Room previews are often stale

[ara4n]

Steps to reproduce

1. View room list
2. Go into room
3. Send some messages
4. Wait for them to echo
5. Go back to room list
6. Room list preview shows the message from before you entered the room (possibly the room cached version). It slowly updates after a second or so to show the right preview. It can switch back and forth between the right and wrong preview as it does so.

Outcome

What did you expect?

reliable room previews

What happened instead?

stale previews and flakiness feeling

Your phone model

No response

Operating system version

No response

Application version

391

Homeserver

No response

Will you send logs?

No

[ara4n]

or at the least it lags the traffic of the msgs you’ve sent by several seconds

[ara4n]

Just caught this in the act. The Dendrite room preview is showing entirely wrong preview from ages ago (perhaps from a previous stale cache when I last launched the app?)

neither allrooms or visiblerooms list appears to have updated the preview correctly. however, the room order is right, as can be confirmed by opening the room and pulling in timeline, which then fixes the preview

[manuroe]

Local echo support in the room preview should fix it. We need to test local echoes on Android. We may then review the complexity if other problems are found.

[ara4n]

I’m worried that this issue is being misunderstood as just related to local echoes, rather than previews in general being painfully unreliable. Someone just asked about it in #EXI and i gave the following explanation:

the problem is likely:

• roomlist only loads most recent event from server for room
• it should load also the last 20 events in the room in order to display a more accurate preview, but in practice that doesn’t seem to happen reliably.
• the most recent event is undisplayable (eg some state event)
• therefore it shows whatever the roomlist cache last had, which will be stale from the last launch of the app.
• meanwhile the timeline correctly loads, but because the roomlist preview doesn’t use the event cache used by the timeline yet, it gets out of sync

the fact the app lies to you about the most recent message in a room is far from great.

see matrix-org/matrix-rust-sdk#4112

[oddlid]

It was me who just asked about this in #EXi.
As you can see in the attached screenshot, the room preview in the left sidebar does not reflect the latest message in the room.