rosbag2_snapshot

Solution for this rosbag2 issue which acts similarly to rosbag_snapshot. It is added as a new package here rather than patching rosbag2 because that's how they did it in ROS 1 ;).

It subscribes to topics and maintains a buffer of recent messages like a dash cam. This is useful in live testing where unexpected events can occur which would be useful to have data on but the opportunity is missed if rosbag record was not running (disk space limits make always running rosbag record impracticable). Instead, users may run snapshot in the background and save data from the recent past to disk as needed.

Usage

rosbag2_snapshot can be configured through ROS params for more granular control. The snapshotter command will run the buffer server and the snapshotter_client command can be used as a client to request that the server write data to disk or freeze the buffer to preserve interesting data until a user can decide what to write.

Server

$ ros2 run rosbag2_snapshot snapshotter

Buffer recent messages until triggered to write or trigger an already running instance.

### Example param file
```yaml
/**:
  ros__parameters:
    default_duration_limit: 10.0           # [Optional, default=-1] Maximum time difference between newest and oldest message in seconds
    default_memory_limit: 64.0             # [Optional, default=-1] Maximum memory used by messages in each topic's buffer, in MB
    topics: ["/topic1", "/topic2"]         # [Optional] List of topics to buffer. If empty, buffer all topics.
    topic_details:
      /topic1:
        type: "sensor_msgs/msg/NavSatFix"  # [Required if topic is specified] Topic type
      /topic2:
        type: "sensor_msgs/msg/Odometry"
        duration: 15.0                     # [Optional] Override duration limit, inherit memory limit
      /topic3:
        type: "sensor_msgs/msg/Image"
        duration: 2.0                      # [Optional] Override both limits
        memory: -1                         # Negative value means no limit

Client

Write all buffered data to <datetime>.bag

ros2 run rosbag2_snapshot snapshotter_client --ros-params -p action_type:=trigger_write

Write buffered data from selected topics to new_lighting<datetime>.bag

ros2 run rosbag2_snapshot snapshotter_client --ros-params -p filename:=new_lighting -p topics:=["/camera/image_raw", "/camera/camera_info"]

Write all buffered data to /home/user/crashed_into_wall.bag

ros2 run rosbag2_snapshot snapshotter_client --ros-params -p filename:="/home/user/crashed_into_wall.bag"

Pause buffering of new data, holding current buffer in memory until resumed or write is triggered

ros2 run rosbag2_snapshot snapshotter_client --ros-params -p action_type:=pause

Resume buffering new data

ros2 run rosbag2_snapshot snapshotter_client --ros-params -p action_type:=resume

Call trigger service manually

$ ros2 service call /trigger_snapshot rosbag2_snapshot_msgs/srv/TriggerSnapshot "{filename: '', topics: [], start_time: {sec: 0, nanosec: 0}, stop_time: {sec: 0, nanosec: 0}}"
requester: making request: rosbag2_snapshot_msgs.srv.TriggerSnapshot_Request(filename='', topics=[], start_time=builtin_interfaces.msg.Time(sec=0, nanosec=0), stop_time=builtin_interfaces.msg.Time(sec=0, nanosec=0))

response:
rosbag2_snapshot_msgs.srv.TriggerSnapshot_Response(success=True, message='')

Call pause/resume service manually

$ ros2 service call /enable_snapshot std_srvs/srv/SetBool "{data: false}"
requester: making request: std_srvs.srv.SetBool_Request(data=False)

response:
std_srvs.srv.SetBool_Response(success=True, message='')