api_skeleton/main.go

package main

import (
	"os"
	"os/signal"
	"runtime"
	"syscall"
	"time"

	"amuz.es/gogs/infra/api_skeleton/subsys/http"
	"amuz.es/gogs/infra/api_skeleton/subsys/periodic"

	"amuz.es/gogs/infra/api_skeleton/util"
	"gopkg.in/alecthomas/kingpin.v2"
	"sync"
	"context"
)

var (
	app        = kingpin.New(util.Config.Name(), "graceful API server").Author("tom.cat")
	verbose    = app.Flag("verbose", "Enable verbose mode.").Short('v').Bool()
	logDir     = app.Flag("log-dir", "logstore directory.").Short('L').String()
	configFile = app.Flag("config-file", "config file path").Default("settings.yml").HintOptions("FILENAME").Short('C').String()
	logger     = util.NewLogger("main")
)

func systemStart(ctx context.Context, errorSignal chan error, waiter *sync.WaitGroup) {
	defer func() {
		if err := recover(); err != nil {
			errorSignal <- err.(error)
		}
	}()
	start := time.Now()
	app.Version(util.Config.Version())
	if _, err := app.Parse(os.Args[1:]); err != nil {
		panic(err)
	}
	setMaxProcs()

	if err := util.LoadConfig(*configFile); err != nil {
		panic(err)
	}

	util.InitLogger(*verbose, *logDir, &util.Config.Logging.Application)
	showBanner(util.Config.Phase, util.Config.Version(), util.Config.BuildDate())
	// init subsystem
	//db.InitDB(&util.Config.Db)
	//redis.InitRedis(&util.Config.Redis)
	//redis.AppTokenInitService(util.Config.Phase, util.Config.AppToken.Expires, util.Config.AppToken.RefreshExpires)
	//redis.UploadFileInitService(util.Config.Phase, util.Config.AppToken.UploadRetryExpires)
	periodic.Start(errorSignal, ctx, waiter)

	http.Start(util.Config.Bind, &util.Config.Logging.Access, errorSignal, ctx, waiter)

	logger.Info("bootstrapped application ", time.Since(start))
	util.NotifyDaemon(util.DaemonStarted)
}

func systemReload() {
	util.RotateLogger()
}

func systemTeardown(exitCode *int, waiter *sync.WaitGroup) {
	logger.Info("closing application")
	util.NotifyDaemon(util.DaemonStopping)
	waiter.Wait()
	//redis.CloseRedis()
	logger.Info("bye")
	os.Exit(*exitCode)
}

func main() {
	var (
		exitCode      = 0
		ctx, canceled = context.WithCancel(context.Background())
		waiter        = &sync.WaitGroup{}
		exitSignal    = make(chan os.Signal, 1)
		errorSignal   = make(chan error, 10)
	)
	systemStart(ctx, errorSignal, waiter)
	defer systemTeardown(&exitCode, waiter)
	signal.Notify(exitSignal, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)

	for {
		select {
		case <-ctx.Done():
			logger.Info("Service request to close this application")
			return
		case sysSignal := <-exitSignal:
			switch sysSignal {
			case syscall.SIGHUP:
				systemReload()
			default:
				canceled()
				logger.Info("SYSCALL! ", sysSignal.String())
				return
			}
		case err := <-errorSignal:
			canceled()
			logger.Error("exception raised! ", err)
			exitCode = -1
			return
		}
	}
}

func setMaxProcs() {
	// TODO(vmarmol): Consider limiting if we have a CPU mask in effect.
	// Allow as many threads as we have cores unless the user specified a value.
	var numProcs int
	// if *maxProcs < 1 {
	numProcs = runtime.NumCPU()
	// } else {
	// numProcs = *maxProcs
	// }
	runtime.GOMAXPROCS(numProcs)

	// Check if the setting was successful.
	actualNumProcs := runtime.GOMAXPROCS(0)
	if actualNumProcs != numProcs {
		logger.Warn("Specified max procs of %v but using %v", numProcs, actualNumProcs)
	}
}

func showBanner(phase string, version string, buildDate string) {
	if util.LoggerIsStd() {
		logger.Info(`
         {
      {   }
       }_{ __{
    .-{   }   }-.       ` + util.Config.Name() + `
   (   }     {   )      version: ` + version + `
   ` + "|`-.._____..-'|      buildDate: " + buildDate + `
   |             ;--.   phase: ` + phase + `
   |            (__  \
   |             | )  )
   |             |/  /
   |             /  /
   |            (  /
   \             y'
    ` + "`-.._____..-'")
	} else {
		logger.
		WithField("version", version).
			WithField("buildDate", buildDate).
			WithField("phase", phase).
			Info("##", util.Config.Name())
	}
}