Very minor revision On Mon, Sep 24, 2018 at 11:45 AM Chris Travers <chris.trav...@adjust.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
