Redis host cache optimizations

[getvictor]

Related issue: Resolves #46338

Changes load tested (osquery load test).

Checklist for submitter

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.

Testing

• Added/updated automated tests
• QA'd all new/changed functionality manually

Summary by CodeRabbit

• Performance Improvements

  • Extended host cache retention period from 60 seconds to 180 seconds to improve overall cache efficiency and hit rates.
  • Optimized host cache invalidation strategy to eliminate unnecessary reverse-index lookups, significantly reducing database reader load and Redis CPU consumption.

• Tests

  • Added test coverage for host update cache invalidation edge cases to ensure proper behavior.

[codecov]

Codecov Report

❌ Patch coverage is 95.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 66.81%. Comparing base (4b04063) to head (387f9ed).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
server/datastore/mysqlredis/host_cache_writes.go	94.73%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #46458      +/-   ##
==========================================
- Coverage   66.82%   66.81%   -0.02%     
==========================================
  Files        2808     2799       -9     
  Lines      223582   223554      -28     
  Branches    11347    11332      -15     
==========================================
- Hits       149413   149358      -55     
- Misses      60615    60643      +28     
+ Partials    13554    13553       -1     

Flag	Coverage Δ
backend	68.55% <95.00%> (+<0.01%)	⬆️

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[claude]

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[getvictor]

@lucasmrod Additional Redis host cache improvements for review, after recent 4.86 loadtest.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: c9343400-e193-4707-966e-f9917b0f55c7

📥 Commits

Reviewing files that changed from the base of the PR and between 4504b11 and 0c70855.

📒 Files selected for processing (5)

• changes/46338-host-cache-ttl-and-invalidation
• server/config/config.go
• server/datastore/mysqlredis/host_cache.go
• server/datastore/mysqlredis/host_cache_writes.go
• server/datastore/mysqlredis/host_cache_writes_test.go

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Walkthrough

This PR increases the default Redis host-cache TTL from 60 seconds to 180 seconds, reducing cache repopulation overhead. It also optimizes the UpdateHost invalidation path to delete host-cache entries using direct key construction instead of reverse-index lookups, eliminating redundant GETs to the database. The changes include configuration updates, documentation adjustments, and test coverage for edge cases where either NodeKey or OrbitNodeKey may be absent.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Redis host cache optimizations' accurately describes the main changes: increasing the Redis host cache TTL and optimizing the invalidation logic to reduce database and Redis CPU load.
Description check	✅ Passed	The PR description adequately provides the related issue (#46338), load test evidence with screenshots, and confirms completion of key checklist items including test additions and manual QA.
Linked Issues check	✅ Passed	The PR implements both proposed fixes from issue #46338: raising default FLEET_REDIS_HOST_CACHE_TTL from 60s to 180s [server/config/config.go] and optimizing invalidation logic to skip reverse-index GETs [server/datastore/mysqlredis/host_cache_writes.go], with supporting test coverage added.
Out of Scope Changes check	✅ Passed	All changes directly support the objectives in issue #46338: TTL increase in config, comment updates in host_cache.go reflecting the new values, invalidation logic optimization in host_cache_writes.go, and corresponding test coverage in host_cache_writes_test.go.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 46338-host-cache

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[Copilot]

Pull request overview

This PR reduces database reader load and Redis CPU usage for the Redis-backed host-by-node_key/orbit_node_key cache by extending the default TTL window and cutting Redis commands on common invalidation paths.

Changes:

• Increased the default redis.host_cache_ttl from 60s to 180s (with existing jitter) to reduce cache repopulation frequency.
• Optimized the UpdateHost/SerialUpdateHost invalidation path to delete known cache keys directly instead of doing reverse-index GETs.
• Added/expanded automated tests covering the updated invalidation behavior.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
server/datastore/mysqlredis/host_cache.go	Updates TTL/jitter documentation to reflect the new 180s default and expected hit rate.
server/datastore/mysqlredis/host_cache_writes.go	Implements direct-key invalidation for host updates to reduce Redis command count.
server/datastore/mysqlredis/host_cache_writes_test.go	Adds tests for update-path invalidation variants (osquery-only, sparse host fallback).
server/config/config.go	Changes the default config value for redis.host_cache_ttl to 180s.
changes/46338-host-cache-ttl-and-invalidation	Release note describing the TTL increase and invalidation optimization.

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