pekko/akka-distributed-data/src/main/scala/akka/cluster/ddata/DistributedData.scala

/**
 * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
 */
package akka.cluster.ddata

import akka.actor.ActorRef
import akka.actor.ActorSystem
import akka.actor.ExtendedActorSystem
import akka.actor.Extension
import akka.actor.ExtensionId
import akka.actor.ExtensionIdProvider
import akka.cluster.Cluster

object DistributedData extends ExtensionId[DistributedData] with ExtensionIdProvider {
  override def get(system: ActorSystem): DistributedData = super.get(system)

  override def lookup = DistributedData

  override def createExtension(system: ExtendedActorSystem): DistributedData =
    new DistributedData(system)
}

/**
 * Akka extension for convenient configuration and use of the
 * [[Replicator]]. Configuration settings are defined in the
 * `akka.cluster.ddata` section, see `reference.conf`.
 */
class DistributedData(system: ExtendedActorSystem) extends Extension {

  private val config = system.settings.config.getConfig("akka.cluster.distributed-data")
  private val settings = ReplicatorSettings(config)

  /**
   * Returns true if this member is not tagged with the role configured for the
   * replicas.
   */
  def isTerminated: Boolean = Cluster(system).isTerminated || !settings.roles.subsetOf(Cluster(system).selfRoles)

  /**
   * `ActorRef` of the [[Replicator]] .
   */
  val replicator: ActorRef =
    if (isTerminated) {
      system.log.warning("Replicator points to dead letters: Make sure the cluster node is not terminated and has the proper role!")
      system.deadLetters
    } else {
      val name = config.getString("name")
      system.systemActorOf(Replicator.props(settings), name)
    }
}