Add id to UserSocket.

[meowjesty]

• Issue fix dup with getsockname/getpeername/accept #1054

Although this does not solve the issue, it's considered a welcome refactor anyway, and will (hopefully) help with #1123 , which is the bigger culprit that needs fixing.

Feedback request

I've left a few warnings in docs saying that you should not use the SOCKET_ALLOCATOR directly, would this be worth it putting into a new module (with the SocketId type) to prevent accidental usage?

[t4lz]

I do not really understand what this change is supposed to achieve or what's the improvement, but I left some comments under the assumption this change is needed.

As a general thought about our socket mechanism:
If what we want at the end is to store and access a UserSocket's connection queue by the actual socket and not by its file descriptor (because different file descriptors could be duplicate descriptors of the same socket) couldn't we maybe just keep the connection queue as a field of the UserSocket struct? The duplicate descriptors already point to the same UserSocket via an Arc.

About this:

I've left a few warnings in docs saying that you should not use the SOCKET_ALLOCATOR directly, would this be worth it putting into a new module (with the SocketId type) to prevent accidental usage?

In my opinion it is worth it to pack it an a module. I think it's a very cheap price to pay (or maybe even just a positive code organization feature) for letting the compiler enforce this for us. I recommend using a module, deleting the warnings, and just having a little 1 line comment above the module explaining it's for preventing direct construction.

[t4lz]

This can be merged now :)
I still do not completely understand the big plan, but given that it was decided that we need a SocketId, this is good.

This is what I would suggest instead of a SocketId:

If what we want at the end is to store and access a UserSocket's connection queue by the actual socket and not by its file descriptor (because different file descriptors could be duplicate descriptors of the same socket) couldn't we maybe just keep the connection queue as a field of the UserSocket struct? The duplicate descriptors already point to the same UserSocket via an Arc.