The aim here is to get to a stage where we have a `PersistEventStore` that holds all the write methods used during event persistence, so that we can take that class out of the `DataStore` mixin and instansiate it separately. This will allow us to instansiate it on processes other than master, while also ensuring it is only available on processes that are configured to write to events stream.
This is a bit of an architectural change, where we end up with multiple classes per data store (rather than one per data store we have now). We end up having:
1. Storage classes that provide high level APIs that can talk to multiple data stores.
2. Data store modules that consist of classes that must point at the same database instance.
3. Classes in a data store that can be instantiated on processes depending on config.
* Increase DB/CPU perf of `_is_server_still_joined` check.
For rooms with large amount of state a single user leaving could cause
us to go and load a lot of membership events and then pull out
membership state in a large number of batches.
* Newsfile
* Update synapse/storage/persist_events.py
Co-Authored-By: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
* Fix adding if too soon
* Update docstring
* Review comments
* Woops typo
Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
When a server leaves a room it may stop sharing a room with remote
users, and thus not get any updates to their device lists. So we need to
check for this case and delete those device lists from the cache.
We don't need to do this if we stop sharing a room because the remote
user leaves the room, because we track that case via looking at
membership changes.
Currently we rely on `current_state_events` to figure out what rooms a
user was in and their last membership event in there. However, if the
server leaves the room then the table may be cleaned up and that
information is lost. So lets add a table that separately holds that
information.
