Akka/Scala example source code file (StatsSampleSpec.scala)

This example Akka source code file (StatsSampleSpec.scala) 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, akka, cluster, concurrent, implicitsender, multinodeconfig, multinodespec, set, statssamplespec, statssamplespecconfig, statssamplespecmultijvmnode1, test, testing, the, wordspeclike

The StatsSampleSpec.scala Akka example source code

package sample.cluster.stats

import language.postfixOps
import scala.concurrent.duration._

import akka.actor.Props
import akka.actor.RootActorPath
import akka.cluster.Cluster
import akka.cluster.Member
import akka.cluster.MemberStatus
import akka.cluster.ClusterEvent.CurrentClusterState
import akka.cluster.ClusterEvent.MemberUp

//#MultiNodeConfig
import akka.remote.testkit.MultiNodeConfig
import com.typesafe.config.ConfigFactory

object StatsSampleSpecConfig extends MultiNodeConfig {
  // register the named roles (nodes) of the test
  val first = role("first")
  val second = role("second")
  val third = role("thrid")

  // this configuration will be used for all nodes
  // note that no fixed host names and ports are used
  commonConfig(ConfigFactory.parseString("""
    akka.actor.provider = "akka.cluster.ClusterActorRefProvider"
    akka.remote.log-remote-lifecycle-events = off
    akka.cluster.roles = [compute]
    # don't use sigar for tests, native lib not in path
    akka.cluster.metrics.collector-class = akka.cluster.JmxMetricsCollector
    #//#router-lookup-config
    akka.actor.deployment {
      /statsService/workerRouter {
          router = consistent-hashing-group
          nr-of-instances = 100
          routees.paths = ["/user/statsWorker"]
          cluster {
            enabled = on
            allow-local-routees = on
            use-role = compute
          }
        }
    }
    #//#router-lookup-config
    """))

}
//#MultiNodeConfig

//#concrete-tests
// need one concrete test class per node
class StatsSampleSpecMultiJvmNode1 extends StatsSampleSpec
class StatsSampleSpecMultiJvmNode2 extends StatsSampleSpec
class StatsSampleSpecMultiJvmNode3 extends StatsSampleSpec
//#concrete-tests

//#abstract-test
import org.scalatest.BeforeAndAfterAll
import org.scalatest.WordSpecLike
import org.scalatest.Matchers
import akka.remote.testkit.MultiNodeSpec
import akka.testkit.ImplicitSender

abstract class StatsSampleSpec extends MultiNodeSpec(StatsSampleSpecConfig)
  with WordSpecLike with Matchers with BeforeAndAfterAll
  with ImplicitSender {

  import StatsSampleSpecConfig._

  override def initialParticipants = roles.size

  override def beforeAll() = multiNodeSpecBeforeAll()

  override def afterAll() = multiNodeSpecAfterAll()

  //#abstract-test

  "The stats sample" must {

    //#startup-cluster
    "illustrate how to startup cluster" in within(15 seconds) {
      Cluster(system).subscribe(testActor, classOf[MemberUp])
      expectMsgClass(classOf[CurrentClusterState])

      //#addresses
      val firstAddress = node(first).address
      val secondAddress = node(second).address
      val thirdAddress = node(third).address
      //#addresses

      //#join
      Cluster(system) join firstAddress
      //#join

      system.actorOf(Props[StatsWorker], "statsWorker")
      system.actorOf(Props[StatsService], "statsService")

      receiveN(3).collect { case MemberUp(m) => m.address }.toSet should be(
        Set(firstAddress, secondAddress, thirdAddress))

      Cluster(system).unsubscribe(testActor)

      testConductor.enter("all-up")
    }
    //#startup-cluster

    //#test-statsService
    "show usage of the statsService from one node" in within(15 seconds) {
      runOn(second) {
        assertServiceOk()
      }

      testConductor.enter("done-2")
    }

    def assertServiceOk(): Unit = {
      val service = system.actorSelection(node(third) / "user" / "statsService")
      // eventually the service should be ok,
      // first attempts might fail because worker actors not started yet
      awaitAssert {
        service ! StatsJob("this is the text that will be analyzed")
        expectMsgType[StatsResult](1.second).meanWordLength should be(
          3.875 +- 0.001)
      }

    }
    //#test-statsService

    "show usage of the statsService from all nodes" in within(15 seconds) {
      assertServiceOk()
      testConductor.enter("done-3")
    }

  }

}