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/*
* Copyright (C) 2009-2020 Lightbend Inc.
*/
package akka.actor
import akka.dispatch.sysmsg._
import akka.dispatch.{ Mailboxes, RequiresMessageQueue, UnboundedMessageQueueSemantics }
import akka.routing._
import akka.event._
import akka.util.Helpers
import akka.util.Collections.EmptyImmutableSeq
import scala.util.control.NonFatal
import java.util.concurrent.atomic.AtomicLong
import scala.concurrent.{ ExecutionContextExecutor, Future, Promise }
import scala.annotation.implicitNotFound
import akka.ConfigurationException
import akka.annotation.DoNotInherit
import akka.annotation.InternalApi
import akka.dispatch.Dispatchers
import akka.serialization.Serialization
import akka.util.OptionVal
/**
* Interface for all ActorRef providers to implement.
* Not intended for extension outside of Akka.
*/
@DoNotInherit trait ActorRefProvider {
/**
* Reference to the supervisor of guardian and systemGuardian; this is
* exposed so that the ActorSystemImpl can use it as lookupRoot, i.e.
* for anchoring absolute actor look-ups.
*/
def rootGuardian: InternalActorRef
/**
* Reference to the supervisor of guardian and systemGuardian at the specified address;
* this is exposed so that the ActorRefFactory can use it as lookupRoot, i.e.
* for anchoring absolute actor selections.
*/
def rootGuardianAt(address: Address): ActorRef
/**
* Reference to the supervisor used for all top-level user actors.
*/
def guardian: LocalActorRef
/**
* Reference to the supervisor used for all top-level system actors.
*/
def systemGuardian: LocalActorRef
/**
* Dead letter destination for this provider.
*/
def deadLetters: ActorRef
/**
* The root path for all actors within this actor system, not including any remote address information.
*/
def rootPath: ActorPath
/**
* The Settings associated with this ActorRefProvider
*/
def settings: ActorSystem.Settings
/**
* INTERNAL API: Initialization of an ActorRefProvider happens in two steps: first
* construction of the object with settings, eventStream, etc.
* and then—when the ActorSystem is constructed—the second phase during
* which actors may be created (e.g. the guardians).
*/
private[akka] def init(system: ActorSystemImpl): Unit
/**
* The Deployer associated with this ActorRefProvider
*/
def deployer: Deployer
/**
* Generates and returns a unique actor path below “/temp”.
*/
def tempPath(): ActorPath
/**
* Returns the actor reference representing the “/temp” path.
*/
def tempContainer: InternalActorRef
/**
* INTERNAL API: Registers an actorRef at a path returned by tempPath(); do NOT pass in any other path.
*/
private[akka] def registerTempActor(actorRef: InternalActorRef, path: ActorPath): Unit
/**
* Unregister a temporary actor from the “/temp” path (i.e. obtained from tempPath()); do NOT pass in any other path.
*/
def unregisterTempActor(path: ActorPath): Unit
/**
* INTERNAL API: Actor factory with create-only semantics: will create an actor as
* described by props with the given supervisor and path (may be different
* in case of remote supervision). If systemService is true, deployment is
* bypassed (local-only). If ``Some(deploy)`` is passed in, it should be
* regarded as taking precedence over the nominally applicable settings,
* but it should be overridable from external configuration; the lookup of
* the latter can be suppressed by setting ``lookupDeploy`` to ``false``.
*/
private[akka] def actorOf(
system: ActorSystemImpl,
props: Props,
supervisor: InternalActorRef,
path: ActorPath,
systemService: Boolean,
deploy: Option[Deploy],
lookupDeploy: Boolean,
async: Boolean): InternalActorRef
/**
* Create actor reference for a specified path. If no such
* actor exists, it will be (equivalent to) a dead letter reference.
*/
def resolveActorRef(path: String): ActorRef
/**
* Create actor reference for a specified path. If no such
* actor exists, it will be (equivalent to) a dead letter reference.
*/
def resolveActorRef(path: ActorPath): ActorRef
/**
* This Future is completed upon termination of this ActorRefProvider, which
* is usually initiated by stopping the guardian via ActorSystem.stop().
*/
def terminationFuture: Future[Terminated]
/**
* Obtain the address which is to be used within sender references when
* sending to the given other address or none if the other address cannot be
* reached from this system (i.e. no means of communication known; no
* attempt is made to verify actual reachability).
*/
def getExternalAddressFor(addr: Address): Option[Address]
/**
* Obtain the external address of the default transport.
*/
def getDefaultAddress: Address
/** INTERNAL API */
@InternalApi private[akka] def serializationInformation: Serialization.Information
/**
* INTERNAL API
*/
@InternalApi
private[akka] def addressString: String
}
/**
* Interface implemented by ActorSystem and ActorContext, the only two places
* from which you can get fresh actors.
*/
@implicitNotFound(
"implicit ActorRefFactory required: if outside of an Actor you need an implicit ActorSystem, inside of an actor this should be the implicit ActorContext")
trait ActorRefFactory {
/**
* INTERNAL API
*/
protected def systemImpl: ActorSystemImpl
/**
* INTERNAL API
*/
protected def provider: ActorRefProvider
/**
* Returns the default MessageDispatcher associated with this ActorRefFactory
*/
implicit def dispatcher: ExecutionContextExecutor
/**
* Parent of all children created by this interface.
*
* INTERNAL API
*/
protected def guardian: InternalActorRef
/**
* INTERNAL API
*/
protected def lookupRoot: InternalActorRef
/**
* Create new actor as child of this context and give it an automatically
* generated name (currently similar to base64-encoded integer count,
* reversed and with “$” prepended, may change in the future).
*
* See [[akka.actor.Props]] for details on how to obtain a `Props` object.
*
* @throws akka.ConfigurationException if deployment, dispatcher
* or mailbox configuration is wrong
* @throws UnsupportedOperationException if invoked on an ActorSystem that
* uses a custom user guardian
*/
def actorOf(props: Props): ActorRef
/**
* Create new actor as child of this context with the given name, which must
* not be null, empty or start with “$”. If the given name is already in use,
* an `InvalidActorNameException` is thrown.
*
* See [[akka.actor.Props]] for details on how to obtain a `Props` object.
*
* @throws akka.actor.InvalidActorNameException if the given name is
* invalid or already in use
* @throws akka.ConfigurationException if deployment, dispatcher
* or mailbox configuration is wrong
* @throws UnsupportedOperationException if invoked on an ActorSystem that
* uses a custom user guardian
*/
def actorOf(props: Props, name: String): ActorRef
/**
* Construct an [[akka.actor.ActorSelection]] from the given path, which is
* parsed for wildcards (these are replaced by regular expressions
* internally). No attempt is made to verify the existence of any part of
* the supplied path, it is recommended to send a message and gather the
* replies in order to resolve the matching set of actors.
*/
def actorSelection(path: String): ActorSelection = path match {
case RelativeActorPath(elems) =>
if (elems.isEmpty) ActorSelection(provider.deadLetters, "")
else if (elems.head.isEmpty) ActorSelection(provider.rootGuardian, elems.tail)
else ActorSelection(lookupRoot, elems)
case ActorPathExtractor(address, elems) =>
ActorSelection(provider.rootGuardianAt(address), elems)
case _ =>
ActorSelection(provider.deadLetters, "")
}
/**
* Construct an [[akka.actor.ActorSelection]] from the given path, which is
* parsed for wildcards (these are replaced by regular expressions
* internally). No attempt is made to verify the existence of any part of
* the supplied path, it is recommended to send a message and gather the
* replies in order to resolve the matching set of actors.
*/
def actorSelection(path: ActorPath): ActorSelection =
ActorSelection(provider.rootGuardianAt(path.address), path.elements)
/**
* Stop the actor pointed to by the given [[akka.actor.ActorRef]]; this is
* an asynchronous operation, i.e. involves a message send.
* If this method is applied to the `self` reference from inside an Actor
* then that Actor is guaranteed to not process any further messages after
* this call; please note that the processing of the current message will
* continue, this method does not immediately terminate this actor.
*/
def stop(actor: ActorRef): Unit
}
/**
* Internal Akka use only, used in implementation of system.stop(child).
*/
private[akka] final case class StopChild(child: ActorRef)
/**
* INTERNAL API
*/
private[akka] object SystemGuardian {
/**
* For the purpose of orderly shutdown it's possible
* to register interest in the termination of systemGuardian
* and receive a notification `TerminationHook`
* before systemGuardian is stopped. The registered hook is supposed
* to reply with `TerminationHookDone` and the
* systemGuardian will not stop until all registered hooks have replied.
*/
case object RegisterTerminationHook
case object TerminationHook
case object TerminationHookDone
}
private[akka] object LocalActorRefProvider {
/*
* Root and user guardian
*/
private class Guardian(override val supervisorStrategy: SupervisorStrategy)
extends Actor
with RequiresMessageQueue[UnboundedMessageQueueSemantics] {
def receive = {
case Terminated(_) => context.stop(self)
case StopChild(child) => context.stop(child)
}
// guardian MUST NOT lose its children during restart
override def preRestart(cause: Throwable, msg: Option[Any]): Unit = {}
}
/**
* System guardian
*/
private class SystemGuardian(override val supervisorStrategy: SupervisorStrategy, val guardian: ActorRef)
extends Actor
with RequiresMessageQueue[UnboundedMessageQueueSemantics] {
import SystemGuardian._
var terminationHooks = Set.empty[ActorRef]
def receive = {
case Terminated(`guardian`) =>
// time for the systemGuardian to stop, but first notify all the
// termination hooks, they will reply with TerminationHookDone
// and when all are done the systemGuardian is stopped
context.become(terminating)
terminationHooks.foreach { _ ! TerminationHook }
stopWhenAllTerminationHooksDone()
case Terminated(a) =>
// a registered, and watched termination hook terminated before
// termination process of guardian has started
terminationHooks -= a
case StopChild(child) => context.stop(child)
case RegisterTerminationHook if sender() != context.system.deadLetters =>
terminationHooks += sender()
context.watch(sender())
}
def terminating: Receive = {
case Terminated(a) => stopWhenAllTerminationHooksDone(a)
case TerminationHookDone => stopWhenAllTerminationHooksDone(sender())
}
def stopWhenAllTerminationHooksDone(remove: ActorRef): Unit = {
terminationHooks -= remove
stopWhenAllTerminationHooksDone()
}
def stopWhenAllTerminationHooksDone(): Unit =
if (terminationHooks.isEmpty) {
context.system.eventStream.stopDefaultLoggers(context.system)
context.stop(self)
}
// guardian MUST NOT lose its children during restart
override def preRestart(cause: Throwable, msg: Option[Any]): Unit = {}
}
}
/**
* Local ActorRef provider.
*
* INTERNAL API!
*
* Depending on this class is not supported, only the [[ActorRefProvider]] interface is supported.
*/
private[akka] class LocalActorRefProvider private[akka] (
_systemName: String,
override val settings: ActorSystem.Settings,
val eventStream: EventStream,
val dynamicAccess: DynamicAccess,
override val deployer: Deployer,
_deadLetters: Option[ActorPath => InternalActorRef])
extends ActorRefProvider {
// this is the constructor needed for reflectively instantiating the provider
def this(
_systemName: String,
settings: ActorSystem.Settings,
eventStream: EventStream,
dynamicAccess: DynamicAccess) =
this(_systemName, settings, eventStream, dynamicAccess, new Deployer(settings, dynamicAccess), None)
override val rootPath: ActorPath = RootActorPath(Address("akka", _systemName))
private[akka] val log: MarkerLoggingAdapter =
Logging.withMarker(eventStream, getClass.getName + "(" + rootPath.address + ")")
override val deadLetters: InternalActorRef =
_deadLetters
.getOrElse((p: ActorPath) => new DeadLetterActorRef(this, p, eventStream))
.apply(rootPath / "deadLetters")
private[this] final val terminationPromise: Promise[Terminated] = Promise[Terminated]()
def terminationFuture: Future[Terminated] = terminationPromise.future
/*
* generate name for temporary actor refs
*/
private val tempNumber = new AtomicLong
private val tempNode = rootPath / "temp"
override def tempPath(): ActorPath = tempNode / Helpers.base64(tempNumber.getAndIncrement())
/**
* Top-level anchor for the supervision hierarchy of this actor system. Will
* receive only Supervise/ChildTerminated system messages or Failure message.
*/
private[akka] val theOneWhoWalksTheBubblesOfSpaceTime: InternalActorRef = new MinimalActorRef {
val causeOfTermination: Promise[Terminated] = Promise[Terminated]()
val path = rootPath / "bubble-walker"
def provider: ActorRefProvider = LocalActorRefProvider.this
def isWalking = !causeOfTermination.future.isCompleted
override def stop(): Unit = {
causeOfTermination.trySuccess(
Terminated(provider.rootGuardian)(existenceConfirmed = true, addressTerminated = true)) //Idempotent
terminationPromise.completeWith(causeOfTermination.future) // Signal termination downstream, idempotent
}
/**
* INTERNAL API
*/
@InternalApi
override private[akka] def isTerminated: Boolean = !isWalking
override def !(message: Any)(implicit sender: ActorRef = Actor.noSender): Unit =
if (isWalking)
message match {
case null => throw InvalidMessageException("Message is null")
case _ => log.error(s"$this received unexpected message [$message]")
}
override def sendSystemMessage(message: SystemMessage): Unit = if (isWalking) {
message match {
case Failed(child: InternalActorRef, ex, _) =>
log.error(ex, s"guardian $child failed, shutting down!")
causeOfTermination.tryFailure(ex)
child.stop()
case Supervise(_, _) => // TODO register child in some map to keep track of it and enable shutdown after all dead
case _: DeathWatchNotification => stop()
case _ => log.error(s"$this received unexpected system message [$message]")
}
}
}
/*
* The problem is that ActorRefs need a reference to the ActorSystem to
* provide their service. Hence they cannot be created while the
* constructors of ActorSystem and ActorRefProvider are still running.
* The solution is to split out that last part into an init() method,
* but it also requires these references to be @volatile and lazy.
*/
@volatile
private var system: ActorSystemImpl = _
@volatile
private var extraNames: Map[String, InternalActorRef] = Map()
/**
* Higher-level providers (or extensions) might want to register new synthetic
* top-level paths for doing special stuff. This is the way to do just that.
* Just be careful to complete all this before ActorSystem.start() finishes,
* or before you start your own auto-spawned actors.
*/
def registerExtraNames(_extras: Map[String, InternalActorRef]): Unit = extraNames ++= _extras
private def guardianSupervisorStrategyConfigurator =
dynamicAccess
.createInstanceFor[SupervisorStrategyConfigurator](settings.SupervisorStrategyClass, EmptyImmutableSeq)
.get
/**
* Overridable supervision strategy to be used by the “/user” guardian.
*/
protected def rootGuardianStrategy: SupervisorStrategy = OneForOneStrategy() {
case ex =>
log.error(ex, "guardian failed, shutting down system")
SupervisorStrategy.Stop
}
/**
* Overridable supervision strategy to be used by the “/user” guardian.
*/
protected def guardianStrategy: SupervisorStrategy = guardianSupervisorStrategyConfigurator.create()
/**
* Overridable supervision strategy to be used by the “/user” guardian.
*/
protected def systemGuardianStrategy: SupervisorStrategy = SupervisorStrategy.defaultStrategy
private def internalDispatcher = system.dispatchers.internalDispatcher
private lazy val defaultMailbox = system.mailboxes.lookup(Mailboxes.DefaultMailboxId)
override lazy val rootGuardian: LocalActorRef =
new LocalActorRef(
system,
Props(classOf[LocalActorRefProvider.Guardian], rootGuardianStrategy),
internalDispatcher,
defaultMailbox,
theOneWhoWalksTheBubblesOfSpaceTime,
rootPath) {
override def getParent: InternalActorRef = this
override def getSingleChild(name: String): InternalActorRef = name match {
case "temp" => tempContainer
case "deadLetters" => deadLetters
case other => extraNames.getOrElse(other, super.getSingleChild(other))
}
}
override def rootGuardianAt(address: Address): ActorRef =
if (address == rootPath.address) rootGuardian
else deadLetters
override lazy val guardian: LocalActorRef = {
val cell = rootGuardian.underlying
cell.reserveChild("user")
// make user provided guardians not run on internal dispatcher
val dispatcher =
system.guardianProps match {
case None => internalDispatcher
case Some(props) =>
val dispatcherId =
if (props.deploy.dispatcher == Deploy.DispatcherSameAsParent) Dispatchers.DefaultDispatcherId
else props.dispatcher
system.dispatchers.lookup(dispatcherId)
}
val ref = new LocalActorRef(
system,
system.guardianProps.getOrElse(Props(classOf[LocalActorRefProvider.Guardian], guardianStrategy)),
dispatcher,
defaultMailbox,
rootGuardian,
rootPath / "user")
cell.initChild(ref)
ref.start()
ref
}
override lazy val systemGuardian: LocalActorRef = {
val cell = rootGuardian.underlying
cell.reserveChild("system")
val ref = new LocalActorRef(
system,
Props(classOf[LocalActorRefProvider.SystemGuardian], systemGuardianStrategy, guardian),
internalDispatcher,
defaultMailbox,
rootGuardian,
rootPath / "system")
cell.initChild(ref)
ref.start()
ref
}
lazy val tempContainer = new VirtualPathContainer(system.provider, tempNode, rootGuardian, log)
def registerTempActor(actorRef: InternalActorRef, path: ActorPath): Unit = {
assert(path.parent eq tempNode, "cannot registerTempActor() with anything not obtained from tempPath()")
tempContainer.addChild(path.name, actorRef)
}
def unregisterTempActor(path: ActorPath): Unit = {
assert(path.parent eq tempNode, "cannot unregisterTempActor() with anything not obtained from tempPath()")
tempContainer.removeChild(path.name)
}
private[akka] def init(_system: ActorSystemImpl): Unit = {
system = _system
rootGuardian.start()
// chain death watchers so that killing guardian stops the application
systemGuardian.sendSystemMessage(Watch(guardian, systemGuardian))
rootGuardian.sendSystemMessage(Watch(systemGuardian, rootGuardian))
eventStream.startDefaultLoggers(_system)
}
def resolveActorRef(path: String): ActorRef = path match {
case ActorPathExtractor(address, elems) if address == rootPath.address => resolveActorRef(rootGuardian, elems)
case _ =>
log.debug("Resolve (deserialization) of unknown (invalid) path [{}], using deadLetters.", path)
deadLetters
}
def resolveActorRef(path: ActorPath): ActorRef = {
if (path.root == rootPath) resolveActorRef(rootGuardian, path.elements)
else {
log.debug(
"Resolve (deserialization) of foreign path [{}] doesn't match root path [{}], using deadLetters.",
path,
rootPath)
deadLetters
}
}
/**
* INTERNAL API
*/
private[akka] def resolveActorRef(ref: InternalActorRef, pathElements: Iterable[String]): InternalActorRef =
if (pathElements.isEmpty) {
log.debug("Resolve (deserialization) of empty path doesn't match an active actor, using deadLetters.")
deadLetters
} else
ref.getChild(pathElements.iterator) match {
case Nobody =>
if (log.isDebugEnabled)
log.debug(
"Resolve (deserialization) of path [{}] doesn't match an active actor. " +
"It has probably been stopped, using deadLetters.",
pathElements.mkString("/"))
new EmptyLocalActorRef(system.provider, ref.path / pathElements, eventStream)
case x => x
}
def actorOf(
system: ActorSystemImpl,
props: Props,
supervisor: InternalActorRef,
path: ActorPath,
systemService: Boolean,
deploy: Option[Deploy],
lookupDeploy: Boolean,
async: Boolean): InternalActorRef = {
props.deploy.routerConfig match {
case NoRouter =>
if (settings.DebugRouterMisconfiguration) {
deployer.lookup(path).foreach { d =>
if (d.routerConfig != NoRouter)
log.warning(
"Configuration says that [{}] should be a router, but code disagrees. Remove the config or add a routerConfig to its Props.",
path)
}
}
def parentDispatcher: String = supervisor match {
case withCell: ActorRefWithCell => withCell.underlying.props.dispatcher
case _ => Deploy.NoDispatcherGiven
}
val props2 =
// mailbox and dispatcher defined in deploy should override props
(if (lookupDeploy) deployer.lookup(path) else deploy) match {
case Some(d) =>
(d.dispatcher, d.mailbox) match {
case (Deploy.NoDispatcherGiven, Deploy.NoMailboxGiven) => props
case (Deploy.DispatcherSameAsParent, Deploy.NoMailboxGiven) => props.withDispatcher(parentDispatcher)
case (dsp, Deploy.NoMailboxGiven) => props.withDispatcher(dsp)
case (Deploy.NoDispatcherGiven, mbx) => props.withMailbox(mbx)
case (Deploy.DispatcherSameAsParent, mbx) => props.withDispatcher(parentDispatcher).withMailbox(mbx)
case (dsp, mbx) => props.withDispatcher(dsp).withMailbox(mbx)
}
case _ =>
// no deployment config found
if (props.deploy.dispatcher == Deploy.DispatcherSameAsParent)
props.withDispatcher(parentDispatcher)
else
props
}
if (!system.dispatchers.hasDispatcher(props2.dispatcher))
throw new ConfigurationException(s"Dispatcher [${props2.dispatcher}] not configured for path $path")
try {
val dispatcher = system.dispatchers.lookup(props2.dispatcher)
val mailboxType = system.mailboxes.getMailboxType(props2, dispatcher.configurator.config)
if (async)
new RepointableActorRef(system, props2, dispatcher, mailboxType, supervisor, path).initialize(async)
else new LocalActorRef(system, props2, dispatcher, mailboxType, supervisor, path)
} catch {
case NonFatal(e) =>
throw new ConfigurationException(
s"configuration problem while creating [$path] with dispatcher [${props2.dispatcher}] and mailbox [${props2.mailbox}]",
e)
}
case router =>
val lookup = if (lookupDeploy) deployer.lookup(path) else None
val r = (router :: deploy.map(_.routerConfig).toList ::: lookup.map(_.routerConfig).toList).reduce((a, b) =>
b.withFallback(a))
val p = props.withRouter(r)
if (!system.dispatchers.hasDispatcher(p.dispatcher))
throw new ConfigurationException(s"Dispatcher [${p.dispatcher}] not configured for routees of $path")
if (!system.dispatchers.hasDispatcher(r.routerDispatcher))
throw new ConfigurationException(s"Dispatcher [${p.dispatcher}] not configured for router of $path")
val routerProps = Props(
p.deploy.copy(dispatcher = p.routerConfig.routerDispatcher),
classOf[RoutedActorCell.RouterActorCreator],
Vector(p.routerConfig))
val routeeProps = p.withRouter(NoRouter)
try {
val routerDispatcher = system.dispatchers.lookup(p.routerConfig.routerDispatcher)
val routerMailbox = system.mailboxes.getMailboxType(routerProps, routerDispatcher.configurator.config)
// routers use context.actorOf() to create the routees, which does not allow us to pass
// these through, but obtain them here for early verification
val routeeDispatcher = system.dispatchers.lookup(p.dispatcher)
system.mailboxes.getMailboxType(routeeProps, routeeDispatcher.configurator.config)
new RoutedActorRef(system, routerProps, routerDispatcher, routerMailbox, routeeProps, supervisor, path)
.initialize(async)
} catch {
case NonFatal(e) =>
throw new ConfigurationException(
s"configuration problem while creating [$path] with router dispatcher [${routerProps.dispatcher}] and mailbox [${routerProps.mailbox}] " +
s"and routee dispatcher [${routeeProps.dispatcher}] and mailbox [${routeeProps.mailbox}]",
e)
}
}
}
def getExternalAddressFor(addr: Address): Option[Address] = if (addr == rootPath.address) Some(addr) else None
def getDefaultAddress: Address = rootPath.address
// no need for volatile, only intended as cached value, not necessarily a singleton value
private var serializationInformationCache: OptionVal[Serialization.Information] = OptionVal.None
@InternalApi override private[akka] def serializationInformation: Serialization.Information = {
Serialization.Information(getDefaultAddress, system)
serializationInformationCache match {
case OptionVal.Some(info) => info
case OptionVal.None =>
if (system eq null)
throw new IllegalStateException("Too early access of serializationInformation")
else {
val info = Serialization.Information(rootPath.address, system)
serializationInformationCache = OptionVal.Some(info)
info
}
}
}
// lazily initialized with fallback since it can depend on transport which is not initialized up front
// worth caching since if it is used once in a system it will very likely be used many times
@volatile private var _addressString: OptionVal[String] = OptionVal.None
override private[akka] def addressString: String = {
_addressString match {
case OptionVal.Some(addr) => addr
case OptionVal.None =>
val addr = getDefaultAddress.toString
_addressString = OptionVal.Some(addr)
addr
}
}
}
