only make NewDefaultServer once when neccessary

Author: greedy52

server/conn.go

@@ -46,6 +46,8 @@ func NewConn(conn net.Conn, user string, password string, h Handler) (*Conn, err
 	p := NewInMemoryProvider()
 	p.AddUser(user, password)
 
+	defaultServer := NewDefaultServer()
+
 	var packetConn *packet.Conn
 	if defaultServer.tlsConfig != nil {
 		packetConn = packet.NewTLSConn(conn)

server/server_conf.go

@@ -8,8 +8,6 @@ import (
 	. "github.com/go-mysql-org/go-mysql/mysql"
 )
 
-var defaultServer = NewDefaultServer()
-
 // Defines a basic MySQL server with configs.
 //
 // We do not aim at implementing the whole MySQL connection suite to have the best compatibilities for the clients.
@@ -43,7 +41,7 @@ type Server struct {
 // non-TLS connection). By default, it will verify the client certificate if present. You can enable TLS support on
 // the client side without providing a client-side certificate. So only when you need the server to verify client
 // identity for maximum security, you need to set a signed certificate for the client.
-func NewDefaultServer() *Server {
+var NewDefaultServer = sync.OnceValue(func() *Server {
 	caPem, caKey := generateCA()
 	certPem, keyPem := generateAndSignRSACerts(caPem, caKey)
 	tlsConf := NewServerTLSConfig(caPem, certPem, keyPem, tls.VerifyClientCertIfGiven)
@@ -58,7 +56,7 @@ func NewDefaultServer() *Server {
 		tlsConfig:         tlsConf,
 		cacheShaPassword:  new(sync.Map),
 	}
-}
+})
 
 // NewServer: New mysql server with customized settings.
 //