高性能转换[]byte 和 string
//这l两个函数是从网上找到的，高频函数使用时性能确实好。原因主要是使用底层指针减少内存 op（内存申请）。
// StringToBytes converts string to byte slice without a memory allocation.
func StringToBytes(s string) (b []byte) {
sh := *(*reflect.StringHeader)(unsafe.Pointer(&s))
bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
bh.Data, bh.Len, bh.Cap = sh.Data, sh.Len, sh.Len
return b
}
// BytesToString converts byte slice to string without a memory allocation.
func BytesToString(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}测试:
func main() {
for i := 0; i < 5; i++ {
test1()
test2()
}
}
func test1() {
start := time.Now()
str := ""
str2 := ""
for i := 0; i < 10000000; i++ {
str = "hello" + strconv.Itoa(i)
s := []byte(str)
str2 = string(s)
}
duration := time.Since(start)
fmt.Println("方法一用时:", duration)
fmt.Println(str2)
}
func test2() {
start := time.Now()
str := ""
str2 := ""
for i := 0; i < 10000000; i++ {
str = "hello" + strconv.Itoa(i)
s := StringToBytes(str)
str2 = BytesToString(s)
}
duration := time.Since(start)
fmt.Println("方法二用时:", duration)
fmt.Println(str2)
}大约 30% 的性能提升
