LongSumAggregator.java

package org.calrissian.flowbox.support.aggregator;

import org.apache.commons.lang.StringUtils;
import org.calrissian.flowbox.model.Event;
import org.calrissian.flowbox.model.Tuple;
import org.calrissian.flowbox.support.AggregatedEvent;
import org.calrissian.flowbox.support.Aggregator;
import org.calrissian.flowbox.support.WindowItem;

import java.util.*;

import static java.lang.System.currentTimeMillis;
import static java.util.UUID.randomUUID;

public class LongSumAggregator implements Aggregator {

  public static final String SUM_FIELD = "sumField";
  public static final String OUTPUT_FIELD = "outputField";

  public static final String DEFAULT_OUTPUT_FIELD = "sum";

  private String sumField;

  private String outputField = DEFAULT_OUTPUT_FIELD;
  private Map<String,Set<Tuple>> groupedValues;

  private String[] groupByFields;
  private long sum = 0;

  @Override
  public void configure(Map<String, String> configuration) {

    if(configuration.get(GROUP_BY) != null)
      groupByFields = StringUtils.splitPreserveAllTokens(configuration.get(GROUP_BY), GROUP_BY_DELIM);

    if(configuration.get(OUTPUT_FIELD) != null)
      outputField = configuration.get(OUTPUT_FIELD);

    if(configuration.get(SUM_FIELD) != null)
      sumField = configuration.get(SUM_FIELD);
    else
      throw new RuntimeException("Sum aggregator needs a field to sum. Property missing: " + SUM_FIELD);

  }

  @Override
    public void added(WindowItem item) {
      if(groupedValues == null && groupByFields != null) {
        groupedValues = new HashMap<String, Set<Tuple>>();
        for(String group : groupByFields)
          groupedValues.put(group, item.getEvent().getAll(group));
      }

      if(item.getEvent().get(sumField) != null)
        sum += ((Long)item.getEvent().get(sumField).getValue());
    }

    @Override
    public void evicted(WindowItem item) {

      if(item.getEvent().get(sumField) != null)
        sum -= ((Long)item.getEvent().get(sumField).getValue());
    }

    @Override
    public List<AggregatedEvent> aggregate() {
      Event event = new Event(randomUUID().toString(), currentTimeMillis());
      if(groupedValues != null && groupByFields != null) {
        for(Set<Tuple> tuples : groupedValues.values())
          event.putAll(tuples);
      }

      event.put(new Tuple(outputField, sum));
      return Collections.singletonList(new AggregatedEvent(event));
    }
}