pkg/statistics: reduce the memory alloc for hot statistics

[nolouch]

What problem does this PR solve?

Issue Number: Close #8207 Ref #7897

What is changed and how does it work?

relative smallnest/chanx#19

pkg/statistics: reduce the memory alloc for hot statistics

Check List

Tests

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

go test -benchmem -run=^$ -bench ^BenchmarkUnbounded github.com/smallnest/chanx  
goos: darwin
goarch: arm64
pkg: github.com/smallnest/chanx
BenchmarkUnboundedChanLen-12            65669220                18.17 ns/op           32 B/op          1 allocs/op
BenchmarkUnboundedBufLen-12             69060109                18.27 ns/op           32 B/op          1 allocs/op

after

goos: darwin
goarch: arm64
pkg: github.com/smallnest/chanx
BenchmarkUnboundedChanLen-12            1000000000               0.2879 ns/op          0 B/op          0 allocs/op
BenchmarkUnboundedBufLen-12             1000000000               0.2846 ns/op          0 B/op          0 allocs/op

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• rleungx

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.33%. Comparing base (0e73b7a) to head (1d52039).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8208      +/-   ##
==========================================
- Coverage   77.36%   77.33%   -0.04%     
==========================================
  Files         471      471              
  Lines       61407    61407              
==========================================
- Hits        47510    47491      -19     
- Misses      10340    10350      +10     
- Partials     3557     3566       +9     

Flag	Coverage Δ
unittests	77.33% <ø> (-0.04%)	⬇️

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[rleungx]

/merge

[ti-chi-bot]

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/run-all-tests

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

Commit hash: 1d52039