The _get_joined_users_from_context cache stores a mapping from user_id
to avatar_url and display_name. Instead of storing those in a dict,
store them in a namedtuple as that uses much less memory.
We also try converting the string to ascii to further reduce the size.
Currently the cache descriptors store deferreds rather than raw values,
this is a simple way of triggering only one database hit and sharing the
result if two callers attempt to get the same value.
However, there are a few caches that simply store a mapping from string
to string (or int). These caches can have a large number of entries,
under the assumption that each entry is small. However, the size of a
deferred (specifically the size of ObservableDeferred) is signigicantly
larger than that of the raw value, 2kb vs 32b.
This PR therefore changes the cache descriptors to store the raw values
rather than the deferreds.
As a side effect cached storage function now either return a deferred or
the actual value, as the cached list decriptor already does. This is
fine as we always end up just yield'ing on the returned value
eventually, which handles that case correctly.
The `except SynapseError` clauses were pointless because the wrapped functions
would never throw a `SynapseError` (they either throw a `CodeMessageException`
or a `RuntimeError`).
The `except CodeMessageException` is now also pointless because the caller
treats all exceptions equally, so we may as well just throw the
`CodeMessageException`.
The logic for marking invites as locally rejected was all well and good, but
didn't happen when the remote server returned a 500, or wasn't reachable, or
had no DNS, or whatever.
Just expand the except clause to catch everything.
Fixes https://github.com/matrix-org/synapse/issues/761.
Also:
- change the REST endpoint to have a "S" on the end (so it's now /read_markers)
- change the content of the m.read_up_to event to have the key "event_id" instead of "marker".
