From 097993aea447cc57c4f5701c6a2e97d6953597e9 Mon Sep 17 00:00:00 2001
From: Philipp Haller <hallerp@gmail.com>
Date: Thu, 16 Jul 2009 17:24:37 +0000
Subject: Fixed memory leak in remote actors.

---
 src/actors/scala/actors/remote/NetKernel.scala |  2 +-
 src/actors/scala/actors/remote/Proxy.scala     | 65 +++++++++++++-------------
 2 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/src/actors/scala/actors/remote/NetKernel.scala b/src/actors/scala/actors/remote/NetKernel.scala
index acc537476f..b7376a4b46 100644
--- a/src/actors/scala/actors/remote/NetKernel.scala
+++ b/src/actors/scala/actors/remote/NetKernel.scala
@@ -26,7 +26,7 @@ case class Locator(node: Node, name: Symbol)
  * @version 0.9.17
  * @author Philipp Haller
  */
-class NetKernel(service: Service) {
+private[remote] class NetKernel(service: Service) {
 
   def sendToNode(node: Node, msg: AnyRef) = {
     val bytes = service.serializer.serialize(msg)
diff --git a/src/actors/scala/actors/remote/Proxy.scala b/src/actors/scala/actors/remote/Proxy.scala
index 425e98635f..1c7e6f4e55 100644
--- a/src/actors/scala/actors/remote/Proxy.scala
+++ b/src/actors/scala/actors/remote/Proxy.scala
@@ -13,11 +13,10 @@ package scala.actors.remote
 import scala.collection.mutable.HashMap
 
 /**
- * @version 0.9.17
  * @author Philipp Haller
  */
 @serializable
-class Proxy(node: Node, name: Symbol, @transient var kernel: NetKernel) extends AbstractActor {
+private[remote] class Proxy(node: Node, name: Symbol, @transient var kernel: NetKernel) extends AbstractActor {
   import java.io.{IOException, ObjectOutputStream, ObjectInputStream}
 
   @transient
@@ -110,15 +109,14 @@ class ExitFun(reason: AnyRef) extends Function2[AbstractActor, Proxy, Unit] {
     "<ExitFun>("+reason.toString+")"
 }
 
-case class Apply0(rfun: Function2[AbstractActor, Proxy, Unit])
+private[remote] case class Apply0(rfun: Function2[AbstractActor, Proxy, Unit])
 
 /**
- * @version 0.9.17
  * @author Philipp Haller
  */
 private[remote] class DelegateActor(creator: Proxy, node: Node, name: Symbol, kernel: NetKernel) extends Actor {
   var channelMap = new HashMap[Symbol, OutputChannel[Any]]
-  var sessionMap = new HashMap[Channel[Any], Symbol]
+  var sessionMap = new HashMap[OutputChannel[Any], Symbol]
 
   def act() {
     Actor.loop {
@@ -132,26 +130,25 @@ private[remote] class DelegateActor(creator: Proxy, node: Node, name: Symbol, ke
         // Request from remote proxy.
         // `this` is local proxy.
         case cmd@SendTo(out, msg, session) =>
-          // is this an active session?
-          channelMap.get(session) match {
-            case None =>
-              // create a new reply channel...
-              val replyCh = new Channel[Any](this)
-
-              // ...that maps to session
-              sessionMap += Pair(replyCh, session)
-
-              // local send
-              out.send(msg, replyCh)
-
-            case Some(replyCh) =>
-              replyCh ! msg
-              // TODO:
-              // remove `replyCh` from mapping
-              // to avoid memory leak (always safe?)
-              // or: use WeakHashMap
-              // however, it's the value (channel)
-              // that should be weak!
+          if (session.name == "nosession") {
+            // local send
+            out.send(msg, this)
+          } else {
+            // is this an active session?
+            channelMap.get(session) match {
+              case None =>
+                // create a new reply channel...
+                val replyCh = new Channel[Any](this)
+                // ...that maps to session
+                sessionMap += Pair(replyCh, session)
+                // local send
+                out.send(msg, replyCh)
+
+              // finishes request-reply cycle
+              case Some(replyCh) =>
+                channelMap -= session
+                replyCh ! msg
+            }
           }
 
         case cmd@Terminate =>
@@ -163,6 +160,7 @@ private[remote] class DelegateActor(creator: Proxy, node: Node, name: Symbol, ke
           // lookup session ID
           sessionMap.get(ch) match {
             case Some(sid) =>
+              sessionMap -= ch
               val msg = resp.asInstanceOf[AnyRef]
               // send back response
               kernel.forward(sender, node, name, msg, sid)
@@ -173,13 +171,16 @@ private[remote] class DelegateActor(creator: Proxy, node: Node, name: Symbol, ke
 
         // remote proxy receives request
         case msg: AnyRef =>
-          // create fresh session ID...
-          val sid = FreshNameCreator.newName(node+"@"+name)
-
-          // ...that maps to reply channel
-          channelMap += Pair(sid, sender)
-
-          kernel.forward(sender, node, name, msg, sid)
+          // find out whether it's a synchronous send
+          if (sender.getClass.toString.contains("Channel")) {
+            // create fresh session ID...
+            val fresh = FreshNameCreator.newName(node+"@"+name)
+            // ...that maps to reply channel
+            channelMap += Pair(fresh, sender)
+            kernel.forward(sender, node, name, msg, fresh)
+          } else {
+            kernel.forward(sender, node, name, msg, 'nosession)
+          }
       }
     }
   }
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