This was done by floatingghost as part of a bigger commit in Akkoma.
See <37ae047e16/lib/pleroma/application.ex (L83)>.
As explained in <https://ihatebeinga.live/objects/860d23e1-dc64-4b07-8b4d-020b9c56cff6>
> there are so many caches that clearing them all can nuke the supervisor, which by default will become an hero if it gets more than 3 restarts in <5 seconds
And further down the thread
> essentially we've got like 11 caches (37ae047e16/lib/pleroma/application.ex (L165))
> then in test we fetch them all (https://akkoma.dev/AkkomaGang/akkoma/src/branch/develop/test/support/data_case.ex#L50) and call clear on them
> so if this clear fails on any 3 of them, the pleroma supervisor itself will die
How it fails?
> idk maybe cachex dies, maybe :ets does a weird thing
> it doesn't log anything, it just consistently dies during cache clearing so i figured it had to be that
> honestly my best bet is locksmith and queuing
> https://github.com/whitfin/cachex/blob/master/lib/cachex/actions/clear.ex#L26
> clear is thrown into a locksmith transaction
> locksmith says
> >If the process is already in a transactional context, the provided function will be executed immediately. Otherwise the required keys will be locked until the provided function has finished executing.
> so if we get 2 clears too close together, maybe it locks, then doesn't like the next clear?
This is based on me setting one up, but I kept it general with mostly linking to other documentation.
The idea is that to just provide some Pleroma-specific info, maybe give some pointers, and point to the right (external) docs.
It used a timer to sleep.
But time also goes on when doing other things, so depending on hardware, the timings could be off.
I slightly changed the tests so we still test what we functionally want.
Instead of waiting until the cache expires I now have a function to expire the test and use that.
That means we're not testing any more if the cache really expires after a certain amount of time,
but that's the responsability of the dependency imo, so shouldn't be a problem.
I also changed `Pleroma.Web.Endpoint, :http, :ip` to `127.0.0.1` because that's the setting people typically have,
and I see no reason to do it differently.
Especially since it's an exernal ip, which may come over as weird or suspicious to people.
It is possible for an earlier Update to be received by us later.
For this, we now
(1) only allows Updates to poll counts if there is no updated field,
or the updated field is the same as the last updated date or
creation date;
(2) does not allow updating anything if the updated field
is older than the last updated date or creation date;
(3) allows updating updatable fields otherwise (normal updates);
(4) if only the updated field is changed, it does not create
a new history item on its own.
