server/core: reduce the cost of CPU for Store.Clone

[AndreMouche]

Signed-off-by: shirly AndreMouche@126.com

What problem does this PR solve?

Issue Number: Close #3291

Check List

Tests

• Unit test

benchmark test

current branch

> $ go test -benchmem -run=^$ -bench ^BenchmarkStoreClone -benchtime=100x                                                                                       [±proto_clone ●]
goos: darwin
goarch: amd64
pkg: github.com/tikv/pd/server/core
cpu: Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
BenchmarkStoreClone-12               100               789.0 ns/op           552 B/op         12 allocs/op
PASS
ok      github.com/tikv/pd/server/core  0.066s
                                                                                                                                                                                 
wuxuelian@fun-2 ~/go/pd/server/core                                                                                                                                   [17:11:16] 
> $ go test -benchmem -run=^$ -bench ^BenchmarkStoreClone -benchtime=100x                                                                                       [±proto_clone ●]
goos: darwin
goarch: amd64
pkg: github.com/tikv/pd/server/core
cpu: Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
BenchmarkStoreClone-12               100               880.3 ns/op           552 B/op         12 allocs/op
PASS
ok      github.com/tikv/pd/server/core  0.070s

master

> $ go test -benchmem -run=^$ -bench ^BenchmarkStoreClone -benchtime=100x                                                                                           [±master ●●]
goos: darwin
goarch: amd64
pkg: github.com/tikv/pd/server/core
cpu: Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
BenchmarkStoreClone-12               100              5115 ns/op             784 B/op         39 allocs/op
PASS
ok      github.com/tikv/pd/server/core  0.069s
                                                                                                                                                                                 
wuxuelian@fun-2 ~/go/pd/server/core                                                                                                                                   [17:12:26] 
> $ go test -benchmem -run=^$ -bench ^BenchmarkStoreClone -benchtime=100x                                                                                           [±master ●●]
goos: darwin
goarch: amd64
pkg: github.com/tikv/pd/server/core
cpu: Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
BenchmarkStoreClone-12               100              5445 ns/op             784 B/op         39 allocs/op
PASS
ok      github.com/tikv/pd/server/core  0.072s

Release note

None.

[ti-chi-bot]

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[codecov]

Codecov Report

Merging #5302 (f244c61) into master (16f8ed7) will decrease coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5302      +/-   ##
==========================================
- Coverage   75.69%   75.64%   -0.05%     
==========================================
  Files         311      311              
  Lines       30808    30817       +9     
==========================================
- Hits        23321    23313       -8     
- Misses       5483     5503      +20     
+ Partials     2004     2001       -3     

Flag	Coverage Δ
unittests	75.64% <100.00%> (-0.05%)	⬇️

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

Impacted Files	Coverage Δ
server/core/store.go	82.43% <100.00%> (+0.19%)	⬆️
server/core/store_option.go	100.00% <100.00%> (ø)
server/core/store_stats.go	75.75% <100.00%> (+2.42%)	⬆️
server/schedule/range_cluster.go	83.33% <100.00%> (ø)
pkg/metricutil/metricutil.go	82.75% <0.00%> (-10.35%)	⬇️
server/storage/kv/etcd_kv.go	79.71% <0.00%> (-5.80%)	⬇️
server/region_syncer/server.go	83.15% <0.00%> (-4.35%)	⬇️
server/tso/allocator_manager.go	61.56% <0.00%> (-3.50%)	⬇️
server/schedulers/random_merge.go	60.00% <0.00%> (-3.34%)	⬇️
server/election/leadership.go	75.25% <0.00%> (-2.07%)	⬇️
... and 15 more

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[nolouch]

lgtm

[nolouch]

/merge

[ti-chi-bot]

@nolouch: 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: c423642

[JmPotato]

/merge

[ti-chi-bot]

@JmPotato: 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]

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

At the same time I will also trigger all tests for you:

/run-all-tests

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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