Experimental Physics and
Industrial Control System

Caution: This email originated from outside of Cosylab.


On 08/07/2022 17:37, Michael Davidsaver wrote:
> On 7/8/22 11:11, Mark Rivers via Tech-talk wrote:
>> Hi Andrew,
>>
>> To be honest I have not paid enough attention to how to correctly
>> handle destructors in asynPortDriver.
>
> On the occasions when I've used asynPortDriver, I put a cantProceed()
> in the sub-class destructor.


Can you say where exactly in the destructor you used cantProceed()? I
can't seem to make it behave correctly: the IOC never exits, though it
does dump a stack trace.


>
> After a call to registerInterface(), the asynInterface::drvPvt pointer
> must remain valid until
> the process exits.  So an asyn port can't be destroyed.
>
>
> I've toyed with the ideas like re-counter asynUser, or somehow later
> setting drvPvt=NULL.
> Both seem possible, but not without quite some effort.
>
>
> This situation is made more complicated by the fact that IOC scan
> threads are not stopped on exit.
> We do now stop them during database unit tests.  However, some ~vague
> compatibility concerns have
> so far kept this from being done for full IOCs.


Where does this choice happen? Could one do it for their own IOC?


>
>
> Personally, as a matter of good practice, drivers I write always
> include an epicsAtExit() handler
> which stops any worker threads.
>
>
> Also, I should mention the de-init hooks added in Base 7.0.4 to
> decouple database shutdown from
> process exit.
>
> https://github.com/epics-base/epics-base/commit/5d5e552a7ec6ef69459c97b0081aa775372a6290#diff-02e4602d43dbb03b4097bb26382a1db92367fb55fe791415cd32d4f234875d92R50
>
>
> For compatibility, the effect of initHookAtShutdown can mostly be
> replicated by calling epicsAtExit()
> at initHookAfterIocRunning.


If I understand correctly, what I'd want for my own code would be
calling the driver's destructor in initHookAfterStopScan? If it ran for
full IOCs, of course.


Aviso Legal: Esta mensagem e seus anexos podem conter informações confidenciais e/ou de uso restrito. Observe atentamente seu conteúdo e considere eventual consulta ao remetente antes de copiá-la, divulgá-la ou distribuí-la. Se você recebeu esta mensagem por engano, por favor avise o remetente e apague-a imediatamente.

Disclaimer: This email and its attachments may contain confidential and/or privileged information. Observe its content carefully and consider possible querying to the sender before copying, disclosing or distributing it. If you have received this email by mistake, please notify the sender and delete it immediately.