[zeromq-dev] question about message buffer

[Mohit Jaggi]

still trying to get to the bottom of this..appreciate any help. Especially
want to know how the VSM data is handled.


On Mon, Mar 4, 2013 at 10:59 AM, Mohit Jaggi <mohitjaggi at gmail.com> wrote:

> This is not fully full but more detailed...'buf' is on stack (so
> destructor will be called) and 'm' is on heap(and I havn't called
> delete...should I?). I want to understand how zmq treats them.
>
> context_t ctx(1);
>
> socket_t *publisher;
>
> void init() {
>
> publisher = new socket....
>
> publisher.bind(...)
>
> }
>
> void publish(myObject) {
>
> string buf;
>
> myObject.SerializeToString(&buf);
>
> message_t m = new message_t(buf.size());
>
> memcpy((*void**) m.data(), buf.c_str(), buf.size());
>
> string topic(string("X") + string("Y") + string("Z"));
>
> publisher->send(topic.c_str(), topic.size(), ZMQ_SNDMORE); //topic
>
> publisher->send(m); //data
>
> }
>
> main() {
>
> init();
>
> ...
>
> publish(obj);
>
> }
>
>
> On Mon, Mar 4, 2013 at 12:51 AM, Pieter Hintjens <ph at imatix.com> wrote:
>
>> Hi Mohit,
>>
>> Can you provide a full example?
>>
>> -Pieter
>>
>>
>> On Mon, Mar 4, 2013 at 8:34 AM, Mohit Jaggi <mohitjaggi at gmail.com> wrote:
>> > Hi,
>> > I am a little confused about how messages and buffers are handled in
>> zmq. In
>> > the following example, valgrind finds a message leak for 'm'.
>> > 1) Should I call delete for 'm' after the send?
>> > 2) zmq will keep the buffer(data) but free memory for 'm' if I do this?
>> > 3) What about 'topic'? It is on stack and data is small, so I guess it
>> uses
>> > the vsm area to store the message?
>> > 4) Will send for 'topic' make a copy of the data then?
>> >
>> > Mohit.
>> >
>> >
>> > string buf;
>> >
>> > myObject.SerializeToString(&buf);
>> >
>> > message_t m = new message_t(buf.size());
>> >
>> > memcpy((void*) m.data(), buf.c_str(), buf.size());
>> >
>> > string topic(string("X") + string("Y") + string("Z"));
>> >
>> > publisher->send(topic.c_str(), topic.size(), ZMQ_SNDMORE); //topic
>> >
>> > publisher->send(m); //data
>> >
>> >
>> > _______________________________________________
>> > zeromq-dev mailing list
>> > zeromq-dev at lists.zeromq.org
>> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>> >
>> _______________________________________________
>> zeromq-dev mailing list
>> zeromq-dev at lists.zeromq.org
>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.zeromq.org/pipermail/zeromq-dev/attachments/20130306/392f2328/attachment.htm>