Otherwise things will get confused.
An alternative would be to make sure that for lagging stream we don't
return anything (and make sure the returned next_batch token doesn't go
backwards). But that is a faff.
There is a problem with `StreamIdGenerator` where it can go backwards
over restarts when a stream ID is requested but then not inserted into
the DB. This is problematic if we want to land #17215, and is generally
a potential cause for all sorts of nastiness.
Instead of trying to fix `StreamIdGenerator`, we may as well move to
`MultiWriterIdGenerator` that does not suffer from this problem (the
latest positions are stored in `stream_positions` table). This involves
adding SQLite support to the class.
This only changes id generators that were already using
`MultiWriterIdGenerator` under postgres, a separate PR will move the
rest of the uses of `StreamIdGenerator` over.
Re-introduces #17191, and includes #17197 and #17214
The basic idea is to stop calling `get_rooms_for_user` everywhere, and
instead use the table `device_lists_changes_in_room`.
Commits reviewable one-by-one.
It's almost always more efficient to query the rooms that have device
list changes, rather than looking at the list of all users whose devices
have changed and then look for shared rooms.
Weakness in auth chain indexing allows DoS from remote room members
through disk fill and high CPU usage.
A remote Matrix user with malicious intent, sharing a room with Synapse
instances before 1.104.1, can dispatch specially crafted events to
exploit a weakness in how the auth chain cover index is calculated. This
can induce high CPU consumption and accumulate excessive data in the
database of such instances, resulting in a denial of service.
Servers in private federations, or those that do not federate, are not
affected.
Resurrecting https://github.com/matrix-org/synapse/pull/13918.
This should reduce IOPs incurred by joining to the events table to
lookup stream ordering, which happens in many receipt handling code
paths. Like the previous PR I believe sufficient time has passed between
the original migration in DB schema 72 and now to merge this as-is. It's
highly unlikely that both the migration is still ongoing AND (active)
users still have any receipts prior to that date.
In the unlikely event there is a receipt without a populated
`event_stream_ordering` synapse will behave just as it does now when
receipts exist for events that don't (yet): for push action calculation
the receipts are just ignored.
I've removed the validation on event IDs as this is already covered
here:
59ceabcb97/synapse/handlers/receipts.py (L189-L192)
Before we were pulling out *all* read receipts for a user for every
event we pushed. Instead let's only pull out the relevant receipts.
This also pulled out the event rows for each receipt, causing load on
the events table.
Fixes https://github.com/element-hq/synapse/issues/16680, as well as a
related bug, where servers which we had *never* successfully sent an
event to would not be retried.
In order to fix the case of pending to-device messages, we hook into the
existing `wake_destinations_needing_catchup` process, by extending it to
look for destinations that have pending to-device messages. The
federation transmission loop then attempts to send the pending to-device
messages as normal.
We do this by adding support to the LRU cache for "extra indices" based
on the cached value. This allows us to efficiently map from room ID to
the cached events and only invalidate those.
This basically reverts a change that was in
https://github.com/element-hq/synapse/pull/16833, where we reduced the
batching.
The smaller batching can cause performance issues on busy servers and
databases.
During the migration the automated script to update the copyright
headers accidentally got rid of some of the existing copyright lines.
Reinstate them.
The current query supports passing in a list of users, which generates a
query using `user_id = ANY(..)`. This is generates a less efficient
query plan that is notably slower than a simple `user_id = ?` condition.
Note: The new function is mostly a copy and paste and then a
simplification of the existing function.
The crux of the change is to try and make the queries simpler and pull
out fewer rows. Before, there were quite a few joins against subqueries,
which caused postgres to pull out more rows than necessary.
Instead, let's simplify the query and do some of the filtering out in
Python instead, letting Postgres do better optimizations now that it
doesn't have to deal with joins against subqueries.
Review note: this is a complete rewrite of the function, so not sure how
useful the diff is.
---------
Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
There are two changes here:
1. Only pull out the required state when handling the request.
2. Change the get filtered state return type to check that we're only
querying state that was requested
---------
Co-authored-by: reivilibre <oliverw@matrix.org>
There are a couple of things we need to be careful of here:
1. The current python code does no validation when loading from the DB,
so we need to be careful to ignore such errors (at least on jki.re there
are some old events with internal metadata fields of the wrong type).
2. We want to be memory efficient, as we often have many hundreds of
thousands of events in the cache at a time.
---------
Co-authored-by: Quentin Gliech <quenting@element.io>
We remove these fields as they're just duplicating data the event
already stores, and (for reasons 🤫) I'd like to simplify
the class to only store simple types.
I'm not entirely convinced that we shouldn't instead add helper methods
to the event class to generate stream tokens, but I don't really think
that's where they belong either
