Add TypeAdaptation support

[3473f]

I am trying to use this package with an adapted data type (using the provided Subscriber class), but it fails when trying to access the header of the adapted message.

/opt/ros/humble/include/flex_sync/exact_sync.hpp:154:35: error: invalid use of member function ‘std_msgs::msg::Header& MyAdaptedDataType::header()’ (did you forget the ‘()’ ?)
  154 |     const rclcpp::Time & t = msg->header.stamp;

Are there any plans to support this? message_filter added this feature in ros2/message_filters#96

[berndpfrommer]

I can try to make it work. Would you mind posting a simple failure example (code)? I have never used TypeAdaption.

[3473f]

Thanks a lot! the code I am working on is for the Jetson platform using a variant of this CUDA type adapter. Since I cannot assume you will have the same setup, I will put together an example using the cv::Mat adapter from cv_bridge and link it here.

[3473f]

Here is a repo providing a sample which fails to compile with the following error

Starting >>> adapted_flex_sync
--- stderr: adapted_flex_sync                             
In file included from /workspace/colcon_ws/src/adapted_flex_sync/include/adapted_flex_sync/adapted_flex_sync_node.hpp:4,
                 from /workspace/colcon_ws/src/adapted_flex_sync/src/adapted_flex_sync_node.cpp:1:
/opt/ros/humble/include/flex_sync/exact_sync.hpp: In instantiation of ‘void flex_sync::ExactSync<MsgTypes>::process(const string&, MsgPtrT) [with MsgPtrT = std::shared_ptr<const image_tools::ROSCvMatContainer>; MsgTypes = {image_tools::ROSCvMatContainer}; std::string = std::__cxx11::basic_string<char>]’:
/opt/ros/humble/include/flex_sync/live_sync.hpp:61:54:   required from ‘void flex_sync::Subscriber<SyncT, T>::callback(flex_sync::Subscriber<SyncT, T>::TConstSharedPtr) [with SyncT = flex_sync::ExactSync<image_tools::ROSCvMatContainer>; T = image_tools::ROSCvMatContainer; flex_sync::Subscriber<SyncT, T>::TConstSharedPtr = std::shared_ptr<const image_tools::ROSCvMatContainer>]’
/opt/ros/humble/include/flex_sync/live_sync.hpp:54:17:   required from ‘flex_sync::Subscriber<SyncT, T>::Subscriber(const string&, rclcpp::Node*, const rclcpp::QoS&, const std::shared_ptr<_Tp>&) [with SyncT = flex_sync::ExactSync<image_tools::ROSCvMatContainer>; T = image_tools::ROSCvMatContainer; std::string = std::__cxx11::basic_string<char>]’
/usr/include/c++/11/ext/new_allocator.h:162:4:   required from ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>]’
/usr/include/c++/11/bits/alloc_traits.h:516:17:   required from ‘static void std::allocator_traits<std::allocator<_Tp1> >::construct(std::allocator_traits<std::allocator<_Tp1> >::allocator_type&, _Up*, _Args&& ...) [with _Up = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; std::allocator_traits<std::allocator<_Tp1> >::allocator_type = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >]’
/usr/include/c++/11/bits/shared_ptr_base.h:519:39:   required from ‘std::_Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp>::_Sp_counted_ptr_inplace(_Alloc, _Args&& ...) [with _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Alloc = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >; __gnu_cxx::_Lock_policy _Lp = __gnu_cxx::_S_atomic]’
/usr/include/c++/11/bits/shared_ptr_base.h:650:16:   required from ‘std::__shared_count<_Lp>::__shared_count(_Tp*&, std::_Sp_alloc_shared_tag<_Alloc>, _Args&& ...) [with _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Alloc = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; __gnu_cxx::_Lock_policy _Lp = __gnu_cxx::_S_atomic]’
/usr/include/c++/11/bits/shared_ptr_base.h:1342:14:   required from ‘std::__shared_ptr<_Tp, _Lp>::__shared_ptr(std::_Sp_alloc_shared_tag<_Tp>, _Args&& ...) [with _Alloc = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; __gnu_cxx::_Lock_policy _Lp = __gnu_cxx::_S_atomic]’
/usr/include/c++/11/bits/shared_ptr.h:409:59:   required from ‘std::shared_ptr<_Tp>::shared_ptr(std::_Sp_alloc_shared_tag<_Tp>, _Args&& ...) [with _Alloc = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}; _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>]’
/usr/include/c++/11/bits/shared_ptr.h:862:14:   required from ‘std::shared_ptr<_Tp> std::allocate_shared(const _Alloc&, _Args&& ...) [with _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Alloc = std::allocator<flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer> >; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}]’
/usr/include/c++/11/bits/shared_ptr.h:878:39:   required from ‘std::shared_ptr<_Tp> std::make_shared(_Args&& ...) [with _Tp = flex_sync::Subscriber<flex_sync::ExactSync<image_tools::ROSCvMatContainer>, image_tools::ROSCvMatContainer>; _Args = {const char (&)[7], adapted_flex_sync::AdaptedFlexSyncNode*, rclcpp::QoS, std::shared_ptr<flex_sync::ExactSync<image_tools::ROSCvMatContainer> >&}]’
/workspace/colcon_ws/src/adapted_flex_sync/src/adapted_flex_sync_node.cpp:16:41:   required from here
/opt/ros/humble/include/flex_sync/exact_sync.hpp:154:35: error: invalid use of member function ‘std_msgs::msg::Header& image_tools::ROSCvMatContainer::header()’ (did you forget the ‘()’ ?)
  154 |     const rclcpp::Time & t = msg->header.stamp;
      |                              ~~~~~^~~~~~
      |                                         ()
gmake[2]: *** [CMakeFiles/adapted_flex_sync_node.dir/build.make:76: CMakeFiles/adapted_flex_sync_node.dir/src/adapted_flex_sync_node.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:137: CMakeFiles/adapted_flex_sync_node.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2
---
Failed   <<< adapted_flex_sync [5.24s, exited with code 2]

In order to get this to compile, I have to chage the following line

flex_sync/include/flex_sync/live_sync.hpp

Line 35 in 9cdec06

using TConstSharedPtr = typename T::ConstSharedPtr;

to this

  using TConstSharedPtr = typename std::shared_ptr<const T>;

[berndpfrommer]

I've been trying to make it work now for several hours but sorry, I just can't figure out how to do it. My feeling is that I could spend another few days on it and it would still not work. I have to punt on this one. Hope you can find a work around!

[3473f]

Thanks for trying. I also had a look before opening this issue but couldn't figure it out. I think the basic idea would be to detect if a type is an adapted type, then access the original type's header without having to convert it back to a ROS 2 type (not sure if that is even possible). I will try to work on that when I have time and contribute it back if successful.

For now I went with message_filters and defining different synchronizers/callbacks in my node. While not elegent, it allows me to continue development until I have time to look at this again.

[berndpfrommer]

I think the problem is that my flex_sync code is poorly written to begin with, such that the message type is actually specified multiple times by the end user. Now I can't figure out what's going on anymore.