If a connection is lost before a request is read from Request, Twisted
sets `method` (and `uri`) attributes to dummy values. These dummy values
have incorrect types (i.e. they're not bytes), and so things like
`__repr__` would raise an exception.
To fix this we had a helper method to return the method with a
consistent type.
In particular, we assume that the name and canonical alias events in
the state have not been rejected. In practice this may not be the case
(though we should probably think about fixing that) so lets ensure that
we gracefully handle that case, rather than 404'ing the sync request
like we do now.
If we have a forward extremity for a room as `E`, and you receive `A`, `B`,
s.t. `A -> B -> E`, and `B` also points to an unknown event `X`, then we need
to do state res between `X` and `E`.
When that happens, we need to make sure we include `X` in the state that goes
into the state res alg.
Fixes#3934.
If we've fetched state events from remote servers in order to resolve the state
for a new event, we need to actually pass those events into
resolve_events_with_factory (so that it can do the state res) and then persist
the ones we need - otherwise other bits of the codebase get confused about why
we have state groups pointing to non-existent events.
get_state_groups returns a map from state_group_id to a list of FrozenEvents,
so was very much the wrong thing to be putting as one of the entries in the
list passed to resolve_events_with_factory (which expects maps from
(event_type, state_key) to event id).
We actually want get_state_groups_ids().values() rather than
get_state_groups().
This fixes the main problem in #3923, but there are other problems with this
bit of code which get discovered once you do so.
* add some comments on things that look a bit bogus
* rename this `state` variable to avoid confusion with the `state` used
elsewhere in this function. (There was no actual conflict, but it was
a confusing bit of spaghetti.)
when processing incoming transactions, it can be hard to see what's going on,
because we process a bunch of stuff in parallel, and because we may end up
recursively working our way through a chain of three or four events.
This commit creates a way to use logcontexts to add the relevant event ids to
the log lines.
This ensures that its resource usage metrics get recorded somewhere rather than
getting lost.
(It also fixes an error when called from a nested logging context which
completes before the bg process)
