AP_DDS: Race condition generating DDS messages (microxrceddsgen is not thread safe)

[Ryanf55]

Bug report

Issue details

Very occasionally, microxrceddsgen fails to generate messages. This is likely because waf is writing to the same file from multiple threads.

Version
4.5
Platform
[ ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

Airframe type
all
Hardware type
sitl
Logs

Details

microxrceddsgen can take an argument for multiple files at the same time. We call bld() once for each file. It would be faster to do batch them per folder, or all together at the same time.

microxrceddsgen -cs -replace -default-container-prealloc-size 8 -d build/IDL -I libraries/AP_DDS/Idl/ /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/ardupilot_msgs/msg/GlobalPosition.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/ardupilot_msgs/srv/ArmMotors.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/ardupilot_msgs/srv/ModeSwitch.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/builtin_interfaces/msg/Duration.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/builtin_interfaces/msg/Time.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geographic_msgs/msg/GeoPoint.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geographic_msgs/msg/GeoPointStamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geographic_msgs/msg/GeoPose.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geographic_msgs/msg/GeoPoseStamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Point.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Pose.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/PoseStamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Quaternion.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Transform.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/TransformStamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Twist.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/TwistStamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Vector3.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/geometry_msgs/msg/Vector3Stamped.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/rosgraph_msgs/msg/Clock.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/sensor_msgs/msg/BatteryState.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/sensor_msgs/msg/Imu.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/sensor_msgs/msg/Joy.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/sensor_msgs/msg/NavSatFix.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/sensor_msgs/msg/NavSatStatus.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/std_msgs/msg/Header.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/tf2_msgs/msg/TFMessage.idl

We'll need to generate them into the right folder too. See eProsima/Micro-XRCE-DDS-Gen#80

A possible workaround is to generate each IDL in it's own folder, or skip dependent files.

Here's gen_cmd on master:

'/home/ryan/Dev/ros2_ws/src/Micro-XRCE-DDS-Gen/scripts/microxrceddsgen -cs -replace -default-container-prealloc-size 8 -d libraries/AP_DDS/generated/ardupilot_msgs/msg -I /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/ardupilot_msgs/msg/GlobalPosition.idl'

And a proposed fix:

'/home/ryan/Dev/ros2_ws/src/Micro-XRCE-DDS-Gen/scripts/microxrceddsgen -cs -replace -default-container-prealloc-size 8 -d libraries/AP_DDS/generated/builtin_interfaces/msg -I /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/builtin_interfaces/msg/Duration.idl /home/ryan/Dev/ardu_ws/src/ardupilot/libraries/AP_DDS/Idl/builtin_interfaces/msg/Time.idl'

[Ryanf55]

I have a branch that is close to fixing this: 28497-fix-waf-dds-gen-race