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/**
 * Copyright (C) 2009-2016 Lightbend Inc. 
 */
package akka.routing

import java.util.concurrent.atomic.AtomicLong
import scala.collection.immutable
import akka.dispatch.Dispatchers
import com.typesafe.config.Config
import akka.actor.SupervisorStrategy
import akka.japi.Util.immutableSeq
import akka.actor.ActorSystem

object RoundRobinRoutingLogic {
  def apply(): RoundRobinRoutingLogic = new RoundRobinRoutingLogic
}

/**
 * Uses round-robin to select a routee. For concurrent calls,
 * round robin is just a best effort.
 */
@SerialVersionUID(1L)
final class RoundRobinRoutingLogic extends RoutingLogic {
  val next = new AtomicLong

  override def select(message: Any, routees: immutable.IndexedSeq[Routee]): Routee =
    if (routees.nonEmpty) {
      val size = routees.size
      val index = (next.getAndIncrement % size).asInstanceOf[Int]
      routees(if (index < 0) size + index - 1 else index)
    } else NoRoutee

}

/**
 * A router pool that uses round-robin to select a routee. For concurrent calls,
 * round robin is just a best effort.
 *
 * The configuration parameter trumps the constructor arguments. This means that
 * if you provide `nrOfInstances` during instantiation they will be ignored if
 * the router is defined in the configuration file for the actor being used.
 *
 * 

Supervision Setup

* * Any routees that are created by a router will be created as the router's children. * The router is therefore also the children's supervisor. * * The supervision strategy of the router actor can be configured with * [[#withSupervisorStrategy]]. If no strategy is provided, routers default to * a strategy of “always escalate”. This means that errors are passed up to the * router's supervisor for handling. * * The router's supervisor will treat the error as an error with the router itself. * Therefore a directive to stop or restart will cause the router itself to stop or * restart. The router, in turn, will cause its children to stop and restart. * * @param nrOfInstances initial number of routees in the pool * * @param resizer optional resizer that dynamically adjust the pool size * * @param supervisorStrategy strategy for supervising the routees, see 'Supervision Setup' * * @param routerDispatcher dispatcher to use for the router head actor, which handles * supervision, death watch and router management messages */ @SerialVersionUID(1L) final case class RoundRobinPool( override val nrOfInstances: Int, override val resizer: Option[Resizer] = None, override val supervisorStrategy: SupervisorStrategy = Pool.defaultSupervisorStrategy, override val routerDispatcher: String = Dispatchers.DefaultDispatcherId, override val usePoolDispatcher: Boolean = false) extends Pool with PoolOverrideUnsetConfig[RoundRobinPool] { def this(config: Config) = this( nrOfInstances = config.getInt("nr-of-instances"), resizer = Resizer.fromConfig(config), usePoolDispatcher = config.hasPath("pool-dispatcher")) /** * Java API * @param nr initial number of routees in the pool */ def this(nr: Int) = this(nrOfInstances = nr) override def createRouter(system: ActorSystem): Router = new Router(RoundRobinRoutingLogic()) override def nrOfInstances(sys: ActorSystem) = this.nrOfInstances /** * Setting the supervisor strategy to be used for the “head” Router actor. */ def withSupervisorStrategy(strategy: SupervisorStrategy): RoundRobinPool = copy(supervisorStrategy = strategy) /** * Setting the resizer to be used. */ def withResizer(resizer: Resizer): RoundRobinPool = copy(resizer = Some(resizer)) /** * Setting the dispatcher to be used for the router head actor, which handles * supervision, death watch and router management messages. */ def withDispatcher(dispatcherId: String): RoundRobinPool = copy(routerDispatcher = dispatcherId) /** * Uses the resizer and/or the supervisor strategy of the given RouterConfig * if this RouterConfig doesn't have one, i.e. the resizer defined in code is used if * resizer was not defined in config. */ override def withFallback(other: RouterConfig): RouterConfig = this.overrideUnsetConfig(other) } /** * A router group that uses round-robin to select a routee. For concurrent calls, * round robin is just a best effort. * * The configuration parameter trumps the constructor arguments. This means that * if you provide `paths` during instantiation they will be ignored if * the router is defined in the configuration file for the actor being used. * * @param paths string representation of the actor paths of the routees, messages are * sent with [[akka.actor.ActorSelection]] to these paths * * @param routerDispatcher dispatcher to use for the router head actor, which handles * router management messages */ @SerialVersionUID(1L) final case class RoundRobinGroup( override val paths: immutable.Iterable[String], override val routerDispatcher: String = Dispatchers.DefaultDispatcherId) extends Group { def this(config: Config) = this(paths = immutableSeq(config.getStringList("routees.paths"))) /** * Java API * @param routeePaths string representation of the actor paths of the routees, messages are * sent with [[akka.actor.ActorSelection]] to these paths */ def this(routeePaths: java.lang.Iterable[String]) = this(paths = immutableSeq(routeePaths)) override def paths(system: ActorSystem): immutable.Iterable[String] = this.paths override def createRouter(system: ActorSystem): Router = new Router(RoundRobinRoutingLogic()) /** * Setting the dispatcher to be used for the router head actor, which handles * router management messages */ def withDispatcher(dispatcherId: String): RoundRobinGroup = copy(routerDispatcher = dispatcherId) }




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