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298 lines
7.3 KiB
298 lines
7.3 KiB
// eventmeter - generic system to subscribe to events and record their frequency.
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package eventmeter
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import (
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"context"
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"encoding/json"
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"fmt"
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"sync"
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"time"
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metrics "github.com/rcrowley/go-metrics"
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client "github.com/tendermint/tendermint/rpc/lib/client"
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"github.com/tendermint/tmlibs/events"
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"github.com/tendermint/tmlibs/log"
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)
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const (
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// Get ping/pong latency and call LatencyCallbackFunc with this period.
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latencyPeriod = 1 * time.Second
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// Check if the WS client is connected every
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connectionCheckPeriod = 100 * time.Millisecond
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)
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// EventMetric exposes metrics for an event.
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type EventMetric struct {
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ID string `json:"id"`
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Started time.Time `json:"start_time"`
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LastHeard time.Time `json:"last_heard"`
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MinDuration int64 `json:"min_duration"`
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MaxDuration int64 `json:"max_duration"`
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// tracks event count and rate
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meter metrics.Meter
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// filled in from the Meter
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Count int64 `json:"count"`
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Rate1 float64 `json:"rate_1" wire:"unsafe"`
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Rate5 float64 `json:"rate_5" wire:"unsafe"`
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Rate15 float64 `json:"rate_15" wire:"unsafe"`
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RateMean float64 `json:"rate_mean" wire:"unsafe"`
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// so the event can have effects in the eventmeter's consumer. runs in a go
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// routine.
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callback EventCallbackFunc
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}
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func (metric *EventMetric) Copy() *EventMetric {
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metricCopy := *metric
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metricCopy.meter = metric.meter.Snapshot()
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return &metricCopy
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}
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// called on GetMetric
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func (metric *EventMetric) fillMetric() *EventMetric {
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metric.Count = metric.meter.Count()
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metric.Rate1 = metric.meter.Rate1()
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metric.Rate5 = metric.meter.Rate5()
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metric.Rate15 = metric.meter.Rate15()
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metric.RateMean = metric.meter.RateMean()
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return metric
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}
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// EventCallbackFunc is a closure to enable side effects from receiving an
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// event.
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type EventCallbackFunc func(em *EventMetric, data interface{})
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// EventUnmarshalFunc is a closure to get the query and data out of the raw
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// JSON received over the RPC WebSocket.
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type EventUnmarshalFunc func(b json.RawMessage) (string, events.EventData, error)
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// LatencyCallbackFunc is a closure to enable side effects from receiving a latency.
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type LatencyCallbackFunc func(meanLatencyNanoSeconds float64)
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// DisconnectCallbackFunc is a closure to notify a consumer that the connection
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// has died.
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type DisconnectCallbackFunc func()
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// EventMeter tracks events, reports latency and disconnects.
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type EventMeter struct {
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wsc *client.WSClient
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mtx sync.Mutex
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queryToMetricMap map[string]*EventMetric
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unmarshalEvent EventUnmarshalFunc
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latencyCallback LatencyCallbackFunc
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disconnectCallback DisconnectCallbackFunc
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subscribed bool
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quit chan struct{}
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logger log.Logger
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}
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func NewEventMeter(addr string, unmarshalEvent EventUnmarshalFunc) *EventMeter {
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return &EventMeter{
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wsc: client.NewWSClient(addr, "/websocket", client.PingPeriod(1*time.Second)),
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queryToMetricMap: make(map[string]*EventMetric),
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unmarshalEvent: unmarshalEvent,
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logger: log.NewNopLogger(),
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}
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}
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// SetLogger lets you set your own logger.
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func (em *EventMeter) SetLogger(l log.Logger) {
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em.logger = l
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em.wsc.SetLogger(l.With("module", "rpcclient"))
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}
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// String returns a string representation of event meter.
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func (em *EventMeter) String() string {
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return em.wsc.Address
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}
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// Start boots up event meter.
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func (em *EventMeter) Start() error {
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if err := em.wsc.Start(); err != nil {
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return err
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}
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em.quit = make(chan struct{})
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go em.receiveRoutine()
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go em.disconnectRoutine()
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err := em.subscribe()
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if err != nil {
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return err
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}
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em.subscribed = true
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return nil
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}
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// Stop stops event meter.
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func (em *EventMeter) Stop() {
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close(em.quit)
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if em.wsc.IsRunning() {
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em.wsc.Stop()
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}
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}
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// Subscribe for the given query. Callback function will be called upon
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// receiving an event.
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func (em *EventMeter) Subscribe(query string, cb EventCallbackFunc) error {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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if err := em.wsc.Subscribe(context.TODO(), query); err != nil {
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return err
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}
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metric := &EventMetric{
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meter: metrics.NewMeter(),
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callback: cb,
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}
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em.queryToMetricMap[query] = metric
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return nil
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}
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// Unsubscribe from the given query.
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func (em *EventMeter) Unsubscribe(query string) error {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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if err := em.wsc.Unsubscribe(context.TODO(), query); err != nil {
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return err
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}
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return nil
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}
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// GetMetric fills in the latest data for an query and return a copy.
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func (em *EventMeter) GetMetric(query string) (*EventMetric, error) {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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metric, ok := em.queryToMetricMap[query]
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if !ok {
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return nil, fmt.Errorf("unknown query: %s", query)
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}
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return metric.fillMetric().Copy(), nil
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}
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// RegisterLatencyCallback allows you to set latency callback.
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func (em *EventMeter) RegisterLatencyCallback(f LatencyCallbackFunc) {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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em.latencyCallback = f
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}
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// RegisterDisconnectCallback allows you to set disconnect callback.
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func (em *EventMeter) RegisterDisconnectCallback(f DisconnectCallbackFunc) {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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em.disconnectCallback = f
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}
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///////////////////////////////////////////////////////////////////////////////
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// Private
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func (em *EventMeter) subscribe() error {
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for query, _ := range em.queryToMetricMap {
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if err := em.wsc.Subscribe(context.TODO(), query); err != nil {
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return err
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}
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}
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return nil
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}
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func (em *EventMeter) receiveRoutine() {
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latencyTicker := time.NewTicker(latencyPeriod)
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for {
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select {
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case resp := <-em.wsc.ResponsesCh:
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if resp.Error != nil {
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em.logger.Error("expected some event, got error", "err", resp.Error.Error())
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continue
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}
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query, data, err := em.unmarshalEvent(resp.Result)
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if err != nil {
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em.logger.Error("failed to unmarshal event", "err", err)
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continue
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}
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if query != "" { // FIXME how can it be an empty string?
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em.updateMetric(query, data)
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}
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case <-latencyTicker.C:
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if em.wsc.IsActive() {
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em.callLatencyCallback(em.wsc.PingPongLatencyTimer.Mean())
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}
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case <-em.wsc.Quit():
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return
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case <-em.quit:
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return
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}
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}
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}
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func (em *EventMeter) disconnectRoutine() {
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ticker := time.NewTicker(connectionCheckPeriod)
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for {
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select {
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case <-ticker.C:
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if em.wsc.IsReconnecting() && em.subscribed { // notify user about disconnect only once
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em.callDisconnectCallback()
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em.subscribed = false
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} else if !em.wsc.IsReconnecting() && !em.subscribed { // resubscribe
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em.subscribe()
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em.subscribed = true
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}
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case <-em.wsc.Quit():
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return
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case <-em.quit:
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return
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}
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}
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}
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func (em *EventMeter) updateMetric(query string, data events.EventData) {
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em.mtx.Lock()
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defer em.mtx.Unlock()
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metric, ok := em.queryToMetricMap[query]
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if !ok {
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// we already unsubscribed, or got an unexpected query
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return
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}
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last := metric.LastHeard
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metric.LastHeard = time.Now()
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metric.meter.Mark(1)
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dur := int64(metric.LastHeard.Sub(last))
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if dur < metric.MinDuration {
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metric.MinDuration = dur
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}
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if !last.IsZero() && dur > metric.MaxDuration {
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metric.MaxDuration = dur
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}
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if metric.callback != nil {
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go metric.callback(metric.Copy(), data)
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}
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}
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func (em *EventMeter) callDisconnectCallback() {
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em.mtx.Lock()
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if em.disconnectCallback != nil {
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go em.disconnectCallback()
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}
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em.mtx.Unlock()
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}
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func (em *EventMeter) callLatencyCallback(meanLatencyNanoSeconds float64) {
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em.mtx.Lock()
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if em.latencyCallback != nil {
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go em.latencyCallback(meanLatencyNanoSeconds)
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}
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em.mtx.Unlock()
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}
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