Add option to specify a message type

[carlossvg]

This PR adds an option to the Performance benchmarking package to use a predefined message type instead of generic type. The motivation for this option is to allow to replicate scenarios with exactly the same message types as the original case.

[carlossvg]

@emersonknapp @adamdbrw Could you please review this PR? As explained in the description the motivation of this PR is to be able to run benchmarks using different message types instead of a generic type. The main reason would be to be able to reproduce as close as possible different scenarios.

For this reason a new option, msg_type, is introduced to specify the message type we want to use. For the moment only sensor_msgs` are included but the idea would be to provide some instructions so people can add their own message types.

A logical question is what happens now when msg_type is used with msg_size_bytes. Here there several cases:

• If msg_type is not used the message type is defaulted to the byte array message type. The behavior should be the same as before.
• If msg_type is used and there is no msg_size_bytes the message is not resized. This makes sense for fixed size messages (i.e. std_msgs::msg::Int32).
• If msg_type is and a non-zero msg_size_bytes the developer should add a function to construct and resize tat message type. In case the message type has multiple bounded/unbounded fields is not obvious how msg_size_bytes should be used. I suggest to assume we want to resize all the fields in the same proportion so the total message size is msg_size_bytes.

Additional notes:

• Currently, only benchmark_publishers support the msg_type option. A suitable error message should be added to inform the user.
• We added automotive.yaml to show a usage example.
• We created rosbag2_performance_benchmarking_msgs to remove the std_msgs dependency and to provide a place to add more message types if needed in the future (i.e. nested types).

[MichaelOrlov]

@carlossvg Kindly ping to reiterate on this PR.

[MichaelOrlov]

Gist: https://gist.githubusercontent.com/MichaelOrlov/7374b636991bac95242b44bc7924e462/raw/192fd2e9264b5bdc3ff901c799249cc8e5de6376/ros2.repos BUILD args: --packages-above-and-dependencies rosbag2_performance_benchmarking rosbag2_performance_benchmarking_msgs TEST args: --packages-above rosbag2_performance_benchmarking rosbag2_performance_benchmarking_msgs ROS Distro: rolling Job: ci_launcher ci_launcher ran: https://ci.ros2.org/job/ci_launcher/11344

• Linux
• Linux-aarch64
• Windows

[MichaelOrlov]

Failure in Test rosbag2 / build_and_test (pull_request) is unrelated to the changes from current PR and relates to the moved mcap packages.

  Package 'mcap_vendor' specified with --packages-up-to was not found
  Package 'rosbag2_storage_mcap' specified with --packages-up-to was not found
  Package 'rosbag2_storage_mcap_testdata' specified with --packages-up-to was not found