Golang util.HandleCrash函數代碼示例

// LaunchHTTP starts an HTTP server for the Resolver, returning a error channel
// to which errors are asynchronously sent.
func (res *Resolver) LaunchHTTP() <-chan error {
	defer util.HandleCrash()

	res.configureHTTP()
	listenAddress := net.JoinHostPort(res.config.HTTPListener, strconv.Itoa(res.config.HTTPPort))

	errCh := make(chan error, 1)
	go func() {
		var err error
		defer func() { errCh <- err }()

		if err = http.ListenAndServe(listenAddress, nil); err != nil {
			err = fmt.Errorf("Failed to setup http server: %v", err)
		} else {
			logging.Error.Println("Not serving http requests any more.")
		}
	}()
	return errCh
}

// Serve starts a DNS server for net protocol (tcp/udp), returns immediately.
// the returned signal chan is closed upon the server successfully entering the listening phase.
// if the server aborts then an error is sent on the error chan.
func (res *Resolver) Serve(proto string) (<-chan struct{}, <-chan error) {
	defer util.HandleCrash()

	ch := make(chan struct{})
	server := &dns.Server{
		Addr:              net.JoinHostPort(res.config.Listener, strconv.Itoa(res.config.Port)),
		Net:               proto,
		TsigSecret:        nil,
		NotifyStartedFunc: func() { close(ch) },
	}

	errCh := make(chan error, 1)
	go func() {
		defer close(errCh)
		err := server.ListenAndServe()
		if err != nil {
			errCh <- fmt.Errorf("Failed to setup %q server: %v", proto, err)
		} else {
			logging.Error.Printf("Not listening/serving any more requests.")
		}
	}()
	return ch, errCh
}

// launches Zookeeper detector, returns immediately two chans: the first fires an empty
// struct whenever there's a new (non-nil) mesos leader, the second if there's an unrecoverable
// error in the master detector.
func (res *Resolver) LaunchZK(initialDetectionTimeout time.Duration) (<-chan struct{}, <-chan error) {
	var startedOnce sync.Once
	startedCh := make(chan struct{})
	errCh := make(chan error, 1)
	leaderCh := make(chan struct{}, 1) // the first write never blocks

	listenerFunc := func(newLeader string) {
		defer func() {
			if newLeader != "" {
				leaderCh <- struct{}{}
				startedOnce.Do(func() { close(startedCh) })
			}
		}()
		res.leaderLock.Lock()
		defer res.leaderLock.Unlock()
		res.leader = newLeader
	}
	go func() {
		defer util.HandleCrash()

		err := res.startZKdetection(res.config.Zk, listenerFunc)
		if err != nil {
			errCh <- err
			return
		}

		logging.VeryVerbose.Println("Warning: waiting for initial information from Zookeper.")
		select {
		case <-startedCh:
			logging.VeryVerbose.Println("Info: got initial information from Zookeper.")
		case <-time.After(initialDetectionTimeout):
			errCh <- fmt.Errorf("timed out waiting for initial ZK detection, exiting")
		}
	}()
	return leaderCh, errCh
}

func main() {
	util.PanicHandlers = append(util.PanicHandlers, func(_ interface{}) {
		// by default the handler already logs the panic
		os.Exit(1)
	})

	var versionFlag bool

	// parse flags
	cjson := flag.String("config", "config.json", "path to config file (json)")
	flag.BoolVar(&versionFlag, "version", false, "output the version")
	flag.Parse()

	// -version
	if versionFlag {
		fmt.Println(Version)
		os.Exit(0)
	}

	// initialize logging
	logging.SetupLogs()

	// initialize resolver
	config := records.SetConfig(*cjson)
	res := resolver.New(Version, config)
	errch := make(chan error)

	// launch DNS server
	if config.DNSOn {
		go func() { errch <- <-res.LaunchDNS() }()
	}

	// launch HTTP server
	if config.HTTPOn {
		go func() { errch <- <-res.LaunchHTTP() }()
	}

	changed := detectMasters(config.Zk, config.Masters)
	reload := time.NewTicker(time.Second * time.Duration(config.RefreshSeconds))
	zkTimeout := time.Second * time.Duration(config.ZkDetectionTimeout)
	timeout := time.AfterFunc(zkTimeout, func() {
		if zkTimeout > 0 {
			errch <- fmt.Errorf("master detection timed out after %s", zkTimeout)
		}
	})

	defer reload.Stop()
	defer util.HandleCrash()
	for {
		select {
		case <-reload.C:
			res.Reload()
		case masters := <-changed:
			if len(masters) == 0 || masters[0] == "" { // no leader
				timeout.Reset(zkTimeout)
			} else {
				timeout.Stop()
			}
			logging.VeryVerbose.Printf("new masters detected: %v", masters)
			res.SetMasters(masters)
			res.Reload()
		case err := <-errch:
			logging.Error.Fatal(err)
		}
	}
}

func main() {
	util.PanicHandlers = append(util.PanicHandlers, func(_ interface{}) {
		// by default the handler already logs the panic
		os.Exit(1)
	})

	var versionFlag bool

	// parse flags
	cjson := flag.String("config", "config.json", "path to config file (json)")
	flag.BoolVar(&versionFlag, "version", false, "output the version")
	flag.Parse()

	// -version
	if versionFlag {
		fmt.Println(version)
		os.Exit(0)
	}

	// initialize logging
	logging.SetupLogs()

	// initialize resolver
	config := records.SetConfig(*cjson)
	res := resolver.New(version, config)
	errch := make(chan error)

	// launch DNS server
	if config.DNSOn {
		go func() { errch <- <-res.LaunchDNS() }()
	}

	// launch HTTP server
	if config.HTTPOn {
		go func() { errch <- <-res.LaunchHTTP() }()
	}

	changed := make(chan []string, 1)
	if config.Zk != "" {
		logging.Verbose.Println("Starting master detector for ZK ", config.Zk)
		if md, err := detector.New(config.Zk); err != nil {
			log.Fatalf("failed to create master detector: %v", err)
		} else if err := md.Detect(detect.NewMasters(config.Masters, changed)); err != nil {
			log.Fatalf("failed to initialize master detector: %v", err)
		}
	} else {
		changed <- config.Masters
	}

	reload := time.NewTicker(time.Second * time.Duration(config.RefreshSeconds))
	timeout := time.AfterFunc(zkInitialDetectionTimeout, func() {
		errch <- fmt.Errorf("master detection timed out after %s", zkInitialDetectionTimeout)
	})

	defer reload.Stop()
	defer util.HandleCrash()
	for {
		select {
		case <-reload.C:
			res.Reload()
		case masters := <-changed:
			timeout.Stop()
			logging.VeryVerbose.Printf("new masters detected: %v", masters)
			res.SetMasters(masters)
			res.Reload()
		case err := <-errch:
			logging.Error.Fatal(err)
		}
	}
}

// Provide allows the provider to provide configurations to traefik
// using the given configuration channel.
func (provider *Mesos) Provide(configurationChan chan<- types.ConfigMessage, pool *safe.Pool, constraints types.Constraints) error {
	operation := func() error {

		// initialize logging
		logging.SetupLogs()

		log.Debugf("%s", provider.IPSources)

		var zk string
		var masters []string

		if strings.HasPrefix(provider.Endpoint, "zk://") {
			zk = provider.Endpoint
		} else {
			masters = strings.Split(provider.Endpoint, ",")
		}

		errch := make(chan error)

		changed := detectMasters(zk, masters)
		reload := time.NewTicker(time.Second * time.Duration(provider.RefreshSeconds))
		zkTimeout := time.Second * time.Duration(provider.ZkDetectionTimeout)
		timeout := time.AfterFunc(zkTimeout, func() {
			if zkTimeout > 0 {
				errch <- fmt.Errorf("master detection timed out after %s", zkTimeout)
			}
		})

		defer reload.Stop()
		defer util.HandleCrash()

		if !provider.Watch {
			reload.Stop()
			timeout.Stop()
		}

		for {
			select {
			case <-reload.C:
				configuration := provider.loadMesosConfig()
				if configuration != nil {
					configurationChan <- types.ConfigMessage{
						ProviderName:  "mesos",
						Configuration: configuration,
					}
				}
			case masters := <-changed:
				if len(masters) == 0 || masters[0] == "" {
					// no leader
					timeout.Reset(zkTimeout)
				} else {
					timeout.Stop()
				}
				log.Debugf("new masters detected: %v", masters)
				provider.Masters = masters
				configuration := provider.loadMesosConfig()
				if configuration != nil {
					configurationChan <- types.ConfigMessage{
						ProviderName:  "mesos",
						Configuration: configuration,
					}
				}
			case err := <-errch:
				log.Errorf("%s", err)
			}
		}
	}

	notify := func(err error, time time.Duration) {
		log.Errorf("mesos connection error %+v, retrying in %s", err, time)
	}
	err := backoff.RetryNotify(operation, job.NewBackOff(backoff.NewExponentialBackOff()), notify)
	if err != nil {
		log.Errorf("Cannot connect to mesos server %+v", err)
	}
	return nil
}

func main() {
	util.PanicHandlers = append(util.PanicHandlers, func(_ interface{}) {
		// by default the handler already logs the panic
		os.Exit(1)
	})

	var versionFlag bool

	// parse flags
	cjson := flag.String("config", "config.json", "path to config file (json)")
	flag.BoolVar(&versionFlag, "version", false, "output the version")
	flag.Parse()

	// -version
	if versionFlag {
		fmt.Println(version)
		os.Exit(0)
	}

	// initialize logging
	logging.SetupLogs()

	// initialize resolver
	config := records.SetConfig(*cjson)
	resolver := resolver.New(version, config)

	var dnsErr, httpErr, zkErr <-chan error
	var newLeader <-chan struct{}

	// launch DNS server
	if config.DNSOn {
		dnsErr = resolver.LaunchDNS()
	}

	// launch HTTP server
	if config.HTTPOn {
		httpErr = resolver.LaunchHTTP()
	}

	// launch Zookeeper listener
	if config.Zk != "" {
		newLeader, zkErr = resolver.LaunchZK(zkInitialDetectionTimeout)
	} else {
		// uniform behavior when new leader from masters field
		leader := make(chan struct{}, 1)
		leader <- struct{}{}
		newLeader = leader
	}

	// print error and terminate
	handleServerErr := func(name string, err error) {
		if err != nil {
			logging.Error.Fatalf("%s failed: %v", name, err)
		} else {
			logging.Error.Fatalf("%s stopped unexpectedly", name)
		}
	}

	// generate reload signal; up to 1 reload pending at any time
	reloadSignal := make(chan struct{}, 1)
	tryReload := func() {
		// non-blocking, attempt to queue a reload
		select {
		case reloadSignal <- struct{}{}:
		default:
		}
	}

	// periodic loading of DNS state (pull from Master)
	go func() {
		defer util.HandleCrash()
		reloadTimeout := time.Second * time.Duration(config.RefreshSeconds)
		reloadTimer := time.AfterFunc(reloadTimeout, tryReload)
		for _ = range reloadSignal {
			resolver.Reload()
			logging.PrintCurLog()
			reloadTimer.Reset(reloadTimeout)
		}
	}()

	// infinite loop until there is fatal error
	for {
		select {
		case <-newLeader:
			tryReload()
		case err := <-dnsErr:
			handleServerErr("DNS server", err)
		case err := <-httpErr:
			handleServerErr("HTTP server", err)
		case err := <-zkErr:
			handleServerErr("ZK watcher", err)
		}
	}
}