[BUG] Subscriptions for Matter devices for user is unnecessarily delayed until next scheduled resub retry in some cases

[ndyck14]

[BUG] Subscriptions for Matter devices for user is unnecessarily delayed until next scheduled resub retry in some cases

[bzbarsky-apple]

We should consider triggering resubscribe on both CASE establishment (using the new session, not creating a new one), and on any IM message received, not just ReportData.

[bzbarsky-apple]

In particular, we only retrigger subscription on receiving a ReportData, not on CASE establishment from the other side or the other side sending any other IM message.

@jtung-apple

[jtung-apple]

I'm taking a look but my first thought is that currently the logic for re-subscription is only triggered when the IME gets called on OnUnsolicitedReportData. I could look into the changes needed to have CASE establishment plumb through to trigger re-subscribe and we can discuss if that's what's needed here.

@ndyck14 Do you happen to be able to readily reproduce this? If so could you upload logs from both devices?

I'm wondering if there's something else wrong / a bug that's causing this, that should be fixed first.

[ndyck14]

Power cycle HPM (unclear if strict precondition)

I did this with the intent of clearing CASE resume contexts (guesswork) so as to test worst case. Basically my brief mental model of resume sub is its a best effort by device. Otherwise CASE is re-established because we're looking for OTA i think.

I can try to reproduce, but is there evidence to suggest that this onus should not be on the subscriber to ensure its done as swiftly as possible? I guess in case the sub is already active, we don't want to double up? Is doubling up even possible?

[ndyck14]

note that my test steps were in done directed after already observing this previously without logs installed, so I've seen this happen multiple times. I've also been tracking CASEs (pun intended) for a year or more where things take too long to reconnect (eg #25091, which Boris reported on my behalf )