Spawned while working on [`get_users_in_room` mis-uses](https://github.com/matrix-org/synapse/pull/13958#discussion_r984074897) and thinking we could use `get_local_users_in_room` here but we can't.
From first glance, it seemed like this was only using local users from all of the `is_mine_id(user_id)` checks but I see that it does actually use remote users. Just making things a little more clear here what it does and mentions remote users so maybe that will be more obvious in the future.
Fixes#13942. Introduced in #13575.
Basically, let's only get the ordered set of hosts out of the DB if we need an ordered set of hosts. Since we split the function up the caching won't be as good, but I think it will still be fine as e.g. multiple backfill requests for the same room will hit the cache.
There is no need to grab thousands of backfill points when we only need 5 to make the `/backfill` request with. We need to grab a few extra in case the first few aren't visible in the history.
Previously, we grabbed thousands of backfill points from the database, then sorted and filtered them in the app. Fetching the 4.6k backfill points for `#matrix:matrix.org` from the database takes ~50ms - ~570ms so it's not like this saves a lot of time 🤷. But it might save us more time now that `get_backfill_points_in_room`/`get_insertion_event_backward_extremities_in_room` are more complicated after https://github.com/matrix-org/synapse/pull/13635
This PR moves the filtering and limiting to the SQL query so we just have less data to work with in the first place.
Part of https://github.com/matrix-org/synapse/issues/13356
c.f. #12993 (comment), point 3
This stores all device list updates that we receive while partial joins are ongoing, and processes them once we have the full state.
Note: We don't actually process the device lists in the same ways as if we weren't partially joined. Instead of updating the device list remote cache, we simply notify local users that a change in the remote user's devices has happened. I think this is safe as if the local user requests the keys for the remote user and we don't have them we'll simply fetch them as normal.
This PR begins work on batching up events during the creation of a room. The PR splits out the creation and sending/persisting of the events. The first three events in the creation of the room-creating the room, joining the creator to the room, and the power levels event are sent sequentially, while the subsequent events are created and collected to be sent at the end of the function. This is currently done by appending them to a list and then iterating over the list to send, the next step (after this PR) would be to send and persist the collected events as a batch.
Since #11482, we're saving sessions IDs from upstream IdPs, but we've been losing them when the user goes through a user mapping session on account registration.
During a `lazy_load_members` `/sync`, we look through auth events in
rooms with partial state to find prior membership events. When such a
membership is not found, an error is logged.
Since the first join event for a user never has a prior membership event
to cite, the error would always be logged when one appeared in the room
timeline.
Avoid logging errors for such events.
Introduced in #13477.
Signed-off-by: Sean Quah <seanq@matrix.org>
This is also using the partial state approximation if needed so we do
not block here during a fast join.
Signed-off-by: Mathieu Velten <mathieuv@matrix.org>
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
Part of the work for #12993.
Once #12993 is fully resolved, we expect `/keys/changes` to behave
sensibly when joined to a room with partial state.
Signed-off-by: Sean Quah <seanq@matrix.org>
Use the provided list of servers in the room from the `/send_join`
response, since we will not know which users are in the room. This
isn't sufficient to ensure that all remote servers receive the right
device list updates, since the `/send_join` response may be inaccurate
or we may calculate the membership state of new users in the room
incorrectly.
Signed-off-by: Sean Quah <seanq@matrix.org>
When a remote user leaves the last room shared with the homeserver, we
have to mark their device list as unsubscribed, otherwise we would hold
on to a stale device list in our cache. Crucially, the device list would
remain cached even after the remote user rejoined the room, which could
lead to E2EE failures until the next change to the remote user's device
list.
Fixes#13651.
Signed-off-by: Sean Quah <seanq@matrix.org>
This is a re-do of 57d334a13d (#13365),
which was backed out in 12abd72497 (#13501).
The `room_id` field represented the parent space for each room
and was made redundant by changes in the API shape where the
`children_state` is now nested underneath each `room`.
The room ID of each child is in the `state_key` field and is still
available.
Optimize how we calculate `likely_domains` during backfill because I've seen this take 17s in production just to `get_current_state` which is used to `get_domains_from_state` (see case [*2. Loading tons of events* in the `/messages` investigation issue](https://github.com/matrix-org/synapse/issues/13356)).
There are 3 ways we currently calculate hosts that are in the room:
1. `get_current_state` -> `get_domains_from_state`
- Used in `backfill` to calculate `likely_domains` and `/timestamp_to_event` because it was cargo-culted from `backfill`
- This one is being eliminated in favor of `get_current_hosts_in_room` in this PR 🕳
1. `get_current_hosts_in_room`
- Used for other federation things like sending read receipts and typing indicators
1. `get_hosts_in_room_at_events`
- Used when pushing out events over federation to other servers in the `_process_event_queue_loop`
Fix https://github.com/matrix-org/synapse/issues/13626
Part of https://github.com/matrix-org/synapse/issues/13356
Mentioned in [internal doc](https://docs.google.com/document/d/1lvUoVfYUiy6UaHB6Rb4HicjaJAU40-APue9Q4vzuW3c/edit#bookmark=id.2tvwz3yhcafh)
### Query performance
#### Before
The query from `get_current_state` sucks just because we have to get all 80k events. And we see almost the exact same performance locally trying to get all of these events (16s vs 17s):
```
synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 16035.612 ms (00:16.036)
synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 4243.237 ms (00:04.243)
```
But what about `get_current_hosts_in_room`: When there is 8M rows in the `current_state_events` table, the previous query in `get_current_hosts_in_room` took 13s from complete freshness (when the events were first added). But takes 930ms after a Postgres restart or 390ms if running back to back to back.
```sh
$ psql synapse
synapse=# \timing on
synapse=# SELECT COUNT(DISTINCT substring(state_key FROM '@[^:]*:(.*)$'))
FROM current_state_events
WHERE
type = 'm.room.member'
AND membership = 'join'
AND room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
count
-------
4130
(1 row)
Time: 13181.598 ms (00:13.182)
synapse=# SELECT COUNT(*) from current_state_events where room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
count
-------
80814
synapse=# SELECT COUNT(*) from current_state_events;
count
---------
8162847
synapse=# SELECT pg_size_pretty( pg_total_relation_size('current_state_events') );
pg_size_pretty
----------------
4702 MB
```
#### After
I'm not sure how long it takes from complete freshness as I only really get that opportunity once (maybe restarting computer but that's cumbersome) and it's not really relevant to normal operating times. Maybe you get closer to the fresh times the more access variability there is so that Postgres caches aren't as exact. Update: The longest I've seen this run for is 6.4s and 4.5s after a computer restart.
After a Postgres restart, it takes 330ms and running back to back takes 260ms.
```sh
$ psql synapse
synapse=# \timing on
Timing is on.
synapse=# SELECT
substring(c.state_key FROM '@[^:]*:(.*)$') as host
FROM current_state_events c
/* Get the depth of the event from the events table */
INNER JOIN events AS e USING (event_id)
WHERE
c.type = 'm.room.member'
AND c.membership = 'join'
AND c.room_id = '!OGEhHVWSdvArJzumhm:matrix.org'
GROUP BY host
ORDER BY min(e.depth) ASC;
Time: 333.800 ms
```
#### Going further
To improve things further we could add a `limit` parameter to `get_current_hosts_in_room`. Realistically, we don't need 4k domains to choose from because there is no way we're going to query that many before we a) probably get an answer or b) we give up.
Another thing we can do is optimize the query to use a index skip scan:
- https://wiki.postgresql.org/wiki/Loose_indexscan
- Index Skip Scan, https://commitfest.postgresql.org/37/1741/
- https://www.timescale.com/blog/how-we-made-distinct-queries-up-to-8000x-faster-on-postgresql/
Use dedicated `get_local_users_in_room` to find local users when calculating `join_authorised_via_users_server` ("the authorising user for joining a restricted room") of a `/make_join` request.
Found while working on https://github.com/matrix-org/synapse/pull/13575#discussion_r953023755 but it's not related.
