feat(Type Cache Deprecation): LookUp Child changes #4290

Tulsishah · 2026-01-19T05:08:43Z

Description

This PR updates the LookUpChild logic to support the deprecation of the typeCache by merging its functionality into a single, unified statCache.

Key Updates:

Unified Cache Logic: Modifies LookUpChild to determine object types directly from metadata in the statCache
Feature Flag: Introduces the EnableTypeCacheDeprecation configuration flag to safely toggle this new behavior
Cache-Only Phase: Implements a two-phase lookup that checks the local cache first before falling back to the GCS backend, optimizing performance.

Link to the issue in case of a bug fix.

b/476918868

Testing details

Manual - NA
Unit tests - Added
Integration tests - Automated, also tested with type cache deprecation enabled

Any backward incompatible change? If so, please explain.

codecov · 2026-01-19T05:26:58Z

Codecov Report

❌ Patch coverage is 85.07463% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.47%. Comparing base (0cb531b) to head (e137a4c).
⚠️ Report is 18 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/fs/inode/dir.go	85.71%	4 Missing and 5 partials ⚠️
cmd/mount.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4290      +/-   ##
==========================================
+ Coverage   83.38%   83.47%   +0.09%     
==========================================
  Files         162      162              
  Lines       19426    19469      +43     
==========================================
+ Hits        16198    16252      +54     
+ Misses       2628     2617      -11     
  Partials      600      600

Flag	Coverage Δ
unittests	`83.47% <85.07%> (+0.09%)`	⬆️

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Tulsishah · 2026-01-20T13:38:31Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces changes related to the deprecation of the type cache, primarily by adding a new configuration flag EnableTypeCacheDeprecation and modifying lookup functions to conditionally use this flag. The changes involve passing this flag down to various GCS operations and introducing a metadataCacheTtlSecs field for future caching logic. New test cases have been added to cover the deprecated type cache path for files and directories. However, there are several areas that require attention, including inconsistencies in passing fetchOnlyFromCache to helper functions, incorrect error handling for cache misses in cache-only lookups, a missing lookup path for implicit directories when the type cache is deprecated, and redeclaration issues for err and result variables. Additionally, the ListPrefix utility hardcodes the IsTypeCacheDeprecated flag to false, which might lead to unintended behavior. The new tests also lack coverage for cache-only lookup scenarios and CacheMissError handling.

internal/fs/inode/dir.go

internal/fs/inode/dir_test.go

internal/fs/inode/hns_dir_test.go

gemini-code-assist · 2026-01-21T05:22:24Z

Summary of Changes

Hello @Tulsishah, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the object type lookup mechanism by deprecating the dedicated typeCache and integrating its responsibilities into the existing statCache. The changes introduce a feature flag for managing this transition and implement a more efficient two-phase lookup strategy, prioritizing local cache access to improve performance and streamline object metadata handling.

Highlights

Unified Cache Logic: The LookUpChild logic has been updated to determine object types directly from metadata stored in the statCache, effectively merging the functionality of the deprecated typeCache.
Feature Flag Implementation: A new configuration flag, EnableTypeCacheDeprecation, has been introduced. This flag allows for safe toggling and controlled rollout of the new cache behavior.
Two-Phase Lookup Optimization: A two-phase lookup mechanism is now in place. It first attempts to retrieve entries from the local cache and only falls back to the GCS backend if a cache miss occurs, optimizing performance.

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gemini-code-assist

Code Review

This pull request effectively implements the deprecation of typeCache by integrating its functionality into the statCache, controlled by the EnableTypeCacheDeprecation feature flag. The changes in LookUpChild to support a two-phase lookup (cache-first, then GCS fallback) are well-implemented. The accompanying tests are comprehensive and cover various scenarios, including cache hits, cache misses, and different object types for both hierarchical and non-hierarchical buckets.

My main feedback is to refactor a duplicated block of code in LookUpChild to improve maintainability. Overall, this is a solid contribution towards unifying the caching logic.

github-actions · 2026-01-22T07:39:19Z

Hi @vadlakondaswetha, @ashmeenkaur, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!

github-actions · 2026-01-23T07:37:43Z

Hi @vadlakondaswetha, @ashmeenkaur, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!

internal/fs/inode/dir.go

vadlakondaswetha · 2026-01-27T08:39:23Z

internal/fs/inode/dir.go

-		MaxResults: 1,
+		Prefix:                name.GcsObjectName(),
+		MaxResults:            1,
+		IsTypeCacheDeprecated: isTypeCacheDeprecated,


why is typeCacheDeprecated flag being passed as part of listObjects request>?

It is to enable new caching logic in fast stat bucket
ref:

gcsfuse/internal/storage/caching/fast_stat_bucket.go

Line 439 in 44e7ca3

if req.IsTypeCacheDeprecated {

internal/fs/inode/dir.go

vadlakondaswetha · 2026-01-27T08:51:24Z

internal/fs/inode/dir.go

+			Prefix:                d.Name().GcsObjectName(),
+			ContinuationToken:     tok,
+			MaxResults:            limit + 1, // to exclude itself
+			IsTypeCacheDeprecated: d.isEnableTypeCacheDeprecation,


same here. we should not pass flag values as part of request object for every call.

If we do this then with list call caching will happen correctly with type cache deprecation otherwise implicit directories will not get cached correctly.

Tulsishah added execute-integration-tests Run only integration tests execute-integration-tests-on-zb To run E2E tests on zonal bucket. type-cache-deprecation labels Jan 19, 2026

gemini-code-assist bot reviewed Jan 20, 2026

View reviewed changes

Tulsishah added 8 commits January 20, 2026 15:13

look up function change

e67738d

testing on Type cache deprecation changes

004a7c4

adding unit tests

f23a1f4

small fix

8f18e49

adding type cache deprecation arg in list req

7c7e473

revert the default value of flag

3aba5a8

review comments

84f0065

rebase and fix tests

27fde0e

Tulsishah force-pushed the look_up_changes branch from aba7a2a to 27fde0e Compare January 20, 2026 15:15

nits

8d43913

Tulsishah marked this pull request as ready for review January 21, 2026 05:22

Tulsishah requested a review from a team as a code owner January 21, 2026 05:22

Tulsishah requested a review from raj-prince January 21, 2026 05:22

github-actions bot added the remind-reviewers Auto remind reviewers in attention set for review post 24hrs of inactivity on PR. label Jan 21, 2026

Tulsishah requested review from vadlakondaswetha and removed request for raj-prince January 21, 2026 05:22

Tulsishah requested a review from ashmeenkaur January 21, 2026 05:22

gemini-code-assist bot reviewed Jan 21, 2026

View reviewed changes

Tulsishah removed the remind-reviewers Auto remind reviewers in attention set for review post 24hrs of inactivity on PR. label Jan 25, 2026

Tulsishah force-pushed the look_up_changes branch from 4b213d5 to 8d43913 Compare January 27, 2026 03:50

vadlakondaswetha reviewed Jan 27, 2026

View reviewed changes

Tulsishah force-pushed the look_up_changes branch from d48c836 to 3871e32 Compare January 27, 2026 09:27

review comments

e137a4c

Tulsishah force-pushed the look_up_changes branch from 3871e32 to e137a4c Compare January 27, 2026 09:28

Tulsishah requested a review from vadlakondaswetha January 28, 2026 03:55

feat(Type Cache Deprecation): LookUp Child changes #4290

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feat(Type Cache Deprecation): LookUp Child changes #4290

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Description

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Testing details

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Tulsishah commented Jan 19, 2026 •

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