Using UDS to seamlessly move Proxygen workloads like that is so slick!
Here's how we've used this file descriptor transfer feature:
We made a transport which can accept local connections on a Unix Domain Socket and then "upgrades" that connection to two pipes (read and write). Those pipes are passed over the UDS and the client/server communicate over them.
We use a kernel-bypass library (OpenOnload) that implement pipes as shared memory in user-space. Very low latency and high throughput.
We made a `boost::asio` implementation of this available on GitHub. It is old and I'm not sure if it works with latest Boost, but it is quite readable for people to play with. We once bolted it onto Redis' Unix Socket transport for fun, but abandoned it as it was a hassle to maintain.