This one is used when caching a thumbnail everywhere, and when
attempting to retrieve it; it gives us a single place where to
coordinate the default `MediaThumbnailSettings` parameters.
The previous values would lead to super large memory allocations, as
observed with `valgrind --tool=massive` on the tiny test added in this
commit:
- for 400 rooms each having 100 events, this led to 540MB of
allocations.
- for 1000 rooms each having 100 events, this led to 1.5GB of
allocations.
This is not acceptable for any kind of devices, especially for mobile
devices which may be more constrained on memory. The bloom filter is an
optimisation to avoid going through events in the room's event list, so
it shouldn't cause a big toll like that; instead, we can reduce the
parameters values given when creating the filters.
With the given parameters, 1000 rooms each having 100 events leads to
1.2MB of allocations.
With this, we get notified of the current verification state almost immediately.
Without it, you may either call it too soon and receive an `Unknown` state or you might have to call `Encryption::wait_for_e2ee_initialization_tasks()` and wait until it's finished to request a valid state value.
This patch introduces `EmptyChunk`, a new enum used to represent whether
empty chunks must be removed/unlink or kept from the `LinkedChunk`. It
is used by `LinkedChunk::remove_item_at`.
Why is it important? For example, imagine the following situation:
- one inserts a single event in a new chunk (possible if a (sliding)
sync is done with `timeline_limit=1`),
- one inserts many events at the position of the previous event,
with one of the new events being a duplicate of the first event
(possible if a (sliding) sync is done with `timeline_limit=10` this
time),
- prior to this patch, the older event was removed, resulting in an
empty chunk, which was removed from the `LinkedChunk`, invalidating
the insertion position!
So, with this patch:
- `RoomEvents::remove_events` does remove empty chunks, but
- `RoomEvents::remove_events_and_update_insert_position` does NOT remove
empty chunks, they are kept in case the position wants to insert in this
same chunk.
This fixes a problem when doing an incremental sync at launch,
where `NotLoaded` event would not be dispatched until data became
available or timeout is reached, leading to app waiting for it.
Changelog: the parameter `room_info_notable_update_receiver` was removed
from `RoomList::entries_with_dynamic_adapters`, since it could be
inferred internally instead.
