ws_signal_tickle.go

package main

import (
	"fmt"
	"net/http"
	"syscall"

	"github.com/frou/stdext"
)

const (
	addr   = ":8113"
	tickle = syscall.SIGUSR1 // $ kill -USR1 pid
)

func main() {
	mutc := make(chan int)
	getc := make(chan chan int)

	go func() {
		var n int
		for {
			select {
			case i := <-mutc:
				n += i
			case c := <-getc:
				c <- n
			}
		}
	}()

	stdext.HandleSignal(tickle, true, func() { mutc <- 1 })

	http.HandleFunc("/",
		func(w http.ResponseWriter, r *http.Request) {
			c := make(chan int)
			getc <- c
			fmt.Fprintln(w, <-c)
		})
	stdext.Exit(http.ListenAndServe(addr, nil))
}