See : https://github.com/tokio-rs/tokio
A high performance, cross platform library that makes event-driven network programming easy.
Reactor is a thin wrapper around mio whose primary goal is to unify the event loops of various networked libraries. The goal is to be able to handle the network event management of a web server and a database client (and connection pool) in the same event_loop.
As with most high level libraries, Reactor is fairly opinionated, you might want to check out the design principles to see if you agree with this approach. Or you can just check out the examples
As mentioned, it is a high performance, low overhead event manager, it allocates very little at runtime, (boxed handlers at connection time), presently, a completely serial message passing benchmark over TCP can run 50,000 round-trips per second on a local machine, that's about 20 microseconds seconds per round-trip.
Reator Contexts are the core abstraction around a socket or datagram receiver. The primary event handler features a mailbox style interface, which matches across all of the events which might effect a socket.
API Docs including a simple example can be found here