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

This example Akka source code file (GossipSpec.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

a, actor, akka, cluster, collection, exiting, gossip, gossipoverview, immutable, joining, leaving, matchers, sortedset, testmember, up

The GossipSpec.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.cluster

import org.scalatest.WordSpec
import org.scalatest.Matchers
import akka.actor.Address
import scala.collection.immutable.SortedSet

@org.junit.runner.RunWith(classOf[org.scalatest.junit.JUnitRunner])
class GossipSpec extends WordSpec with Matchers {

  import MemberStatus._

  val a1 = TestMember(Address("akka.tcp", "sys", "a", 2552), Up)
  val a2 = TestMember(a1.address, Joining)
  val b1 = TestMember(Address("akka.tcp", "sys", "b", 2552), Up)
  val b2 = TestMember(b1.address, Removed)
  val c1 = TestMember(Address("akka.tcp", "sys", "c", 2552), Leaving)
  val c2 = TestMember(c1.address, Up)
  val c3 = TestMember(c1.address, Exiting)
  val d1 = TestMember(Address("akka.tcp", "sys", "d", 2552), Leaving)
  val e1 = TestMember(Address("akka.tcp", "sys", "e", 2552), Joining)
  val e2 = TestMember(e1.address, Up)
  val e3 = TestMember(e1.address, Down)

  "A Gossip" must {

    "reach convergence when it's empty" in {
      Gossip.empty.convergence should be(true)
    }

    "merge members by status priority" in {
      val g1 = Gossip(members = SortedSet(a1, c1, e1))
      val g2 = Gossip(members = SortedSet(a2, c2, e2))

      val merged1 = g1 merge g2
      merged1.members should be(SortedSet(a2, c1, e1))
      merged1.members.toSeq.map(_.status) should be(Seq(Up, Leaving, Up))

      val merged2 = g2 merge g1
      merged2.members should be(SortedSet(a2, c1, e1))
      merged2.members.toSeq.map(_.status) should be(Seq(Up, Leaving, Up))

    }

    "merge unreachable" in {
      val r1 = Reachability.empty.unreachable(b1.uniqueAddress, a1.uniqueAddress).unreachable(b1.uniqueAddress, c1.uniqueAddress)
      val g1 = Gossip(members = SortedSet(a1, b1, c1), overview = GossipOverview(reachability = r1))
      val r2 = Reachability.empty.unreachable(a1.uniqueAddress, d1.uniqueAddress)
      val g2 = Gossip(members = SortedSet(a1, b1, c1, d1), overview = GossipOverview(reachability = r2))

      val merged1 = g1 merge g2
      merged1.overview.reachability.allUnreachable should be(Set(a1.uniqueAddress, c1.uniqueAddress, d1.uniqueAddress))

      val merged2 = g2 merge g1
      merged2.overview.reachability.allUnreachable should be(merged1.overview.reachability.allUnreachable)
    }

    "merge members by removing removed members" in {
      // c3 removed
      val r1 = Reachability.empty.unreachable(b1.uniqueAddress, a1.uniqueAddress)
      val g1 = Gossip(members = SortedSet(a1, b1), overview = GossipOverview(reachability = r1))
      val r2 = r1.unreachable(b1.uniqueAddress, c3.uniqueAddress)
      val g2 = Gossip(members = SortedSet(a1, b1, c3), overview = GossipOverview(reachability = r2))

      val merged1 = g1 merge g2
      merged1.members should be(SortedSet(a1, b1))
      merged1.overview.reachability.allUnreachable should be(Set(a1.uniqueAddress))

      val merged2 = g2 merge g1
      merged2.overview.reachability.allUnreachable should be(merged1.overview.reachability.allUnreachable)
      merged2.members should be(merged1.members)
    }

    "have leader as first member based on ordering, except Exiting status" in {
      Gossip(members = SortedSet(c2, e2)).leader should be(Some(c2.uniqueAddress))
      Gossip(members = SortedSet(c3, e2)).leader should be(Some(e2.uniqueAddress))
      Gossip(members = SortedSet(c3)).leader should be(Some(c3.uniqueAddress))
    }

    "merge seen table correctly" in {
      val vclockNode = VectorClock.Node("something")
      val g1 = (Gossip(members = SortedSet(a1, b1, c1, d1)) :+ vclockNode).seen(a1.uniqueAddress).seen(b1.uniqueAddress)
      val g2 = (Gossip(members = SortedSet(a1, b1, c1, d1)) :+ vclockNode).seen(a1.uniqueAddress).seen(c1.uniqueAddress)
      val g3 = (g1 copy (version = g2.version)).seen(d1.uniqueAddress)

      def checkMerged(merged: Gossip) {
        val seen = merged.overview.seen.toSeq
        seen.length should be(0)

        merged seenByNode (a1.uniqueAddress) should be(false)
        merged seenByNode (b1.uniqueAddress) should be(false)
        merged seenByNode (c1.uniqueAddress) should be(false)
        merged seenByNode (d1.uniqueAddress) should be(false)
        merged seenByNode (e1.uniqueAddress) should be(false)
      }

      checkMerged(g3 merge g2)
      checkMerged(g2 merge g3)
    }

    "know who is youngest" in {
      // a2 and e1 is Joining
      val g1 = Gossip(members = SortedSet(a2, b1.copyUp(3), e1), overview = GossipOverview(reachability =
        Reachability.empty.unreachable(a2.uniqueAddress, e1.uniqueAddress)))
      g1.youngestMember should be(b1)
      val g2 = Gossip(members = SortedSet(a2, b1.copyUp(3), e1), overview = GossipOverview(reachability =
        Reachability.empty.unreachable(a2.uniqueAddress, b1.uniqueAddress).unreachable(a2.uniqueAddress, e1.uniqueAddress)))
      g2.youngestMember should be(b1)
      val g3 = Gossip(members = SortedSet(a2, b1.copyUp(3), e2.copyUp(4)))
      g3.youngestMember should be(e2)
    }
  }
}