use channel as callback

main.go

package main

import (
	"fmt"
	"time"
)

// oneshot_channel make sender/receiver
func oneshot_channel() (chan<- int, <-chan int) {
	ch := make(chan int)
	return ch, ch
}

type MPSCStruct struct {
	sender chan<- int
	value  int
}

// mpsc_channel make sender/receiver
func mpsc_channel(size int) (chan<- MPSCStruct, <-chan MPSCStruct) {
	ch := make(chan MPSCStruct, size)
	return ch, ch
}

func doMath(receiver <-chan MPSCStruct) {
	for s := range receiver {
		newValue := s.value + 1
		s.sender <- newValue
	}
	fmt.Println("doMath done")
}

func client(mathSender chan<- MPSCStruct, value int) int {
	sender, receiver := oneshot_channel()

	mathSender <- MPSCStruct{
		sender: sender,
		value:  value,
	}

	return <-receiver
}

func main() {
	sender, receiver := mpsc_channel(2)
	go doMath(receiver)

	for i := 0; i < 10; i++ {
		go func(value int) {
			newValue := client(sender, value)
			fmt.Printf("%d -> %d\n", value, newValue)
		}(i)
	}

	time.Sleep(time.Second)
}