vtorc: wait for configuration before initializing forgetAliases cache

[arthurschreiber]

Description

Follow-up to #19843. That PR replaced the busy-wait cache init with a sync.Once, but the initForgetAliasesCache body still reads config.GetInstancePollTime() without first waiting for configuration to be loaded.

If InstanceIsForgotten or ForgetInstance reaches the cache before config.MarkConfigurationLoaded() has been called, the cache is built with the default instance-poll-time and sync.Once then prevents it from ever being rebuilt with the configured value.

This moves the WaitForConfigurationToBeLoaded() call inside the forgetAliasesOnce.Do block so the cache is always created from the loaded configuration, regardless of which goroutine wins the race to initialize it.

Spotted by Copilot in #19846 (comment).

The go/vt/vtorc/logic tests call inst.InitializeForgetAliasesCache() directly, which now waits for configuration. The inst package already had a test-only init() calling config.MarkConfigurationLoaded() (instance_test.go); this PR mirrors that in logic via a new main_test.go so the affected tests don't deadlock.

Related Issue(s)

Follow-up to #19843.

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

None.

AI Disclosure

Most of this was written by Claude Code — I provided direction and review.

[vitess-bot]

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[Copilot]

Pull request overview

This PR fixes a configuration race in VTOrc’s forgetAliases cache initialization: the cache is now guaranteed to be created using loaded configuration values, even if InstanceIsForgotten/ForgetInstance wins the race to initialize it before MarkConfigurationLoaded() runs.

Changes:

• Moved config.WaitForConfigurationToBeLoaded() into the forgetAliasesOnce.Do(...) initialization block so the cache TTL is always derived from the configured instance-poll-time.
• Removed the now-redundant configuration wait from initializeInstanceDao().

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.45%. Comparing base (70c7a72) to head (1186a4b).
⚠️ Report is 270 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #20163       +/-   ##
===========================================
+ Coverage   69.67%   77.45%    +7.78%     
===========================================
  Files        1614       14     -1600     
  Lines      216793     2187   -214606     
===========================================
- Hits       151044     1694   -149350     
+ Misses      65749      493    -65256     

Flag	Coverage Δ
partial	77.45% <100.00%> (?)

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[mattlord]

I think that we should add the missing vtorc logic test configuration setup here: go/vt/vtorc/inst/instance_dao.go:78-80

Moving config.WaitForConfigurationToBeLoaded() inside forgetAliasesOnce.Do fixes the production race, but the current PR diff only changes instance_dao.go. The go/vt/vtorc/logic tests still call inst.InitializeForgetAliasesCache() directly without ever calling config.MarkConfigurationLoaded(), so the unit-test jobs are timing out in TestRefreshTabletsInKeyspaceShard while blocked in initForgetAliasesCache. The PR description mentions adding a logic/main_test.go, but that file is not present in the current diff. Please add the test-package init setup, similar to go/vt/vtorc/inst/instance_test.go, so these tests do not deadlock.