eventsourced processor example

eventsourced-example.scala

case class ManyCommand(nums: List[Int])

case class State(count: Int) {
  def updated(more: Int) = State(count + more)
}

sealed trait Event
case class AddOneEvent(num: Int) extends Event

class MultiCounter extends EventsourcedProcessor {

  var state = State(count = 0)

  def updateState(e: Event): Any = {
    case event: AddOneEvent => state.updated(event.num)
  }

  def receiveCommand = {
    case ManyCommand(many) =>
      for(event <- many map AddOneEvent)
        persist(event)(updateState(_))

    case event: AddOneEvent =>
      persist(event)(updateState(_))
  }

  /** MUST NOT SIDE-EFFECT! */
  def receiveRecover = {
    case SnapshotOffer(meta, snapshot: State) => this.state = state
    case replayedEvent: Event                 => updateState(replayedEvent)
  }
}