[zeromq-dev] Anyone managed to use zeromq with Qt (QSocketNotifier) ?

Chuck Remes cremes.devlist at mac.com
Mon Sep 19 20:46:00 CEST 2011


On Sep 19, 2011, at 1:41 PM, Gaspard Bucher wrote:

> Hi list !
> 
> I am trying to use zeromq with a Qt application and I want to avoid having multiple threads
> so I tried to use ZMQ_FD and pass this to QSocketNotifier but only the first message is
> signaled. My guess is that zmq does not keep the file descriptor in read-ready state but
> just signals the first element ?
> 
> Pseudo-code:
> 
> 1. get zmq fd
> 2. create QSocketNotifier with 'Read' events
> 3. app exec
> ..
> 4. first (or many) messages arrive
> 5. ---> QSocketNotifier fires
> 6. get 1 message
> 7. wait for QSocketNotifier to fire again
> 8. .... never happens
> 
> My guess is that there is something I do not understand regarding the ZMQ_FD file descriptor.
> Maybe it only retriggers "read-ready" if the queue has been emptied ?

Your last statement is correct. You need to read all messages from the queue before it can trigger again.

cr





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