Add a checkpoint to index newly encrypted rooms.

[poljar]

This intends to fix element-hq/element-web#13682, it waits for m.room.encryption events in the timeline and indexes a room if one is received. Though if a limited timeline was received the m.room.encryption event will be missed.

A suggestion was made to use the RoomState.events event and catch a m.room.encryption event there, but due to the way our locally cached sync gets stored/restored that event will be fired every time Riot gets started.

Suggestions on how to handle a limited sync there are welcome.

[dbkr]

Hmm, but won't this equally apply to rooms that have an m.room.encryption event in recent history when starting up, ie. the event will still get replayed? Using RoomState.events does sound like the correct answer, but you will need to check whether you've already started indexing a room. You'll also need to ensure the room is actually encrypted as this will just look for an encryption event with any algorithm which could be one we don't understand. Hopefully you can do this by checking isRoomEncrypted (if that's up to date when you get the event).

[poljar]

Hmm, but won't this equally apply to rooms that have an m.room.encryption event in recent history when starting up, ie. the event will still get replayed?

I don't think I observed that happening, but will re-check.

Using RoomState.events does sound like the correct answer, but you will need to check whether you've already started indexing a room.

That's a bit annoying, that'll need a new method in Seshat but I guess other people might find it useful as well.

[jryans]

@poljar Do you plan to revise this, or were you waiting for a review here? I wasn't sure if the above:

That's a bit annoying, that'll need a new method in Seshat but I guess other people might find it useful as well.

...meant you would revise this to address that, or if you see it as future work...?

[poljar]

I meant that I'll add the feature to Seshat and I'll update this PR after Seshat gets support. It's just a bit stuck behind getting the paginated search going and keeping the rust-sdk rolling.

[jryans]

Okay, for now I'll clear the review request here then.

[poljar]

This has now been updated, it requires the following PRs:
matrix-org/seshat#65
element-hq/element-web#13957
element-hq/element-desktop#100

Also a Seshat release will be required.

[jryans]

Thanks, looks good to me! 😄