It looks better except for the use of "size" in the loop control. The return code from zmq_poll is the *number of sockets* that have pending events. The way you are using it appears as though you believe the return code indicates the *number of messages* which is incorrect. The way the loop is written now, it will loop once and exit at most.
On Feb 19, 2013, at 10:29 AM, Lee Sylvester <[email protected]> wrote: > Okay, thank you. So I now have the following: > > int read_zmq_connections() { > zmq_pollitem_t items [] = { > { zmq_responder, 0, ZMQ_POLLIN, 0 } > }; > errno = 0; > int ret = 0, size = zmq_poll(items, 1, 0); > zmq_msg_t message; > while ( size > 0 && errno == 0 ) { > char *str = s_recv(zmq_responder); > parse_new_data(str); > free(str); > ++ret; > --size; > } > return ret; > } > > I'm going to test it a little later once I've written my client code. :-) > > Thanks again. > > Cheers, > Lee > > > > On 19 Feb 2013, at 16:21, Charles Remes <[email protected]> wrote: > >> Yes, you are missing out on being able to differentiate between reads & >> writes since you aren't checking the revents. However, in your case you only >> have a single socket and you only register for POLLIN, so you can just use >> the return code and skip the hard stuff. Any time it returns 1 then you know >> that your socket is readable. >> >> >> On Feb 19, 2013, at 10:18 AM, Lee Sylvester <[email protected]> wrote: >> >>> Okay, thanks. I'm looking at the reference and I can see that zmq_poll >>> returns the number of items, but it feels like I'm missing something when I >>> rely on that :-S >>> >>> Lee >>> >>> >>> On 19 Feb 2013, at 15:52, Charles Remes <[email protected]> wrote: >>> >>>> Hmmm, I'm not sure that's exactly right. >>>> >>>> The basic idea is that you want to check the return code from zmq_poll. If >>>> it is greater than 0, then the socket can be read from. You should then >>>> read from the socket until no more messages are available. I don't know >>>> how it works with the #s_recv() function (presumably that is part of the >>>> czmq binding) but you want to read until the socket is empty or you get >>>> EAGAIN. Perhaps that function does that for you under the covers. >>>> >>>> So, the loop should be around reading from the socket and *not* around >>>> zmq_poll. Does that make sense? >>>> >>>> >>>> >>>> On Feb 19, 2013, at 9:16 AM, Lee Sylvester <[email protected]> wrote: >>>> >>>>> Thank you, that's great. So, based on what I've read, does this look >>>>> correct for what I'm trying to accomplish? >>>>> >>>>> int read_zmq_connections() { >>>>> zmq_pollitem_t items [] = { >>>>> { zmq_responder, 0, ZMQ_POLLIN, 0 } >>>>> }; >>>>> while (1) { >>>>> zmq_msg_t message; >>>>> zmq_poll(items, 1, 0); >>>>> if (items[0].revents & ZMQ_POLLIN) { >>>>> char *str = s_recv(zmq_responder); >>>>> parse_new_data(str); >>>>> free(str); >>>>> } else { >>>>> break; >>>>> } >>>>> } >>>>> return 0; >>>>> } >>>>> >>>>> Thanks, >>>>> Lee >>>>> >>>>> >>>>> >>>>> >>>>> On 19 Feb 2013, at 14:52, Charles Remes <[email protected]> wrote: >>>>> >>>>>> Take a look at the man page for zmq_poll. You can do a non-blocking poll >>>>>> for incoming messages on your socket. If it returns immediately with 0, >>>>>> then no sockets in your pollset have pending messages to read. >>>>>> >>>>>> Be aware that when zmq_poll does indicate that you have messages, you >>>>>> must read *all* of them from the socket before zmq_poll will work again. >>>>>> I'm pretty sure the man page explains this. >>>>>> >>>>>> Good luck. >>>>>> >>>>>> On Feb 19, 2013, at 8:44 AM, Lee Sylvester <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> Hey guys, >>>>>>> >>>>>>> So, I've integrated ØMQ into my server. Now, I want to use ØMQ as a >>>>>>> means to supply information to a HTTP server from a separate management >>>>>>> app. So, in theory, it will look something like this >>>>>>> >>>>>>> int read_zmq_connections() { >>>>>>> int ret = 0; >>>>>>> while (zmq_has_messages(zmq_responder)) { >>>>>>> char *str = s_recv(zmq_responder); >>>>>>> parse_new_data(str); >>>>>>> free(str); >>>>>>> ++ret; >>>>>>> } >>>>>>> return ret; >>>>>>> } >>>>>>> >>>>>>> This way, if there are no messages on zmq_responder, then the function >>>>>>> will simply return. What I don't know how to do (and can't quite find) >>>>>>> is how to check if messages exist on the connection. Can anyone please >>>>>>> point me in the right direction? >>>>>>> >>>>>>> The reason why I need this non-blocking is that I will only be calling >>>>>>> 'read_zmq_connections' approximately once every five minutes and I >>>>>>> don't want my app to hang while waiting for messages. >>>>>>> >>>>>>> Thanks loads in advance, >>>>>>> Lee >>>>>>> _______________________________________________ >>>>>>> zeromq-dev mailing list >>>>>>> [email protected] >>>>>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >>>>>> >>>>>> _______________________________________________ >>>>>> zeromq-dev mailing list >>>>>> [email protected] >>>>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >>>>> >>>>> _______________________________________________ >>>>> zeromq-dev mailing list >>>>> [email protected] >>>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >>>> >>>> _______________________________________________ >>>> zeromq-dev mailing list >>>> [email protected] >>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >>> >>> _______________________________________________ >>> zeromq-dev mailing list >>> [email protected] >>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >> >> _______________________________________________ >> zeromq-dev mailing list >> [email protected] >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev > > _______________________________________________ > zeromq-dev mailing list > [email protected] > http://lists.zeromq.org/mailman/listinfo/zeromq-dev _______________________________________________ zeromq-dev mailing list [email protected] http://lists.zeromq.org/mailman/listinfo/zeromq-dev
