redirectFixer.scala

  private object noCometResponseSent extends SessionVar[Boolean](false)


    LiftRules.redirectAjaxOnSessionLoss = false
    LiftRules.noCometSessionPage = "/home"

    // Returns true if we should send an empty response for a comet request,
    // false otherwise. This is used to ensure we don't send multiple
    // window.location redirects in the event of a server restart in response
    // to comet requests. Sending multiple ones can send Firefox into an
    // infinite request loop that quickly consumes JVM resources and slows
    // down the browser itself.
    //
    // It should only return true if this is the first time in this session
    // that we see a comet request and meet the criteria for Lift sending
    // back a window.location redirect to LiftRules.noCometSessionPage. Code
    // for determining whether the actor list is empty was borrowed directly
    // from LiftServlet.java.
    def sendEmptyResponseForCometRequest(req:Req) = {
      req.path.wholePath match {
        case prefix :: tail if prefix == LiftRules.cometPath && (tail.length != 2 || tail(1) != LiftRules.cometScriptName()) =>
          val actors: List[(LiftCometActor, Long)] =
          req.params.toList.flatMap {
            case (name, when) =>
              S.session.open_!.getAsyncComponent(name).toList.map(c => (c, toLong(when)))
          }

          if (actors.isEmpty) {
            if (noCometResponseSent.is)
              true // clear the response, we don't want to send a redirect again
            else {
              noCometResponseSent(true)
              false // send the response this time
            }
          }
          else
            false
        case _ => false // don't clear the response, not a comet request
      }
    }
    LiftRules.dispatch.append(NamedPF("CometRedirectStopper") {
      case req if sendEmptyResponseForCometRequest(req) => () => Empty
    })