Re: Portabilty of poll trick

[Bastien ROUCARIES <roucaries.bastien@gmail.com>]

Le mar. 27 avr. 2021 à 22:51, Ben Pfaff <blp@cs.stanford.edu> a écrit :
>
> On Tue, Apr 27, 2021 at 3:47 PM Bastien ROUCARIES
> <roucaries.bastien@gmail.com> wrote:
> >
> > Le mar. 27 avr. 2021 à 22:40, Bruno Haible <bruno@clisp.org> a écrit :
> > >
> > > Hi Bastien,
> > >
> > > > I want to assess the safety and portability of the following trick,
> > >
> > > I would want to help you with this, but I can't. You have not stated:
> > >   - What is this code supposed to do?
> > I want to shutdown (2) a pipe, in a multithread application, in order
> > to get out a poll(2) wait state
> > >   - Why is it a "trick"? What advantages does it have compared to the code
> > >     a naïve developer would write?
> > The naive delevopper will:
> > - close the end of the pipe, but it does not break poll(2), and
> > moreover in multithread context
> > it is not safe due to fd reuse
> > -use timeout but in this case why use poll...
> >
> > The goal is also to shutdown an eventfd but without kernel support, I
> > suppose it is not possible...
>
> Can you use socketpair() instead of pipe()?
Yes I can but socket are bidirectionnal and cost more about
memory/speed than pipe.

Bastien