refactor: introduce CacheManager

[acpana]

meta

• in support of the sync set proposal
• CacheManager (CM) will be built on to encapsulate the replay of the cache in upcoming PRs

---

Factors out data mgmt & replication from the sync_controller.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@2413cf8). Click here to learn what that means.
Patch coverage: 48.33% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #2785   +/-   ##
=========================================
  Coverage          ?   53.58%           
=========================================
  Files             ?      132           
  Lines             ?    11550           
  Branches          ?        0           
=========================================
  Hits              ?     6189           
  Misses            ?     4882           
  Partials          ?      479           

Flag	Coverage Δ
unittests	53.58% <48.33%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/controller/constraint/constraint_controller.go	5.68% <ø> (ø)
...onstrainttemplate/constrainttemplate_controller.go	59.23% <ø> (ø)
pkg/controller/expansion/expansion_controller.go	52.29% <ø> (ø)
pkg/syncutil/opadataclient.go	0.00% <ø> (ø)
pkg/syncutil/stats_reporter.go	21.25% <5.08%> (ø)
pkg/syncutil/cachemanager/cachemanager.go	89.58% <89.58%> (ø)
pkg/controller/config/config_controller.go	63.51% <90.90%> (ø)
pkg/readiness/object_tracker.go	84.09% <100.00%> (ø)

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[maxsmythe]

The PR title should avoid using an abbreviation for a net-new concept (CMT) as it will make release notes harder to read

[acpana]

@anlandu fyi

[acpana]

Let's remember that config_controller_test, by definition, tests the sync controller, which will test that the CM handles the current uses cases as well.

So the new tests here are meant to only target the cachemanager in as much isolation as possible from controllers.

Another point to remember is that as we build the background replay process more into the cachemanager, the tests will change to cover the new functionality.

[acpana]

@maxsmythe @ritazh @sozercan PTAL when y'all have some time! 🙏🏼

[julianKatz]

@maxsmythe @ritazh @sozercan PTAL when y'all have some time! 🙏🏼

ping :)

[maxsmythe]

LGTM

[acpana]

@ritazh or @sozercan kindly let me know if y'all have any questions or concerns.

[sozercan]

Sorry for the delay, thanks! LGTM