Question

I wanted to add a ZeroMQ socket to a glib program.

The pitty is, a zmq socket is not poll()-able, and they give their implementation, which overloads the old poll() func. How could I integrate that into the main loop efficiently? I tried using their poll ( zmq_poll() ) instead of the default one, but there’s no good way of giving it the zmq socket, besides from making it a global.

Defining a new GSource works, but it can get high CPU usage ( by setting timeout = 0 ) or arbitrary poll timeouts ( e.g. setting timeout = 100 to be polled at least every 100 ms ), which is not really efficient, since there is the possibility of polling.

Answer 1

I found that newer zmq libraries support the ZMQ_FD getsockopt() parameter, which gives you back a unix fd which you can poll(). The only caveat is that you can’t just poll() it to know if you can recv() or send() from / to it, but you need to use the ZMQ_EVENTS getsockopt() parameter to get back the real fd status.

It seems to be working quite well in glib.