Re: [lwip-devel] Removing the restriction on number of sockets

[Joel Cunningham]

> On Aug 7, 2017, at 4:19 PM, Joan Lledó <address@hidden> wrote:
> 
> 2017-08-07 22:16 GMT+02:00 address@hidden <address@hidden>:
>> The proposal doesn't look too bad overall. However, I'm not sure using a
>> linked list is the best solution. If you implement this to not have the
>> total number of sockets limited, a linked list might hurt...
>> 
> 
> Yeah, I don't like it neither, but I need a way to find a lwip_sock
> from a socket number, and iterating a linked list was the first idea
> that came to my mind. Any suggestion?


> 
>> An I wouldn't limit the "open socket count" functionality to
>> MEM_LIBC_MALLOC. We do have a heap which can be used for this.
>> 
> 
> Wouldn't that limit the amount of sockets due to MEM_SIZE?

I think Simon meant that systems with MEM_LIBC_MALLOC = 0 could also use 
dynamic sockets because mem_malloc() comes from LwIP’s internal heap in that 
case.

It may be worth noting that there aren’t existing example of “static” versus 
“dynamic” implementations of data structures within LwIP.  I would think we’d 
want a solution that could work for all systems so two don’t have to be 
maintained.

Maybe a memory pool for sockets would allow a dynamic/unrestricted size when 
used with MEMP_MEM_MALLOC = 1 (as Simon suggested) and MEM_LIBC_MALLOC = 1, but 
a fixed size for systems with MEMP_MEM_MALLOC = 0.  Since memory pools 
typically allocate one at a time, we’d need to figure out how to link the 
allocations together that allows fast lookup or maybe use some type of slab 
allocation...I’ll brainstorm this some more

Joel