Previously, we just had very basic partial room exclusion based on
whether we were lazy-loading room members. Now with this PR, we added
`must_await_full_state(...)` with rules to check if we have a we're only
requesting `required_state` which is completely satisfied even with
partial state.
Partially-stated rooms should have all state events except for remote
membership events so if we require a remote membership event anywhere,
then we need to return `True`.
This triggers the client to start a new sliding sync connection. If we
don't do this and the client asks for the full range of rooms, we end up
sending down all rooms and their state from scratch (which can be very
slow)
This causes things like
https://github.com/element-hq/element-x-ios/issues/3115 after we restart
the server
---------
Co-authored-by: Eric Eastwood <eric.eastwood@beta.gouv.fr>
Update `filters.is_encrypted` and `filters.types`/`filters.not_types` to
be robust when dealing with remote invite rooms in Sliding Sync.
Part of
[MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575):
Sliding Sync
Follow-up to https://github.com/element-hq/synapse/pull/17434
We now take into account current state, fallback to stripped state
for invite/knock rooms, then historical state. If we can't determine
the info needed to filter a room (either from state or stripped state),
it is filtered out.
Rather than always including all rooms in range.
Also adds a pre-filter to rooms that checks the stream change cache to
see if anything might have happened.
Based on #17447
---------
Co-authored-by: Eric Eastwood <eric.eastwood@beta.gouv.fr>
The basic idea is that we introduce a new token for a sliding sync
connection, which stores the mapping of room to room "status" (i.e. have
we sent the room down?). This token allows us to handle duplicate
requests properly. In future it can be used to store more
"per-connection" information safely.
In future this should be migrated into the DB, so its important that we
try to reduce the number of syncs where we need to update the
per-connection information. In this PoC this only happens when we: a)
send down a set of room for the first time, or b) we have previously
sent down a room and there are updates but we are not sending the room
down the sync (due to not falling in a list range)
Co-authored-by: Eric Eastwood <eric.eastwood@beta.gouv.fr>
Backfill events have a negative stream ordering, and so its not useful
to use to compare with other (positive) stream orderings.
Plus, the Rust SDK currently assumes `bump_stamp` is positive.
Prior to this PR, remote downloads which did not provide a
`content-length` were decremented from the remote download ratelimiter
at the max allowable size, leading to excessive ratelimiting - see
https://github.com/element-hq/synapse/issues/17394.
This PR adds a linearizer to limit concurrent remote downloads to 6 per
IP address, and decrements remote downloads without a `content-length`
from the ratelimiter *after* the download is complete and the response
length is known.
Also adds logic to ensure that responses with a known length respect the
`max_download_size`.
Add room subscriptions to Sliding Sync `/sync`
Based on
[MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575):
Sliding Sync
Currently, you can only subscribe to rooms you have had *any* membership
in before.
In the future, we will allow `world_readable` rooms to be subscribed to
without joining.
`bump_stamp` corresponds to the `stream_ordering` of the latest `DEFAULT_BUMP_EVENT_TYPES` in the room. This helps clients sort more readily without them needing to pull in a bunch of the timeline to determine the last activity. `bump_event_types` is a thing because for example, we don't want display name changes to mark the room as unread and bump it to the top. For encrypted rooms, we just have to consider any activity as a bump because we can't see the content and the client has to figure it out for themselves.
Outside of Synapse, `bump_stamp` is just a free-form counter so other implementations could use `received_ts`or `origin_server_ts` (see the [*Security considerations* section in MSC3575 about the potential pitfalls of using `origin_server_ts`](https://github.com/matrix-org/matrix-spec-proposals/blob/kegan/sync-v3/proposals/3575-sync.md#security-considerations)). It doesn't have any guarantee about always going up. In the Synapse case, it could go down if an event was redacted/removed (or purged in cases of retention policies).
In the future, we could add `bump_event_types` as [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) mentions if people need to customize the event types.
---
In the Sliding Sync proxy, a similar [`timestamp` field was added](https://github.com/matrix-org/sliding-sync/pull/247) for the same purpose but the name is not obvious what it pertains to or what it's for.
The `timestamp` field was also added to Ruma in https://github.com/ruma/ruma/pull/1622
Follows on from @H-Shay's great work at
https://github.com/matrix-org/synapse/pull/15344 and MSC4026.
Also enables its use for MSC3881, mainly as an easy but concrete example
of how to use it.
Fixes https://github.com/element-hq/synapse/issues/17274, hopefully.
Basically, old versions of Synapse could advance streams without
persisting anything in the DB (fixed in #17229). On restart those
updates would get lost, and so the position of the stream would revert
to an older position. If this happened across an upgrade to a later
Synapse version which included #17215, then sync could get blocked
indefinitely (until the stream advanced to the position in the token).
We fix this by bounding the stream positions we'll wait for to the
maximum position of the underlying stream ID generator.
Sort is no longer configurable and we always sort rooms by the `stream_ordering` of the last event in the room or the point where the user can see up to in cases of leave/ban/invite/knock.
