Re: How to manage shared library lifetime through C functions

Seref Arikan wrote:
> I hope this is the right group to ask this question; apologies if this should go the general or some
> other list.
> 
> 
> I have multiple shared libraries that can be called from C that I'd like to use from a C based
> postgresql function.
> 
> These libraries perform some expensive initialization and they require the C code to properly release
> resources when the library is no longer needed.
> 
> 
> This means that I need a mechanism to keep a session level pointer to a library, initialize it when it
> is called first from a C based function and dispose the library properly when the session ends (and
> terminated due to a problem) I would like to keep the libraries available as long as the session is
> alive, so multiple calls are supposed to avoid initialization/disposal costs every time.
> 
> 
> I could probably use a temp table as a container for the initalization and even pointer values (sounds
> dirty) but I have no idea how to hook to session end to clean up when session ends.
> 
> 
> What would be a good strategy here?

You could register a callback at process exit with on_proc_exit() from storage/ipc.h.

Yours,
Laurenz Albe