fix registry check issue (#1067)

fix #1066

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

server/rpc_server.go

@@ -835,17 +835,20 @@ func (s *rpcServer) Start() error {
 				s.RLock()
 				registered := s.registered
 				s.RUnlock()
-				if err = s.opts.RegisterCheck(s.opts.Context); err != nil && registered {
+				rerr := s.opts.RegisterCheck(s.opts.Context)
+				if rerr != nil && registered {
 					log.Logf("Server %s-%s register check error: %s, deregister it", config.Name, config.Id, err)
 					// deregister self in case of error
 					if err := s.Deregister(); err != nil {
 						log.Logf("Server %s-%s deregister error: %s", config.Name, config.Id, err)
 					}
-				} else {
+				} else if rerr != nil && !registered {
+					log.Logf("Server %s-%s register check error: %s", config.Name, config.Id, err)
+					continue
+				}
 				if err := s.Register(); err != nil {
 					log.Logf("Server %s-%s register error: %s", config.Name, config.Id, err)
 				}
-				}
 			// wait for exit
 			case ch = <-s.exit:
 				t.Stop()
@@ -854,10 +857,15 @@ func (s *rpcServer) Start() error {
 			}
 		}
 
+		s.RLock()
+		registered := s.registered
+		s.RUnlock()
+		if registered {
 			// deregister self
 			if err := s.Deregister(); err != nil {
 				log.Logf("Server %s-%s deregister error: %s", config.Name, config.Id, err)
 			}
+		}
 
 		s.Lock()
 		swg := s.wg