Higher performance UnsafeStringToSlice #370
Description
Line 279 in 44a7f98
建议用如下函数替换UnsafeStringToSlice，经过benchmark测试，性能提高约30%左右，代码也更优雅
func UnsafeStringToSlice2(s string) []byte {
return *(*[]byte)(unsafe.Pointer(
&struct {
string
int
}{s, len(s)},
))
}
### 测试详情
go test -bench . -benchmem
goos: darwin
goarch: arm64
pkg: gitlab-vywrajy.zd100.net/slice/service
BenchmarkToSlice/UnsafeStringToSlice-8 737677520 1.542 ns/op 0 B/op 0 allocs/op
BenchmarkToSlice/UnsafeStringToSlice2-8 1000000000 1.188 ns/op 0 B/op 0 allocs/op
PASS
ok gitlab-vywrajy.zd100.net/slice/service 2.928s
### 相关测试代码
package service
import (
"reflect"
"testing"
"unsafe"
)
func BenchmarkToSlice(b *testing.B) {
a := "hello world"
var bs []byte
b.Run("UnsafeStringToSlice", func(b *testing.B) {
for i := 0; i < b.N; i++ {
bs = UnsafeStringToSlice(a)
}
})
b.Run("UnsafeStringToSlice2", func(b *testing.B) {
for i := 0; i < b.N; i++ {
bs = UnsafeStringToSlice2(a)
}
})
_ = bs
}
func UnsafeStringToSlice(s string) (b []byte) {
p := unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&s)).Data)
hdr := (*reflect.SliceHeader)(unsafe.Pointer(&b))
hdr.Data = uintptr(p)
hdr.Cap = len(s)
hdr.Len = len(s)
return b
}
func UnsafeStringToSlice2(s string) []byte {
return *(*[]byte)(unsafe.Pointer(
&struct {
string
int
}{s, len(s)},
))
}