infoschema,metrics: add a metric for infoschema v2 cache objects count

[tiancaiamao]

What problem does this PR solve?

Issue Number: ref #50959

Problem Summary:

What changed and how does it work?

Add a metrics for infoschema v2 schema cache objects count.
So that the user can calculate or estimate the size of each table.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

Use the new tidb.json

• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[tiprow]

Hi @tiancaiamao. Thanks for your PR.

PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test all.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.3894%. Comparing base (67249cb) to head (de299a2).
Report is 14 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #58781        +/-   ##
================================================
+ Coverage   73.0858%   74.3894%   +1.3036%     
================================================
  Files          1676       1721        +45     
  Lines        463685     471775      +8090     
================================================
+ Hits         338888     350951     +12063     
+ Misses       103941      98510      -5431     
- Partials      20856      22314      +1458     

Flag	Coverage Δ
integration	46.4669% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.6910% <ø> (ø)
parser	∅ <ø> (∅)
br	61.5657% <ø> (+15.8447%)	⬆️

[ti-chi-bot]

@tiancaiamao: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/check_dev	de299a2	link	true	/test check-dev
idc-jenkins-ci-tidb/unit-test	de299a2	link	true	/test unit-test

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tangenta

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [tangenta]
• pkg/infoschema/OWNERS [tangenta]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-01-09 08:22:22.69298678 +0000 UTC m=+428285.981818486: ☑️ agreed by tangenta.