subscribe多次调用，参数被覆盖

[splusz]

1. 证券代码被覆盖
   调用subscribe两次，每次指定不同的证券代码。收到dataserver推送的行情数据里只包含最后一次订阅的证券。问题可能出在这里(PublisherActor.scala):

 def onSubscribeReq(req: SubscribeReq, client: ActorRef) {

        // Assume one actor has a unique path
        logger.info("onSubscribeReq: " + req.symbols.mkString(","))
        val id = client.path.toString

        var oldList = subscriberInfoMap.getOrElse(id, null)

        if (oldList == null) oldList = Seq[String]()
        val newList = req.symbols

        val exist_subscribed = oldList.intersect(req.symbols)   // 问题出在这儿，exist_subscribed应等于oldList ，而不是取交集
        // ... ...

2. 订阅指标（fields）被覆盖
   调用subscribe两次，每次指定不同的指标，第二次subscribe时指定的指标会覆盖前一次的指标