查看tidb源代码:::util/charset/charset.go,下面有段代码:
// GetAllCharsets gets all charset descriptions in the local charsets.
func GetAllCharsets() []*Desc {
descs := make([]*Desc, 0, len(charsets))
// The charsetInfos is an array, so the iterate order will be stable.
for _, ci := range charsetInfos {
c, ok := charsets[ci.Name]
if !ok {
continue
}
desc := &Desc{
Name: c.Name,
DefaultCollation: c.DefaultCollation.Name,
Desc: c.Desc,
Maxlen: c.Maxlen,
}
descs = append(descs, desc)
}
return descs
}
查看append,思考一个问题,调用本方法之后,descs内存地址是否重新分配?
特做如下例子进行测试:
type Names struct {
Name string
}
mynames := make([]*Names, 0)
for i := 0; i < 10; i++ {
my := &Names{
Name: "append"}
mynames = append(mynames, my)
fmt.Println(&mynames)
}
运行结果如下:
从10次的输出结果来看,调用append内部函数,不改变内存地址,也就是不产生性能损耗。