Hi there,

I am currently trying to add logging capabilities to GenServers. I am aware that there are existing solutions that provide insights into a GenServer’s behavior, including logging, but this is not what I am looking for. I am looking to implement a solution myself, one I can afterwards customize and expand upon (e.g. instead of logging make API calls). For this purpose, I found the Interceptor library. This seems great for what I want to do as it allows for some custom code could be executed before/after/… a specified function each time it is executed.

What I did until now is the following. First, I made my own module called GenServerViz. In this module I basically copied all of the regular GenServer code I found on GitHub, but then expanded it with the Interceptor library. I then use GenServerViz instead of the regular GenServer. Using this approach I was able to intercept all functions that are explicitly defined in GenServers, such as start, start_link, stop, call, cast, etc. However, I am currently clueless how I would go about intercepting the callbacks such as handle_cast, handle_call, init, etc as these functions are not explicitly defined in GenServers but are usually defined in the user modules themselves.

The ‘ugly’ solution would be to setup the interception for each module that makes use of my GenServerViz. This would include adding import statements, setting up configuration and either annotating or wrapping the relevant functions inside an intercept block. This would be a very cumbersome process on a bigger scale. It would also mean that one cannot easily switch from the regular GenServer to GenServerViz by just changing the use/import statements in existing projects, something I would like to be easily possible.

Any suggestions?