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Improvements based on review feedback, see #944

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This commit is contained in:
Patrik Nordwall 2012-09-13 18:06:35 +02:00
parent d74464ba50
commit 5a90d7198c
9 changed files with 106 additions and 86 deletions
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61
akka-actor/src/main/scala/akka/routing/ConsistentHashingRouter.scala
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@ -5,13 +5,13 @@ package akka.routing
import scala.collection.JavaConversions.iterableAsScalaIterable
import scala.util.control.NonFatal
import akka.actor.ActorRef
import akka.actor.SupervisorStrategy
import akka.actor.Props
import akka.dispatch.Dispatchers
import akka.event.Logging
import akka.serialization.SerializationExtension
import java.util.concurrent.atomic.AtomicReference
object ConsistentHashingRouter {
/**
@ -46,19 +46,13 @@ object ConsistentHashingRouter {
/**
* If messages can't implement [[akka.routing.ConsistentHashable]]
* themselves they can we wrapped by something implementing
* this interface instead. The router will only send the
* wrapped message to the destination, i.e. the envelope will
* be stripped off.
* themselves they can we wrapped by this envelope instead. The
* router will only send the wrapped message to the destination,
* i.e. the envelope will be stripped off.
*/
trait ConsistentHashableEnvelope extends ConsistentHashable with RouterEnvelope {
def message: Any
}
/**
* Default number of replicas (virtual nodes) used in [[akka.routing.ConsistantHash]]
*/
val DefaultReplicas: Int = 10
@SerialVersionUID(1L)
case class ConsistentHashableEnvelope(message: Any, consistentHashKey: Any)
extends ConsistentHashable with RouterEnvelope
}
/**
@ -88,14 +82,14 @@ object ConsistentHashingRouter {
*
* @param routees string representation of the actor paths of the routees that will be looked up
* using `actorFor` in [[akka.actor.ActorRefProvider]]
* @param replicas number of replicas (virtual nodes) used in [[akka.routing.ConsistantHash]]
* @param virtualNodesFactor number of virtual nodes per node, used in [[akka.routing.ConsistantHash]]
*/
@SerialVersionUID(1L)
case class ConsistentHashingRouter(
nrOfInstances: Int = 0, routees: Iterable[String] = Nil, override val resizer: Option[Resizer] = None,
val routerDispatcher: String = Dispatchers.DefaultDispatcherId,
val supervisorStrategy: SupervisorStrategy = Router.defaultSupervisorStrategy,
val replicas: Int = ConsistentHashingRouter.DefaultReplicas)
val virtualNodesFactor: Int = 0)
extends RouterConfig with ConsistentHashingLike {
/**
@ -130,9 +124,9 @@ case class ConsistentHashingRouter(
def withSupervisorStrategy(strategy: SupervisorStrategy): ConsistentHashingRouter = copy(supervisorStrategy = strategy)
/**
* Java API for setting the number of replicas (virtual nodes) used in [[akka.routing.ConsistantHash]]
* Java API for setting the number of virtual nodes per node, used in [[akka.routing.ConsistantHash]]
*/
def withReplicas(replicas: Int): ConsistentHashingRouter = copy(replicas = replicas)
def withVirtualNodesFactor(vnodes: Int): ConsistentHashingRouter = copy(virtualNodesFactor = vnodes)
/**
* Uses the resizer of the given RouterConfig if this RouterConfig
@ -145,6 +139,10 @@ case class ConsistentHashingRouter(
}
}
/**
* The core pieces of the routing logic is located in this
* trait to be able to extend.
*/
trait ConsistentHashingLike { this: RouterConfig ⇒
import ConsistentHashingRouter._
@ -153,7 +151,7 @@ trait ConsistentHashingLike { this: RouterConfig ⇒
def routees: Iterable[String]
def replicas: Int
def virtualNodesFactor: Int
override def createRoute(routeeProvider: RouteeProvider): Route = {
if (resizer.isEmpty) {
@ -162,20 +160,25 @@ trait ConsistentHashingLike { this: RouterConfig ⇒
}
val log = Logging(routeeProvider.context.system, routeeProvider.context.self)
val vnodes =
if (virtualNodesFactor == 0) routeeProvider.context.system.settings.DefaultVirtualNodesFactor
else virtualNodesFactor
// consistentHashRoutees and consistentHash are updated together, synchronized on the consistentHashLock
val consistentHashLock = new Object
var consistentHashRoutees: IndexedSeq[ActorRef] = null
var consistentHash: ConsistentHash[ActorRef] = null
upateConsistentHash()
var consistentHashRoutees = new AtomicReference[IndexedSeq[ActorRef]]
@volatile var consistentHash: ConsistentHash[ActorRef] = null
updateConsistentHash()
// update consistentHash when routees has changed
// changes to routees are rare and when no changes this is a quick operation
def upateConsistentHash(): ConsistentHash[ActorRef] = consistentHashLock.synchronized {
def updateConsistentHash(): ConsistentHash[ActorRef] = {
val currentRoutees = routeeProvider.routees
if ((currentRoutees ne consistentHashRoutees) && currentRoutees != consistentHashRoutees) {
consistentHashRoutees = currentRoutees
consistentHash = ConsistentHash(currentRoutees, replicas)
if (currentRoutees ne consistentHashRoutees.get) {
val oldConsistentHashRoutees = consistentHashRoutees.get
val rehash = currentRoutees != oldConsistentHashRoutees
// when other instance, same content, no need to re-hash, but try to set currentRoutees
// ignore, don't update, in case of CAS failure
if (consistentHashRoutees.compareAndSet(oldConsistentHashRoutees, currentRoutees) && rehash)
consistentHash = ConsistentHash(currentRoutees, vnodes)
}
consistentHash
}
@ -186,13 +189,13 @@ trait ConsistentHashingLike { this: RouterConfig ⇒
case str: String ⇒ str.getBytes("UTF-8")
case x: AnyRef ⇒ SerializationExtension(routeeProvider.context.system).serialize(x).get
}
val currentConsistenHash = upateConsistentHash()
val currentConsistenHash = updateConsistentHash()
if (currentConsistenHash.isEmpty) routeeProvider.context.system.deadLetters
else currentConsistenHash.nodeFor(hash)
} catch {
case NonFatal(e) ⇒
// serialization failed
log.warning("Couldn't route message with consistentHashKey [%s] due to [%s]".format(hashData, e.getMessage))
log.warning("Couldn't route message with consistentHashKey [{}] due to [{}]", hashData, e.getMessage)
routeeProvider.context.system.deadLetters
}