I don't think it is a docu thing. What the docu says (and what the source looks like) zmq_getsockopt(ZMQ_FD) returns a fd (the mailbox's), which becomes readable, whenever the corresponding socket might have become readable and/or writeable for operation with the NOBLOCK option. To check which of these conditions are true, you have to use zmq_getsockopt(ZMQ_EVENTS) and check for ZMQ_POLLIN / ZMQ_POLLOUT respectively.
If this is true, users should ONLY select/poll for the read event, e.g. using libev EV_READ, regardless if the user wants to zmq_recv(ZMQ_NOBLOCK) or zmq_send(ZMQ_NOBLOCK). Then the example code shows a bug or I am using the XREQ/XREP in a wrong way. Else, you are right and the documentation has to be updated to select/poll for read AND write events. I guess the "solution/workaround" of the example (using ev.READ + ev.WRITE) does not work reliable and under all circumstances, but just in this primitive scenario. greets On Fri, Apr 27, 2012 at 11:07 AM, Paul Colomiets <p...@colomiets.name> wrote: > Hi Gerhard, > > On Fri, Apr 27, 2012 at 11:41 AM, Gerhard Lipp <gel...@googlemail.com> wrote: >>> Probably I don't understand the code. You must poll only for reading >>> on ZMQ_FD. But every zmq_send and zmq_recv cosumes mailbox. >>> Which means you must update you applications' state of readable >>> and writable flags (I mean your IO framework doesn't know that >>> socket became readable or writable). >>> >>> If you don't care about ZMQ_POLLOUT event, you still must check >>> ZMQ_EVENTS for reading on each zmq_send. >> >> You are right, I am actually just waiting to be able to zmq_recv with >> ZMQ_NOBLOCK. I dont care about the ZMQ_POLLOUT in this example. As the >> docs state, either event is signaled by the mailbox (ZMQ_FD) becoming >> ready to read (ev.READ). That is why i am checking for ZMQ_POLLIN >> before entering the zmq_recv/zmq_send. >> > > So the real problem is misleading documentation? I think it would > be nice if you'd update documentation in a way that's understandable > for you, and send a pull request. > > -- > Paul > _______________________________________________ > zeromq-dev mailing list > zeromq-dev@lists.zeromq.org > http://lists.zeromq.org/mailman/listinfo/zeromq-dev _______________________________________________ zeromq-dev mailing list zeromq-dev@lists.zeromq.org http://lists.zeromq.org/mailman/listinfo/zeromq-dev
