Support UnixStream on Windows

[sullivan-sean]

Windows 10 added support for unix sockets in a 2018 general Windows 10 release. Building this functionality into Mio would allow support in Tokio and other downstream libs.

This seems to be of interest in several downstream libs, example issues here:

• Tokio
• Tonic

Mio's current AFD approach on Windows actually seems to be compatible with AF_UNIX sockets (noted e.g. in this wepoll issue).

[sullivan-sean]

With some tinkering I've put together a first pass here that uses the existing AFD approach and passes all of the corresponding unix unix_stream and unix_listener tests in mio.

There are a few tweaks that need to be made, e.g. right now the selector must be re-registered between events which I think quirk may be related to how user_evt flags are not fully reset on the selector after an event:

mio/src/sys/windows/selector.rs

Lines 230 to 233 in c6b5f13

	// In mio, we have to simulate Edge-triggered behavior to match API usage.
	// The strategy here is to intercept all read/write from user that could cause WouldBlock usage,
	// then reregister the socket to reset the interests.
	self.user_evts &= !afd_events;

Another question is where the windows analog of std::os::unix::net should live, given that UDS is not in std yet

For now I have included a module directly within the repo modeled after https://crates.io/crates/uds_windows using windows-sys instead of winapi. But I hope there is a better way to do this

[dojyorin]

Hi😀

I want to implement an IPC mechanism in an application using Windows version of Deno.

Currently, Deno UDS is a trial support only for the Linux version, but I hope that it will eventually support the Windows version.

And I'm very interested in implementing this feature upstream of Deno.

Thanks for development😄

[Noah-Kennedy]

There is a PR right now open for this. It hasn't been updated in several weeks though. Not sure if stalled or just going slowly.