fix: fix the error of database is locked when use sqlite (#60)

pkg/ldap/record.go

@@ -40,6 +40,13 @@ func NewRecord(rule *Rule, flag, path, ip, area string) (r *Record, err error) {
 		Path: path,
 		Rule: *rule,
 	}
+
+	// sqlite db-level lock to prevent too much write operation lead to error of `database is locked` #54
+	if database.Driver == database.Sqlite {
+		database.Locker.Lock()
+		defer database.Locker.Unlock()
+	}
+
 	return r, database.DB.Create(r).Error
 }