changes to minimize allocations and provide useful info

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

server/rpc_server.go

@@ -405,6 +405,7 @@ func (s *rpcServer) Register() error {
 		if err != nil {
 			return err
 		}
+		log.Logf("Subscribing %s to topic: %s", node.Id, sub.Topic())
 		s.subscribers[sb] = []broker.Subscriber{sub}
 	}
 
@@ -465,7 +466,7 @@ func (s *rpcServer) Deregister() error {
 
 	for sb, subs := range s.subscribers {
 		for _, sub := range subs {
-			log.Logf("Unsubscribing from topic: %s", sub.Topic())
+			log.Logf("Unsubscribing %s from topic: %s", node.Id, sub.Topic())
 			sub.Unsubscribe()
 		}
 		s.subscribers[sb] = nil