func determineProperties(sizes []int) *expvar.Map {
	var sum int
	props := new(expvar.Map).Init()
	for _, n := range sizes {
		sum += n
	}
	// Determine properties
	sort.Ints(sizes)
	if len(sizes) > 0 {
		summary := map[string]int{
			"min":    sizes[0],
			"max":    sizes[len(sizes)-1],
			"length": len(sizes),
			"sum":    sum,
			"95e":    sizes[int(float64(len(sizes))*0.95)],
		}
		mean := float64(sum) / float64(summary["length"])

		// Pack them into an expvar Map
		for k, v := range summary {
			n := new(expvar.Int)
			n.Set(int64(v))
			props.Set(k, n)
		}
		avge := new(expvar.Float)
		avge.Set(mean)
		props.Set("avg", avge)
	}

	return props
}

// Export populates a expvar.Map with the state of all
// of the features.
func Export(m *expvar.Map) {
	fMu.RLock()
	defer fMu.RUnlock()
	for f, v := range features {
		m.Set(f.String(), boolVar(v))
	}
}

// HTTP Dynamic Streaming prober.
// Parse and probe F4M playlists and report time statistics and errors.
func SanjoseProber(ctl *bcast.Group, tasks chan *Task, debugvars *expvar.Map) {
	for {
		task := <-tasks
		result := ExecHTTP(task)
		task.ReplyTo <- result
		debugvars.Add("hds-tasks-done", 1)
	}
}

func newListener(nl net.Listener, ns *expvar.Map) *listener {
	statNS := new(expvar.Map).Init()
	ns.Set("handshake", statNS)
	lis := &listener{
		Listener:       nl,
		handshakeStats: newHandshakeStats(statNS),
	}
	return lis
}

// snapshotMap recursively walks expvar Maps and records their integer expvars
// in a separate flat map.
func snapshotMap(varsMap map[string]int64, path string, mp *expvar.Map) {
	mp.Do(func(kv expvar.KeyValue) {
		switch kv.Value.(type) {
		case *expvar.Int:
			varsMap[path+"."+kv.Key], _ = strconv.ParseInt(kv.Value.String(), 10, 64)
		case *expvar.Map:
			snapshotMap(varsMap, path+"."+kv.Key, kv.Value.(*expvar.Map))
		}
	})
}

func statsPageHandler(w http.ResponseWriter, r *http.Request, bctx *BasePageContext) {
	ctx := &struct {
		*BasePageContext
		Stats []*stat
	}{
		BasePageContext: bctx,
		Stats:           []*stat{},
	}

	var stats *expvar.Map
	stats = expvar.Get("counters").(*expvar.Map)
	servStat := expvar.Get("states").(*expvar.Map)
	errors := expvar.Get("errors").(*expvar.Map)

	for _, ep := range bctx.Globals.GetEndpoints() {
		epname := ep.Name
		all := stats.Get(epname)
		success := stats.Get(epname + "|pass")
		unauth := stats.Get(epname + "|401")
		fail := stats.Get(epname + "|403")
		status := servStat.Get(epname)
		statusSSL := servStat.Get(epname + "|ssl")
		err := errors.Get(epname)
		errSSL := errors.Get(epname + "|ssl")
		ctx.Stats = append(ctx.Stats, &stat{epname, fail, success, unauth, all, status, statusSSL,
			err, errSSL})
	}

	RenderTemplateStd(w, ctx, "stats.tmpl")
}

func resetVarMap(varMap *expvar.Map) {
	// There is no easy way to delete/clear expvar.Map.  As such there is a slight
	// race here.  *sigh*
	keys := []string{}
	varMap.Do(func(kv expvar.KeyValue) {
		keys = append(keys, kv.Key)
	})

	for _, key := range keys {
		varMap.Set(key, new(expvar.Int))
	}
}

func writeHistogramForDuration(expvarMap *expvar.Map, duration time.Duration, prefix string) {

	if base.LogEnabled("PerfStats") {
		var durationMs int
		if duration < 1*time.Second {
			durationMs = int(duration/(100*time.Millisecond)) * 100
		} else {
			durationMs = int(duration/(1000*time.Millisecond)) * 1000
		}
		expvarMap.Add(fmt.Sprintf("%s-%06dms", prefix, durationMs), 1)
	}
}

func TestSnapshotExpvarsMap(t *testing.T) {
	test := expvar.NewMap("testMap")
	test.Add("hello", 42)

	map2 := new(expvar.Map).Init()
	map2.Add("test", 5)
	test.Set("map2", map2)

	vals := map[string]int64{}
	snapshotExpvars(vals)

	assert.Equal(t, vals["testMap.hello"], int64(42))
	assert.Equal(t, vals["testMap.map2.test"], int64(5))
}

func init() {
	pacStatementSplit = regexp.MustCompile(`\s*;\s*`)
	pacItemSplit = regexp.MustCompile(`\s+`)

	pacCallFindProxyForURLResultCount = new(expvar.Map).Init()
	pacCallFindProxyForURLParamHostCount = new(expvar.Map).Init()

	callFindProxyForURLMap := new(expvar.Map).Init()
	callFindProxyForURLMap.Set("resultCount", pacCallFindProxyForURLResultCount)
	callFindProxyForURLMap.Set("urlHostCount", pacCallFindProxyForURLParamHostCount)

	pacExpvarMap := expvar.NewMap("pac")
	pacExpvarMap.Set("callFindProxyForURL", callFindProxyForURLMap)

}

func getExpvarAsString(expvar *expvar.Map, name string) string {
	value := expvar.Get(name)
	if value != nil {
		return value.String()
	} else {
		return ""
	}
}

func newOriginAllower(blockedDomains []string, hostname string, gclog logClient, ns *expvar.Map) *originAllower {
	mu := &sync.RWMutex{}
	topKAllDomains := topk.New(100)
	topKOfflistDomains := topk.New(100)
	lifetime := new(expvar.Map).Init()
	ns.Set("lifetime", lifetime)
	lifetime.Set("top_all_domains", expvar.Func(func() interface{} {
		mu.RLock()
		defer mu.RUnlock()
		return topKAllDomains.Keys()
	}))
	lifetime.Set("top_offlist_domains", expvar.Func(func() interface{} {
		mu.RLock()
		defer mu.RUnlock()
		return topKOfflistDomains.Keys()
	}))

	oa := &originAllower{
		m:                  make(map[string]struct{}),
		ns:                 ns,
		hostname:           hostname,
		gclog:              gclog,
		mu:                 mu,
		topKAllDomains:     topKAllDomains,
		topKOfflistDomains: topKOfflistDomains,
	}
	for _, d := range blockedDomains {
		oa.m[d] = struct{}{}
	}
	return oa
}

func init() {
	// NOTE(stevvooe): Setup registry metrics structure to report to expvar.
	// Ideally, we do more metrics through logging but we need some nice
	// realtime metrics for queue state for now.

	registry := expvar.Get("registry")

	if registry == nil {
		registry = expvar.NewMap("registry")
	}

	var notifications expvar.Map
	notifications.Init()
	notifications.Set("endpoints", expvar.Func(func() interface{} {
		endpoints.mu.Lock()
		defer endpoints.mu.Unlock()

		var names []interface{}
		for _, v := range endpoints.registered {
			var epjson struct {
				Name string `json:"name"`
				URL  string `json:"url"`
				EndpointConfig

				Metrics EndpointMetrics
			}

			epjson.Name = v.Name()
			epjson.URL = v.URL()
			epjson.EndpointConfig = v.EndpointConfig

			v.ReadMetrics(&epjson.Metrics)

			names = append(names, epjson)
		}

		return names
	}))

	registry.(*expvar.Map).Set("notifications", &notifications)
}

// calculateTargetSummaryStats builds per-tier, per-target, metric-to-host summary stats
func calculateTargetSummaryStats(tiers *[]Tier) {
	for _, tier := range *tiers {
		totalSizes := []int{}
		tierStats := new(expvar.Map).Init()
		// Determine summary stats per target
		for target, hosts := range tier.Mappings {
			sizes := []int{}
			for _, metrics := range hosts {
				sizes = append(sizes, len(metrics))
				totalSizes = append(totalSizes, len(metrics))
			}
			if len(sizes) == 0 {
				continue
			}
			// Build summary
			props := determineProperties(sizes)
			tierStats.Set(target, props)
		}
		props := determineProperties(totalSizes)
		tierStats.Set("total", props)
		distCounts.Set(tier.Name, tierStats)
	}
}

// incrementMetric increments a value in the specified expvar.Map. The key
// should be a windows syscall.Errno or a string. Any other types will be
// reported under the "other" key.
func incrementMetric(v *expvar.Map, key interface{}) {
	switch t := key.(type) {
	default:
		v.Add("other", 1)
	case string:
		v.Add(t, 1)
	case syscall.Errno:
		v.Add(strconv.Itoa(int(t)), 1)
	}
}

func NewStatusStats(outer *expvar.Map) *statusStats {
	m := new(expvar.Map).Init()
	outer.Set("statuses", m)
	status1xx := &expvar.Int{}
	status2xx := &expvar.Int{}
	status3xx := &expvar.Int{}
	status4xx := &expvar.Int{}
	status5xx := &expvar.Int{}
	m.Set("1xx", status1xx)
	m.Set("2xx", status2xx)
	m.Set("3xx", status3xx)
	m.Set("4xx", status4xx)
	m.Set("5xx", status5xx)
	return &statusStats{
		status1xx,
		status2xx,
		status3xx,
		status4xx,
		status5xx,
	}
}

func getMetricSetExpvarMap(module, name string) (*expvar.Map, error) {
	key := fmt.Sprintf("%s-%s", module, name)
	fetchesLock.Lock()
	defer fetchesLock.Unlock()

	expVar := fetches.Get(key)
	switch m := expVar.(type) {
	case nil:
		expMap := new(expvar.Map).Init()
		fetches.Set(key, expMap)
		expMap.Add(successesKey, 0)
		expMap.Add(failuresKey, 0)
		expMap.Add(eventsKey, 0)
		return expMap, nil
	case *expvar.Map:
		return m, nil
	default:
		return nil, fmt.Errorf("unexpected expvar.Var type (%T) found for key '%s'", m, key)
	}
}

// TODO к реализации
// Probe HTTP with additional checks for Widevine.
// Really now only http-range check supported.
func WidevineProber(ctl *bcast.Group, tasks chan *Task, debugvars *expvar.Map) {
	var result *Result

	defer func() {
		if r := recover(); r != nil {
			fmt.Println("trace dumped in Widevine prober:", r)
		}
	}()

	for {
		queueCount := debugvars.Get("wv-tasks-queue")
		queueCount.(*expvar.Int).Set(int64(len(tasks)))
		task := <-tasks
		if time.Now().Before(task.TTL) {
			result = ExecHTTP(task)
			debugvars.Add("wv-tasks-done", 1)
		} else {
			result = TaskExpired(task)
			debugvars.Add("wv-tasks-expired", 1)
		}
		task.ReplyTo <- result
	}
}

// Container keep single stream properties and regulary make tasks for appropriate probers.
func StreamBox(ctl *bcast.Group, stream Stream, streamType StreamType, taskq chan *Task, debugvars *expvar.Map) {
	var checkCount uint64 // число прошедших проверок
	var addSleepToBrokenStream time.Duration
	var tid int64 = time.Now().Unix() // got increasing offset on each program start
	var min, max int
	var command Command
	var online bool = false
	var stats Stats

	defer func() {
		if r := recover(); r != nil {
			fmt.Printf("Stream %s trace: %s\n", stream.Name, r)
		}
	}()

	task := &Task{Stream: stream, ReplyTo: make(chan *Result)}
	switch streamType {
	case HTTP:
		task.ReadBody = false
	case HLS:
		task.ReadBody = true
	case HDS:
		task.ReadBody = true
	case WV:
		task.ReadBody = false
	default:
		task.ReadBody = false
	}
	ctlrcv := ctl.Join() // управление мониторингом
	timer := time.Tick(3 * time.Second)

	for {
		select {
		case recv := <-ctlrcv.In:
			command = recv.(Command)
			switch command {
			case START_MON:
				online = true
			case STOP_MON:
				online = false
			}
		case <-timer:
			SaveStats(stream, stats)
		default:
			if !online {
				time.Sleep(1 * time.Second)
				continue
			}
			max = int(cfg.Params(stream.Group).TimeBetweenTasks)
			min = int(cfg.Params(stream.Group).TimeBetweenTasks / 4. * 3.)
			time.Sleep(time.Duration(rand.Intn(max-min)+min)*time.Second + addSleepToBrokenStream) // randomize streams order
			tid++
			task.Tid = tid
			task.TTL = time.Now().Add(time.Duration(cfg.Params(stream.Group).TaskTTL * time.Second))
			stats.Checks++ // TODO potentially overflow
			taskq <- task
			debugvars.Add("requested-tasks", 1)
			result := <-task.ReplyTo
			if result.ErrType == TTLEXPIRED {
				continue
			} else {
				checkCount++
				if checkCount > 144 {
					fmt.Printf("Repeated %d times %s\n", checkCount, task.Name)
				}
			}

			for _, subres := range result.SubResults {
				subres.Pid = result
				go SaveResult(stream, *subres)
			}
			go SaveResult(stream, *result)

			max = int(cfg.Params(stream.Group).CheckBrokenTime)
			min = int(cfg.Params(stream.Group).CheckBrokenTime / 4. * 3.)

			switch {
			// permanent error, not a timeout:
			case result.ErrType > CRITICAL_LEVEL, result.ErrType == TTLEXPIRED:
				addSleepToBrokenStream = time.Duration(rand.Intn(max-min)+min) * time.Second
			// works ok:
			case result.ErrType == SUCCESS:
				addSleepToBrokenStream = 0
			default:
				addSleepToBrokenStream = 0
			}

			if result.ErrType != TTLEXPIRED {
				if result.ErrType >= WARNING_LEVEL {
					go Log(ERROR, stream, *result)
				} else {
					if result.Elapsed >= cfg.Params(stream.Group).VerySlowWarningTimeout*time.Second {
						result.ErrType = VERYSLOW
						go Log(WARNING, stream, *result)
					} else if result.Elapsed >= cfg.Params(stream.Group).SlowWarningTimeout*time.Second {
						result.ErrType = SLOW
						go Log(WARNING, stream, *result)
					}
				}
//.........这里部分代码省略.........

// TODO: maybe we should use Func() and just keep a stats structure.
// But that would require locking and nngh nngh.
func setupExpvars() {
	var m expvar.Map
	m.Init()
	m.Set("notls", expvar.Func(notls.Stats))
	m.Set("yakkers", expvar.Func(yakkers.Stats))
	stats.Set("sizes", &m)
	stats.Set("dnsbl_hits", expvar.Func(dblcounts.Stats))
	stats.Set("sbl_hits", expvar.Func(sblcounts.Stats))

	// BUG: must remember to do this for all counters so they have
	// an initial value.
	var evts expvar.Map
	evts.Init()
	evts.Set("connections", &events.connections)
	evts.Set("tls_errors", &events.tlserrs)
	evts.Set("yakkers", &events.yakkers)
	evts.Set("notls_conns", &events.notlscnt)
	evts.Set("rules_errors", &events.ruleserr)
	evts.Set("yakker_adds", &events.yakads)
	evts.Set("rsetdrops", &events.rsetdrops)
	evts.Set("abandons", &events.abandons)
	evts.Set("refuseds", &events.refuseds)
	stats.Set("events", &evts)
	var mailevts expvar.Map
	var goodevts expvar.Map
	var cmds expvar.Map
	mailevts.Init()
	goodevts.Init()
	cmds.Init()
	// Maybe these should track refused commands? Not sure.
	cmds.Set("ehlo", &events.ehlo)
	cmds.Set("mailfrom", &events.mailfrom)
	cmds.Set("rcptto", &events.rcptto)
	cmds.Set("data", &events.data)
	mailevts.Set("commands", &cmds)

	// These are counts of *accepted* commands.
	// TODO: maybe revise how things are counted? Dunno.
	goodevts.Set("ehlo", &events.ehloAccept)
	goodevts.Set("mailfrom", &events.mailfromAccept)
	goodevts.Set("rcptto", &events.rcpttoAccept)
	goodevts.Set("data", &events.dataAccept)
	goodevts.Set("messages", &events.messages)
	mailevts.Set("accepted", &goodevts)

	mailevts.Set("ehlo_tlson", &events.tlson)
	mailevts.Set("quits", &events.quits)
	mailevts.Set("aborts", &events.aborts)
	mailevts.Set("rsets", &events.rsets)
	stats.Set("smtpcounts", &mailevts)

	// constants
	stats.Add("pid", int64(os.Getpid()))
	var stime expvar.String
	stime.Set(time.Now().String())
	stats.Set("startTime", &stime)

	var conntime expvar.String
	times.Init()
	// We're going to have connections, so we set this now.
	times.Set("connection", &conntime)
	stats.Set("last", &times)
}