>From the man page for zmq_getsockopt: "after calling zmq_send the socket may become readable (and vice versa) without triggering a read event on the file descriptor." On 1 May 2016 3:33 am, "Kalle Huttunen" <khut...@gmail.com> wrote:
> The ZeroMQ FAQ (http://zeromq.org/area:faq#toc5) states in the "Why can't > I use standard I/O multiplexing functions such as select() or poll() on > ZeroMQ sockets?" question: > > > Note that there's a way to retrieve a file descriptor from ZeroMQ socket > (ZMQ_FD socket option) that you can poll on from version 2.1 onwards, > however, there are some serious caveats when using it. Check the > documentation carefully before using this feature. > > I've prototyped integrating ZeroMQ socket receiving to Qt's and custom > select() based event loops, and on the first glance everything seems to > work. > > From the documentation I have identified two "caveats" that I handle in my > code: > > 1. The ability to read from the returned file descriptor does not > necessarily indicate that messages are available to be read from the socket > > This I have solved by checking ZMQ_EVENTS before reading from the socket. > > 2. Events are signaled in edge-triggered fashion > > This one I have solved by always receiving all the messages from the > socket when the file descriptor signals. > > Are there some caveats that I'm missing? > > -- > Kalle Huttunen > > _______________________________________________ > zeromq-dev mailing list > zeromq-dev@lists.zeromq.org > http://lists.zeromq.org/mailman/listinfo/zeromq-dev >
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