Event Handler

event_handler.go

package main

import (
	"fmt"
	"log"
	"time"
	"net/http"
)

var c chan string

func watcher(interval time.Duration) {
	ticker := time.NewTicker(interval / 2)
	sessions := make(map[string]time.Time)
	for {
		select {
			case guid := <-c:
				if _, ok := sessions[guid]; !ok {
					log.Printf("creating session")
				}
				sessions[guid] = time.Now().Add(interval)
			case now := <-ticker.C:
				for guid, t := range(sessions) {
					if t.Before(now) {
						log.Printf("closing session")
						delete(sessions, guid)
					}
				}
		}
	}
}

func ping(w http.ResponseWriter, r *http.Request) {
	guid := r.URL.Query().Get("guid")
	if guid != "" {
		c <- guid
	}
}

func main() {
	c = make(chan string)
	http.HandleFunc("/ping", ping)
	go watcher(3 * time.Second)
	http.ListenAndServe(":8080", nil)
}