trick

event_server.go

package main

import "fmt"

type ev struct {
	target      interface{}
	returnValue interface{}
	c           chan error
}

func server(c chan *ev) {
	for {
		select {
		case event := <-c:
			switch event.target.(type) {
			case string:
				event.returnValue = "hello, world"
				event.c <- nil
				break
			case int:
				event.returnValue = 42
				event.c <- nil
				break
			default:
				fmt.Println("unknown type")
				return
			}
		}
	}
}

func stringClient(c chan *ev) {
	e := &ev{target: "foo", c: make(chan error)}
	c <- e
	<-e.c // make sure server have handled the event
	fmt.Println(e.returnValue.(string))
}

func intClient(c chan *ev) {
	e := &ev{target: 1024, c: make(chan error)}
	c <- e
	<-e.c
	fmt.Printf("%d\n", e.returnValue.(int))
}

func main() {
	c := make(chan *ev)

	go server(c)

	for i := 0; i < 64; i++ {
		go stringClient(c)
	}

	for i := 0; i < 64; i++ {
		go intClient(c)
	}

	stringClient(c)
}