Fixes a bug where rejected events were persisted with the wrong state group.
Also fixes an occasional internal-server-error when receiving events over
federation which are rejected and (possibly because they are
backwards-extremities) have no prev_group.
Fixes#6289.
* Raise an exception if accessing state for rejected events
Add some sanity checks on accessing state_group etc for
rejected events.
* Skip calculating push actions for rejected events
It didn't actually cause any bugs, because rejected events get filtered out at
various later points, but there's not point in trying to calculate the push
actions for a rejected event.
The intention here is to make it clearer which fields we can expect to be
populated when: notably, that the _event_type etc aren't used for the
synchronous impl of EventContext.
We don't want to bother pulling out the current state from the DB since
until we know we have to. Checking the context for state is just an
optimisation.
* Split state group persist into seperate storage func
* Add per database engine code for state group id gen
* Move store_state_group to StateReadStore
This allows other workers to use it, and so resolve state.
* Hook up store_state_group
* Fix tests
* Rename _store_mult_state_groups_txn
* Rename StateGroupReadStore
* Remove redundant _have_persisted_state_group_txn
* Update comments
* Comment compute_event_context
* Set start val for state_group_id_seq
... otherwise we try to recreate old state groups
* Update comments
* Don't store state for outliers
* Update comment
* Update docstring as state groups are ints
A few non-functional changes:
* A bunch of docstrings to document types
* Split `EventsStore._persist_events_txn` up a bit. Hopefully it's a bit more
readable.
* Rephrase `EventFederationStore._update_min_depth_for_room_txn` to avoid
mind-bending conditional.
* Rephrase rejected/outlier conditional in `_update_outliers_txn` to avoid
mind-bending conditional.
Patrick Cloke