Pause and resume recording via service call.

[rshanor]

Recorder already has a pause and resume feature: #905
Feature would look a lot like the SplitBagfile service: #1115

Figured I would add a file rosbag2_interfaces/srv/EnableRecorder.srv that looks something like

bool is_enabled
---

@MichaelOrlov thoughts? My robot sits around running but not doing anything useful 90% of the time.

[MichaelOrlov]

@rshanor Agree that it would be nice to have such feature.
Please reuse interface and subset of APIs from rosbag2 player instead of creating new rosbag2_interfaces/srv/EnableRecorder.srv

rosbag2/rosbag2_transport/src/rosbag2_transport/player.cpp

Lines 798 to 829 in 5b8b658

	srv_pause_ = create_service<rosbag2_interfaces::srv::Pause>(
	"~/pause",
	[this](
	rosbag2_interfaces::srv::Pause::Request::ConstSharedPtr,
	rosbag2_interfaces::srv::Pause::Response::SharedPtr)
	{
	pause();
	});
	srv_resume_ = create_service<rosbag2_interfaces::srv::Resume>(
	"~/resume",
	[this](
	rosbag2_interfaces::srv::Resume::Request::ConstSharedPtr,
	rosbag2_interfaces::srv::Resume::Response::SharedPtr)
	{
	resume();
	});
	srv_toggle_paused_ = create_service<rosbag2_interfaces::srv::TogglePaused>(
	"~/toggle_paused",
	[this](
	rosbag2_interfaces::srv::TogglePaused::Request::ConstSharedPtr,
	rosbag2_interfaces::srv::TogglePaused::Response::SharedPtr)
	{
	toggle_paused();
	});
	srv_is_paused_ = create_service<rosbag2_interfaces::srv::IsPaused>(
	"~/is_paused",
	[this](
	rosbag2_interfaces::srv::IsPaused::Request::ConstSharedPtr,
	rosbag2_interfaces::srv::IsPaused::Response::SharedPtr response)
	{
	response->paused = is_paused();
	});

Also to accomplish this feature it would be nice to add bool start_paused flag to the RecordOptions and expose it as command line option. The same way as it was done for player.

rosbag2/rosbag2_transport/include/rosbag2_transport/play_options.hpp

Lines 83 to 84 in 5b8b658

	// Start paused.
	bool start_paused = false;

and

rosbag2/ros2bag/ros2bag/verb/play.py

Lines 129 to 131 in 5b8b658

	parser.add_argument(
	'-p', '--start-paused', action='store_true', default=False,
	help='Start the playback player in a paused state.')

[rshanor]

Ack, I will work on getting this PRed soon. Thanks!

[MichaelOrlov]

@rshanor Thank you. Your contribution very welcome.
We have this "feature" in our roadmap in ApexAI. But unfortunately I am very busy with other high priority tasks.
There are to much on my plate currently.

[MichaelOrlov]

This feature will be very useful for distributed recording 😉