lwgeom_init_backend()

void lwgeom_init_backend

(

void

)

Definition at line 116 of file lwgeom_backend_api.c.

References intersects(), lwgeom_backend_name, lwgeom_backend_switch(), lwgeom_backend_definition::name, and PG_FUNCTION_INFO_V1().

Referenced by _PG_init().

{
        /* #2382 Before trying to create a user GUC, make sure */
        /* that the name is not already in use. Why would it be in use? */
        /* During an upgrade, a prior copy of the PostGIS library will */
        /* already be loaded in memory and the GUC already defined. We */
        /* can skip GUC definition in this case, so we just return. */
        static const char *guc_name = "postgis.backend";
        // const char *guc_installed = GetConfigOption(guc_name, TRUE, FALSE);

        /* Uh oh, this GUC name already exists. Ordinarily we could just go on */
        /* our way, but the way the postgis.backend works is by using the "assign" */
        /* callback to change which backend is in use by flipping a global variable */
        /* over. This saves the overhead of looking up the engine every time, at */
        /* the expense of the extra complexity. */
        if ( postgis_guc_find_option(guc_name) )
        {
                /* In this narrow case the previously installed GUC is tied to the callback in */
                /* the previously loaded library. Probably this is happening during an */
                /* upgrade, so the old library is where the callback ties to. */
                elog(WARNING, "'%s' is already set and cannot be changed until you reconnect", guc_name);
                return;
        }

        /* Good, the GUC name is not already in use, so this must be a fresh */
        /* and clean new load of the library, and we can define the user GUC */
        DefineCustomStringVariable( guc_name, /* name */
                                "Sets the PostGIS Geometry Backend.", /* short_desc */
                                "Sets the PostGIS Geometry Backend (allowed values are 'geos' or 'sfcgal')", /* long_desc */
                                &lwgeom_backend_name, /* valueAddr */
                                (char *)lwgeom_backends[0].name, /* bootValue */
                                PGC_USERSET, /* GucContext context */
                                0, /* int flags */
                                NULL, /* GucStringCheckHook check_hook */
                                lwgeom_backend_switch, /* GucStringAssignHook assign_hook */
                                NULL  /* GucShowHook show_hook */
                                );
}

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