Recommend an alternative coroutine implementation

[lihuiba]

Hi,

I'm one of the maintainers of Photon, and I also have past experiences of using state-threads in a major project before, during which I even reported an issue to SRS's fork of state-threads.

I have recently written a compatibility layer for Photon to emulate ST. It passed all UTs of ST. The layer aims to be 100% compatible to ST in compilation, and possibly in linking (simply replace libst.a/so with libphoton.a/so);

And I'd like to recommend Photon as an alternative coroutine implementation for SRS for the following reasons:

• Photon is more performant than ST (actually than all coroutine libs known to us);
• Photon supports multi-core CPU in a single process, and modern I/O features like io_uring, zero-copy TCP, RDMA, libaio, etc.
• Photon has a built-in HTTP server that is more performant than boost.beast or nginx;