public int getServerCount(boolean onlyAvailable) {
        if (onlyAvailable) {
            return upServerList.size();
        } else {
            return allServerList.size();
        }
    }
get the count of servers.

@param onlyAvailable
           if true, return only up servers.
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/BaseLoadBalancer.java