Only fetch events once for all rooms

[recht]

This refactors PDUStreamProvider a bit so that it doesn't trigger a database query per room, but instead utilizes the fact that it's possible to bulk query. This improves sync performance significantly when you have 1000s of rooms.

Pull Request Checklist

• I have added Go unit tests or Complement integration tests for this PR or I have justified why this PR doesn't need tests
• Pull request includes a sign off below using a legally identifiable name or I have already signed off privately

Signed-off-by: Joakim Recht <joakim@beyondwork.ai>

[S7evinK]

I think I tried something similar, but that made Sytest unhappy with regards to newly joined rooms on incremental syncs.

[codecov]

Codecov Report

Attention: 41 lines in your changes are missing coverage. Please review.

Comparison is base (7863a40) 65.71% compared to head (c48a7aa) 65.85%.
Report is 26 commits behind head on main.

Files	Patch %	Lines
syncapi/streams/stream_pdu.go	29.31%	34 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3311      +/-   ##
==========================================
+ Coverage   65.71%   65.85%   +0.13%     
==========================================
  Files         507      509       +2     
  Lines       57291    58904    +1613     
==========================================
+ Hits        37651    38793    +1142     
- Misses      15830    16207     +377     
- Partials     3810     3904      +94     

Flag	Coverage Δ
unittests	50.05% <29.31%> (+0.54%)	⬆️

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[recht]

I think I tried something similar, but that made Sytest unhappy with regards to newly joined rooms on incremental syncs.

Hmm yes I see - I have changed it a bit so that it handles the newly joined case too, and that seems to make tests run locally at least.

[recht]

I see a build is still failing, but I'm not sure the failure is related to my change?

[S7evinK]

Looks more like GHA being upset. Started a retry.

[S7evinK]

LGTM! Thank you!
I'd like to test this on my server for a bit before merging, but my server is down as of today.. (disc I/O issues, as it seems :/)

[S7evinK]

Right, so regarding speed, it doesn't seem to change that much (well, at least for my few rooms). Most of the time is spent in GetStateDeltas (when setting the PDU token to current - 100k), but that may be something for a different PR.

[recht]

I expect for a few rooms it doesn't make any noticeable difference, but if you have many (1000s) it's very significant

[S7evinK]

Thank you for this! :)