Cache session outcome count

[elsirion]

Introduces a DB entry that caches the number of session outcomes in the DB so that we don't have to scan the entire DB every time we need this number.

Fixes #4066

[elsirion]

I ran into some trouble with DB migration tests, could you take a look at 487a5c4 in particular please @m1sterc001guy? Is my attempt to fix it correct or am I missing something?

[codecov]

Codecov Report

Attention: 23 lines in your changes are missing coverage. Please review.

Comparison is base (9c36777) 58.28% compared to head (edf8d46) 58.29%.

Files	Patch %	Lines
fedimint-server/src/db.rs	66.66%	9 Missing ⚠️
fedimint-dbtool/src/dump.rs	0.00%	8 Missing ⚠️
fedimint-server/src/consensus/server.rs	53.84%	6 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4072   +/-   ##
=======================================
  Coverage   58.28%   58.29%           
=======================================
  Files         193      193           
  Lines       42580    42605   +25     
=======================================
+ Hits        24819    24836   +17     
- Misses      17761    17769    +8     

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[m1sterc001guy]

I ran into some trouble with DB migration tests, could you take a look at 487a5c4 in particular please @m1sterc001guy? Is my attempt to fix it correct or am I missing something?

This is correct, thanks for pointing that out. It hadn't mattered before since we were just reading from old dbs to catch breaking changes, but now with a migration it is needed.

[dpc]

I don't think it's a cache, but LGTM.

[fedimint-backports]

Backport failed for releases/v0.2, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin releases/v0.2
git worktree add -d .worktree/backport-4072-to-releases/v0.2 origin/releases/v0.2
cd .worktree/backport-4072-to-releases/v0.2
git switch --create backport-4072-to-releases/v0.2
git cherry-pick -x a29d1ff79feeade7c384088b8c1c8a5b5520f421 62b6df4cef5c804d1fd5e61faee510f4d5b25586 edf8d46813780bf8603867a37cb47fb2d905b140

[dpc]

@fedimint-backports Disappointing.

[elsirion]

I don't think it's a cache

What would you call it? It's redundant/something we could re-build any time, but at considerable cost.

[douglaz]

I don't think it's a cache

What would you call it? It's redundant/something we could re-build any time, but at considerable cost.

I call it "denormalized data"