Thanks! this pointed me in the right direction, I think. Adding a LiftActor that removes my Peer entity to sessionWatchers would solve part of the problem I suppose. However, a corner case is when a single peer changes it's ip for some reason and connects from the new IP address. This would create a new session. I suppose I could create an actor that gets a message each time a peer connects and if it doesn't connect in time deletes the peer...
Would using thin approach be a good idea? Should the PeerMonitorActor hook up to some Watcher that can restart it (similar to the Supervisor behaviour in Erlang/OTP)? Is there any documentation on how to use actors in lift? Should I write something on it? I'm sure the issue of removing database entries unless something happens within a timeperiod is a pretty common use case (e.g. registering an account on a site). Cheers, Emil On Nov 6, 5:45 pm, David Pollak <[email protected]> wrote: > On Fri, Nov 6, 2009 at 1:15 AM, Emil <[email protected]> wrote: > > > Hi! > > > For fun I have started to develop a very basic bittorrent tracker > > using Lift while I'm on parental leave. So far so good, it manages to > > share peer information and I can upload/download and search for > > torrent files. > > > However, if a peer stop their client ungracefully and a stop event is > > not sent to my tracker the peer will continue to appear as connected. > > I think I read somewhere that it is possible to add a delete method > > that is run after X amount of time, but I don't remember where. Is > > this possible using some built-in feature of vanilla Lift? If so, > > anyone got a short how-to? > > This is probably more elaborate than you want, but it's how Lift manages > sessions. You can find the code in LiftSession.scala: > > private[http] case class AddSession(session: LiftSession) > private[http] case class RemoveSession(sessionId: String) > case class SessionWatcherInfo(sessions: Map[String, LiftSession]) > > /** > * Manages LiftSessions because the servlet container is less than optimal > at > * timing sessions out. > */ > object SessionMaster extends LiftActor { > private var sessions: Map[String, LiftSession] = Map.empty > private object CheckAndPurge > > def getSession(id: String, otherId: Box[String]): Box[LiftSession] = > synchronized { > otherId.flatMap(sessions.get) or Box(sessions.get(id)) > } > > /** > * Put an Actor in this list and the Actor will receive a message > * every 10 seconds with the current list of sessions: > * SessionWatcherInfo > */ > @volatile var sessionWatchers: List[LiftActor] = Nil > > /** > * Returns a LiftSession or Empty if not found > */ > def getSession(httpSession: => HTTPSession, otherId: Box[String]): > Box[LiftSession] = > synchronized { > otherId.flatMap(sessions.get) or > Box(sessions.get(httpSession.sessionId)) > } > > /** > * Returns a LiftSession or Empty if not found > */ > def getSession(req: HTTPRequest, otherId: Box[String]): Box[LiftSession] = > synchronized { > otherId.flatMap(sessions.get) or > Box(sessions.get(req.session.sessionId)) > } > > /** > * Adds a new session to SessionMaster > */ > def addSession(liftSession: LiftSession) { > synchronized { > sessions = sessions + (liftSession.uniqueId -> liftSession) > } > liftSession.startSession() > liftSession.httpSession.foreach(_.link(liftSession)) > } > > protected def messageHandler = reaction > > private val reaction: PartialFunction[Any, Unit] = { > case RemoveSession(sessionId) => > val ses = synchronized(sessions) > ses.get(sessionId).foreach { > s => > try { > s.doShutDown > try { > s.httpSession.foreach(_.unlink(s)) > } catch { > case e => // ignore... sometimes you can't do this and > it's okay > } > } catch { > case e => Log.error("Failure in remove session", e) > > } finally { > synchronized {sessions = sessions - sessionId} > } > } > > case CheckAndPurge => > val now = millis > val ses = synchronized {sessions} > for ((id, session) <- ses.elements) { > session.doCometActorCleanup() > if (now - session.lastServiceTime > session.inactivityLength || > session.markedForTermination) { > Log.info(" Session " + id + " expired") > this.sendMsg(RemoveSession(id)) > } else { > session.cleanupUnseenFuncs() > } > } > if (!Props.inGAE) { > sessionWatchers.foreach(_ ! SessionWatcherInfo(ses)) > doPing() > } > } > > private[http] def sendMsg(in: Any): Unit = > if (!Props.inGAE) this ! in > else { > this.synchronized { > tryo { > if (reaction.isDefinedAt(in)) reaction.apply(in) > } > } > } > > private def doPing() { > if (!Props.inGAE) { > try { > ActorPing schedule (this, CheckAndPurge, 10 seconds) > } catch { > case e => Log.error("Couldn't start SessionMaster ping", e) > } > } > } > > } > > Hope this helps. > > > > > If anyone is interested I'll put the code on github, when I've cleaned > > it up a little... > > > Cheers, > > Emil Hellman > > -- > Lift, the simply functional web frameworkhttp://liftweb.net > Beginning Scalahttp://www.apress.com/book/view/1430219890 > Follow me:http://twitter.com/dpp > Surf the harmonics --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Lift" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/liftweb?hl=en -~----------~----~----~----~------~----~------~--~---
