server: allow to call server.Close() twice

server.go

@@ -225,7 +225,7 @@ func (s *Server) Start(address string) error {
 		return err
 	}
 
-	s.terminate = make(chan struct{})
+	s.terminate = make(chan struct{}, 1)
 	s.done = make(chan struct{})
 
 	go s.run()
@@ -233,6 +233,22 @@ func (s *Server) Start(address string) error {
 	return nil
 }
 
+// Close closes all the server resources and waits for the server to exit.
+func (s *Server) Close() error {
+	select {
+	case s.terminate <- struct{}{}:
+	default:
+	}
+	<-s.done
+	return nil
+}
+
+// Wait waits until a fatal error.
+func (s *Server) Wait() error {
+	<-s.done
+	return s.exitError
+}
+
 func (s *Server) run() {
 	s.sessions = make(map[string]*ServerSession)
 	s.conns = make(map[*ServerConn]struct{})
@@ -386,19 +402,6 @@ outer:
 	close(s.done)
 }
 
-// Close closes all the server resources and waits for the server to exit.
-func (s *Server) Close() error {
-	close(s.terminate)
-	<-s.done
-	return nil
-}
-
-// Wait waits until a fatal error.
-func (s *Server) Wait() error {
-	<-s.done
-	return s.exitError
-}
-
 // StartAndWait starts the server and waits until a fatal error.
 func (s *Server) StartAndWait(address string) error {
 	err := s.Start(address)