * Query "12", 'Processing time windows' (Not in original suite.)
   *
   * <p>Group bids by the same user into processing time windows of windowSize. Emit the count of bids
   * per window.
   */
  public class Query12 extends NexmarkQueryTransform<BidsPerSession> {
    private final NexmarkConfiguration configuration;
  
    public Query12(NexmarkConfiguration configuration) {
      super("Query12");
      this.configuration = configuration;
    }
  
    @Override
    public PCollection<BidsPerSession> expand(PCollection<Event> events) {
      return events
          .apply(NexmarkQueryUtil.JUST_BIDS)
          .apply(
              ParDo.of(
                  new DoFn<Bid, Long>() {
                    @ProcessElement
                    public void processElement(ProcessContext c) {
                      c.output(c.element().bidder);
                    }
                  }))
          .apply(
              Window.<Long>into(new GlobalWindows())
                  .triggering(
                      Repeatedly.forever(
                          AfterProcessingTime.pastFirstElementInPane()
                              .plusDelayOf(Duration.standardSeconds(configuration.windowSizeSec))))
                  .discardingFiredPanes()
                  .withAllowedLateness(Duration.ZERO))
          .apply(Count.perElement())
          .apply(
              name + ".ToResult",
              ParDo.of(
                  new DoFn<KV<Long, Long>, BidsPerSession>() {
                    @ProcessElement
                    public void processElement(ProcessContext c) {
                      c.output(new BidsPerSession(c.element().getKey(), c.element().getValue()));
                    }
                  }));
    }
  }
  