[zeromq-dev] Poller choice in configure or poller.hpp

Olaf Mandel o.mandel at menlosystems.com
Fri Feb 14 14:30:19 CET 2014


Am 14.02.2014 13:01, schrieb Pieter Hintjens:
> On Fri, Feb 14, 2014 at 11:38 AM, Olaf Mandel <o.mandel at menlosystems.com> wrote:
>> Now my first question: is this particular example (Cygwin and poll) a
>> bug and where? ZMQ_USE_POLL works for me up to a 1021 sockets, while
>> ZMQ_USE_SELECT works only up to 28 (!) sockets. What is the "correct"
>> default for Cygwin?
> When poll() is available it generally works better than select().[...]

Now the question becomes: does Cygwin _always_ provide poll(): then
poller.hpp should be updated. Or is this only on my system?

> [...] It's
> rather surprising that select() only handles 28 sockets.
Opened an issue on this: https://github.com/zeromq/libzmq/issues/893

>> And my second question: is there a need and way to make the potential
>> ambiguity clearer?
> Sounds like cleaning this up would be beneficial. Two mechanisms to do
> the same work feels bogus. Either poller.hpp should choose, or
> configure should choose. I think the FORCE macros were originally
> meant as a manual override; they've then been abused for Cygwin, and
> perhaps elsewhere.

Then the question becomes: is the mapping from a used operation system
to the best available poller constant? Then implement it into poller.hpp
and remove the configure code. If there is even a chance that the best
poller on an operation system is optional (i.e. may be missing), then
keep the configure code and clean out poller.hpp.

Are either Martin Sustrik (who last touched the poller.hpp code in
question) or Mikko Koppanen (who wrote the LIBZMQ_CHECK_POLLER configure
function) on this list and have any insight?

Best regards,
Olaf Mandel

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