[Bug Report] Sensors mutate in observe

[Gamenot]

High Level Description

Sensors change their state in sensors.observe(...). This mutability complicates management of sensors.

Note the following that sensors observe:

SMARTS/smarts/core/sensors/__init__.py

Lines 253 to 267 in a93a6a9

	return (
	dict(
	drivable_area_grid_map=get_camera_sensor_result(
	vehicle_sensors, "drivable_area_grid_map_sensor", renderer
	),
	occupancy_grid_map=get_camera_sensor_result(
	vehicle_sensors, "ogm_sensor", renderer
	),
	top_down_rgb=get_camera_sensor_result(
	vehicle_sensors, "rgb_sensor", renderer
	),
	lidar_point_cloud=lidar,
	),
	updated_sensors,
	)

SMARTS/smarts/core/sensors/__init__.py

Lines 455 to 479 in a93a6a9

	updated_sensors = {
	sensor_name: sensor
	for sensor_name, sensor in vehicle_sensors.items()
	if sensor.mutable and sensor.serializable
	}
	return (
	Observation(
	dt=sim_frame.last_dt,
	step_count=sim_frame.step_count,
	steps_completed=sensor_state.steps_completed,
	elapsed_sim_time=sim_frame.elapsed_sim_time,
	events=events,
	ego_vehicle_state=ego_vehicle,
	under_this_agent_control=agent_controls,
	neighborhood_vehicle_states=neighborhood_vehicle_states,
	waypoint_paths=waypoint_paths,
	distance_travelled=distance_travelled,
	road_waypoints=road_waypoints,
	via_data=via_data,
	signals=signals,
	),
	done,
	updated_sensors,
	)

Then pushes up to the SensorResolver interface:

SMARTS/smarts/core/sensors/local_sensor_resolver.py

Line 80 in a93a6a9

return observations, dones, updated_sensors

Then propagates up to sensor manager observe:

SMARTS/smarts/core/sensor_manager.py

Lines 106 to 121 in a93a6a9

	observations, dones, updated_sensors = self._sensor_resolver.observe(
	sim_frame,
	sim_local_constants,
	agent_ids,
	renderer_ref,
	physics_ref,
	)
	for actor_id, sensors in updated_sensors.items():
	for sensor_name, sensor in sensors.items():
	self._sensors[
	SensorManager._actor_and_sensor_name_to_sensor_id(
	sensor_name, actor_id
	)
	] = sensor
	return observations, dones

Version

smarts==1.0.11

Steps to reproduce the bug

No response

System info

No response

Error logs and screenshots

No response

Impact (If known)

This complicates reusing sensors for multiple interested clients (e.g. multiple agents.)
This also means that individual sensors have to sync back to the main process when dealing with the parallel processing of sensors.