Re: [lwip-users] Multithreading

[Leon Woestenberg]

Hello all,

Craig Graham wrote:
> On Tuesday 11 April 2006 09:28, Kieran Mansley wrote:
>   
> > On Tue, 2006-04-11 at 09:53 +0200, Julika Burger wrote:
> >     
> > > Hi,
> > >
> > > I have a question about lwip.
> > > Is lwip really multi threading able?
> > > Is it possible to open two sockets at the same time and read and write
> > > data to them?
> > > We use the PSOS Operating system and I can not control if two threads at
> > > the same
> > > time use a socket or not.
> > >       
> > No.  To be honest, the sockets API doesn't really allow you to do that
> > in any meaningful way on other operating systems either.  You need to
> > add a mutex to protect access to the socket and use that so that only
> > one thread is using it at any one time.
> >
> > Kieran
> >     
>
> I think what Julika was trying to ask was can two threads open two separate 
> sockets and both threads use their own sockets (rather than can two threads 
> access the same socket). And the answer to that question is, of course, yes.
>   
The answer depends:

If using the raw API, "no", and "yes" only if *you* provide mutual 
exclusive access to lwIP. This is the way we do
it under uCOS-II, a hard real-time OS. Note that all core calls are O(1) 
without any waiting loops.

If using the sysarch layer, "yes" provided you made a good match between 
underlying OS and sysarch layer and
so lwIP can use the right synchronization methods in the right way.

Regards,

Leon.