Re: [lwip-users] Query amount of free buffers

[address@hidden]

Marco Jakobs wrote:
> This is not so easy as i'm using the LwIP access in different tasks from
> the LwIP task, and the socket API is not thread-safe. So the netconn API
> is the most convenient way (and also working really smooth).
>    
The netconn API is no more thread-safe than the netconn API: The lack of 
thread-safety (which is really only a lack of full-duplex thread-safety) 
in the socket API comes from the fact that it uses the netconn API. As 
long as you are only using one socket from one thread at a time, there 
is not problem.

However, with nonblocking-write, the problem should be solved with the 
netconn API as well.
> But in this case we *have* still all buffers full.
Not really: these are only the per-connection limits that are reached. 
That doesn't mean all buffers are used. Other connections (or UDP) may 
still use more buffers. lwIP TCP has 2 limits per connection: the number 
of pbufs enqueued (TCP_SND_QUEUELEN) and the number of bytes enqueued 
(TCP_SND_BUF). Both may be configured much smaller than the actual 
available buffers!

Simon