planner: refactor a few code of plan cache

[qw4990]

What problem does this PR solve?

Issue Number: ref #54057

Problem Summary: planner: refactor a few code of plan cache

What changed and how does it work?

no logical change, only refactor

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• 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 @qw4990. Thanks for your PR.

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[codecov]

Codecov Report

Attention: Patch coverage is 34.61538% with 17 lines in your changes missing coverage. Please review.

Project coverage is 55.3807%. Comparing base (53901e8) to head (6530776).
Report is 2 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #54058         +/-   ##
=================================================
- Coverage   74.5312%   55.3807%   -19.1506%     
=================================================
  Files          1515       1635        +120     
  Lines        360764     606296     +245532     
=================================================
+ Hits         268882     335771      +66889     
- Misses        72371     247303     +174932     
- Partials      19511      23222       +3711     

Flag	Coverage Δ
integration	22.1188% <15.3846%> (?)

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

Components	Coverage Δ
dumpling	52.9656% <ø> (-2.2339%)	⬇️
parser	∅ <ø> (∅)
br	50.5342% <ø> (+6.5619%)	⬆️

[hawkingrei]

it can use slices.Equal.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, time-and-fate

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• pkg/planner/OWNERS [hawkingrei,time-and-fate]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-17 14:17:09.657329844 +0000 UTC m=+37956.142818677: ☑️ agreed by time-and-fate.
• 2024-06-18 02:09:29.712608451 +0000 UTC m=+80696.198097283: ☑️ agreed by hawkingrei.