akka.routing.Router.scala Maven / Gradle / Ivy
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/**
* Copyright (C) 2009-2016 Lightbend Inc.
*/
package akka.routing
import scala.collection.immutable
import akka.actor.ActorRef
import akka.actor.ActorSelection
import akka.actor.InternalActorRef
import akka.japi.Util.immutableSeq
import akka.actor.NoSerializationVerificationNeeded
/**
* The interface of the routing logic that is used in a [[Router]] to select
* destination routed messages.
*
* The implementation must be thread safe.
*/
trait RoutingLogic extends NoSerializationVerificationNeeded {
/**
* Pick the destination for a given message. Normally it picks one of the
* passed `routees`, but in the end it is up to the implementation to
* return whatever [[Routee]] to use for sending a specific message.
*
* When implemented from Java it can be good to know that
* `routees.apply(index)` can be used to get an element
* from the `IndexedSeq`.
*/
def select(message: Any, routees: immutable.IndexedSeq[Routee]): Routee
}
/**
* Abstraction of a destination for messages routed via a [[Router]].
*/
trait Routee {
def send(message: Any, sender: ActorRef): Unit
}
/**
* [[Routee]] that sends the messages to an [[akka.actor.ActorRef]].
*/
final case class ActorRefRoutee(ref: ActorRef) extends Routee {
override def send(message: Any, sender: ActorRef): Unit =
ref.tell(message, sender)
}
/**
* [[Routee]] that sends the messages to an [[akka.actor.ActorSelection]].
*/
final case class ActorSelectionRoutee(selection: ActorSelection) extends Routee {
override def send(message: Any, sender: ActorRef): Unit =
selection.tell(message, sender)
}
/**
* [[Routee]] that doesn't send the message to any routee.
* The [[Router]] will send the message to `deadLetters` if
* `NoRoutee` is returned from [[RoutingLogic#select]]
*/
object NoRoutee extends Routee {
override def send(message: Any, sender: ActorRef): Unit = ()
}
/**
* [[Routee]] that sends each message to all `routees`.
*/
final case class SeveralRoutees(routees: immutable.IndexedSeq[Routee]) extends Routee {
/**
* Java API
*/
def this(rs: java.lang.Iterable[Routee]) = this(routees = immutableSeq(rs).toVector)
/**
* Java API
*/
def getRoutees(): java.util.List[Routee] = {
import scala.collection.JavaConverters._
routees.asJava
}
override def send(message: Any, sender: ActorRef): Unit =
routees.foreach(_.send(message, sender))
}
/**
* For each message that is sent through the router via the [[#route]] method the
* [[RoutingLogic]] decides to which [[Routee]] to send the message. The [[Routee]] itself
* knows how to perform the actual sending. Normally the [[RoutingLogic]] picks one of the
* contained `routees`, but that is up to the implementation of the [[RoutingLogic]].
*
* A `Router` is immutable and the [[RoutingLogic]] must be thread safe.
*/
final case class Router(val logic: RoutingLogic, val routees: immutable.IndexedSeq[Routee] = Vector.empty) {
/**
* Java API
*/
def this(logic: RoutingLogic) = this(logic, Vector.empty)
/**
* Java API
*/
def this(logic: RoutingLogic, routees: java.lang.Iterable[Routee]) = this(logic, immutableSeq(routees).toVector)
/**
* Send the message to the destination [[Routee]] selected by the [[RoutingLogic]].
* If the message is a [[akka.routing.RouterEnvelope]] it will be unwrapped
* before sent to the destinations.
* Messages wrapped in a [[Broadcast]] envelope are always sent to all `routees`.
*/
def route(message: Any, sender: ActorRef): Unit =
message match {
case akka.routing.Broadcast(msg) ⇒ SeveralRoutees(routees).send(msg, sender)
case msg ⇒ send(logic.select(msg, routees), message, sender)
}
private def send(routee: Routee, msg: Any, sender: ActorRef): Unit = {
if (routee == NoRoutee && sender.isInstanceOf[InternalActorRef])
sender.asInstanceOf[InternalActorRef].provider.deadLetters.tell(unwrap(msg), sender)
else
routee.send(unwrap(msg), sender)
}
private def unwrap(msg: Any): Any = msg match {
case env: RouterEnvelope ⇒ env.message
case _ ⇒ msg
}
/**
* Create a new instance with the specified routees and the same [[RoutingLogic]].
*/
def withRoutees(rs: immutable.IndexedSeq[Routee]): Router = copy(routees = rs)
/**
* Create a new instance with one more routee and the same [[RoutingLogic]].
*/
def addRoutee(routee: Routee): Router = copy(routees = routees :+ routee)
/**
* Create a new instance with one more [[ActorRefRoutee]] for the
* specified [[akka.actor.ActorRef]] and the same [[RoutingLogic]].
*/
def addRoutee(ref: ActorRef): Router = addRoutee(ActorRefRoutee(ref))
/**
* Create a new instance with one more [[ActorSelectionRoutee]] for the
* specified [[akka.actor.ActorSelection]] and the same [[RoutingLogic]].
*/
def addRoutee(sel: ActorSelection): Router = addRoutee(ActorSelectionRoutee(sel))
/**
* Create a new instance without the specified routee.
*/
def removeRoutee(routee: Routee): Router = copy(routees = routees.filterNot(_ == routee))
/**
* Create a new instance without the [[ActorRefRoutee]] for the specified
* [[akka.actor.ActorRef]].
*/
def removeRoutee(ref: ActorRef): Router = removeRoutee(ActorRefRoutee(ref))
/**
* Create a new instance without the [[ActorSelectionRoutee]] for the specified
* [[akka.actor.ActorSelection]].
*/
def removeRoutee(sel: ActorSelection): Router = removeRoutee(ActorSelectionRoutee(sel))
}
/**
* Used to broadcast a message to all routees in a router; only the
* contained message will be forwarded, i.e. the `Broadcast(...)`
* envelope will be stripped off.
*/
@SerialVersionUID(1L)
final case class Broadcast(message: Any) extends RouterEnvelope
/**
* Only the contained message will be forwarded to the
* destination, i.e. the envelope will be stripped off.
*/
trait RouterEnvelope {
def message: Any
}