golang select 选择器
常规模式:
package main
import (
"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 := 0
finished := 0
for finished < 3 {
select {
case v, ok := <-chs1:
if ok {
done = done + 1
fmt.Println(0, v)
}
case v, ok := <-chs2:
if ok {
done = done + 1
fmt.Println(1, v)
}
case v, ok := <-chs3:
if ok {
done = done + 1
fmt.Println(2, v)
}
case _, ok := <- ch4close:
if ok {
finished = finished+1
}
}
}
fmt.Println("Done", done)
}reflect设计
package main
import (
"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.SelectRecv
selectCase[0].Chan = reflect.ValueOf(chs1)
selectCase[1].Dir = reflect.SelectRecv
selectCase[1].Chan = reflect.ValueOf(chs2)
selectCase[2].Dir = reflect.SelectRecv
selectCase[2].Chan = reflect.ValueOf(chs3)
selectCase[3].Dir = reflect.SelectRecv
selectCase[3].Chan = reflect.ValueOf(ch4close)
done := 0
finished := 0
for finished < len(selectCase)-1 {
chosen, recv, recvOk := reflect.Select(selectCase)
if recvOk {
done = done+1
switch 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+1
done = done-1
// fmt.Println("finished\t", finished)
}
}
}
fmt.Println("Done", done)
}
