chore(performance): improve countParams

[appleboy]

package convert

import (
	"bytes"
	"strings"
	"testing"
)

var (
	strColon = []byte(":")
	strStar  = []byte("*")
)

func countParamsOld(path string) uint16 {
	var n uint
	for i := range []byte(path) {
		switch path[i] {
		case ':', '*':
			n++
		}
	}
	return uint16(n)
}

func countParamsNew(path string) uint16 {
	var n uint
	s := strToBytes(path)
	n += uint(bytes.Count(s, strColon))
	n += uint(bytes.Count(s, strStar))
	return uint16(n)
}

var foo = strings.Repeat("/:param", 256)

func BenchmarkCountParamsOld(b *testing.B) {
	for i := 0; i < b.N; i++ {
		countParamsOld(foo)
	}
}

func BenchmarkCountParamsNew(b *testing.B) {
	for i := 0; i < b.N; i++ {
		countParamsNew(foo)
	}
}

Performance result

goos: linux
goarch: amd64
BenchmarkCountParamsOld-48    	 3000000	      1751 ns/op	       0 B/op	       0 allocs/op
BenchmarkCountParamsNew-48    	30000000	       148 ns/op	       0 B/op	       0 allocs/op

[codecov]

Codecov Report

Merging #2378 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2378   +/-   ##
=======================================
  Coverage   98.63%   98.64%           
=======================================
  Files          41       41           
  Lines        2349     2359   +10     
=======================================
+ Hits         2317     2327   +10     
  Misses         18       18           
  Partials       14       14           

Impacted Files	Coverage Δ
tree.go	100.00% <100.00%> (ø)

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[thinkerou]

lgtm

[thinkerou]

@appleboy maybe we should also commit the pr to httprouter? thanks!

[appleboy]

@thinkerou Yes, I will create a new PR on https://github.com/julienschmidt/httprouter