Rooms incorrectly marked as unread

[Sorunome]

Description

Rooms which only had a whole ton of m.room.member changes are incorrectly marked as unread. It mostly happens with discord linked rooms as the discord appservice tends to generate quite a few m.room.member events.

Steps to reproduce

• Join a room with little activity
• wait for tons of m.room.member changes
• room will be marked as unread upon starting riot

Room should not be unread

Logs being sent: yes/no

Version information

Pretty much all versions since a very long time, currently on 1.3.2 desktop.

• Platform: web (in-browser) or desktop?

For the web app:

• Browser: Waterfox 56.2.12
• OS: Arch Linux
• URL: https://ponies.im/_matrix/client/develop/ and others

For the desktop app:

• OS: Arch Linux
• Version: 1.3.2

[aaronraimist]

Related: #8513 element-hq/element-meta#1088

[matejdro]

Also happens on Android client 0.9.10

[matejdro]

I did some digging and I think I found root cause of the issue:

Riot gets its unread status by Getting short list of last events and attempts to find last read message. However, this list of events is very short and if it gets filled by status messages, riot will never find any read messages there and always mark the list as read.

I am not sure what would be the best way to fix this though.

[andybalaam]

I saw this problem again this morning. Up until recently, this problem has been masked by much worse unread problems that have hopefully now been fixed by the work on stuck notifications #24392.