Slow call to olmMachine.getRoomSettings()

[florianduros]

A bit of context first: we are migrating from the legacy crypto stack to rust crypto stack. In EW, we need to know if the room is encrypted to display it. This assertion is a part of the critical path of EW.

To know if the room is encrypted, we look at the room settings thanks to olmMachine.getRoomSettings().

We have spot a performance issue when trying to get this value from less than 1sec to multiple secs to respond.

[poljar]

The relevant method for EW should live in the indexedDB crate:

matrix-rust-sdk/crates/matrix-sdk-indexeddb/src/crypto_store/mod.rs

Lines 1317 to 1327 in 3e7d7e8

	async fn get_room_settings(&self, room_id: &RoomId) -> Result<Option<RoomSettings>> {
	let key = self.serializer.encode_key(keys::ROOM_SETTINGS, room_id);
	self
	.inner
	.transaction_on_one_with_mode(keys::ROOM_SETTINGS, IdbTransactionMode::Readonly)?
	.object_store(keys::ROOM_SETTINGS)?
	.get(&key)?
	.await?
	.map(|v| self.serializer.deserialize_value(v))
	.transpose()
	}

Nothing really jumps out, looks like a simple key/value get operation.

[poljar]

No objections here, though I don't have any particular guidance on how to improve the situation.