Re: [lwip-users] lwip_select() blocks even if timeout is 0

[Jonathan Larmour]

Chu, Zhenwei wrote:
> Yes, it is lwIP 1.3.0. timeout is set to 0, and timeout->tv_sec = 0  
> and timeout->tv_usec=0. The section of code from sockets.c is copied
> here.

I was wondering how you called lwip_select, not the code that's called.

> lwip_select()
> {
> ....
> 
>     /* add our semaphore to list */
>     /* We don't actually need any dynamic memory. Our entry on the
>      * list is only valid while we are in this function, so it's ok
>      * to use local variables */
>     
>     select_cb.sem = sys_sem_new(0);
[snip]

But the code that deals with not blocking is in the bit you have cut out
with "....".

As Rishi said, the bit that starts:
  /* If we don't have any current events, then suspend if we are supposed to */
  if (!nready) {
    if (timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0) {

is the bit which means that lwip_select does not block if the timeout
duration is 0.

Jifl
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