design bfe program launch as service

[kwanhur]

bfe's entrance include many jobs to do, split them into different parts as below example. It'll take more scalabilities, like

1. support callback when Init or Start
2. register signal syscall.SIGHUP func as to do reload config
3. close logger when Stop etc.

reference from go-svc

type bfe struct {
}

// Init do initialize
func (b *bfe) Init(env svc.Environment) error {
	flag.Parse()
	if *help {
		flag.PrintDefaults()
		return nil
	}

	return nil
}

// Start do start
func (b *bfe) Start() error {
	var err error
	var config bfe_conf.BfeConfig

	// start and serve
	if err = bfe_server.StartUp(config, version, *confRoot); err != nil {
		log.Logger.Error("main(): bfe_server.StartUp(): %s", err.Error())
		return err
	}

	return nil
}

// Stop do stop
func (b *bfe) Stop() error {
	return nil
}

func main() {
	b := &bfe{}
	if err := svc.Run(b, syscall.SIGINT, syscall.SIGTERM); err != nil {
		bfe_util.AbnormalExit()
	}
}