Instead of returning False when auth is incomplete, throw an exception which
can be caught with a wrapper.

Fix the test to pass the right number of args to the Store constructors

what could possibly go wrong

May as well do it whenever we parse a Group ID. We check the sigil and basic
structure here so it makes sense to check the grammar in the same place.

The file under test is logcontext.py, not log_context.py

This isn't used anywhere.

1. make it not blow out the stack when there are more than 50 things waiting
   for a lock. Fixes https://github.com/matrix-org/synapse/issues/2505.

2. Make it not mess up the log contexts.

Support SRV records which point at AAAA records, as well as A records.

Fixes https://github.com/matrix-org/synapse/issues/2405

Fix a bug where we could end up firing off multiple requests for server_keys
for the same server at the same time.

- allows sysadmins the ability to lock down their servers so that people can't
send their users room invites.

I'm still unclear on what the intended behaviour for
`verify_json_objects_for_server` is, but at least I now understand the
behaviour of most of the things it calls...

Instead of every time a new email pusher is created, as loading jinja2
templates is slow.

Most of the time was spent copying a dict to filter out sentinel values
that indicated that keys did not exist in the dict. The sentinel values
were added to ensure that we cached the non-existence of keys.

By updating DictionaryCache to keep track of which keys were known to
not exist itself we can remove a dictionary copy.

might help us figure out if https://github.com/vector-im/riot-web/issues/3868
has happened.

When a client retries a key upload, don't give an error if the signature has
changed (but the key is the same).

Fixes https://github.com/vector-im/riot-android/issues/1208, hopefully.

As the TCP replication uses a slightly different API and streams than
the HTTP replication.

This breaks HTTP replication.

The cache wrappers had a habit of leaking the logcontext into the reactor while
the lookup function was running, and then not restoring it correctly when the
lookup function had completed. It's all the fault of
`preserve_context_over_{fn,deferred}` which are basically a bit broken.

This prevents unnecessary construction of lists

 * use a valid filter in rest/client/v2_alpha test

Signed-off-by: pik <alexander.maznev@gmail.com>