This was broken in PR #4405, commit 886e5ac, where we changed remote
rejections to be outliers.
The fix is to explicitly add the leave event in when we know its an out
of band invite. We can't always add the event as if the server is/was in
the room there might be more events to send down the sync than just the
leave.
Currently when fetching state groups from the data store we make two
hits two the database: once for members and once for non-members (unless
request is filtered to one or the other). This adds needless load to the
datbase, so this PR refactors the lookup to make only a single database
hit.
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.
Given we have disabled lazy loading for incr syncs in #3840, we can make self-LL more efficient by only doing it on initial sync. Also adds a bounds check for if/when we change our mind, so that we don't try to include LL members on sync responses with no timeline.
* speed up room summaries by pulling their data from room_memberships rather than room state
* disable LL for incr syncs, and log incr sync stats (#3840)
When a user joined a room any existing tags were not sent down the sync
stream. Ordinarily this isn't a problem because the user needs to be in
the room to have set tags in it, however synapse will sometimes add tags
for a user to a room, e.g. for server notices, which need to come down
sync.
* attempt at deduplicating lazy-loaded members
as per the proposal; we can deduplicate redundant lazy-loaded members
which are sent in the same sync sequence. we do this heuristically
rather than requiring the client to somehow tell us which members it
has chosen to cache, by instead caching the last N members sent to
a client, and not sending them again. For now we hardcode N to 100.
Each cache for a given (user,device) tuple is in turn cached for up to
X minutes (to avoid the caches building up). For now we hardcode X to 30.
* add include_redundant_members filter option & make it work
* remove stale todo
* add tests for _get_some_state_from_cache
* incorporate review
