Just leave DNS out, are there any POSIX standard async functionality for networking or even normal IO? All I know by reading some libraries is epoll or io_uring used on Linux, kevent on BSDs.

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comex 3 days ago | parent | next [-]

Yes for networking. You set your sockets into O_NONBLOCK mode and use poll() or select(). These APIs are in POSIX and also have direct equivalents in Winsock.

There is also POSIX AIO for async I/O on any file descriptor, but at least historically speaking it doesn't work properly on Linux.

	▲	epcoa 3 days ago \| parent [-]
		POSIX AIO on “Linux” is implemented in glibc with userland threads using regular blocking syscalls behind the scenes. It basically works properly, it just doesn’t gain any potential efficiency benefits, it adds avoidable overhead, prone to priority inversion, etc. The linux kernel has no provision for POSIX AIO. Until io_uring the only asynchronous disk IO interface was the io_* syscalls, which were confusingly referred to as Asynchronous IO, though these have nothing to do with POSIX AIO and can only be used bypassing the page cache, and suck for general purpose use.

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mort96 3 days ago | parent | prev [-]

POSIX has poll for that.