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|
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2005-2006, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.actors
case object TIMEOUT
class SuspendActorException extends Throwable {
/*
* For efficiency reasons we do not fill in
* the execution stack trace.
*/
override def fillInStackTrace(): Throwable = {
this
}
}
/**
* This class provides a means for typed communication among
* actors. Only the actor creating an instance of a
* <code>Channel</code> may receive from it.
*
* @author Philipp Haller
*/
class Channel[Msg] extends InputChannel[Msg] with OutputChannel[Msg] {
private[actors] var receiver: Actor = synchronized {
// basically Actor.self, but can be null
val t = Thread.currentThread()
val a = Actor.selfs.get(t).asInstanceOf[Actor]
a
}
private var received: Msg = _
private val waitingForNone = (m: Msg) => false
private var waitingFor: Msg => boolean = waitingForNone
private var waitingForSender: Actor = null
//private val messageQueue = new MessageQueue[Msg]
private val mailbox = new scala.collection.mutable.Queue[Pair[Msg, Actor]]
private def send(msg: Msg, sender: Actor) = receiver.synchronized {
receiver.tick()
if (waitingFor(msg) && ((waitingForSender == null) ||
(waitingForSender == sender))) {
received = msg
receiver.pushSender(sender)
waitingFor = waitingForNone
waitingForSender = null
if (receiver.isInstanceOf[Reactor]) {
val myReactor = receiver.asInstanceOf[Reactor]
if (myReactor.timeoutPending) {
myReactor.timeoutPending = false
TimerThread.trashRequest(myReactor)
}
}
if (isSuspended)
receiver.resumeActor()
else
receiver.scheduleActor(null, msg)
} else {
//messageQueue.append(msg, sender)
mailbox += Pair(msg, sender)
}
}
/**
* Sends <code>msg</code> to this <code>Channel</code>.
*/
def !(msg: Msg): unit = send(msg, Actor.self)
/**
* Sends <code>msg</code> to this <code>Channel</code> and
* awaits reply.
*/
def !?(msg: Msg): Any = {
Actor.self.freshReply()
this ! msg
Actor.self.reply.receiveFrom(receiver) {
case x => x
}
}
/**
* Forwards <code>msg</code> to <code>this</code> keeping the
* last sender as sender instead of <code>self</code>.
*/
def forward(msg: Msg): unit = send(msg, receiver.sender)
private var isSuspended = false
/**
* Receives a message from this <code>Channel</code>.
*/
def receive[R](f: PartialFunction[Msg, R]): R = {
assert(Actor.self == receiver, "receive from channel belonging to other actor")
//assert(receiver.isThreaded, "receive invoked from reactor")
receiver.synchronized {
receiver.tick()
waitingFor = f.isDefinedAt
/*
val q = messageQueue.extractFirst(waitingFor)
if (q != null) {
received = q.msg
receiver.pushSender(q.sender)
}
// acquire lock because we might call wait()
else synchronized {
isSuspended = true
receiver.suspendActor()
}
*/
mailbox.dequeueFirst((p: Pair[Msg, Actor]) => {
waitingFor(p._1)
}) match {
case Some(Pair(msg, sender)) => {
received = msg
receiver.pushSender(sender)
}
case None => {
// acquire lock because we might call wait()
this.synchronized {
isSuspended = true
receiver.suspendActor()
}
}
}
isSuspended = false
waitingFor = waitingForNone
}
receiver.resetActor()
val result = f(received)
receiver.popSender()
result
}
private[actors] def receiveFrom[R](r: Actor)(f: PartialFunction[Msg, R]): R = {
assert(Actor.self == receiver, "receive from channel belonging to other actor")
//assert(receiver.isThreaded, "receive invoked from reactor")
receiver.synchronized {
receiver.tick()
waitingFor = f.isDefinedAt
waitingForSender = r
/*
var q = messageQueue.dequeueFirst((item: MessageQueueResult[Msg]) => {
waitingFor(item.msg) && item.sender == r
})
if (q != null) {
received = q.msg
receiver.pushSender(q.sender)
}
else synchronized {
isSuspended = true
receiver.suspendActor()
}
*/
mailbox.dequeueFirst((p: Pair[Msg, Actor]) => {
waitingFor(p._1) && p._2 == r
}) match {
case Some(Pair(msg, sender)) => {
received = msg
receiver.pushSender(sender)
}
case None => {
// acquire lock because we might call wait()
this.synchronized {
isSuspended = true
receiver.suspendActor()
}
}
}
isSuspended = false
waitingFor = waitingForNone
waitingForSender = null
}
receiver.resetActor()
val result = f(received)
receiver.popSender()
result
}
/**
* Receives a message from this <code>Channel</code>. If no
* message could be received before <code>msec</code>
* milliseconds elapsed, the <code>TIMEOUT</code> action is
* executed if specified.
*/
def receiveWithin[R](msec: long)(f: PartialFunction[Any, R]): R = {
assert(Actor.self == receiver, "receive from channel belonging to other actor")
//assert(receiver.isThreaded, "receive invoked from reactor")
receiver.synchronized {
receiver.tick()
waitingFor = f.isDefinedAt
/*
val q = messageQueue.extractFirst(waitingFor)
if (q != null) {
received = q.msg
receiver.pushSender(q.sender)
}
else synchronized {
isSuspended = true
receiver.suspendActorFor(msec)
if (received == null)
if (f.isDefinedAt(TIMEOUT)) {
isSuspended = false
receiver.resetActor()
val result = f(TIMEOUT)
return result
}
else
error("unhandled timeout")
}
*/
mailbox.dequeueFirst((p: Pair[Msg, Actor]) => {
waitingFor(p._1)
}) match {
case Some(Pair(msg, sender)) => {
received = msg
receiver.pushSender(sender)
}
case None => {
// acquire lock because we might call wait()
this.synchronized {
isSuspended = true
receiver.suspendActorFor(msec)
if (received == null)
if (f.isDefinedAt(TIMEOUT)) {
isSuspended = false
receiver.resetActor()
val result = f(TIMEOUT)
return result
}
else
error("unhandled timeout")
}
}
}
isSuspended = false
waitingFor = waitingForNone
}
receiver.resetActor()
val result = f(received)
receiver.popSender()
result
}
/**
* <code>receive</code> for reactors.
*/
def react(f: PartialFunction[Any, Unit]): Nothing = {
assert(Actor.self == receiver, "react on channel belonging to other actor")
receiver.synchronized {
receiver.tick()
waitingFor = f.isDefinedAt
/*
val q = messageQueue.extractFirst(waitingFor)
if (q != null) {
received = q.msg
receiver.pushSender(q.sender)
waitingFor = waitingForNone
receiver.scheduleActor(f, received)
}
else synchronized {
receiver.detachActor(f)
}
*/
mailbox.dequeueFirst((p: Pair[Msg, Actor]) => {
waitingFor(p._1)
}) match {
case Some(Pair(msg, sender)) => {
received = msg
receiver.pushSender(sender)
waitingFor = waitingForNone
receiver.scheduleActor(f, received)
}
case None => {
this.synchronized {
receiver.detachActor(f)
}
}
}
throw new SuspendActorException
}
}
/**
* <code>receiveWithin</code> for reactors.
*/
def reactWithin(msec: long)(f: PartialFunction[Any, Unit]): Nothing = {
assert(Actor.self == receiver, "react on channel belonging to other actor")
receiver.synchronized {
receiver.tick()
waitingFor = f.isDefinedAt
/*
val q = messageQueue.extractFirst(waitingFor)
if (q != null) {
received = q.msg
receiver.pushSender(q.sender)
waitingFor = waitingForNone
receiver.scheduleActor(f, received)
}
else synchronized {
TimerThread.requestTimeout(receiver.asInstanceOf[Reactor], f, msec)
receiver.asInstanceOf[Reactor].timeoutPending = true
receiver.detachActor(f)
}
*/
mailbox.dequeueFirst((p: Pair[Msg, Actor]) => {
waitingFor(p._1)
}) match {
case Some(Pair(msg, sender)) => {
received = msg
receiver.pushSender(sender)
waitingFor = waitingForNone
receiver.scheduleActor(f, received)
}
case None => {
this.synchronized {
TimerThread.requestTimeout(receiver.asInstanceOf[Reactor], f, msec)
receiver.asInstanceOf[Reactor].timeoutPending = true
receiver.detachActor(f)
}
}
}
throw new SuspendActorException
}
}
}
|