golang select 選取器的兩種方案

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

golang select 選取器

常規模式:

package mainimport ("fmt""strconv")func main() {var chs1 = make(chan int)var chs2 = make(chan float64)var chs3 = make(chan string)var ch4close = make(chan int)defer close(ch4close)go func(c chan int, ch4close chan int) {for i := 0; i < 5; i++ {c <- i}close(c)ch4close <- 1}(chs1, ch4close)go func(c chan float64, ch4close chan int) {for i := 0; i < 5; i++ {c <- float64(i) + 0.1}close(c)ch4close <- 1}(chs2, ch4close)go func(c chan string, ch4close chan int) {for i := 0; i < 5; i++ {c <- "string:" + strconv.Itoa(i)}close(c)ch4close <- 1}(chs3, ch4close)done := 0finished := 0for finished < 3 {select {case v, ok := <-chs1:if ok {done = done + 1fmt.Println(0, v)}case v, ok := <-chs2:if ok {done = done + 1fmt.Println(1, v)}case v, ok := <-chs3:if ok {done = done + 1fmt.Println(2, v)}case _, ok := <- ch4close:if ok {finished = finished+1}}}fmt.Println("Done", done)}

reflect設計

package mainimport ("fmt""reflect""strconv")func main() {var chs1 = make(chan int)var chs2 = make(chan float64)var chs3 = make(chan string)var ch4close = make(chan int)defer close(ch4close)go func(c chan int, ch4close chan int) {for i := 0; i < 5; i++ {c <- i}close(c)ch4close <- 1}(chs1, ch4close)go func(c chan float64, ch4close chan int) {for i := 0; i < 5; i++ {c <- float64(i) + 0.1}close(c)ch4close <- 1}(chs2, ch4close)go func(c chan string, ch4close chan int) {for i := 0; i < 5; i++ {c <- "string:" + strconv.Itoa(i)}close(c)ch4close <- 1}(chs3, ch4close)var selectCase = make([]reflect.SelectCase, 4)selectCase[0].Dir = reflect.SelectRecvselectCase[0].Chan = reflect.ValueOf(chs1)selectCase[1].Dir = reflect.SelectRecvselectCase[1].Chan = reflect.ValueOf(chs2)selectCase[2].Dir = reflect.SelectRecvselectCase[2].Chan = reflect.ValueOf(chs3)selectCase[3].Dir = reflect.SelectRecvselectCase[3].Chan = reflect.ValueOf(ch4close)done := 0finished := 0for finished < len(selectCase)-1 {chosen, recv, recvOk := reflect.Select(selectCase)if recvOk {done = done+1switch chosen {case 0:fmt.Println(chosen, recv.Int())case 1:fmt.Println(chosen, recv.Float())case 2:fmt.Println(chosen, recv.String())case 3:finished = finished+1done = done-1// fmt.Println("finished\t", finished)}}}fmt.Println("Done", done)}