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Callback Isolated Executor for Agnocast

agnocast::CallbackIsolatedAgnocastExecutor and agnocast_component_container_cie are the Agnocast versions of the Callback Isolated Executor, which can handle both ROS 2 callbacks and Agnocast callbacks. For basic usage, please refer to the callback_isolated_executor README.

Differences from the Original

Package, Class, and Executable Names

Original Agnocast Version
Package callback_isolated_executor agnocast_components (recommended) or agnocastlib (deprecated)
Executor Class CallbackIsolatedExecutor agnocast::CallbackIsolatedAgnocastExecutor
Container Executable component_container_callback_isolated agnocast_component_container_cie

Features

agnocast_components_register_node Macro

Instead of manually configuring component containers and launch files, you can use the agnocast_components_register_node() CMake macro (provided by the agnocast_components package) as a drop-in replacement for rclcpp_components_register_node(). This macro generates a standalone executable that uses the specified Agnocast executor.

find_package(agnocast_components REQUIRED)

add_library(my_component SHARED src/my_node.cpp)
ament_target_dependencies(my_component rclcpp rclcpp_components agnocastlib ...)

agnocast_components_register_node(
  my_component
  PLUGIN "MyNode"
  EXECUTABLE my_node
  EXECUTOR CallbackIsolatedAgnocastExecutor
)

Multiple ROS domain support

agnocast_cie_thread_configurator can handle callback groups from multiple ROS domains. Use ROS parameters to specify domain IDs:

# Option 1: Run prerun_node directly with ROS parameters
ros2 run agnocast_cie_thread_configurator prerun_node --ros-args -p domains:=[0,1]

# Option 2: Use the launch file
ros2 launch agnocast_cie_thread_configurator thread_configurator.launch.xml prerun:=true domains:=[0,1]

RT Throttling

The rt_throttling feature configures the kernel's real-time scheduling bandwidth parameters (sched_rt_period_us and sched_rt_runtime_us). At startup, agnocast_cie_thread_configurator validates that the current kernel values match the configuration and reports an error if they differ.

Since /proc/sys/kernel/sched_rt_period_us and /proc/sys/kernel/sched_rt_runtime_us can only be written by root (uid 0) — Linux capabilities such as CAP_SYS_ADMIN cannot bypass the /proc/sys/ permission check — these values must be pre-configured via /etc/sysctl.d/:

# /etc/sysctl.d/99-rt-throttling.conf
kernel.sched_rt_period_us = 1000000
kernel.sched_rt_runtime_us = 950000

After creating the file, apply it immediately with:

sudo sysctl --system

The values will also be applied automatically on subsequent boots.