DetectFederationLag should tell me what the homeservers in question are

[Mikaela]

Is your feature request related to a problem? Please describe.

When I enable the protection to DetectFederationLag, I see messages like these that don't tell me much:

Room !REDACTED:REDACTED lag has decreased to an acceptable level. Currently, 0 homeservers are still lagging

The only thing changing is the number which kept going between 0 to 4.

Describe the solution you'd like

I would like to know which are these lagging homeservers, so I would have better idea if this is something actionable upon.

Describe alternatives you've considered

Disabling the DetectFederationLag protection, which I did.

Additional context

I may also not understand the point of DetectFederationLag.

[Yoric]

I would like to know which are these lagging homeservers, so I would have better idea if this is something actionable upon.

Good idea! This should even be a one-line patch!

Sadly, I have zero time to work on it these days but I'd be happy to mentor/review someone with time to do so!

The code that prints this error message lives here. See here for how to get the names of homeservers.

I may also not understand the point of DetectFederationLag.

We've noticed a few times that federation lag is a good indicator that your homeserver (or a homeserver you may be connected to) is either under DDoS or having some other problem and that you should start paying attention.