The system is based on Config::General and reads configuration files like this:

<Database>
        username        name
        password        secret
        host            someserver
        dbname          database
</Database>

HostRoot        /home/httpd/kinotrope
Templates       var/templates/
...
[download]

When an application needs to access the configuration variables it uses something like:

$c = Kinotrope::Configuration->new();

$username = $c->conf('database/username');
%db_conf = $c->conf_hash('database'); # { username => 'name', password
+ => ... }
[download]

I want to be able to use class Kinotrope::Configuration from within mod_perl handlers, cgi-bin and plain shell scripts. At the moment it is possible to create a new instance by passing the name of a configuration file or using an environment variable as default for the same purpose. This way it is possible to share the same configuration class between multiple projects having different configuration files. And every application or mod_perl handler can get cfg by calling new without arguments.

The default configuration file can be set in %ENV using PerlSetEnv inside apache's VirtualHost or Location sections. Here is my first question:

1. Different approaches for the same problem?

I would like to add caching of configuration files. Two distinct implementations come to my mind:

- use private variables inside Configuration class to store cfg data; it is extremely useful if you create new cfg objects wherever needed, without having to pass one object all around;

- use shared memory, maybe with IPC::Shareable, for the same purpose.

I know that the first approach is practical with a small number of concurrent projects, because of memory consumption problems, but can it be very fast. The second approach is better with many cfg files; it is slower but permits sharing of configuration data with batch applications.

I can implement both solutions and choose which solution should be used by inspecting a dedicated %ENV variable. Is this awful trick acceptable? I'm looking for some flexibility here.

2) Which caching solution would you use? Any different approach?

This system can be improved by installing an handler in an earlier phase of apache life cycle which would store the current configuration data somewhere in pnotes. So every following call to new can retrieve cfg data directly from pnotes. The resulting class would be a Singleton, I think.

3) Would you preload configuration files if under mod_perl? Can this be an answer for previous question?

Thanks in advance for every suggestion, criticism or pearl of wisdom!

Ciao, Valerio

p.s.: if someone is curious about Kinotrope, please visit my home node. Note that the project is really young and it is not what you would expect from a usable framework. It is just another way to learn something new.