Previously, we would spin in a tight loop until
`update_state_for_partial_state_event` stopped raising
`FederationPullAttemptBackoffError`s. Replace the spinloop with a wait
until the backoff period has expired.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Tweak docstring and type hint
* Flip logic and provide better name
* Separate decision from action
* Track a set of strings, not EventBases
* Require explicit boolean options from callers
* Add explicit option for partial state rooms
* Changelog
* Rename param
Previously, when creating a join event in /make_join, we would decide
whether to include additional fields to satisfy restricted room checks
based on the current state of the room. Then, when building the event,
we would capture the forward extremities of the room to use as prev
events.
This is subject to race conditions. For example, when leaving and
rejoining a room, the following sequence of events leads to a misleading
403 response:
1. /make_join reads the current state of the room and sees that the user
is still in the room. It decides to omit the field required for
restricted room joins.
2. The leave event is persisted and the room's forward extremities are
updated.
3. /make_join builds the event, using the post-leave forward extremities.
The event then fails the restricted room checks.
To mitigate the race, we move the read of the forward extremities closer
to the read of the current state. Ideally, we would compute the state
based off the chosen prev events, but that can involve state resolution,
which is expensive.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Fix order of partial state tables when purging
`partial_state_rooms` has an FK on `events` pointing to the join event we
get from `/send_join`, so we must delete from that table before deleting
from `events`.
**NB:** It would be nice to cancel any resync processes for the room
being purged. We do not do this at present. To do so reliably we'd need
an internal HTTP "replication" endpoint, because the worker doing the
resync process may be different to that handling the purge request.
The first time the resync process tries to write data after the deletion
it will fail because we have deleted necessary data e.g. auth
events. AFAICS it will not retry the resync, so the only downside to
not cancelling the resync is a scary-looking traceback.
(This is presumably extremely race-sensitive.)
* Changelog
* admist(?) -> between
* Warn about a race
* Fix typo, thanks Sean
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
---------
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
Fixes#12801.
Complement tests are at
https://github.com/matrix-org/complement/pull/567.
Avoid blocking on full state when handling a subsequent join into a
partial state room.
Also always perform a remote join into partial state rooms, since we do
not know whether the joining user has been banned and want to avoid
leaking history to banned users.
Signed-off-by: Mathieu Velten <mathieuv@matrix.org>
Co-authored-by: Sean Quah <seanq@matrix.org>
Co-authored-by: David Robertson <davidr@element.io>
Ensure that the list of servers in a partial state room always contains
the server we joined off.
Also refactor `get_partial_state_servers_at_join` to return `None` when
the given room is no longer partial stated, to explicitly indicate when
the room has partial state. Otherwise it's not clear whether an empty
list means that the room has full state, or the room is partial stated,
but the server we joined off told us that there are no servers in the
room.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Allow `AbstractSet` in `StrCollection`
Or else frozensets are excluded. This will be useful in an upcoming
commit where I plan to change a function that accepts `List[str]` to
accept `StrCollection` instead.
* `rooms_to_exclude` -> `rooms_to_exclude_globally`
I am about to make use of this exclusion mechanism to exclude rooms for
a specific user and a specific sync. This rename helps to clarify the
distinction between the global config and the rooms to exclude for a
specific sync.
* Better function names for internal sync methods
* Track a list of excluded rooms on SyncResultBuilder
I plan to feed a list of partially stated rooms for this sync to ignore
* Exclude partial state rooms during eager sync
using the mechanism established in the previous commit
* Track un-partial-state stream in sync tokens
So that we can work out which rooms have become fully-stated during a
given sync period.
* Fix mutation of `@cached` return value
This was fouling up a complement test added alongside this PR.
Excluding a room would mean the set of forgotten rooms in the cache
would be extended. This means that room could be erroneously considered
forgotten in the future.
Introduced in #12310, Synapse 1.57.0. I don't think this had any
user-visible side effects (until now).
* SyncResultBuilder: track rooms to force as newly joined
Similar plan as before. We've omitted rooms from certain sync responses;
now we establish the mechanism to reintroduce them into future syncs.
* Read new field, to present rooms as newly joined
* Force un-partial-stated rooms to be newly-joined
for eager incremental syncs only, provided they're still fully stated
* Notify user stream listeners to wake up long polling syncs
* Changelog
* Typo fix
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
* Unnecessary list cast
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
* Rephrase comment
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
* Another comment
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
* Fixup merge(?)
* Poke notifier when receiving un-partial-stated msg over replication
* Fixup merge whoops
Thanks MV :)
Co-authored-by: Mathieu Velen <mathieuv@matrix.org>
Co-authored-by: Mathieu Velten <mathieuv@matrix.org>
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
* Faster joins: Update room stats and user directory on workers when done
When finishing a partial state join to a room, we update the current
state of the room without persisting additional events. Workers receive
notice of the current state update over replication, but neglect to wake
the room stats and user directory updaters, which then get incidentally
triggered the next time an event is persisted or an unrelated event
persister sends out a stream position update.
We wake the room stats and user directory updaters at the appropriate
time in this commit.
Part of #12814 and #12815.
Signed-off-by: Sean Quah <seanq@matrix.org>
* fixup comment
Signed-off-by: Sean Quah <seanq@matrix.org>
* Enable Complement tests for Faster Remote Room Joins on worker-mode
* (dangerous) Add an override to allow Complement to use FRRJ under workers
* Newsfile
Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>
* Fix race where we didn't send out replication notification
* MORE HACKS
* Fix get_un_partial_stated_rooms_token to take instance_name
* Fix bad merge
* Remove warning
* Correctly advance un_partial_stated_room_stream
* Fix merge
* Add another notify_replication
* Fixups
* Create a separate ReplicationNotifier
* Fix test
* Fix portdb
* Create a separate ReplicationNotifier
* Fix test
* Fix portdb
* Fix presence test
* Newsfile
* Apply suggestions from code review
* Update changelog.d/14752.misc
Co-authored-by: Erik Johnston <erik@matrix.org>
* lint
Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>
Co-authored-by: Erik Johnston <erik@matrix.org>
* Avoid clearing out forward extremities when doing a second remote join
When joining a restricted room where the local homeserver does not have
a user able to issue invites, we perform a second remote join. We want
to avoid clearing out forward extremities in this case because the
forward extremities we have are up to date and clearing out forward
extremities creates a window in which the room can get bricked if
Synapse crashes.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Do a full join when doing a second remote join into a full state room
We cannot persist a partial state join event into a joined full state
room, so we perform a full state join for such rooms instead. As a
future optimization, we could always perform a partial state join and
compute or retrieve the full state ourselves if necessary.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Add lock around partial state flag for rooms
Signed-off-by: Sean Quah <seanq@matrix.org>
* Preserve partial state info when doing a second partial state join
Signed-off-by: Sean Quah <seanq@matrix.org>
* Add newsfile
* Add a TODO(faster_joins) marker
Signed-off-by: Sean Quah <seanq@matrix.org>
Currently, we will try to start a new partial state sync every time we
perform a remote join, which is undesirable if there is already one
running for a given room.
We intend to perform remote joins whenever additional local users wish
to join a partial state room, so let's ensure that we do not start more
than one concurrent partial state sync for any given room.
------------------------------------------------------------------------
There is a race condition where the homeserver leaves a room and later
rejoins while the partial state sync from the previous membership is
still running. There is no guarantee that the previous partial state
sync will process the latest join, so we restart it if needed.
Signed-off-by: Sean Quah <seanq@matrix.org>
Then adapts calling code to retry when needed so it doesn't 500
to clients.
Signed-off-by: Mathieu Velten <mathieuv@matrix.org>
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
Remove type hints from comments which have been added
as Python type hints. This helps avoid drift between comments
and reality, as well as removing redundant information.
Also adds some missing type hints which were simple to fill in.
1. `federation_client.timestamp_to_event(...)` now handles all `destination` looping and uses our generic `_try_destination_list(...)` helper.
2. Consistently handling `NotRetryingDestination` and `FederationDeniedError` across `get_pdu` , backfill, and the generic `_try_destination_list` which is used for many places we use this pattern.
3. `get_pdu(...)` now returns `PulledPduInfo` so we know which `destination` we ended up pulling the PDU from
While https://github.com/matrix-org/synapse/pull/13635 stops us from doing the slow thing after we've already done it once, this PR stops us from doing one of the slow things in the first place.
Related to
- https://github.com/matrix-org/synapse/issues/13622
- https://github.com/matrix-org/synapse/pull/13635
- https://github.com/matrix-org/synapse/issues/13676
Part of https://github.com/matrix-org/synapse/issues/13356
Follow-up to https://github.com/matrix-org/synapse/pull/13815 which tracks event signature failures.
With this PR, we avoid the call to the costly `_get_state_ids_after_missing_prev_event` because the signature failure will count as an attempt before and we filter events based on the backoff before calling `_get_state_ids_after_missing_prev_event` now.
For example, this will save us 156s out of the 185s total that this `matrix.org` `/messages` request. If you want to see the full Jaeger trace of this, you can drag and drop this `trace.json` into your own Jaeger, https://gist.github.com/MadLittleMods/4b12d0d0afe88c2f65ffcc907306b761
To explain this exact scenario around `/messages` -> backfill, we call `/backfill` and first check the signatures of the 100 events. We see bad signature for `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` and `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` (both member events). Then we process the 98 events remaining that have valid signatures but one of the events references `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` as a `prev_event`. So we have to do the whole `_get_state_ids_after_missing_prev_event` rigmarole which pulls in those same events which fail again because the signatures are still invalid.
- `backfill`
- `outgoing-federation-request` `/backfill`
- `_check_sigs_and_hash_and_fetch`
- `_check_sigs_and_hash_and_fetch_one` for each event received over backfill
- ❗ `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` fails with `Signature on retrieved event was invalid.`: `unable to verify signature for sender domain xxx: 401: Failed to find any key to satisfy: _FetchKeyRequest(...)`
- ❗ `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` fails with `Signature on retrieved event was invalid.`: `unable to verify signature for sender domain xxx: 401: Failed to find any key to satisfy: _FetchKeyRequest(...)`
- `_process_pulled_events`
- `_process_pulled_event` for each validated event
- ❗ Event `$Q0iMdqtz3IJYfZQU2Xk2WjB5NDF8Gg8cFSYYyKQgKJ0` references `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` as a `prev_event` which is missing so we try to get it
- `_get_state_ids_after_missing_prev_event`
- `outgoing-federation-request` `/state_ids`
- ❗ `get_pdu` for `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` which fails the signature check again
- ❗ `get_pdu` for `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` which fails the signature check
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.
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/
Bounce recalculation of current state to the correct event persister and
move recalculation of current state into the event persistence queue, to
avoid concurrent updates to a room's current state.
Also give recalculation of a room's current state a real stream
ordering.
Signed-off-by: Sean Quah <seanq@matrix.org>
Whenever we want to persist an event, we first compute an event context,
which includes the state at the event and a flag indicating whether the
state is partial. After a lot of processing, we finally try to store the
event in the database, which can fail for partial state events when the
containing room has been un-partial stated in the meantime.
We detect the race as a foreign key constraint failure in the data store
layer and turn it into a special `PartialStateConflictError` exception,
which makes its way up to the method in which we computed the event
context.
To make things difficult, the exception needs to cross a replication
request: `/fed_send_events` for events coming over federation and
`/send_event` for events from clients. We transport the
`PartialStateConflictError` as a `409 Conflict` over replication and
turn `409`s back into `PartialStateConflictError`s on the worker making
the request.
All client events go through
`EventCreationHandler.handle_new_client_event`, which is called in
*a lot* of places. Instead of trying to update all the code which
creates client events, we turn the `PartialStateConflictError` into a
`429 Too Many Requests` in
`EventCreationHandler.handle_new_client_event` and hope that clients
take it as a hint to retry their request.
On the federation event side, there are 7 places which compute event
contexts. 4 of them use outlier event contexts:
`FederationEventHandler._auth_and_persist_outliers_inner`,
`FederationHandler.do_knock`, `FederationHandler.on_invite_request` and
`FederationHandler.do_remotely_reject_invite`. These events won't have
the partial state flag, so we do not need to do anything for then.
The remaining 3 paths which create events are
`FederationEventHandler.process_remote_join`,
`FederationEventHandler.on_send_membership_event` and
`FederationEventHandler._process_received_pdu`.
We can't experience the race in `process_remote_join`, unless we're
handling an additional join into a partial state room, which currently
blocks, so we make no attempt to handle it correctly.
`on_send_membership_event` is only called by
`FederationServer._on_send_membership_event`, so we catch the
`PartialStateConflictError` there and retry just once.
`_process_received_pdu` is called by `on_receive_pdu` for incoming
events and `_process_pulled_event` for backfill. The latter should never
try to persist partial state events, so we ignore it. We catch the
`PartialStateConflictError` in `on_receive_pdu` and retry just once.
Refering to the graph of code paths in
https://github.com/matrix-org/synapse/issues/12988#issuecomment-1156857648
may make the above make more sense.
Signed-off-by: Sean Quah <seanq@matrix.org>
Instead, use the `room_version` property of the event we're validating.
The `room_version` was originally added as a parameter somewhere around #4482,
but really it's been redundant since #6875 added a `room_version` field to `EventBase`.
