Re: [opendds-main] Problem with QoS Policies

[Massimo P. <mas...@gm...>]

Hi there,

I see a some potentials causes of your problem:

a) DataWriter start publication before the association with the DataReader
is setup. In this case all samples published before the association is
established are lost, unless you enable support for late subscribers in the
data writer setting the Durability QOS to at least
TRANSIENT_LOCAL_DURABILITY;
b) the Durability Service QoS *max_xxx* enforce a lower level of max
samples/instances that can be kept in the data writer cache
c) the on_data_available callback should invoke the take_next_sample in a
loop otherwise samples queued in the data reader cache can remain
unprocessed

best regards
Massimo



2014-11-27 10:02 GMT+01:00 Alex Douckas <ale...@gm...>:

> Hello,
>
> I have created a publisher application and a subscriber one ( both in
> C++ ) with the following QoS policies on both Topic and DataWriter (
> and DataReader respectively ) :
>
> DDS::TopicQos default_topic_qos;
> participant->get_default_topic_qos(default_topic_qos);
> default_topic_qos.history.kind = DDS::KEEP_LAST_HISTORY_QOS;
> default_topic_qos.history.depth = 140000;
> default_topic_qos.reliability.kind = DDS::RELIABLE_RELIABILITY_QOS;
>
> DDS::DataWriterQos dw_default_qos;
> pub->get_default_datawriter_qos (dw_default_qos);
> dw_default_qos.history.kind = DDS::KEEP_LAST_HISTORY_QOS;
> dw_default_qos.history.depth = 140000;
> dw_default_qos.reliability.kind = DDS::RELIABLE_RELIABILITY_QOS;
>
> Now, the publisher is sending about 3000 data samples, each one every
> 100 miliseconds. So to test the history and reliability policies, I
> set a delay on the subscriber ( with usleep) of 500 miliseconds on the
> "on_data_available" class like this :
>
>       DDS::SampleInfo si ;
>       DDS::ReturnCode_t status = measurement_dr->take_next_sample(data,
> si) ;
>
>       if (status == DDS::RETCODE_OK) {
>          //omitted Code that manipulates the data sample
>
>              usleep (500000);
>
>        } else if (status == DDS::RETCODE_NO_DATA) {
>         cerr << "INFO: reading complete after " << count << " samples." <<
> endl;
>         break;
>       }
>
> The problem is that after about 1000 received samples, the subscriber
> somehow stops receiving the rest samples. Since the depth of History
> is bigger than the samples, the subscriber should receive everything.
> The same thing happens even if I use KEEP_ALL_HISTORY instead of
> KEEP_LAST. Do you have any idea about this issue ?  Am I using the
> policies wrong ?
>
> Thanks,
> Alex
>
>
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-- 
Massimo