Get rid of the labyrinthine `recoverer_fn` code, and clean up the startup code
(it seemed to be previously inexplicably split between
`ApplicationServiceScheduler.start` and `_Recoverer.start`).
Add some docstrings too.
While I was going through uses of preserve_fn for other PRs, I converted places
which only use the wrapped function once to use run_in_background, to avoid
creating the function object.
There were a bunch of places where we fire off a process to happen in the
background, but don't have any exception handling on it - instead relying on
the unhandled error being logged when the relevent deferred gets
garbage-collected.
This is unsatisfactory for a number of reasons:
- logging on garbage collection is best-effort and may happen some time after
the error, if at all
- it can be hard to figure out where the error actually happened.
- it is logged as a scary CRITICAL error which (a) I always forget to grep for
and (b) it's not really CRITICAL if a background process we don't care about
fails.
So this is an attempt to add exception handling to everything we fire off into
the background.
Adds a `.wrap` method to ResponseCache which wraps up the boilerplate of a
(get, set) pair, and then use it throughout the codebase.
This will be largely non-functional, but does include the following functional
changes:
* federation_server.on_context_state_request: drops use of _server_linearizer
which looked redundant and could cause incorrect cache misses by yielding
between the get and the set.
* RoomListHandler.get_remote_public_room_list(): fixes logcontext leaks
* the wrap function includes some logging. I'm hoping this won't be too noisy
on production.
via registration file "users" namespace:
```YAML
...
namespaces:
users:
- exclusive: true
regex: '.*luke.*'
group_id: '+all_the_lukes:hsdomain'
...
```
This is part of giving App Services their own groups for matching users. With this, ghost users will be given the appeareance that they are in a group and that they have publicised the fact, but _only_ from the perspective of the `get_publicised_groups_for_user` API.
This adds a flag loaded from the registration file of an AS that will determine whether or not its users are rate limited (by ratelimit in _base.py). Needed for IRC bridge reasons - see https://github.com/matrix-org/matrix-appservice-irc/issues/240.
If 'url' is not specified, they will not be pushed for events or queries. This
is useful for bots who simply wish to reserve large chunks of user/alias
namespace, and don't care about being pushed for events.
