This patch does the following:
1. changes `add_timeline_listener` to be async, thus removing one
`RUNTIME.block_on`.
2. simplifies the logic by adopting a more classical pattern we use
elsewhere:
* removes one `spawn_blocking`,
* let's move the `listener` into the task as a `Box` instead of
cloning it as an `Arc`.
Imagine the room list has the viewport set to the range `0..=19`. The
user scrolls quickly to `50..=69` to see something below and immediately
scrolls back to its initial position, without stopping the scroll
at any moment in between. The app using this API might update the
viewport from `0..=19` to… `0..=19`. Updating the viewport, updates the
`visible_rooms` sliding sync list. Since a list is modified, the current
sync-loop iteration is skipped over and a new one restarts, i.e. the
current in-flight request is cancelled… for nothing.
This patch prevents this situation. The current viewport ranges is
stored in `RoomListService`. `RoomListService::apply_input` used to
return `Result<(), Error>`, now it returns `Result<InputResult, Error>`.
The `InputResult` enum is a new type. It represents whether an input has
been applied or ignored, which must be differentiate from errors.
So now, if the viewport changes and it's not different from the previous
value, `InputResult::Ignored` is returned.
According to the spec, when a device receives a verification request and wants
to refuse it, it should send the `m.key.verification.cancel` to the originating
device, rather than broadcasting it.
This opens up a possible race condition where an embedder calls the method twice, generating two new rooms,
but then it's fine as long as they don't cache them somewhere, which we expect they don't.
That avoids recreating a timeline object every time a user calls `RoomListService::room()` with the same room id, so that should speed up
operations like fetching the latest event for rooms we've already entered before.
This patch changes the capacity of the internal buffer of
`ObservableVector` for `SlidingSyncList::room_list` from 16 to 4096.
With an increased capacity, we reduce the probability to send a
`VectorDiff::Reset` to subscribers. `Reset` are happening quite often
for apps using `matrix-sdk`, and it impacts their performance. This
patch tries to improve this situation. This `room-list` contains
`RoomListEntry`, which is can cheap in terms of memory, compared to the
impact of sending `Reset`s too often. That's a tradeoff.
Ivan Enderlin