scheduler: reduce GetStore in hot-region-scheduler (#3870)

[ti-chi-bot]

This is an automated cherry-pick of #3870

Signed-off-by: HunDunDM [email protected]

What problem does this PR solve?

• fix hot scheduler causes pd panic when scale out #3868

What is changed and how it works?

Reduce GetStore in hot-region-scheduler. In addition to preventing panic caused by data inconsistency, it can also reduce the use of BasicCluster locks.

Check List

Tests

• Unit test

Code changes

Side effects

Related changes

• Need to cherry-pick to the release branch

Release note

Fix the bug that PD may panic during scaling out TiKV.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[lhy1024]

plz fix conflict

[codecov]

Codecov Report

Merging #3909 (bdbb318) into release-4.0 (f94e000) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@               Coverage Diff               @@
##           release-4.0    #3909      +/-   ##
===============================================
- Coverage        74.82%   74.82%   -0.01%     
===============================================
  Files              211      211              
  Lines            20010    20017       +7     
===============================================
+ Hits             14973    14978       +5     
+ Misses            3707     3701       -6     
- Partials          1330     1338       +8     

Flag	Coverage Δ
unittests	74.82% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
server/schedulers/utils.go	91.97% <ø> (ø)
server/schedulers/hot_region.go	80.86% <100.00%> (+0.89%)	⬆️
server/schedulers/shuffle_hot_region.go	69.64% <100.00%> (+0.83%)	⬆️
server/region_syncer/client.go	78.74% <0.00%> (-4.73%)	⬇️
server/member/leader.go	66.05% <0.00%> (-3.67%)	⬇️
server/schedulers/random_merge.go	61.29% <0.00%> (-3.23%)	⬇️
pkg/etcdutil/etcdutil.go	79.41% <0.00%> (-2.95%)	⬇️
server/api/operator.go	42.02% <0.00%> (-1.60%)	⬇️
server/tso/tso.go	78.98% <0.00%> (-1.45%)	⬇️
tools/pd-ctl/pdctl/command/operator.go	61.77% <0.00%> (-1.34%)	⬇️
... and 6 more

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[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: bdbb318