先看下sort.Sort(data Interface)，参数中Interface定义如下
type Interface interface {
// Len is the number of elements in the collection.
Len() int
// Less reports whether the element with
// index i should sort before the element with index j.
Less(i, j int) bool
// Swap swaps the elements with indexes i and j.
Swap(i, j int)
}
如果我们想给结构体排序怎么办？只需要实现上面的三个接口即可，代码如下：
type Favors []Favor
type Favor struct {
ID int
Name string
}
func (favors Favors) Len() int {
return len(favors)
}
func (favors Favors) Less(i, j int) bool {
favorLeft := favors[i]
favorRight := favors[j]
return favorLeft.ID < favorRight.ID
}
func (favors Favors) Swap(i, j int) {
favors[i], favors[j] = favors[j], favors[i]
}
func main() {
favors := []Favor{{ID: 2, Name: "123"}, {ID: 19, Name: "234"},{ID: 5, Name: "123"}, {ID: 3, Name: "234"},{ID: 4, Name: "123"}, {ID: 31, Name: "234"},{ID: 12, Name: "123"}, {ID: 21, Name: "234"}}
sort.Sort(Favors(favors))
for _, favor := range favors {
fmt.Println(favor)
}
}
另一种用法
type Favor struct {
ID int
Name string
}
type customSort struct {
favor []*Favor
less func(i, j *Favor) bool
}
func (custom customSort) Len() int {
return len(custom.favor)
}
func (custom customSort) Less(i, j int) bool {
return custom.less(custom.favor[i], custom.favor[j])
}
func (custom customSort) Swap(i, j int) {
custom.favor[i], custom.favor[j] = custom.favor[j], custom.favor[i]
}
func main() {
favors := []*Favor{{ID: 2, Name: "123"}, {ID: 19, Name: "234"}, {ID: 5, Name: "123"}, {ID: 3, Name: "234"}, {ID: 4, Name: "123"}, {ID: 31, Name: "234"}, {ID: 12, Name: "123"}, {ID: 21, Name: "234"}}
sort.Sort(customSort{favors, func(i, j *Favor) bool {
return i.ID < j.ID
}})
for _, favor := range favors {
fmt.Println(favor)
}
}
contextwithtimeout的使用，先来看一段代码
func slowOperation() {
fmt.Println("slow operation start")
time.Sleep(time.Second * 3)
fmt.Println("slow operation end")
}
func operationTimeOut(ctx context.Context) {
fmt.Println("operation time out start ")
slowOperation()
fmt.Println("operation time out end ")
}
func main() {
fmt.Println("Program started ...")
start := time.Now()
ctx := context.Background()
operationTimeOut(ctx)
useTime := time.Since(start)
fmt.Printf("Program end... It took %v seconds", useTime)
}
上面这段代码我们都能猜出结果
Program started ...
operation Time Out start
slow operation start
slow operation end
operation Time Out end
Program end... It took 3.000236344s seconds
这时候我们想用一个协程，设置一个超时时间，如果在那个时间内没有处理完就强制退出
func slowOperation() {
fmt.Println("slow operation start")
time.Sleep(time.Second * 3)
fmt.Println("slow operation end")
}
func operationTimeOut(ctx context.Context) {
fmt.Println("operation time out start ")
signalChan := make(chan struct{})
go func() {
slowOperation()
signalChan <- struct{}{}
}()
ctx, cancel := context.WithTimeout(ctx, 1*time.Second)
defer cancel()
select {
case <-signalChan:
fmt.Println("task is succ")
case <-ctx.Done():
fmt.Println(ctx.Err())
}
fmt.Println("operation time out end ")
}
func main() {
fmt.Println("Program started ...")
start := time.Now()
ctx := context.Background()
operationTimeOut(ctx)
useTime := time.Since(start)
fmt.Printf("Program end... It took %v seconds", useTime)
}
输出如下：
Program started ...
operation time out start
slow operation start
context deadline exceeded
operation time out end
Program end... It took 1.00526883s seconds
