Pub/Sub graph generation

[stephanbro]

This script looks through each file within the scope passed to it to generate a list of the publishers and subscribers for each topic. The current output prints a JSON of each key and within that a list of the publishers and subscribers. Additionally there is the ability to use graphviz to generate a plot, but that is currently commented out.

Usage: ./px_generate_pubsub_graph.py <cmake-file-scoping>, where the value of <cmake-file-scoping> is a config file found in cmake/configs.

See #6189

[LorenzMeier]

Nice! What is the value for <cmake-file-scoping>?

[stephanbro]

I used the files in the cmake/configs folder. I updated the first comment to reflect that.

[bartslinger]

Great idea! I've not tested it yet, but looking at the script I think not everything is captured. For example in the mc pos controller: https://github.com/PX4/Firmware/blob/master/src/modules/mc_pos_control/mc_pos_control_main.cpp#L2328

In this case, it actually depends on whether or not the vehicle is VTOL which topic is used. Therefore I'm also not sure what would be the appropriate solution.

[jgoppert]

cmakeparser is getting nuked here (#6385) , it didn't know how to parse include statements, so it is better to just use cmake to parse the cmake files.

To do this, make this script take a list of modules like I did in the PR. Then you can tie this script into cmake to do the scoping and pub sub graph creation.

[stephanbro]

@jgoppert Thanks for the heads up! I will update this PR accordingly

[TSC21]

@stephanbro what's the current status?

[dagar]

Continued in #8393