Move creation of periodic stats task inside proxy library

This adds a new type of SnowflakeEvent. EventOnProxyStats is triggered
by the periodic task run at SummaryInterval and produces an event with a
proxy stats output string.

proxy/lib/pt_event_logger.go

@@ -1,54 +1,67 @@
 package snowflake_proxy
 
 import (
-	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/task"
+	"fmt"
 	"io"
 	"log"
 	"time"
 
+	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/task"
+
 	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/event"
 )
 
-func NewProxyEventLogger(logPeriod time.Duration, output io.Writer) event.SnowflakeEventReceiver {
+func NewProxyEventLogger(output io.Writer) event.SnowflakeEventReceiver {
 	logger := log.New(output, "", log.LstdFlags|log.LUTC)
-	el := &logEventLogger{logPeriod: logPeriod, logger: logger}
-	el.task = &task.Periodic{Interval: logPeriod, Execute: el.logTick}
-	el.task.WaitThenStart()
-	return el
+	return &proxyEventLogger{logger: logger}
 }
 
-type logEventLogger struct {
+type proxyEventLogger struct {
+	logger *log.Logger
+}
+
+func (p *proxyEventLogger) OnNewSnowflakeEvent(e event.SnowflakeEvent) {
+	p.logger.Println(e.String())
+}
+
+type periodicProxyStats struct {
 	inboundSum      int64
 	outboundSum     int64
 	connectionCount int
 	logPeriod       time.Duration
 	task            *task.Periodic
-	logger          *log.Logger
+	dispatcher      event.SnowflakeEventDispatcher
 }
 
-func (p *logEventLogger) OnNewSnowflakeEvent(e event.SnowflakeEvent) {
+func newPeriodicProxyStats(logPeriod time.Duration, dispatcher event.SnowflakeEventDispatcher) *periodicProxyStats {
+	el := &periodicProxyStats{logPeriod: logPeriod, dispatcher: dispatcher}
+	el.task = &task.Periodic{Interval: logPeriod, Execute: el.logTick}
+	el.task.WaitThenStart()
+	return el
+}
+
+func (p *periodicProxyStats) OnNewSnowflakeEvent(e event.SnowflakeEvent) {
 	switch e.(type) {
 	case event.EventOnProxyConnectionOver:
 		e := e.(event.EventOnProxyConnectionOver)
 		p.inboundSum += e.InboundTraffic
 		p.outboundSum += e.OutboundTraffic
 		p.connectionCount += 1
-	default:
-		p.logger.Println(e.String())
 	}
 }
 
-func (p *logEventLogger) logTick() error {
+func (p *periodicProxyStats) logTick() error {
 	inbound, inboundUnit := formatTraffic(p.inboundSum)
 	outbound, outboundUnit := formatTraffic(p.outboundSum)
-	p.logger.Printf("In the last %v, there were %v connections. Traffic Relayed ↓ %v %v, ↑ %v %v.\n",
+	statString := fmt.Sprintf("In the last %v, there were %v connections. Traffic Relayed ↓ %v %v, ↑ %v %v.\n",
 		p.logPeriod.String(), p.connectionCount, inbound, inboundUnit, outbound, outboundUnit)
+	p.dispatcher.OnNewSnowflakeEvent(&event.EventOnProxyStats{StatString: statString})
 	p.outboundSum = 0
 	p.inboundSum = 0
 	p.connectionCount = 0
 	return nil
 }
 
-func (p *logEventLogger) Close() error {
+func (p *periodicProxyStats) Close() error {
 	return p.task.Close()
 }