memory leak? Does this malloc ever get freed? about rmw_cyclonedds

[eboasson]

@rotu you have sharp eyes! As long as the caller dutifully frees the memory all is well, but I never really looked into the details of how the result of deserialization is handled, other than in returning it to the caller of rmw_take. I simply followed the example Fast-RTPS's dynamic RMW code, assuming that it would get these details correct.

A little bit of digging now tells me that this particular case is never used! It is implemented in the eProsima Fast-CDR library with good reason — that's a generic tool for applications to build upon — but this particular use in TypeSupport_impl.h always uses the std::string case.

Deleting the char * case would be best.

There’s a lot of other questionable code in here, including much use of macros where templates would be more appropriate and repeated code.

I agree with that assessment. What I tried originally was classifying types as primitive or not, then have a single templatized one for all primitive ones and handling the few others with special cases, but I got lost in the C++ template error messages. Macros were simply the quickest way to getting something up and running. Now that times have changed, I'm all for cleaning this up.

The best thing would be to rewrite TypeSupport and serdes both. There is quite a bit of code involved in interpreting the ROS type description and some — I would suspect, common — types such as arrays of records of floats involve a significant bit of overhead now. It makes much more sense to preprocess the type to a simpler form that can be interpreted more efficiently.

[rotu]

I agree that a rewrite is in order, and I’ll pitch in with a few PRs.

You may find (as I do) that Clang is tons better than gcc for writing template code. It gives clearer error messages.