Time Sync between Node bootup and rosbag reply

[snknitheesh]

I was testing this with perception pipeline and I found that my Node takes like 35 seconds to load everything up but my rosbag is just 15 second bag. There are 2 options for this now,

1. Time sync so that rosbag starts replay after the node is up. Or add a provision for delay in the node.

2. Capture a bigger rosbag file.

Option 2 is a bit annoying as my rosbag size goes exponentially huge to the data that I am collecting.

Let me know if I can fix this and PR upstream.

Thanks for this wonderful repo.

[troygibb]

Thanks @snknitheesh for the suggestion-- option 1 definitely seems like a cleaner experience. I've seen similar issues in replay, where there is a "hot start" / "saturation time" delay in replay so that systems like localization can converge before the assertable part of the replay begins.

Did you already have an implementation in mind for option 1?

[snknitheesh]

@troygibb One option I can think of is a /node/hearbeat topic. When the heatbeat topic publishes, we can start the replay. That is what I plan to implement in my stack. Let me know if that sounds good and I can PR into this repo.

Something like this

class RunnerArgs(BaseModel):
    use_clock: bool = True
    playback_rate: float = 1.0
    wait_for_heartbeat: Optional[Union[str, List[str]]] = None  # Topic(s) to wait for before starting playback
    heartbeat_timeout: float = 120.0  # Timeout in seconds to wait for heartbeat(s)

This is kept as optional for backward compatibility.

[troygibb]

@snknitheesh I like it. How would the heartbeat be typed? But yea feel free to go ahead and open a PR. Make sure to add tests here that assert on this behavior.