On Tue, Aug 31, 2021 at 9:29 AM Ruediger Pluem <rpl...@apache.org> wrote:
> On 8/30/21 8:04 PM, yla...@apache.org wrote:
> >
> > +            /* We want to write if we asked for POLLOUT and got:
> > +             * - POLLOUT: the socket is ready for write;
> > +             * - !POLLIN: the socket is in error state (POLLERR) so we let
> > +             *   the user know by failing the write and log, OR the socket
> > +             *   is shutdown for read already (POLLHUP) so we have to
> > +             *   shutdown for write.
> >               */
> >              if ((tc->pfd->reqevents & APR_POLLOUT)
> >                      && ((pfd->rtnevents & APR_POLLOUT)
> > +                        || !(tc->pfd->reqevents & APR_POLLIN)
> Why should we write if we requested POLLOUT did not get POLLOUT back, but did 
> not request for POLLIN?

What I want to avoid in this loop is to handle all the POLLIN|POLLERR
or POLLOUT|POLLERR or POLLERR alone which depend on the system.
So it's written such that there is no "blank" pass, when no
POLLIN|POLLHUP or POLLOUT is returned (likely an error condition) we
will issue either a read or a write (in that order of preference) to
catch the error at the core filters' level.
This was missing the POLLOUT|POLLHUP case when the socket is shutdown
for read already, meaning that we will never get POLLIN anymore, and
this is fixed by this !(reqevents & APR_POLLIN) case to issue a write
(well a shutdown for write exactly here) when no read is to be issued

Does it make sense?


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