func main() {
	var (
		listen = flag.String("listen", ":8080", "HTTP listen address")
		proxy  = flag.String("proxy", "", "Optional comma-separated list of URLs to proxy uppercase requests")
	)
	flag.Parse()

	var logger log.Logger
	logger = log.NewLogfmtLogger(os.Stderr)
	logger = log.NewContext(logger).With("listen", *listen).With("caller", log.DefaultCaller)

	ctx := context.Background()

	fieldKeys := []string{"method", "error"}
	requestCount := kitprometheus.NewCounter(stdprometheus.CounterOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)
	requestLatency := metrics.NewTimeHistogram(time.Microsecond, kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_latency_microseconds",
		Help:      "Total duration of requests in microseconds.",
	}, fieldKeys))
	countResult := kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "count_result",
		Help:      "The result of each count method.",
	}, []string{})

	var svc StringService
	svc = stringService{}
	svc = proxyingMiddleware(*proxy, ctx, logger)(svc)
	svc = loggingMiddleware(logger)(svc)
	svc = instrumentingMiddleware(requestCount, requestLatency, countResult)(svc)

	uppercaseHandler := httptransport.NewServer(
		ctx,
		makeUppercaseEndpoint(svc),
		decodeUppercaseRequest,
		encodeResponse,
	)
	countHandler := httptransport.NewServer(
		ctx,
		makeCountEndpoint(svc),
		decodeCountRequest,
		encodeResponse,
	)

	http.Handle("/uppercase", uppercaseHandler)
	http.Handle("/count", countHandler)
	http.Handle("/metrics", stdprometheus.Handler())
	logger.Log("msg", "HTTP", "addr", *listen)
	logger.Log("err", http.ListenAndServe(*listen, nil))
}

func main() {
	ctx := context.Background()

	logger := log.NewLogfmtLogger(os.Stderr)

	fieldKeys := []string{"method", "error"}
	requestCount := kitprometheus.NewCounter(stdprometheus.CounterOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)
	requestLatency := metrics.NewTimeHistogram(time.Microsecond, kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_latency_microseconds",
		Help:      "Total duration of requests in microseconds.",
	}, fieldKeys))
	countResult := kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "count_result",
		Help:      "The result of each count method.",
	}, []string{}) // no fields here

	var svc StringService
	svc = stringService{}
	svc = loggingMiddleware{logger, svc}
	svc = instrumentingMiddleware{requestCount, requestLatency, countResult, svc}

	var uppercase endpoint.Endpoint
	uppercase = makeUppercaseEndpoint(svc)

	var count endpoint.Endpoint
	count = makeCountEndpoint(svc)

	uppercaseHandler := httptransport.Server{
		Context:            ctx,
		Endpoint:           uppercase,
		DecodeRequestFunc:  decodeUppercaseRequest,
		EncodeResponseFunc: encodeResponse,
	}

	countHandler := httptransport.Server{
		Context:            ctx,
		Endpoint:           count,
		DecodeRequestFunc:  decodeCountRequest,
		EncodeResponseFunc: encodeResponse,
	}

	http.Handle("/uppercase", uppercaseHandler)
	http.Handle("/count", countHandler)
	http.Handle("/metrics", stdprometheus.Handler())

	stdlog.Fatal(http.ListenAndServe(":8080", nil))
}

func main() {
	ctx := context.Background()
	logger := log.NewLogfmtLogger(os.Stderr)

	//Define metrics to be collected  for this service
	fieldKeys := []string{"method", "error"}
	requestCount := kitprometheus.NewCounter(stdprometheus.CounterOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)

	requestLatency := metrics.NewTimeHistogram(time.Microsecond, kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_latency_microseconds",
		Help:      "Total duration of requests in Microseconds.",
	}, fieldKeys))

	countResult := kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "count_result",
		Help:      "The result of eac count method",
	}, []string{})

	//Declare the string service
	var svc StringService
	svc = stringService{}
	svc = loggingMiddleware{logger, svc}
	svc = instrumentingMiddleware{requestCount, requestLatency, countResult, svc}

	//Declare and define a http server that exposes the string service to clients via httptransport
	uppercaseHandler := httptransport.NewServer(
		ctx,
		makeUppercaseEndpoint(svc),
		decodeUppercaseRequest,
		encodeResponse,
	)

	countHandler := httptransport.NewServer(
		ctx,
		makeCountEndpoint(svc),
		decodeCountRequest,
		encodeResponse,
	)

	//Define the content routes
	http.Handle("/uppercase", uppercaseHandler)
	http.Handle("/count", countHandler)
	http.Handle("/metrics", stdprometheus.Handler())
	logger.Log("msg", "HTTP", "addr", ":8080")
	logger.Log("err", http.ListenAndServe(":8080", nil))
}

func TestPrometheusSummary(t *testing.T) {
	h := prometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "test",
		Subsystem: "prometheus_summary_histogram",
		Name:      "foobar",
		Help:      "Qwerty asdf.",
	}, []string{})

	const mean, stdev int64 = 50, 10
	teststat.PopulateNormalHistogram(t, h, 34, mean, stdev)
	teststat.AssertPrometheusNormalSummary(t, "test_prometheus_summary_histogram_foobar", mean, stdev)
}

func TestMultiHistogram(t *testing.T) {
	quantiles := []int{50, 90, 99}
	h := metrics.NewMultiHistogram(
		expvar.NewHistogram("omicron", 0, 100, 3, quantiles...),
		prometheus.NewSummary(stdprometheus.SummaryOpts{
			Namespace: "test",
			Subsystem: "multi_histogram",
			Name:      "nu",
			Help:      "Nu histogram.",
		}, []string{}),
	)

	const seed, mean, stdev int64 = 123, 50, 10
	populateNormalHistogram(t, h, seed, mean, stdev)
	assertExpvarNormalHistogram(t, "omicron", mean, stdev, quantiles)
	assertPrometheusNormalHistogram(t, `test_multi_histogram_nu`, mean, stdev)
}

func main() {
	var (
		listen = flag.String("listen", ":8080", "HTTP listen address")
		target = flag.String("proxy", "https://www.marksandspencer.com", "target URL for reverse proxy")
	)
	flag.Parse()

	var logger log.Logger
	logger = log.NewLogfmtLogger(os.Stderr)
	logger = log.NewContext(logger).With("listen", *listen).With("caller", log.DefaultCaller)

	fieldKeys := []string{"method", "error"}
	requestCount := kitprometheus.NewCounter(stdprometheus.CounterOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)
	requestLatency := metrics.NewTimeHistogram(time.Microsecond, kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "my_group",
		Subsystem: "string_service",
		Name:      "request_latency_microseconds",
		Help:      "Total duration of requests in microseconds.",
	}, fieldKeys))

	u, err := url.Parse(*target)
	if err != nil {
		logger.Log(err)
	}

	var svc http.Handler
	svc = newReverseProxy(u)
	svc = loggingMiddleware(logger)(svc)
	svc = instrumentingMiddleware(requestCount, requestLatency)(svc)

	http.Handle("/", svc)
	http.Handle("/_metrics", stdprometheus.Handler())
	logger.Log("msg", "HTTP", "addr", *listen)
	logger.Log("err", http.ListenAndServe(*listen, nil))
}

func Register() {
	ctx := context.Background()

	fieldKeys := []string{"method", "error"}
	requestCount := gkprometheus.NewCounter(prometheus.CounterOpts{
		Namespace: "blueplanet",
		Subsystem: "bp2_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)
	requestLatency := gkmetrics.NewTimeHistogram(time.Microsecond, gkprometheus.NewSummary(prometheus.SummaryOpts{
		Namespace: "blueplanet",
		Subsystem: "bp2_service",
		Name:      "request_latency_microseconds",
		Help:      "Total duraction of the requests in microseconds.",
	}, fieldKeys))

	var svc StringService
	svc = stringService{}
	svc = instrumentingMiddleware{requestCount, requestLatency, svc}

	uppercaseHandler := gkhttptransport.NewServer(
		ctx,
		makeUppercaseEndpoint(svc),
		decodeUppercaseRequest,
		encodeResponse,
	)

	countHandler := gkhttptransport.NewServer(
		ctx,
		makeCountEndpoint(svc),
		decodeCountRequest,
		encodeResponse,
	)

	http.Handle("/string/uppercase", uppercaseHandler)
	http.Handle("/string/count", countHandler)
	http.Handle("/string/metrics", prometheus.Handler())
}

func prometheusMiddleware() func(http.Handler) http.Handler {
	requestDuration := prometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "walkhub",
		Subsystem: "main",
		Name:      "request_duration_nanoseconds_count",
		Help:      "Total time spent serving requests.",
	}, []string{
		"method",
		"url",
	})

	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			defer func(begin time.Time) {
				requestDuration.
					With(metrics.Field{Key: "method", Value: r.Method}).
					With(metrics.Field{Key: "url", Value: r.URL.String()}).
					Observe(int64(time.Since(begin)))
			}(time.Now())
			next.ServeHTTP(w, r)
		})
	}
}

func makeInstrumentation(namespace, name, helpCounter, helpDuration string) (metrics.Counter, metrics.TimeHistogram) {
	counter := metrics.NewMultiCounter(
		expvar.NewCounter(fmt.Sprintf("requests_%s", name)),
		statsd.NewCounter(ioutil.Discard, fmt.Sprintf("requests_%s_total", name), time.Second),
		prometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: name,
			Name:      "requests_total",
			Help:      helpCounter,
		}, []string{}),
	)
	duration := metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
		expvar.NewHistogram(fmt.Sprintf("duration_%s_nanoseconds_total", name), 0, 1e9, 3, 50, 95, 99),
		statsd.NewHistogram(ioutil.Discard, fmt.Sprintf("duration_%s_nanoseconds_total", name), time.Second),
		prometheus.NewSummary(stdprometheus.SummaryOpts{
			Namespace: namespace,
			Subsystem: name,
			Name:      "duration_nanoseconds_total",
			Help:      helpDuration,
		}, []string{}),
	))

	return counter, duration
}

func main() {
	// Flag domain. Note that gRPC transitively registers flags via its import
	// of glog. So, we define a new flag set, to keep those domains distinct.
	fs := flag.NewFlagSet("", flag.ExitOnError)
	var (
		debugAddr        = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
		httpAddr         = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
		grpcAddr         = fs.String("grpc.addr", ":8002", "Address for gRPC server")
		netrpcAddr       = fs.String("netrpc.addr", ":8003", "Address for net/rpc server")
		thriftAddr       = fs.String("thrift.addr", ":8004", "Address for Thrift server")
		thriftProtocol   = fs.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
		thriftBufferSize = fs.Int("thrift.buffer.size", 0, "0 for unbuffered")
		thriftFramed     = fs.Bool("thrift.framed", false, "true to enable framing")

		// Supported OpenTracing backends
		zipkinAddr           = fs.String("zipkin.kafka.addr", "", "Enable Zipkin tracing via a Kafka server host:port")
		appdashAddr          = fs.String("appdash.addr", "", "Enable Appdash tracing via an Appdash server host:port")
		lightstepAccessToken = fs.String("lightstep.token", "", "Enable LightStep tracing via a LightStep access token")
	)
	flag.Usage = fs.Usage // only show our flags
	if err := fs.Parse(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "%v", err)
		os.Exit(1)
	}

	// package log
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC).With("caller", log.DefaultCaller)
		stdlog.SetFlags(0)                             // flags are handled by Go kit's logger
		stdlog.SetOutput(log.NewStdlibAdapter(logger)) // redirect anything using stdlib log to us
	}

	// package metrics
	var requestDuration metrics.TimeHistogram
	{
		requestDuration = metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
			"request_duration_ns",
			expvar.NewHistogram("request_duration_ns", 0, 5e9, 1, 50, 95, 99),
			prometheus.NewSummary(stdprometheus.SummaryOpts{
				Namespace: "myorg",
				Subsystem: "addsvc",
				Name:      "duration_ns",
				Help:      "Request duration in nanoseconds.",
			}, []string{"method"}),
		))
	}

	// Set up OpenTracing
	var tracer opentracing.Tracer
	{
		switch {
		case *appdashAddr != "" && *lightstepAccessToken == "" && *zipkinAddr == "":
			tracer = appdashot.NewTracer(appdash.NewRemoteCollector(*appdashAddr))
		case *appdashAddr == "" && *lightstepAccessToken != "" && *zipkinAddr == "":
			tracer = lightstep.NewTracer(lightstep.Options{
				AccessToken: *lightstepAccessToken,
			})
			defer lightstep.FlushLightStepTracer(tracer)
		case *appdashAddr == "" && *lightstepAccessToken == "" && *zipkinAddr != "":
			collector, err := zipkin.NewKafkaCollector(
				strings.Split(*zipkinAddr, ","),
				zipkin.KafkaLogger(logger),
			)
			if err != nil {
				logger.Log("err", "unable to create collector", "fatal", err)
				os.Exit(1)
			}
			tracer, err = zipkin.NewTracer(
				zipkin.NewRecorder(collector, false, "localhost:80", "addsvc"),
			)
			if err != nil {
				logger.Log("err", "unable to create zipkin tracer", "fatal", err)
				os.Exit(1)
			}
		case *appdashAddr == "" && *lightstepAccessToken == "" && *zipkinAddr == "":
			tracer = opentracing.GlobalTracer() // no-op
		default:
			logger.Log("fatal", "specify a single -appdash.addr, -lightstep.access.token or -zipkin.kafka.addr")
			os.Exit(1)
		}
	}

	// Business domain
	var svc server.AddService
	{
		svc = pureAddService{}
		svc = loggingMiddleware{svc, logger}
		svc = instrumentingMiddleware{svc, requestDuration}
	}

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()
//.........这里部分代码省略.........

func main() {
	var (
		debugAddr        = flag.String("debug.addr", ":8080", "Debug and metrics listen address")
		httpAddr         = flag.String("http.addr", ":8081", "HTTP listen address")
		grpcAddr         = flag.String("grpc.addr", ":8082", "gRPC (HTTP) listen address")
		thriftAddr       = flag.String("thrift.addr", ":8083", "Thrift listen address")
		thriftProtocol   = flag.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
		thriftBufferSize = flag.Int("thrift.buffer.size", 0, "0 for unbuffered")
		thriftFramed     = flag.Bool("thrift.framed", false, "true to enable framing")
		zipkinAddr       = flag.String("zipkin.addr", "", "Enable Zipkin tracing via a Kafka server host:port")
		appdashAddr      = flag.String("appdash.addr", "", "Enable Appdash tracing via an Appdash server host:port")
		lightstepToken   = flag.String("lightstep.token", "", "Enable LightStep tracing via a LightStep access token")
	)
	flag.Parse()

	// Logging domain.
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stdout)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC)
		logger = log.NewContext(logger).With("caller", log.DefaultCaller)
	}
	logger.Log("msg", "hello")
	defer logger.Log("msg", "goodbye")

	// Metrics domain.
	var ints, chars metrics.Counter
	{
		// Business level metrics.
		ints = prometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Name:      "integers_summed",
			Help:      "Total count of integers summed via the Sum method.",
		}, []string{})
		chars = prometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Name:      "characters_concatenated",
			Help:      "Total count of characters concatenated via the Concat method.",
		}, []string{})
	}
	var duration metrics.TimeHistogram
	{
		// Transport level metrics.
		duration = metrics.NewTimeHistogram(time.Nanosecond, prometheus.NewSummary(stdprometheus.SummaryOpts{
			Namespace: "addsvc",
			Name:      "request_duration_ns",
			Help:      "Request duration in nanoseconds.",
		}, []string{"method", "success"}))
	}

	// Tracing domain.
	var tracer stdopentracing.Tracer
	{
		if *zipkinAddr != "" {
			logger := log.NewContext(logger).With("tracer", "Zipkin")
			logger.Log("addr", *zipkinAddr)
			collector, err := zipkin.NewKafkaCollector(
				strings.Split(*zipkinAddr, ","),
				zipkin.KafkaLogger(logger),
			)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
			tracer, err = zipkin.NewTracer(
				zipkin.NewRecorder(collector, false, "localhost:80", "addsvc"),
			)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
		} else if *appdashAddr != "" {
			logger := log.NewContext(logger).With("tracer", "Appdash")
			logger.Log("addr", *appdashAddr)
			tracer = appdashot.NewTracer(appdash.NewRemoteCollector(*appdashAddr))
		} else if *lightstepToken != "" {
			logger := log.NewContext(logger).With("tracer", "LightStep")
			logger.Log() // probably don't want to print out the token :)
			tracer = lightstep.NewTracer(lightstep.Options{
				AccessToken: *lightstepToken,
			})
			defer lightstep.FlushLightStepTracer(tracer)
		} else {
			logger := log.NewContext(logger).With("tracer", "none")
			logger.Log()
			tracer = stdopentracing.GlobalTracer() // no-op
		}
	}

	// Business domain.
	var service addsvc.Service
	{
		service = addsvc.NewBasicService()
		service = addsvc.ServiceLoggingMiddleware(logger)(service)
		service = addsvc.ServiceInstrumentingMiddleware(ints, chars)(service)
	}

	// Endpoint domain.
	var sumEndpoint endpoint.Endpoint
	{
//.........这里部分代码省略.........

func main() {
	fieldKeys := []string{"method", "error"}
	requestCount := kitprometheus.NewCounter(stdprometheus.CounterOpts{
		Namespace: "user_srv",
		Subsystem: "account_service",
		Name:      "request_count",
		Help:      "Number of requests received.",
	}, fieldKeys)
	requestLatency := metrics.NewTimeHistogram(time.Microsecond, kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "user_srv",
		Subsystem: "account_service",
		Name:      "request_latency",
		Help:      "Total duration of requests in microseconds.",
	}, fieldKeys))
	countResult := kitprometheus.NewSummary(stdprometheus.SummaryOpts{
		Namespace: "user_srv",
		Subsystem: "account_service",
		Name:      "count_result",
		Help:      "The result of each count method.",
	}, []string{})

	var ctx context.Context
	{
		ctx = context.Background()
	}

	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
	}

	var db batallion.Database
	{
		db = batallion.Database{
			Host: "localhost",
			Name: "micro",
		}
	}
	db.Connect()

	var svc batallion.AccountService
	{

		svc = batallion.AccountSvc{Collection: db.Handler.C("accounts")}
		svc = batallion.LoggingMiddleware{logger, svc}
		svc = batallion.InstrumentingMiddleware{requestCount, requestLatency, countResult, svc}
	}

	var h http.Handler
	{
		h = batallion.MakeHTTPHandler(ctx, svc, log.NewContext(logger).With("component", "HTTP"))
	}

	errs := make(chan error)

	go func() {
		logger.Log("transport", "HTTP", "addr", "8010")
		errs <- http.ListenAndServe(":8010", h)
	}()

	logger.Log("exit", <-errs)
}

func main() {
	// Flag domain. Note that gRPC transitively registers flags via its import
	// of glog. So, we define a new flag set, to keep those domains distinct.
	fs := flag.NewFlagSet("", flag.ExitOnError)
	var (
		debugAddr                    = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
		httpAddr                     = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
		grpcAddr                     = fs.String("grpc.addr", ":8002", "Address for gRPC server")
		netrpcAddr                   = fs.String("netrpc.addr", ":8003", "Address for net/rpc server")
		thriftAddr                   = fs.String("thrift.addr", ":8004", "Address for Thrift server")
		thriftProtocol               = fs.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
		thriftBufferSize             = fs.Int("thrift.buffer.size", 0, "0 for unbuffered")
		thriftFramed                 = fs.Bool("thrift.framed", false, "true to enable framing")
		zipkinHostPort               = fs.String("zipkin.host.port", "my.service.domain:12345", "Zipkin host:port")
		zipkinServiceName            = fs.String("zipkin.service.name", "addsvc", "Zipkin service name")
		zipkinCollectorAddr          = fs.String("zipkin.collector.addr", "", "Zipkin Scribe collector address (empty will log spans)")
		zipkinCollectorTimeout       = fs.Duration("zipkin.collector.timeout", time.Second, "Zipkin collector timeout")
		zipkinCollectorBatchSize     = fs.Int("zipkin.collector.batch.size", 100, "Zipkin collector batch size")
		zipkinCollectorBatchInterval = fs.Duration("zipkin.collector.batch.interval", time.Second, "Zipkin collector batch interval")
	)
	flag.Usage = fs.Usage // only show our flags
	if err := fs.Parse(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "%v", err)
		os.Exit(1)
	}

	// package log
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC).With("caller", log.DefaultCaller)
		stdlog.SetFlags(0)                             // flags are handled by Go kit's logger
		stdlog.SetOutput(log.NewStdlibAdapter(logger)) // redirect anything using stdlib log to us
	}

	// package metrics
	var requestDuration metrics.TimeHistogram
	{
		requestDuration = metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
			expvar.NewHistogram("request_duration_ns", 0, 5e9, 1, 50, 95, 99),
			prometheus.NewSummary(stdprometheus.SummaryOpts{
				Namespace: "myorg",
				Subsystem: "addsvc",
				Name:      "duration_ns",
				Help:      "Request duration in nanoseconds.",
			}, []string{"method"}),
		))
	}

	// package tracing
	var collector zipkin.Collector
	{
		zipkinLogger := log.NewContext(logger).With("component", "zipkin")
		collector = loggingCollector{zipkinLogger} // TODO(pb)
		if *zipkinCollectorAddr != "" {
			var err error
			if collector, err = zipkin.NewScribeCollector(
				*zipkinCollectorAddr,
				*zipkinCollectorTimeout,
				zipkin.ScribeBatchSize(*zipkinCollectorBatchSize),
				zipkin.ScribeBatchInterval(*zipkinCollectorBatchInterval),
				zipkin.ScribeLogger(zipkinLogger),
			); err != nil {
				zipkinLogger.Log("err", err)
				os.Exit(1)
			}
		}
	}

	// Business domain
	var svc server.AddService
	{
		svc = pureAddService{}
		svc = loggingMiddleware{svc, logger}
		svc = instrumentingMiddleware{svc, requestDuration}
	}

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()

	// Debug/instrumentation
	go func() {
		transportLogger := log.NewContext(logger).With("transport", "debug")
		transportLogger.Log("addr", *debugAddr)
		errc <- http.ListenAndServe(*debugAddr, nil) // DefaultServeMux
	}()

	// Transport: HTTP/JSON
	go func() {
		var (
			transportLogger = log.NewContext(logger).With("transport", "HTTP/JSON")
			tracingLogger   = log.NewContext(transportLogger).With("component", "tracing")
			newSumSpan      = zipkin.MakeNewSpanFunc(*zipkinHostPort, *zipkinServiceName, "sum")
			newConcatSpan   = zipkin.MakeNewSpanFunc(*zipkinHostPort, *zipkinServiceName, "concat")
//.........这里部分代码省略.........

func main() {
	// Flag domain. Note that gRPC transitively registers flags via its import
	// of glog. So, we define a new flag set, to keep those domains distinct.
	fs := flag.NewFlagSet("", flag.ExitOnError)
	var (
		debugAddr     = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
		httpAddr      = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
		netrpcAddr    = fs.String("netrpc.addr", ":8003", "Address for net/rpc server")
		proxyHTTPAddr = fs.String("proxy.http.url", "", "if set, proxy requests over HTTP to this addsvc")

		zipkinServiceName            = fs.String("zipkin.service.name", "addsvc", "Zipkin service name")
		zipkinCollectorAddr          = fs.String("zipkin.collector.addr", "", "Zipkin Scribe collector address (empty will log spans)")
		zipkinCollectorTimeout       = fs.Duration("zipkin.collector.timeout", time.Second, "Zipkin collector timeout")
		zipkinCollectorBatchSize     = fs.Int("zipkin.collector.batch.size", 100, "Zipkin collector batch size")
		zipkinCollectorBatchInterval = fs.Duration("zipkin.collector.batch.interval", time.Second, "Zipkin collector batch interval")
	)
	flag.Usage = fs.Usage // only show our flags
	fs.Parse(os.Args[1:])

	// `package log` domain
	var logger kitlog.Logger
	logger = kitlog.NewLogfmtLogger(os.Stderr)
	logger = kitlog.NewContext(logger).With("ts", kitlog.DefaultTimestampUTC)
	stdlog.SetOutput(kitlog.NewStdlibAdapter(logger)) // redirect stdlib logging to us
	stdlog.SetFlags(0)                                // flags are handled in our logger

	// `package metrics` domain
	requests := metrics.NewMultiCounter(
		expvar.NewCounter("requests"),
		statsd.NewCounter(ioutil.Discard, "requests_total", time.Second),
		prometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Subsystem: "add",
			Name:      "requests_total",
			Help:      "Total number of received requests.",
		}, []string{}),
	)
	duration := metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
		expvar.NewHistogram("duration_nanoseconds_total", 0, 1e9, 3, 50, 95, 99),
		statsd.NewHistogram(ioutil.Discard, "duration_nanoseconds_total", time.Second),
		prometheus.NewSummary(stdprometheus.SummaryOpts{
			Namespace: "addsvc",
			Subsystem: "add",
			Name:      "duration_nanoseconds_total",
			Help:      "Total nanoseconds spend serving requests.",
		}, []string{}),
	))

	_, _ = requests, duration

	// `package tracing` domain
	zipkinHostPort := "localhost:1234" // TODO Zipkin makes overly simple assumptions about services
	var zipkinCollector zipkin.Collector = loggingCollector{logger}
	if *zipkinCollectorAddr != "" {
		var err error
		if zipkinCollector, err = zipkin.NewScribeCollector(
			*zipkinCollectorAddr,
			*zipkinCollectorTimeout,
			zipkin.ScribeBatchSize(*zipkinCollectorBatchSize),
			zipkin.ScribeBatchInterval(*zipkinCollectorBatchInterval),
			zipkin.ScribeLogger(logger),
		); err != nil {
			logger.Log("err", err)
			os.Exit(1)
		}
	}
	zipkinMethodName := "add"
	zipkinSpanFunc := zipkin.MakeNewSpanFunc(zipkinHostPort, *zipkinServiceName, zipkinMethodName)

	// Our business and operational domain
	var a add.Adder = pureAdd{}
	if *proxyHTTPAddr != "" {
		var e endpoint.Endpoint
		e = add.NewAdderAddHTTPClient("GET", *proxyHTTPAddr, zipkin.ToRequest(zipkinSpanFunc))
		e = zipkin.AnnotateClient(zipkinSpanFunc, zipkinCollector)(e)
		a = add.MakeAdderClient(func(method string) endpoint.Endpoint {
			if method != "Add" {
				panic(fmt.Errorf("unknown method %s", method))
			}
			return e
		})
	}
	// This could happen at endpoint level.
	// a = logging(logger)(a)
	// a = instrument(requests, duration)(a)

	// Server domain
	var e endpoint.Endpoint
	e = add.MakeAdderEndpoints(a).Add
	e = zipkin.AnnotateServer(zipkinSpanFunc, zipkinCollector)(e)

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()

//.........这里部分代码省略.........

func main() {
	// Flag domain. Note that gRPC transitively registers flags via its import
	// of glog. So, we define a new flag set, to keep those domains distinct.
	fs := flag.NewFlagSet("", flag.ExitOnError)
	var (
		debugAddr        = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
		httpAddr         = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
		grpcAddr         = fs.String("grpc.addr", ":8002", "Address for gRPC server")
		netrpcAddr       = fs.String("netrpc.addr", ":8003", "Address for net/rpc server")
		thriftAddr       = fs.String("thrift.addr", ":8004", "Address for Thrift server")
		thriftProtocol   = fs.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
		thriftBufferSize = fs.Int("thrift.buffer.size", 0, "0 for unbuffered")
		thriftFramed     = fs.Bool("thrift.framed", false, "true to enable framing")

		proxyHTTPAddr = fs.String("proxy.http.url", "", "if set, proxy requests over HTTP to this addsvc")

		zipkinServiceName            = fs.String("zipkin.service.name", "addsvc", "Zipkin service name")
		zipkinCollectorAddr          = fs.String("zipkin.collector.addr", "", "Zipkin Scribe collector address (empty will log spans)")
		zipkinCollectorTimeout       = fs.Duration("zipkin.collector.timeout", time.Second, "Zipkin collector timeout")
		zipkinCollectorBatchSize     = fs.Int("zipkin.collector.batch.size", 100, "Zipkin collector batch size")
		zipkinCollectorBatchInterval = fs.Duration("zipkin.collector.batch.interval", time.Second, "Zipkin collector batch interval")
	)
	flag.Usage = fs.Usage // only show our flags
	fs.Parse(os.Args[1:])

	// `package log` domain
	var logger kitlog.Logger
	logger = kitlog.NewLogfmtLogger(os.Stderr)
	logger = kitlog.With(logger, "ts", kitlog.DefaultTimestampUTC)
	stdlog.SetOutput(kitlog.NewStdlibAdapter(logger)) // redirect stdlib logging to us
	stdlog.SetFlags(0)                                // flags are handled in our logger

	// `package metrics` domain
	requests := metrics.NewMultiCounter(
		expvar.NewCounter("requests"),
		statsd.NewCounter(ioutil.Discard, "requests_total", time.Second),
		prometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Subsystem: "add",
			Name:      "requests_total",
			Help:      "Total number of received requests.",
		}, []string{}),
	)
	duration := metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
		expvar.NewHistogram("duration_nanoseconds_total", 0, 1e9, 3, 50, 95, 99),
		statsd.NewHistogram(ioutil.Discard, "duration_nanoseconds_total", time.Second),
		prometheus.NewSummary(stdprometheus.SummaryOpts{
			Namespace: "addsvc",
			Subsystem: "add",
			Name:      "duration_nanoseconds_total",
			Help:      "Total nanoseconds spend serving requests.",
		}, []string{}),
	))

	// `package tracing` domain
	zipkinHostPort := "localhost:1234" // TODO Zipkin makes overly simple assumptions about services
	var zipkinCollector zipkin.Collector = loggingCollector{logger}
	if *zipkinCollectorAddr != "" {
		var err error
		if zipkinCollector, err = zipkin.NewScribeCollector(
			*zipkinCollectorAddr,
			*zipkinCollectorTimeout,
			*zipkinCollectorBatchSize,
			*zipkinCollectorBatchInterval,
		); err != nil {
			logger.Log("err", err)
			os.Exit(1)
		}
	}
	zipkinMethodName := "add"
	zipkinSpanFunc := zipkin.MakeNewSpanFunc(zipkinHostPort, *zipkinServiceName, zipkinMethodName)
	zipkin.Log.Swap(logger) // log diagnostic/error details

	// Our business and operational domain
	var a Add = pureAdd
	if *proxyHTTPAddr != "" {
		var e endpoint.Endpoint
		e = httpclient.NewClient("GET", *proxyHTTPAddr, zipkin.ToRequest(zipkinSpanFunc))
		e = zipkin.AnnotateClient(zipkinSpanFunc, zipkinCollector)(e)
		a = proxyAdd(e, logger)
	}
	a = logging(logger)(a)
	a = instrument(requests, duration)(a)

	// Server domain
	var e endpoint.Endpoint
	e = makeEndpoint(a)
	e = zipkin.AnnotateServer(zipkinSpanFunc, zipkinCollector)(e)

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()

	// Transport: HTTP (debug/instrumentation)
	go func() {
//.........这里部分代码省略.........

func main() {
	fs := flag.NewFlagSet("", flag.ExitOnError)
	var (
		debugAddr = fs.String("debug.addr", ":8000", "Address for HTTP debug/instrumentation server")
		httpAddr  = fs.String("http.addr", ":8001", "Address for HTTP (JSON) server")
	)

	flag.Usage = fs.Usage // only show our flags
	if err := fs.Parse(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "%v", err)
		os.Exit(1)
	}

	// package log
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC).With("caller", log.DefaultCaller)
		stdlog.SetFlags(0)                             // flags are handled by Go kit's logger
		stdlog.SetOutput(log.NewStdlibAdapter(logger)) // redirect anything using stdlib log to us
	}

	// package metrics
	var requestDuration metrics.TimeHistogram
	{
		requestDuration = metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
			expvar.NewHistogram("request_duration_ns", 0, 5e9, 1, 50, 95, 99),
			prometheus.NewSummary(stdprometheus.SummaryOpts{
				Namespace: "myorg",
				Subsystem: "addsvc",
				Name:      "duration_ns",
				Help:      "Request duration in nanoseconds.",
			}, []string{"method"}),
		))
	}

	// Business domain
	var svc server.InfoService
	{
		svc = pureInfoService{}
		svc = loggingMiddleware{svc, logger}
		svc = instrumentingMiddleware{svc, requestDuration}
	}

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()

	// Debug/instrumentation
	go func() {
		transportLogger := log.NewContext(logger).With("transport", "debug")
		_ = transportLogger.Log("addr", *debugAddr)
		errc <- http.ListenAndServe(*debugAddr, nil) // DefaultServeMux
	}()

	// Transport: HTTP/JSON
	go func() {
		var (
			transportLogger = log.NewContext(logger).With("transport", "HTTP/JSON")
			mux             = http.NewServeMux()
			hello, host     endpoint.Endpoint
		)

		hello = makeHelloEndpoint(svc)
		mux.Handle("/hello", httptransport.NewServer(
			root,
			hello,
			server.DecodeHelloRequest,
			server.EncodeHelloResponse,
			httptransport.ServerErrorLogger(transportLogger),
		))

		host = makeHostEndpoint(svc)
		mux.Handle("/host", httptransport.NewServer(
			root,
			host,
			server.DecodeHostRequest,
			server.EncodeHostResponse,
			httptransport.ServerErrorLogger(transportLogger),
		))

		_ = transportLogger.Log("addr", *httpAddr)
		errc <- http.ListenAndServe(*httpAddr, mux)
	}()

	_ = logger.Log("fatal", <-errc)
}

func main() {
	flag.Parse()

	// package log
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stderr)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC).With("caller", log.DefaultCaller)
		stdlog.SetFlags(0)                             // flags are handled by Go kit's logger
		stdlog.SetOutput(log.NewStdlibAdapter(logger)) // redirect anything using stdlib log to us
	}

	// package metrics
	var (
		requestCount   metrics.Counter
		requestLatency metrics.TimeHistogram
	)
	{
		fieldKeys := []string{"method", "error"}
		requestCount = kitprometheus.NewCounter(stdprometheus.CounterOpts{
			Namespace: "gmuch",
			Subsystem: "api",
			Name:      "request_count",
			Help:      "Number of requests received.",
		}, fieldKeys)
		requestLatency = metrics.NewTimeHistogram(time.Nanosecond, metrics.NewMultiHistogram(
			expvar.NewHistogram("request_duration_ns", 0, 5e9, 1, 50, 95, 99),
			kitprometheus.NewSummary(stdprometheus.SummaryOpts{
				Namespace: "gmuch",
				Subsystem: "api",
				Name:      "duration_ns",
				Help:      "Request duration in nanoseconds.",
			}, fieldKeys),
		))
	}

	// Business domain
	var g server.GmuchService
	{
		g = gmuch.New(*dbPath, logger)
		g = server.LoggingMiddleware(logger)(g)
		g = server.InstrumentingMiddleware(requestCount, requestLatency)(g)
	}

	// Mechanical stuff
	rand.Seed(time.Now().UnixNano())
	root := context.Background()
	errc := make(chan error)

	go func() {
		errc <- interrupt()
	}()

	// Debug/instrumentation
	go func() {
		transportLogger := log.NewContext(logger).With("tran