DRAFT: trying to make add safe

[keepsimple1]

To follow up on the issue #191, I'm experimenting with some changes to make Poller::add safe.

Since I'm new to I/O Safety, I probably missed something or maybe totally wrong. But I wanted to post this PR to get comments and find out what I've missed at least.

This draft change only applied on macOS, i.e. kqueue as I'm trying to see if I was on the right direction. Thanks in advance.

[keepsimple1]

Does this comment make sense at all? I'm new to I/O safety, please advise.

[notgull]

I don't think it's possible to make add safe in the general case; the Windows and poll()-based backends can't be made safe. However it is possible to make it safe for certain backends.

[keepsimple1]

I don't think it's possible to make add safe in the general case; the Windows

What if we change RawSocket to BorrowedSocket in the following? Will that help?

polling/src/iocp/mod.rs

Line 174 in 0b4afca

socket: RawSocket,

and poll()-based backends can't be made safe. However it is possible to make it safe for certain backends.

Is it this one? (seems it is still / already safe?)

polling/src/poll.rs

Line 102 in 0b4afca

pub fn add(&self, fd: RawFd, ev: Event, mode: PollMode) -> io::Result<()> {