Passing current_database to BackgroundWorkerInitializeConnection

I am having trouble figuring out the right way to do this, clearly missing something obvious.  I am simply trying to pass the current database to BackgroundWorkerInitializeConnection, but MyDatabaseId is showing as 0, and I am getting this error in the running of function get_database_name here at the top:

ERROR:  invalid cache ID: 21

char       *database_name = get_database_name(MyDatabaseId);

/*

...

*/

    /* Connect to our database */

    BackgroundWorkerInitializeConnection(database_name, NULL);

Any direction would be much appreciated.  I have tried to look at example uses of MyDatabaseId and not sure what I'm missing here.

Thanks,

Jeremy