Enable negative cache in VirtualTableInfoManager to improve performance

[brfrn169]

Description

Previously, when a virtual table did not exist, VirtualTableInfoManager returned null without caching the result. This caused repeated queries to the storage admin for non-existent virtual tables, leading to unnecessary overhead. By implementing negative caching, we can avoid these redundant lookups.

Related issues and/or PRs

N/A

Changes made

• Enabled negative caching in VirtualTableInfoManager to cache non-existent virtual table lookups
• Updated corresponding test to verify negative caching behavior

Checklist

The following is a best-effort checklist. If any items in this checklist are not applicable to this PR or are dependent on other, unmerged PRs, please still mark the checkboxes after you have read and understood each item.

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• I have considered whether similar issues could occur in other products, components, or modules if this PR is for bug fixes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

N/A

Release notes

N/A

[gemini-code-assist]

Summary of Changes

Hello @brfrn169, 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 introduces negative caching to the VirtualTableInfoManager to enhance performance. By caching the absence of virtual table information, the system avoids redundant calls to the storage admin for non-existent tables, thereby reducing overhead and improving efficiency in scenarios where virtual tables are frequently queried but not found.

Highlights

• Negative Caching: Enabled negative caching in VirtualTableInfoManager to store the absence of virtual table information, preventing repeated queries for non-existent tables.
• Cache Type Update: The virtualTableInfoCache now stores Optional<VirtualTableInfo> instead of VirtualTableInfo directly, allowing it to cache Optional.empty() for non-existent entries.
• Performance Improvement: This change significantly reduces unnecessary overhead by avoiding redundant lookups to the storage admin for virtual tables that do not exist.
• Test Case Update: An existing test case was updated to verify that the admin.getVirtualTableInfo method is called only once for a non-existent virtual table after the negative caching implementation.

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[gemini-code-assist]

Code Review

This pull request introduces negative caching to VirtualTableInfoManager to improve performance by caching lookups for non-existent virtual tables. The implementation correctly uses Optional<VirtualTableInfo> in the LoadingCache to store both successful lookups and negative results. The corresponding tests are also updated to verify the new caching behavior. The change is logical and well-executed. I have one suggestion regarding cache configuration to enhance robustness against potential memory issues.

[Copilot]

Pull request overview

This PR implements negative caching in VirtualTableInfoManager to improve performance by caching non-existent virtual table lookups. Previously, when a virtual table did not exist, the manager would return null without caching, causing repeated queries to the storage admin. The implementation wraps the cache value type in Optional to distinguish between "not yet cached" and "cached as non-existent".

Key changes:

• Changed cache type from LoadingCache<TableKey, VirtualTableInfo> to LoadingCache<TableKey, Optional<VirtualTableInfo>> to enable negative caching
• Updated cache loader to return Optional directly instead of unwrapping with orElse(null)
• Modified getVirtualTableInfo to unwrap the cached Optional value with orElse(null) to maintain API compatibility

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
VirtualTableInfoManager.java	Changed cache type to use Optional wrapper and updated cache loader and retrieval logic to support negative caching
VirtualTableInfoManagerTest.java	Updated test name and assertions to verify that non-existent virtual tables are cached (1 admin call instead of 3)

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[feeblefakie]

LGTM! Thank you!

[komamitsu]

LGTM, thank you!

[Torch3333]

LGTM, thank you!