The ivykis library is a thin, portable wrapper around OS-provided
mechanisms such as epoll(4), kqueue(2), poll(2) and select(2). It was
mainly designed for building high-performance network applications,
but can be used in any event-driver application that uses pollable
file descriptors as its event sources.

Programs written to the ivykis API are generally single-threaded (or
use only a small number of threads), and never block on I/O. All
input and output is done in a nonblocking fashion, with I/O readiness
notification delivered via callback functions.

WWW: https://github.com/buytenh/ivykis