expvarmon/main.go

package main

import (
	"flag"
	"log"
	"path/filepath"
	"strings"
	"time"

	"github.com/gizak/termui"
)

var (
	interval = flag.Duration("i", 2*time.Second, "Polling interval")
	portsArg = flag.String("ports", "40001,40002,40000,40004", "Ports for accessing services expvars")
	dummy    = flag.Bool("dummy", false, "Use dummy (console) output")
)

func main() {
	flag.Parse()
	ports, err := ParsePorts(*portsArg)
	if err != nil {
		log.Fatal("cannot parse ports:", err)
	}

	var data Data
	var source Source = NewExpvarsSource(ports)
	for _, port := range ports {
		service := NewService(port)
		data.Services = append(data.Services, service)
	}

	var ui UI = &TermUI{}
	if *dummy {
		ui = &DummyUI{}
	}
	ui.Init()
	defer ui.Close()

	tick := time.NewTicker(*interval)
	evtCh := termui.EventCh()

	update := func() {
		d, err := source.Update()
		if err != nil {
			log.Println("[ERROR] Cannot update data from source:", err)
			return
		}
		switch source.(type) {
		case *ExpvarsSource:
			dat := d.(Expvars)

			for _, port := range source.(*ExpvarsSource).Ports {
				service := data.FindService(port)
				if service == nil {
					continue
				}

				service.Err = dat[port].Err
				service.Memstats = dat[port].MemStats
				service.Goroutines = dat[port].Goroutines
				service.Cmdline = strings.Join(dat[port].Cmdline, " ")
				if dat[port].Cmdline != nil {
					service.Name = filepath.Base(dat[port].Cmdline[0])
				}
			}
		}
		data.LastTimestamp = time.Now()
		ui.Update(data)
	}
	update()
	for {
		select {
		case <-tick.C:
			update()
		case e := <-evtCh:
			if e.Type == termui.EventKey && e.Ch == 'q' {
				return
			}
		}
	}
}