Re: [Cgi-session-user] writing CGI::Session sessions only when necessary

[Mark S. <ma...@su...>]

On Tue, 26 Jan 2010 16:42:38 -0800
Jonathan Swartz <SW...@PO...> wrote:

> On our site we create a new CGI::Session object at the beginning of  
> the request, so that it can be used anywhere in the web code.
> 
> However, sessions are rarely written to, so at the end of the request  
> I'd like to avoid actually writing out a new session to backing store  
> unless a param actually got set. The expense of writing out new  
> sessions, and cleaning them up later, has become significant.

Jon,

For a model of how to do this, see CGI::Application::Plugin::Session.
I think you'll find the concepts there portable to your own code.
Here's the overview:

session_config() collects the necessary config details, but doesn't do
anything with them. This runs on every request and just takes a momeent.

session() lazy-loads a CGI::Session object using the details collected
in session_config(). That is to say, the session is not loaded until you
call a method on CGI::Session somewhere in your code like:

$self->session->param('foo'); 

Many CGI::Application plugins are designed this way, often deferring
loading even the helper modules themselves. This is one of the design
principles that helps CGI::Application projects run well under CGI,
because in a sense you only pay for what you use.

    Mark