feat(Type Cache Deprecation): Add FetchFromCache flag and enable/disable caching with respect to flag value

[Tulsishah]

Description

The primary goal of this PR is to provide a mechanism to explicitly control whether a metadata request should be served from the local cache or fetched directly from GCS.

Changes By adding FetchFromCache to the request structs, the system can now prioritize fetching responses from the stat cache. If the entry is not found, it will fall back to making GCS calls.

Updates to Fast Stat Bucket

1. ListObjects: If the deprecation flag is enabled and FetchFromCache is true, the method attempts to retrieve the entry from the cache. Otherwise, it falls back to the existing approach of fetching directly from GCS.
2. StatObject / GetFolder: Added checks for the TypeCache deprecation flag to handle scenarios where FetchFromCache is either true or false.

Link to the issue in case of a bug fix.

b/473671143

Testing details

1. Manual - NA
2. Unit tests - NA
3. Integration tests - Automated

Any backward incompatible change? If so, please explain.

[codecov]

Codecov Report

❌ Patch coverage is 86.36364% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.10%. Comparing base (8985dad) to head (b8f1a0e).

Files with missing lines	Patch %	Lines
internal/storage/debug_bucket.go	0.00%	3 Missing ⚠️
internal/monitor/bucket.go	0.00%	2 Missing ⚠️
internal/ratelimit/throttled_bucket.go	0.00%	2 Missing ⚠️
internal/storage/caching/fast_stat_bucket.go	94.44%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4243   +/-   ##
=======================================
  Coverage   83.09%   83.10%           
=======================================
  Files         154      154           
  Lines       18980    19008   +28     
=======================================
+ Hits        15772    15796   +24     
- Misses       2631     2635    +4     
  Partials      577      577           

Flag	Coverage Δ
unittests	83.10% <86.36%> (+<0.01%)	⬆️

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[Tulsishah]

/gemini review

[gemini-code-assist]

Code Review

This pull request refactors the GetFolder function across various bucket abstraction layers to accept a *gcs.GetFolderRequest struct instead of a direct folder name string, with corresponding updates to test files. The gcs.GetFolderRequest struct, along with StatObjectRequest and ListObjectsRequest, now includes a FetchFromCache boolean field. Review comments indicate that the FetchFromCache flag is not yet implemented for StatObject within fastStatBucket.StatObject and that fastStatBucket.ListObjects does not currently utilize caching for listings, prompting a need for further implementation or clarification on future plans.

[Tulsishah]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a FetchFromCache flag to give callers explicit control over using the stat cache, which is a useful feature for performance tuning and consistency. The changes are well-contained, primarily affecting the fastStatBucket and propagating the new request structs through various bucket wrappers.

My review focuses on the new caching logic in fast_stat_bucket.go. I've identified a couple of areas for improvement:

• A potential panic due to an unsafe type assertion in ListObjects.
• A minor formatting inconsistency in an error message.

The addition of extensive unit tests for the new caching scenarios is excellent and greatly improves confidence in the changes. Overall, this is a solid contribution.