Re: [lwip-users] socket functionality - nonblocking?

[Simon Goldschmidt]

> I understand that there are reasons for not supporting non-blocked io, but
> are there any plans or work in progress regarding this? Or doesn't the
> current infrastructure lend it self to this easily?

This always bugs me, too. Not that I need it right now, but I think this is 
still a major downside of the lwIP sockets implementation if compared to other 
stacks.

The main problem with nonblocking IO is that someone has to implement it. 
Currently, there are 4 'active' developers maintaining lwIP (plus some for 
documentation) and none of us seem to currently use nonblocking IO :-(

> I guess it must have been discussed before. I saw some old posts about a
> socket2.c?

Hehe, socket2.c is an idea started by Frédéric and me to speed up sockets on 
lwIP. The main goal was to prevent sockets using netconn but directly using the 
raw API. My preference would be to implement normal socket functions and fast 
functions that resemble the netconn API advantages so that we would only have 
to maintain 2 APIs in the far future. But that's not going to happen soon, I 
guess.

Writing this, if it was me who fixed nonblocking IO, I guess I'd write sockets2 
first and then implement nonblocking IO on it... ;-)

> I am now at the cross section with the sign saying Left "lwip" Right
> "commercial IP stack". :)

Well, I guess we all came across that... Don't let marketing confuse you too 
much! ;-)

> If I choose lwip, I guess I will have to either do some implementation
> outside the socket layer, or try to help the development of lwip in the
> non-blocking way.

Of course, help is always welcome! Implementing nonblocking IO for the current 
sockets API should not be that tricky, since there is not that much work left, 
I think: after all, some nonblocking calls are already supported...


Simon
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