Akka/Scala example source code file (StatsAggregator.java)

This example Akka source code file (StatsAggregator.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor, actorref, akka, arraylist, cluster, concurrent, duration, integer, jobfailed, list, override, service, statsaggregator, statsresult, time, untypedactor

The StatsAggregator.java Akka example source code

package sample.cluster.stats;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

import sample.cluster.stats.StatsMessages.JobFailed;
import sample.cluster.stats.StatsMessages.StatsResult;
import scala.concurrent.duration.Duration;
import akka.actor.ActorRef;
import akka.actor.ReceiveTimeout;
import akka.actor.UntypedActor;

//#aggregator
public class StatsAggregator extends UntypedActor {

  final int expectedResults;
  final ActorRef replyTo;
  final List<Integer> results = new ArrayList<Integer>();

  public StatsAggregator(int expectedResults, ActorRef replyTo) {
    this.expectedResults = expectedResults;
    this.replyTo = replyTo;
  }

  @Override
  public void preStart() {
    getContext().setReceiveTimeout(Duration.create(3, TimeUnit.SECONDS));
  }

  @Override
  public void onReceive(Object message) {
    if (message instanceof Integer) {
      Integer wordCount = (Integer) message;
      results.add(wordCount);
      if (results.size() == expectedResults) {
        int sum = 0;
        for (int c : results)
          sum += c;
        double meanWordLength = ((double) sum) / results.size();
        replyTo.tell(new StatsResult(meanWordLength), getSelf());
        getContext().stop(getSelf());
      }

    } else if (message == ReceiveTimeout.getInstance()) {
      replyTo.tell(new JobFailed("Service unavailable, try again later"),
          getSelf());
      getContext().stop(getSelf());

    } else {
      unhandled(message);
    }
  }

}
//#aggregator