moving_filter: fix data race with cache result

[lhy1024]

What problem does this PR solve?

Issue Number: Close #6069

What is changed and how does it work?

after #5798 we use cache result in median.Get to reduce memory, but it introduces a write operation in get, so we remove write op in get function to avoid data race. And considering there is more get than add, it still is valid to reduce memory and CPU time.

Check List

Tests

• Unit test
• Integration test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• CabinfeverB
• HunDunDM

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[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.26 ⚠️

Comparison is base (6fa2bc9) 74.10% compared to head (6a60d16) 73.84%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6080      +/-   ##
==========================================
- Coverage   74.10%   73.84%   -0.26%     
==========================================
  Files         381      381              
  Lines       37809    37801       -8     
==========================================
- Hits        28020    27916     -104     
- Misses       7335     7416      +81     
- Partials     2454     2469      +15     

Flag	Coverage Δ
unittests	73.84% <100.00%> (-0.26%)	⬇️

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

Impacted Files	Coverage Δ
pkg/movingaverage/median_filter.go	100.00% <100.00%> (ø)
pkg/tso/local_allocator.go	62.16% <0.00%> (-16.22%)	⬇️
pkg/tso/allocator_manager.go	58.83% <0.00%> (-7.46%)	⬇️
pkg/utils/metricutil/metricutil.go	82.75% <0.00%> (-6.90%)	⬇️
client/resource_group/controller/limiter.go	61.25% <0.00%> (-6.25%)	⬇️
server/region_syncer/server.go	82.96% <0.00%> (-4.40%)	⬇️
pkg/tso/tso.go	67.97% <0.00%> (-3.94%)	⬇️
pkg/id/id.go	86.44% <0.00%> (-3.39%)	⬇️
pkg/storage/kv/etcd_kv.go	72.22% <0.00%> (-3.18%)	⬇️
pkg/tso/global_allocator.go	60.20% <0.00%> (-1.05%)	⬇️
... and 13 more

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[rleungx]

Do you just revert the changes before?

[lhy1024]

Do you just revert the changes before?

Use another way to reduce unnecessary memory in get

[lhy1024]

/merge

[ti-chi-bot]

@lhy1024: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: b8ef9f9

[ti-chi-bot]

@lhy1024: Your PR was out of date, I have automatically updated it for you.

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #6087.