Okay, so this brings me kinda to where I was before:
int read_zmq_connections() {
zmq_pollitem_t items [] = {
{ zmq_responder, 0, ZMQ_POLLIN, 0 }
};
errno = 0;
int ret = 0;
while ( errno == 0 ) {
zmq_poll(items, 1, 0);
if (items [0].revents & ZMQ_POLLIN) {
char *str = s_recv(zmq_responder);
add_remote_account(str);
free(str);
++ret;
} else {
break;
}
}
return ret;
}
So, I poll the events and, if an error occurs or if there is no event, then I
return the number of messages retrieved. Have I missed something?
Thanks,
Lee
On 19 Feb 2013, at 17:11, Charles Remes <[email protected]> wrote:
> 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
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