18.5.4.Server Main Function
The server main function for a customized Virtuoso server has the following format:
static void (*old_ddl_hook) (client_connection_t *cli) = NULL; static void ddl_hook (client_connection_t *cli) { if (old_ddl_hook) old_ddl_hook (cli); /* DDL code (depending on the server being fully initialized (ex: create table) ) goes here */ } static void init_func (void) { old_ddl_hook = set_ddl_init_hook (ddl_hook); /* initialization code (prerequisite for server initialization (bif_define, unrelated init code) goes here */ } int main (int argc, char *argv[]) { VirtuosoServerSetInitHook (init_func); return VirtuosoServerMain (argc, argv); }
There are three phases to custom code initialization:
execution of the main()
function |
execution of the init_func()
function |
execution of the ddl_hook()
function |
The init_func()
function is called
before any server initialization functions are called. This is
typically a place for defining new VSEs, allocation of
synchronization objects (since the server does not have any threads
yet), and/or custom code initialization not related to Virtuoso.
Here, the set_ddl_init_hook()
should
be called also, if it exists, to register the ddl_hook()
callback function.
Note: | |
---|---|
The |
The ddl_hook()
function is called
during normal startup just before the roll forward, but after the
server's internal structure has been initialized. This is typically
a place to execute SQL statements to initialize the extension. The
variable client_connection_t
*
is passed to the function to provide the client
connection that should be used for SQL execution.
The main()
function can call
VirtuosoServerSetInitHook()
if there
is any Virtuoso-related initialization to be performed, and should
then call the VirtuosoServerMain()
function to start the Virtuoso server. The VirtuosoServerMain()
function will return control
after the server has been shut down.