I've been writing C++ code that needs to get wrapped into a postgresql extension and it has a few singleton classes like:
1. Config object that holds some general configuration information. 2. Stats object for global stats collection. 3. Logger object for enabling/disabling debug logging to a file. 4. curlpp class for making outbound calls to an OSRM web service from the c++ code
I can probably do without 1-3 if I had to when the code is integrated, but they are handy to keep around in the code for when we are developing and working outside the postgresql database. I could #ifdef then all, but I would like to avoid cluttering the code with tons of #ifdef.
Item 4 is a little more problematic and needs to be kept around or something else implemented to take its place. I have looked at the curl extension and actual built another module in C that uses those ideas., but the curlpp is a nice OO class that encapsules and hides all the curl stuff from the C++ code.
So my question(s) are:
1. Any insights into singletons working/not working within the postgresql server extensions? My understanding is that these are implemented as global static classes with a lifetime of the process and they have no destructor, so I'm a little worried about memory leaks or multiple queries sharing the singleton.
2. Is there another way implement the equivalent of a singleton for C++ code that has a lifetime of the query in the server?
3. What do for logging classes when integrating C++ code into postgresql?
Any help or ideas would be appreciated.
I would have written extension in pure C. And I would get rid of
singletones. (Singletone - artificial constraints that the programmer
creates for himself. Btw, C++ - too :-) )
I would use Extension Configuration Tables to store the
