Go => Using expvar

counter01.go

package main

import (
	"expvar"
	"log"
)

var (
	counter = expvar.NewInt("counter for my program")
)

func printVars() {
	log.Println("expvars:")
	expvar.Do(func(kv expvar.KeyValue) {
		switch kv.Key {
		case "memstats":
			// Do nothing, this is a big output.
		default:
			log.Printf("\t%s -> %s", kv.Key, kv.Value)
		}
	})
}

func main() {
	counter.Add(1)
	counter.Add(2)
	counter.Add(1)
	printVars()
}

counter02.go

package main

import (
	"expvar"
	"io"
	"log"
	"net/http"
)

var (
	counter = expvar.NewInt("counter for my program")
)

func CounterServer(w http.ResponseWriter, req *http.Request) {
	counter.Add(1)
	io.WriteString(w, "Count data ...")
}

func main() {
	http.HandleFunc("/", CounterServer)
	http.ListenAndServe(":8080", nil)
}

counter_graphite.go

package main

import (
	"g2g"
	"expvar"
	"time"
	"fmt"
	"net/http"
	"io"
)

var (
	myCounter = expvar.NewInt("Demo counter")
)

func CounterServer(w http.ResponseWriter, req *http.Request) {
	io.WriteString(w, "Count data ...")

	go myCounter.Add(1)
}


func main() {
	interval := 5 * time.Second
	timeout := 3 * time.Second
	g, err := g2g.NewGraphite("127.0.0.1:2003", interval, timeout)
	if err != nil {
		fmt.Printf("Error =>%v", err)
	}

	g.Register("up1.demo.counter", myCounter)

	http.HandleFunc("/", CounterServer)
	http.ListenAndServe(":8080", nil)
}

g2g.go

func (g *Graphite) loop() {
	ticker := time.NewTicker(g.interval)
	defer ticker.Stop()
	for {
		select {
		case nv := <-g.registrations:
			g.vars[nv.name] = nv.v
		case <-ticker.C:
			g.postAll()
		case q := <-g.shutdown:
			g.connection.Close()
			g.connection = nil
			q <- true
			return
		}
	}
}