Statefull Akka Prime Example

StatefulPrime.java

package com.lightbend.akka.sample;

import akka.actor.*;

public class StatefulPrime {

    static class IsPrimeActor extends AbstractLoggingActor {

        // Define the actor protocol
        static class IsPrimeRequest {
            long candidate;
            IsPrimeRequest(long candidate){this.candidate = candidate;}
        }

        static class IsPrimeResponse {
            long candidate;
            boolean isPrime;

            IsPrimeResponse(long candidate, boolean isPrime){
                this.candidate = candidate;
                this.isPrime = isPrime;
            }
        }

        // The actor can have "state"
        private int numberOfPrimeRequests;

        public static Props props() {
            return Props.create(IsPrimeActor.class);
        }

        @Override
        public void preStart() {
            log().info("Starting the isPrime actor");
            numberOfPrimeRequests = 0;
        }

        private void onPrimeRequest(IsPrimeRequest msg) {

            numberOfPrimeRequests++;
            long candidate = msg.candidate;
            boolean prime = isPrime(candidate);
            log().info("Request {} '{}' prime? {}", + numberOfPrimeRequests, candidate, prime);
            getSender().tell(new IsPrimeResponse(candidate, prime), getSelf());
        }

        @Override
        public Receive createReceive() {
            return receiveBuilder()
                    .match(IsPrimeRequest.class, this::onPrimeRequest)
                    .build();
        }

        private boolean isPrime(long n) {
            if (n <= 3) {
                return n > 1;
            } else if (n % 2 == 0 || n % 3 == 0) {
                return false;
            } else {
                for (int i = 5; i * i <= n; i += 6) {
                    if (n % i == 0 || n % (i + 2) == 0) {
                        return false;
                    }
                }
                return true;
            }
        }
    }
}

StatefulPrimeTest.java

package com.lightbend.akka.sample;

import static org.junit.Assert.*;

import akka.actor.ActorRef;
import akka.actor.ActorSystem;

import akka.testkit.javadsl.TestKit;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import java.util.Optional;

import static org.junit.Assert.*;

public class StatefulPrimeTest {
  static ActorSystem system;

  @BeforeClass
  public static void setup() {
    system = ActorSystem.create();
  }

  @AfterClass
  public static void teardown() {
    TestKit.shutdownActorSystem(system);
    system = null;
  }

  @Test
  public void testReplyWithSmallCandidates() {
    TestKit probe = new TestKit(system);
    ActorRef primeActor = system.actorOf(StatefulPrime.IsPrimeActor.props());

    primeActor.tell(new StatefulPrime.IsPrimeActor.IsPrimeRequest(42L), probe.getRef());

    StatefulPrime.IsPrimeActor.IsPrimeResponse response = probe.expectMsgClass(StatefulPrime.IsPrimeActor.IsPrimeResponse.class);

    assertEquals(42L, response.candidate);
    assertEquals(false, response.isPrime);
  }

  @Test
  public void testReplyWithMultipleCandidates() {
    TestKit probe = new TestKit(system);
    ActorRef primeActor = system.actorOf(StatefulPrime.IsPrimeActor.props());

    for (long i = 0; i < 100; i++) {
      primeActor.tell(new StatefulPrime.IsPrimeActor.IsPrimeRequest(i), probe.getRef());

      StatefulPrime.IsPrimeActor.IsPrimeResponse response = probe.expectMsgClass(StatefulPrime.IsPrimeActor.IsPrimeResponse.class);

      assertEquals(i, response.candidate);
    }
  }

}