People are also building compilers for P4 that are targeting other runtimes like BPF. Recently, there's been an effort to run a subset of BPF on hardware (NPF?).
As for "unfortunately", what don't you like about it, apart from it not being what you're used to from elsewhere? I've used Visual Sourcesafe, Perforce and git, and Perforce seems like a perfectly decent source control system.
However, I won't deny that it would be nice to be able to manage multiple revisions locally so that I can explore different approaches and easily backtrack without having to commit to the central server.
I don't think be able to build a full p4 implementation with Snabb running as a substrate (although it's been 6 months since I last worked on it, and am blanking at the moment why not), but I think it could get pretty close. But it will be a ton of work if I get around to it, plus I don't have much experience doing networking programming at this low of a level. I got a bit distracted with work and other obligations, but I hope to pick it back up soon, particularly if p4 is finally starting to get some well-deserved attention.
p4 is an awesome idea, and solves a lot of the problems OpenFlow was running into with having to constantly update the spec for new network protocols. With p4, that's just a software update, not a protocol update. It has some other neat features as well, but unfortunately it doesn't seem as though p4 has yet caught on like OpenFlow did, even though it has many of the same people behind it as OpenFlow.
Some of the cool things that people have done with p4:
To get a taste of what is P4 like, you can get started with the Behavioural Model [1], which you can imagine as some sort of emulator over x86. My understanding is that it is also being reworked in C++ [2].
Finally, there's a module coming up for OpenVSwitch.
is this project linux only?
Does FreeBSD nowadays provide some form of network isolation like it is available with Linux network namespaces? Nothing relevant shows up in the likely places, so I don't think it does.
That said, Elixir is an awesome language, and lovely to write lexer/parsers in. I took me only a few hours to build a functioning parser in Elixir, compared to several days to build one in Lua.
The p4 parser/lexer in Lua is here: https://github.com/esbullington/snabbp4
Next step would be to generate the parse graph.
Actually, p4 is aimed a solving a lot of the problems with OpenFlow that led to the situation you describe: incomplete support by vendors of all the different versions of OpenFlow. That's because each individual network protocol supported had to be written into the OpenFlow spec, thus the proliferation of versions. Whereas with p4, the vendors basically just provide a hardware runtime for the p4 language, and you install whichever protocols you wish to support (or write it yourself, if it's custom or new). It also has the potential to work very well with a scaled-down version of OpenFlow.
I'm not an SDN expert and am probably not doing justice to p4 with my description above, but it is important to realize this isn't just another network protocol. It would be like describing the Python or JS as just another program (the interpreter), and not as a program capable of running other programs.