Re: [lwip-users] Can you connect a MQTT client directly from a PPPoS status callback?

[address@hidden]

Am 16.05.2019 um 20:56 schrieb Freddie Chopin:
> On Thu, 2019-05-16 at 19:51 +0200, address@hidden wrote:
> > It's probably not safe as you risk calling back into modules that are
> > not reentrant. I don't know this for sure, just as a saftey
> > measurement...
>
> Yes, this is what I was afraid of.

And it shows you're actually asking the correct question :-)

> > Maybe you could use tcpip_trycallback() from that callback?
>
> I assume you are talking about tcpip_try_callback() right?

Yeah, sorry.

> Only thing I could find about tcpip_trycallback() is this:
>
> tcpip_trycallback() was renamed to tcpip_callbackmsg_trycallback() to avoid 
> confusion
>      with tcpip_try_callback()
>
> It seems that the name was (and still is) very confusing (;

Hrmpf :(

> Anyway tcpip_try_callback() does indeed look as what I could use for my
> purpose, so thanks for info! I'll try that tomorrow, however I'm not
> sure how will I be able to deal with an error when posting the callback
> (or allocating the message) will not be possible.

Yeah, well, but what would you do inside that callback when
mqtt_connect() (or whatever) would return such an out-of-resources
error? In such an embedded system, you just have to implement guards to
either set the red lamp or keep retrying... Probably in a
state-machine-like cyclic task... but that's far beyond what lwIP provides.

Regards,
Simon

> The other function -
> tcpip_callbackmsg_trycallback() -  also looks like I could use it, one
> possible failure point less.
>
> Regards,
> FCh
>
>
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