This was discussed in the review of #29999:
https://github.com/zulip/zulip/pull/29999#discussion_r1620818568
The previous way of handling wasn't entirely correct, as unnecessary
events were omitted, with a bad guarantee of even being in the correct
order.
This is an improvement as now the function detects that it ended up
doing nothing and can skip sending an event.
The race condition is hard to make up in an automated test, but we can
hackily simulate it by injecting a side_effect which will create a
conflicting UserPresence row when the function requests a cursor. Aside
of that, the actual race was simulated in manual testing to verify the
expected behavior.
This commit has the mechanism for setting the .last_update_id on the
backend for UserPresence objects, without introducing any API changes.
Therefore this should invisible to clients and able to be deployed
safely without impact to users.
Rename and restructure these comparison variables such that we don't
have a possibly impossible case for presence.last_connected_time being
None.
Fixes#25498.
The presence and user status update events are only sent to accessible
users, i.e. guests do not receive presence and user status updates for
users they cannot access.
This also removes the error in one of these functions that was using a
different constant instead of
PRESENCE_LEGACY_EVENT_OFFSET_FOR_ACTIVITY_SECONDS.
This implements the core of the rewrite described in:
For the backend data model for UserPresence to one that supports much
more efficient queries and is more correct around handling of multiple
clients. The main loss of functionality is that we no longer track
which Client sent presence data (so we will no longer be able to say
using UserPresence "the user was last online on their desktop 15
minutes ago, but was online with their phone 3 minutes ago"). If we
consider that information important for the occasional investigation
query, we have can construct that answer data via UserActivity
already. It's not worth making Presence much more expensive/complex
to support it.
For slim_presence clients, this sends the same data format we sent
before, albeit with less complexity involved in constructing it. Note
that we at present will always send both last_active_time and
last_connected_time; we may revisit that in the future.
This commit doesn't include the finalizing migration, which drops the
UserPresenceOld table.
The way to deploy is to start the backfill migration with the server
down and then start the server *without* the user_presence queue worker,
to let the migration finish without having new data interfering with it.
Once the migration is done, the queue worker can be started, leading to
the presence data catching up to the current state as the queue worker
goes over the queued up events and updating the UserPresence table.
Co-authored-by: Mateusz Mandera <mateusz.mandera@zulip.com>
We need to move this function to a separate actions file specifically
for `user_status` because otherwise we will have a circular import
between `actions/user_settings.py` and `actions/presence.py` in an
upcoming commit.
Prep commit for migrating "unavailable" user status feature to
"invisible" user presence feature.
Mateusz Mandera
Anders Kaseorg
Tim Abbott
Sahil Batra
Lauryn Menard
Adam Sah