Using GUIDs in the API

[eboasson]

Adds dds_guid_t as a less confusing alias for dds_builtintopic_guid_t. It is alias to retain backwards compatibility. All uses in the sources of Cyclone have been updated.

Adds dds_get_guid to retrieve the GUID of an participant, reader or writer (the only entities visible in the discovery). This is much more convenient (and more efficient) than something like:

dds_entity_t x = dds_create_reader(h, matching_builtin_topic, NULL, NULL);
dds_sample_info_t si;
void *raw = NULL;
dds_instance_handle_t ih;
dds_get_instance_handle(h, &ih);
int32_t n;
dds_read_instance(x, &raw, &si, 1, 1, ih);
(e.g. dds_builtintopic_participant_t *)s = raw;
guid = &s->key;
dds_return_loan(x, &raw, 1);
dds_delete(x);

[dpotman]

LGTM. The only thing I could find is that you're not testing getting a guid from invalid entity kinds in the test case, but as the code in dds_get_guid is so trivial thats not really worth the effort.

[eboasson]

Thanks @dennis-adlink for checking! I agree without about the test ... both in the sense that it really feels like spending time on this particular detail is a waste and in that spending time on improving the tests in that area in general would be a valuable exercise.