Fix negative offset of reconnect delay (#8718)

[alexander-at-t]

Fix for #8718

[changeset-bot]

🦋 Changeset detected

Latest commit: c06bdd7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@firebase/database	Patch
firebase	Patch
@firebase/database-compat	Patch

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[DellaBitta]

HI @alexander-at-t,

Thanks for the contribution! You'll need to sign the Google CLA before we can merge this PR. Thanks!

[alexander-at-t]

Hi @DellaBitta ,

Thanks for the contribution! You'll need to sign the Google CLA before we can merge this PR. Thanks!

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[maneesht]

LGTM

[maneesht]

Thanks for this change. @alexander-at-t what use-case is this for? I understand it's if the clock goes back, is this in the situation when a user might be changing time zones?

[alexander-at-t]

Thanks for this change. @alexander-at-t what use-case is this for? I understand it's if the clock goes back, is this in the situation when a user might be changing time zones?

@maneesht We found an issue by report from our users. Then we found these log records in Realtime DB logs:

2025-01-23T07:15:57.317Z p:0: Trying to reconnect in 609303.1190405517ms 
...
2025-01-23T07:56:03.534Z event: /.info/serverTimeOffset:value:312809 

"reconnect in 609303.1190405517ms" is not expected, taking into account max reconnect constants.

And it doesn't look like changing time zones, because it should not affect serverTimeOffset and offset would be multiple of 30/60 minutes.

We don't know exact steps how it was reproduced by our users. Is it possible that their laptop drained battery, and so clocks become unsynchronized? I don't have other ideas of these 5-10 minutes differences. Or maybe there is a bug in serverTimeOffset calculation by Realtime DB in some edge cases?

The fix is important even if we don't know how to reproduce the bug, because autoreconnecting Realtime DB with 10 minutes delay breaks our app's users experience. We use Realtime DB for tracking users online status.

[maneesht]

@alexander-at-t there's still a chance that the user changed time zones and the delay ends up being 10 minutes, as we multiply the reconnectDelay by Math.random(), which could incidentally return a fraction that, when multiplied by 60 minutes, could give 10