Wrap calls to deferToThread() in a thing which uses a child logcontext to
attribute CPU usage to the right request.
While we're in the area, remove the logcontext_tracer stuff, which is never
used, and afaik doesn't work.
Fixes#4064
`on_new_notifications` and `on_new_receipts` in `HttpPusher` and `EmailPusher`
now always return synchronously, so we can remove the `defer.gatherResults` on
their results, and the `run_as_background_process` wrappers can be removed too
because the PusherPool methods will now complete quickly enough.
It's quite important that get_missing_events returns the *latest* events in the
room; however we were pulling event ids out of the database until we got *at
least* 10, and then taking the *earliest* of the results.
We also shouldn't really be relying on depth, and should be checking the
room_id.
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.
