[lwip-users] timeouts in multi-threaded implementation.

[David Ryan]

Hi all..

Something I touched on a while ago was the issue of timeouts in a 
multi-threaded implementation.  Looking at the code there doesn't seem 
to be a good reason to always call sys_mbox_fetch rather than 
sys_arch_mbox_fetch... and similarly sys_sem_wait over sys_arch_sem_wait.

For instance the main tcpip thread in an API based implementation should 
easily be able to handle any of the main timeouts by calling the 
sys_mbox_fetch as it does now.  Is it neccessary to call sys_mbox_fetch 
on threads that are calling socket functions using threads external to 
the application?  Before I change the calls in my code, I'm curious to 
know if I'm missing something here?

If these calls to sys_mbox_fetch in the api_lib.c code do not need to 
call or handle timeouts I'd rather not have it call sys_mbox_fetch.

The same applies to the mem.c, memp.c, and pbuf.c use of sys_sem_wait.   
I would rather they call sys_arch_sem_wait directly than handle timeouts 
in areas of the code which I know can be handled sufficiently by the 
tcpip thread.  Could these mutexes be replaced with sys_arch_protect 
instead?

Does this make sense, or does checking these timeouts take precendance 
over everything else?

Thanks,
David.