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.sdk.nexmark.queries;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  import org.apache.beam.sdk.nexmark.NexmarkConfiguration;
  import org.apache.beam.sdk.nexmark.NexmarkUtils;
  import org.apache.beam.sdk.nexmark.model.AuctionCount;
  import org.apache.beam.sdk.nexmark.model.Bid;
  import org.apache.beam.sdk.nexmark.model.Event;
  import org.apache.beam.sdk.values.TimestampedValue;
  import org.joda.time.Duration;
  import org.joda.time.Instant;
  
  /** A direct implementation of {@link Query5}. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class Query5Model extends NexmarkQueryModel<AuctionCount> implements Serializable {
    /** Simulator for query 5. */
    private class Simulator extends AbstractSimulator<Event, AuctionCount> {
      /** Time of bids still contributing to open windows, indexed by their auction id. */
      private final Map<Long, List<Instant>> bids;
  
      /** When oldest active window starts. */
      private Instant windowStart;
  
      public Simulator(NexmarkConfiguration configuration) {
        super(NexmarkUtils.standardEventIterator(configuration));
        bids = new TreeMap<>();
        windowStart = NexmarkUtils.BEGINNING_OF_TIME;
      }
  
      /**
       * Count bids per auction id for bids strictly before {@code end}. Add the auction ids with the
       * maximum number of bids to results.
       */
      private void countBids(Instant end) {
        Map<Long, Long> counts = new TreeMap<>();
        long maxCount = 0L;
        for (Map.Entry<Long, List<Instant>> entry : bids.entrySet()) {
          long count = 0L;
          long auction = entry.getKey();
          for (Instant bid : entry.getValue()) {
            if (bid.isBefore(end)) {
              count++;
            }
          }
          if (count > 0) {
            counts.put(auction, count);
            maxCount = Math.max(maxCount, count);
          }
        }
        for (Map.Entry<Long, Long> entry : counts.entrySet()) {
          long auction = entry.getKey();
          long count = entry.getValue();
          if (count == maxCount) {
            AuctionCount result = new AuctionCount(auction, count);
            addResult(TimestampedValue.of(result, end));
          }
        }
      }
  
      /**
       * Retire bids which are strictly before {@code cutoff}. Return true if there are any bids
       * remaining.
       */
      private boolean retireBids(Instant cutoff) {
        boolean anyRemain = false;
        for (Map.Entry<Long, List<Instant>> entry : bids.entrySet()) {
          long auction = entry.getKey();
          Iterator<Instant> itr = entry.getValue().iterator();
          while (itr.hasNext()) {
            Instant bid = itr.next();
            if (bid.isBefore(cutoff)) {
              NexmarkUtils.info("retire: %s for %s", bid, auction);
              itr.remove();
            } else {
              anyRemain = true;
            }
          }
        }
        return anyRemain;
      }
  
      /** Retire active windows until we've reached {@code newWindowStart}. */
      private void retireWindows(Instant newWindowStart) {
        while (!newWindowStart.equals(windowStart)) {
          NexmarkUtils.info("retiring window %s, aiming for %s", windowStart, newWindowStart);
          // Count bids in the window (windowStart, windowStart + size].
          countBids(windowStart.plus(Duration.standardSeconds(configuration.windowSizeSec)));
          // Advance the window.
          windowStart = windowStart.plus(Duration.standardSeconds(configuration.windowPeriodSec));
          // Retire bids which will never contribute to a future window.
          if (!retireBids(windowStart)) {
            // Can fast forward to latest window since no more outstanding bids.
            windowStart = newWindowStart;
          }
        }
      }
  
      /** Add bid to state. */
      private void captureBid(Bid bid, Instant timestamp) {
        List<Instant> existing = bids.computeIfAbsent(bid.auction, k -> new ArrayList<>());
        existing.add(timestamp);
      }
  
      @Override
      public void run() {
        TimestampedValue<Event> timestampedEvent = nextInput();
        if (timestampedEvent == null) {
          // Drain the remaining windows.
          retireWindows(NexmarkUtils.END_OF_TIME);
          allDone();
          return;
        }
  
        Event event = timestampedEvent.getValue();
        if (event.bid == null) {
          // Ignore non-bid events.
          return;
        }
        Instant timestamp = timestampedEvent.getTimestamp();
        Instant newWindowStart =
            windowStart(
                Duration.standardSeconds(configuration.windowSizeSec),
                Duration.standardSeconds(configuration.windowPeriodSec),
                timestamp);
        // Capture results from any windows we can now retire.
        retireWindows(newWindowStart);
        // Capture current bid.
        captureBid(event.bid, timestamp);
      }
    }
  
    public Query5Model(NexmarkConfiguration configuration) {
      super(configuration);
    }
  
    @Override
    public AbstractSimulator<?, AuctionCount> simulator() {
      return new Simulator(configuration);
    }
  
    @Override
    protected Collection<String> toCollection(Iterator<TimestampedValue<AuctionCount>> itr) {
      return toValue(itr);
    }
  }
  