status and session_tracik callback function:

This feature allows client applications to register a callback function,
which is called as soon as the server status changes or session_track
information was sent by the server.

Registration is handled via mysql_optionsv() API function:

mysql_optionsv(mysql, MARIADB_OPT_STATUS_CALLBACK, function, data)

The callback function must be defined as follws:

void status_callback(void *data, enum enum_mariadb_status_info type, ..)

  Parameters:
    - data  Pointer passed with registration of callback function
            (usually a connection handle)
    - type  Information type  STATUS_TYPE or SESSION_TRACK_TYPE

  Variadic Parameters:

  if (type == STATUS_TYPE):
    - server status (unsigned int)

  if (type == SESSION_TRACK_TYPE)
    - enum enum_session_state_type track_type - session track type

    if (track_type == SESSION_TRACK_SYSTEM_VARIABLES)
      - MARIADB_CONST_STRING *key
      - MARIADB_CONST_STRING *value

    else
      - MARIADB_CONST_STRING *value

An example can be found in connection.c (test_status_callback)

include/mariadb_com.h

@@ -306,6 +306,13 @@ enum enum_mysql_set_option
   MYSQL_OPTION_MULTI_STATEMENTS_OFF
 };
 
+/* for status callback function */
+enum enum_mariadb_status_info
+{
+  STATUS_TYPE= 0,
+  SESSION_TRACK_TYPE
+};
+
 enum enum_session_state_type
 {
   SESSION_TRACK_SYSTEM_VARIABLES= 0,