publisher_member_function_with_unique_network_flow_endpoints leads to coredump

fujitatomoya commented 3 years ago

Bug report

Required Info:

Operating System:
- Ubuntu 20.04
Installation type:
- source build
Version or commit hash:
- https://github.com/ros2/ros2/commit/2c3dcb37040365ee5f09eede264cd05910134076
DDS implementation:
- cyclonedds
Client library (if applicable):
- rclcpp

Steps to reproduce issue

root@134f29e8f25f:~/ros2_ws/colcon_ws# ros2 run examples_rclcpp_minimal_publisher publisher_member_function_with_unique_network_flow_endpoints
terminate called after throwing an instance of 'rclcpp::exceptions::RCLError'
  what():  error obtaining network flows of publisher: rmw_publisher_get_network_flow_endpoints not implemented, at /root/ros2_ws/colcon_ws/src/ros2/rmw_cyclonedds/rmw_cyclonedds_cpp/src/rmw_get_network_flow_endpoints.cpp:31, at /root/ros2_ws/colcon_ws/src/ros2/rcl/rcl/src/rcl/network_flow_endpoints.c:83, also error cleaning up network flow array: network_flow_endpoint_array->allocator is null, at /root/ros2_ws/colcon_ws/src/ros2/rmw/rmw/src/network_flow_endpoint_array.c:81: error not set

Expected behavior

example should not get crashed even if rmw implementation does not support rmw_publisher_get_network_flow_endpoints

Actual behavior

publisher_member_function_with_unique_network_flow_endpoints coredump

Additional information

rmw_fastdds_cpp supports rmw_publisher_get_network_flow_endpoints so this problem cannot be observed.

fujitatomoya commented 3 years ago

@anamud friendly ping, since you were original author.

anamud commented 3 years ago

@fujitatomoya Thanks for spotting the issue and submitting a good solution. I have reviewed the patch and suggested a minor change.

endre90 commented 3 years ago

Hi,

I can't find much info on this type of pubs/subs, so I thought I might just ask the question here. Could somebody elaborate on what does having unique network flow endpoints mean in DDS and what are the benefits compared to nodes that don't use this option? Either that or maybe point me to a link where this is explained?

Thanks in advance, Endre

anamud commented 3 years ago

@endre90 Unique network flows enable fine-grained QoS assignment in IP-based networks such as 5G. Please have a look at the design doc for unique network flows to understand more.

endre90 commented 3 years ago

Interesting.

Thanks @anamud for the thorough explanation in unique_network_flows.md. There might come a time when something like this could come in handy.

Best Regards, Endre

clalancette commented 3 years ago

@fujitatomoya Now that we've merged #313, can we close this?

ros2 / examples