I have written a program which records protocol messages between an application

Question

I have written a program which records protocol messages between an application and a hardware device which matches each application request with each hardware response. This is so that I can later remove the hardware, connect a 'replay' application to the main application and wait for an application request and reply with a matched copy of the requisite hardware reply message.

My replay application saves the matched request/response in a list (using C++ std::list).

This works fine on a small interaction session. My problem now is that I need to be able to use the replay over a long long session. With my current implementation, the replay program eventually uses up all available memory on my computer and crashes.

So I need some sort of lookahead - and not parse the whole session in one go.

Can anyone make any suggestions on how to get started?

Explanation / Answer

(Just re-iterating so that you know that I know what you are saying)
It sounds like you are effectively creating an in-memory structure of the various requests and responses. With a large session, this is creating a significantly large structure that is then taking more memory than you have available.

Instead of trying to keep the entire thing in memory, would it be feasible to go to a disk based system? For example one could go to a Berkeley db on disk. It has C and C++ bindings that you could use to tie into your current application.

With this approach, one could hash the request (last I recall, Berkeley db likes to have simple keys) and store/retrieve based on the hash. This way, one doesn't keep the entire database (or list) in memory, but rather does fast indexed lookups on disk.

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