Re: Proposal for Signal Detection Refactoring

Very minor revision
On Mon, Sep 24, 2018 at 11:45 AM Chris Travers <chris(dot)travers(at)adjust(dot)com>
wrote:

>
> Ok so having looked into this a bit more....
>
> It looks like to be strictly conforming, you can't just use a series of
> flags because neither C 89 or 99 guarantee that sig_atomic_t is read/write
> round-trip safe in signal handlers. In other words, if you read, are
> pre-empted by another signal, and then write, you may clobber what the
> other signal handler did to the variable. So you need atomics, which are
> C11....
>
> What I would suggest instead at least for an initial approach is:
>
> 1. A struct of volatile bools statically stored
>

These would be implemented as sig_atomic_t which is defined in C89 but has
no atomic operators other than writing the full value.

> 2. macros for accessing/setting/clearing flags
> 3. Consistent use of these macros throughout the codebase.
>
> To make your solution work it looks like we'd need C11 atomics which would
> be nice and maybe at some point we decide to allow newer feature, or we
> could wrap this itself in checks for C11 features and provide atomic flags
> in the future. It seems that the above solution would strictly comply to
> C89 and pose no concurrency issues.
>
> --
>> Best Regards,
>> Chris Travers
>> Head of Database
>>
>> Tel: +49 162 9037 210 | Skype: einhverfr | www.adjust.com
>> Saarbrücker Straße 37a, 10405 Berlin
>>
>>
>
> --
> Best Regards,
> Chris Travers
> Head of Database
>
> Tel: +49 162 9037 210 | Skype: einhverfr | www.adjust.com
> Saarbrücker Straße 37a, 10405 Berlin
>
>

--
Best Regards,
Chris Travers
Head of Database

Tel: +49 162 9037 210 | Skype: einhverfr | www.adjust.com
Saarbrücker Straße 37a, 10405 Berlin