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/**
* Copyright (C) 2009-2014 Typesafe Inc.
*/
package akka.actor
import language.implicitConversions
import scala.annotation.tailrec
import scala.collection.immutable
import scala.concurrent.Future
import scala.concurrent.Promise
import scala.concurrent.duration._
import scala.util.Success
import scala.util.Failure
import java.util.regex.Pattern
import akka.pattern.ask
import akka.routing.MurmurHash
import akka.util.Helpers
import akka.util.Timeout
import akka.dispatch.ExecutionContexts
/**
* An ActorSelection is a logical view of a section of an ActorSystem's tree of Actors,
* allowing for broadcasting of messages to that section.
*/
@SerialVersionUID(1L)
abstract class ActorSelection extends Serializable {
this: ScalaActorSelection ⇒
protected[akka] val anchor: ActorRef
protected val path: immutable.IndexedSeq[SelectionPathElement]
/**
* Sends the specified message to the sender, i.e. fire-and-forget
* semantics, including the sender reference if possible.
*
* Pass [[ActorRef#noSender]] or `null` as sender if there is nobody to reply to
*/
def tell(msg: Any, sender: ActorRef): Unit =
ActorSelection.deliverSelection(anchor.asInstanceOf[InternalActorRef], sender,
ActorSelectionMessage(msg, path, wildcardFanOut = false))
/**
* Forwards the message and passes the original sender actor as the sender.
*
* Works, no matter whether originally sent with tell/'!' or ask/'?'.
*/
def forward(message: Any)(implicit context: ActorContext) = tell(message, context.sender())
/**
* Resolve the [[ActorRef]] matching this selection.
* The result is returned as a Future that is completed with the [[ActorRef]]
* if such an actor exists. It is completed with failure [[ActorNotFound]] if
* no such actor exists or the identification didn't complete within the
* supplied `timeout`.
*
* Under the hood it talks to the actor to verify its existence and acquire its
* [[ActorRef]].
*/
def resolveOne()(implicit timeout: Timeout): Future[ActorRef] = {
implicit val ec = ExecutionContexts.sameThreadExecutionContext
val p = Promise[ActorRef]()
this.ask(Identify(None)) onComplete {
case Success(ActorIdentity(_, Some(ref))) ⇒ p.success(ref)
case _ ⇒ p.failure(ActorNotFound(this))
}
p.future
}
/**
* Resolve the [[ActorRef]] matching this selection.
* The result is returned as a Future that is completed with the [[ActorRef]]
* if such an actor exists. It is completed with failure [[ActorNotFound]] if
* no such actor exists or the identification didn't complete within the
* supplied `timeout`.
*
* Under the hood it talks to the actor to verify its existence and acquire its
* [[ActorRef]].
*/
def resolveOne(timeout: FiniteDuration): Future[ActorRef] = resolveOne()(timeout)
override def toString: String = {
val builder = new java.lang.StringBuilder()
builder.append("ActorSelection[Anchor(").append(anchor.path)
if (anchor.path.uid != ActorCell.undefinedUid)
builder.append("#").append(anchor.path.uid)
builder.append("), Path(").append(path.mkString("/", "/", "")).append(")]")
builder.toString
}
/**
* The [[akka.actor.ActorPath]] of the anchor actor.
*/
def anchorPath: ActorPath = anchor.path
/**
* String representation of the path elements, starting with "/" and separated with "/".
*/
def pathString: String = path.mkString("/", "/", "")
/**
* String representation of the actor selection suitable for storage and recreation.
* The output is similar to the URI fragment returned by [[akka.actor.ActorPath.toSerializationFormat]].
* @return URI fragment
*/
def toSerializationFormat: String = {
val anchorPath = anchor match {
case a: ActorRefWithCell ⇒ anchor.path.toStringWithAddress(a.provider.getDefaultAddress)
case _ ⇒ anchor.path.toString
}
val builder = new java.lang.StringBuilder()
builder.append(anchorPath)
val lastChar = builder.charAt(builder.length - 1)
if (path.nonEmpty && lastChar != '/')
builder.append(path.mkString("/", "/", ""))
else if (path.nonEmpty)
builder.append(path.mkString("/"))
builder.toString
}
override def equals(obj: Any): Boolean = obj match {
case s: ActorSelection ⇒ this.anchor == s.anchor && this.path == s.path
case _ ⇒ false
}
override lazy val hashCode: Int = {
import MurmurHash._
var h = startHash(anchor.##)
h = extendHash(h, path.##, startMagicA, startMagicB)
finalizeHash(h)
}
}
/**
* An ActorSelection is a logical view of a section of an ActorSystem's tree of Actors,
* allowing for broadcasting of messages to that section.
*/
object ActorSelection {
//This cast is safe because the self-type of ActorSelection requires that it mixes in ScalaActorSelection
implicit def toScala(sel: ActorSelection): ScalaActorSelection = sel.asInstanceOf[ScalaActorSelection]
/**
* Construct an ActorSelection from the given string representing a path
* relative to the given target. This operation has to create all the
* matching magic, so it is preferable to cache its result if the
* intention is to send messages frequently.
*/
def apply(anchorRef: ActorRef, path: String): ActorSelection = apply(anchorRef, path.split("/+"))
/**
* Construct an ActorSelection from the given string representing a path
* relative to the given target. This operation has to create all the
* matching magic, so it is preferable to cache its result if the
* intention is to send messages frequently.
*/
def apply(anchorRef: ActorRef, elements: Iterable[String]): ActorSelection = {
val compiled: immutable.IndexedSeq[SelectionPathElement] = elements.collect({
case x if !x.isEmpty ⇒
if ((x.indexOf('?') != -1) || (x.indexOf('*') != -1)) SelectChildPattern(x)
else if (x == "..") SelectParent
else SelectChildName(x)
})(scala.collection.breakOut)
new ActorSelection with ScalaActorSelection {
override val anchor = anchorRef
override val path = compiled
}
}
/**
* INTERNAL API
* The receive logic for ActorSelectionMessage. The idea is to recursively descend as far as possible
* with local refs and hand over to that “foreign” child when we encounter it.
*/
private[akka] def deliverSelection(anchor: InternalActorRef, sender: ActorRef, sel: ActorSelectionMessage): Unit =
if (sel.elements.isEmpty)
anchor.tell(sel.msg, sender)
else {
val iter = sel.elements.iterator
@tailrec def rec(ref: InternalActorRef): Unit = {
ref match {
case refWithCell: ActorRefWithCell ⇒
def emptyRef = new EmptyLocalActorRef(refWithCell.provider, anchor.path / sel.elements.map(_.toString),
refWithCell.underlying.system.eventStream)
iter.next() match {
case SelectParent ⇒
val parent = ref.getParent
if (iter.isEmpty)
parent.tell(sel.msg, sender)
else
rec(parent)
case SelectChildName(name) ⇒
val child = refWithCell.getSingleChild(name)
if (child == Nobody) {
// don't send to emptyRef after wildcard fan-out
if (!sel.wildcardFanOut) emptyRef.tell(sel, sender)
} else if (iter.isEmpty)
child.tell(sel.msg, sender)
else
rec(child)
case p: SelectChildPattern ⇒
// fan-out when there is a wildcard
val chldr = refWithCell.children
if (iter.isEmpty) {
// leaf
val matchingChildren = chldr.filter(c ⇒ p.pattern.matcher(c.path.name).matches)
if (matchingChildren.isEmpty && !sel.wildcardFanOut)
emptyRef.tell(sel, sender)
else
matchingChildren.foreach(_.tell(sel.msg, sender))
} else {
val matchingChildren = chldr.filter(c ⇒ p.pattern.matcher(c.path.name).matches)
// don't send to emptyRef after wildcard fan-out
if (matchingChildren.isEmpty && !sel.wildcardFanOut)
emptyRef.tell(sel, sender)
else {
val m = sel.copy(elements = iter.toVector,
wildcardFanOut = sel.wildcardFanOut || matchingChildren.size > 1)
matchingChildren.foreach(c ⇒ deliverSelection(c.asInstanceOf[InternalActorRef], sender, m))
}
}
}
case _ ⇒
// foreign ref, continue by sending ActorSelectionMessage to it with remaining elements
ref.tell(sel.copy(elements = iter.toVector), sender)
}
}
rec(anchor)
}
}
/**
* Contains the Scala API (!-method) for ActorSelections) which provides automatic tracking of the sender,
* as per the usual implicit ActorRef pattern.
*/
trait ScalaActorSelection {
this: ActorSelection ⇒
def !(msg: Any)(implicit sender: ActorRef = Actor.noSender) = tell(msg, sender)
}
/**
* INTERNAL API
* ActorRefFactory.actorSelection returns a ActorSelection which sends these
* nested path descriptions whenever using ! on them, the idea being that the
* message is delivered by traversing the various actor paths involved.
*/
@SerialVersionUID(2L) // it has protobuf serialization in akka-remote
private[akka] case class ActorSelectionMessage(
msg: Any,
elements: immutable.Iterable[SelectionPathElement],
wildcardFanOut: Boolean)
extends AutoReceivedMessage with PossiblyHarmful {
def identifyRequest: Option[Identify] = msg match {
case x: Identify ⇒ Some(x)
case _ ⇒ None
}
}
/**
* INTERNAL API
*/
@SerialVersionUID(1L)
private[akka] sealed trait SelectionPathElement
/**
* INTERNAL API
*/
@SerialVersionUID(2L)
private[akka] case class SelectChildName(name: String) extends SelectionPathElement {
override def toString: String = name
}
/**
* INTERNAL API
*/
@SerialVersionUID(2L)
private[akka] case class SelectChildPattern(patternStr: String) extends SelectionPathElement {
val pattern: Pattern = Helpers.makePattern(patternStr)
override def toString: String = patternStr
}
/**
* INTERNAL API
*/
@SerialVersionUID(2L)
private[akka] case object SelectParent extends SelectionPathElement {
override def toString: String = ".."
}
/**
* When [[ActorSelection#resolveOne]] can't identify the actor the
* `Future` is completed with this failure.
*/
@SerialVersionUID(1L)
case class ActorNotFound(selection: ActorSelection) extends RuntimeException("Actor not found for: " + selection)
