rule: optimize `Clone()` method

okJiang commented 2 weeks ago

What problem does this PR solve?

Issue Number: Close https://github.com/tikv/pd/issues/8298

What is changed and how does it work?

Check List

Tests

Unit test

func BenchmarkCloneWithJSON(b *testing.B) {
    r := &Rule{
        GroupID:  "g1",
        ID:       "r1",
        StartKey: []byte("start"),
        EndKey:   []byte("end"),
    }
    b.ResetTimer()

    for i := 0; i < b.N; i++ {
        var clone Rule
        json.Unmarshal([]byte(r.String()), &clone)
        clone.StartKey = append(r.StartKey[:0:0], r.StartKey...)
        clone.EndKey = append(r.EndKey[:0:0], r.EndKey...)
    }
}

func BenchmarkCloneWithAssignment(b *testing.B) {
    r := &Rule{
        GroupID:  "g1",
        ID:       "r1",
        StartKey: []byte("start"),
        EndKey:   []byte("end"),
    }
    b.ResetTimer()

    for i := 0; i < b.N; i++ {
        clone := *r
        clone.StartKey = append(clone.StartKey[:0:0], r.StartKey...)
        clone.EndKey = append(clone.EndKey[:0:0], r.EndKey...)
    }
}

goos: darwin
goarch: arm64
pkg: github.com/tikv/pd/pkg/schedule/placement
BenchmarkCloneWithJSON-8              735308          1961 ns/op         784 B/op         12 allocs/op
BenchmarkCloneWithAssignment-8      30597870            34.23 ns/op       16 B/op          2 allocs/op
PASS

Code changes

Has the configuration change
Has HTTP API interfaces changed (Don't forget to add the declarative for the new API)
Has persistent data change

Side effects

Possible performance regression
Increased code complexity
Breaking backward compatibility

Related changes

PR to update pingcap/docs/pingcap/docs-cn:
PR to update pingcap/tiup:
Need to cherry-pick to the release branch

Release note

None.

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codecov[bot] commented 2 weeks ago

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.35%. Comparing base (463aee9) to head (f320b19). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8299 +/- ## ========================================== - Coverage 77.39% 77.35% -0.04% ========================================== Files 470 470 Lines 61387 61391 +4 ========================================== - Hits 47508 47491 -17 - Misses 10315 10338 +23 + Partials 3564 3562 -2 ``` | [Flag](https://app.codecov.io/gh/tikv/pd/pull/8299/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/tikv/pd/pull/8299/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv) | `77.35% <100.00%> (-0.04%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#carryforward-flags-in-the-pull-request-comment) to find out more.

tikv / pd