This patch lands the first design of the `Input` API. An `Input` is
something external that can be understood by the `RoomList` state
machine. The first inpuput is `Viewport` to change the “viewport” of the
`RoomList`, which translates to the change of the ranges of one specific
Sliding Sync list.
This patch implements `RoomList::update_entries_stream_filter` which
allows to… change the… entries stream filter. This patch also provides a
test for that. How nice it is.
This patch adds a new method on `SlidingSyncList` named
`room_list_filtered_stream`, which uses the new `eyeball-im-util` crate
with its new `FilteredSubscriber` type.
This patch does several things.
First, `SlidingSync::on_list` is now async, and accept async closures.
Second, `SlidingSync::lists` and `::rooms` are behind an `AsyncRwLock`
instead of a `StdRwLock`. The rest of the patch updates the consequence
of this.
This patch replaces a panic (`Option::expect`) by a `tracing::error`
log.
Imagine the Sliding Sync proxy responds with the following payload:
```json
{
"pos": …,
"lists": {
…: {
"count": …,
"ops": [
{
"op": "INSERT",
"index": 0,
"room_id": !foo:bar.org",
}
]
}
},
"rooms": []
}
```
It's an invalid response, as it will update the room list entry (because
it's present in `lists.$list.ops`), but the room won't be created (it's
absent in the `rooms`).
This situation creates a panic in the patched code. We don't want to
crash if the server replies with invalid data.
Ultimately, we should check that the sync operations are valid regarding
the rooms' updates.
This patch uses `FutureExt::now_or_never` so that we don't wait on the
future to be resolved to get a result. If we have a bug in our code and
the test expects a value, the test will hang forever, which is not a
desired behavior. With `now_or_never`, this situation cannot happen.
The only reason why a sender can fail to send a message is because there
is no receiver. In the current design of `SlidingSync`, there is only
one receiver active per sync-loop. Thus, calling `SlidingSync::add_list`
may fail if `sync` has not been started. Hence the need for a new
`internal_channel_send_if_possible` method which will never fail: it
will send a message is possible, otherwise it won't do anything.
This turns more functions infallible.
