do not get stuck on NeedMorePeers

internal/announcer/periodic.go

@@ -3,6 +3,7 @@ package announcer
 import (
 	"math"
 	"net"
+	"sync"
 	"time"
 
 	"github.com/cenkalti/backoff"
@@ -20,25 +21,28 @@ const (
 )
 
 type PeriodicalAnnouncer struct {
-	Tracker        tracker.Tracker
-	status         Status
-	statsCommandC  chan statsRequest
-	numWant        int
-	interval       time.Duration
-	minInterval    time.Duration
-	seeders        int
-	leechers       int
-	lastError      error
-	log            logger.Logger
-	completedC     chan struct{}
-	newPeers       chan []*net.TCPAddr
-	backoff        backoff.BackOff
-	requests       chan *Request
-	lastAnnounce   time.Time
-	HasAnnounced   bool
-	needMorePeersC chan bool
-	closeC         chan struct{}
-	doneC          chan struct{}
+	Tracker       tracker.Tracker
+	status        Status
+	statsCommandC chan statsRequest
+	numWant       int
+	interval      time.Duration
+	minInterval   time.Duration
+	seeders       int
+	leechers      int
+	lastError     error
+	log           logger.Logger
+	completedC    chan struct{}
+	newPeers      chan []*net.TCPAddr
+	backoff       backoff.BackOff
+	requests      chan *Request
+	lastAnnounce  time.Time
+	HasAnnounced  bool
+	closeC        chan struct{}
+	doneC         chan struct{}
+
+	needMorePeers  bool
+	mNeedMorePeers sync.RWMutex
+	needMorePeersC chan struct{}
 }
 
 type Request struct {
@@ -61,7 +65,7 @@ func NewPeriodicalAnnouncer(trk tracker.Tracker, numWant int, minInterval time.D
 		completedC:     completedC,
 		newPeers:       newPeers,
 		requests:       requests,
-		needMorePeersC: make(chan bool),
+		needMorePeersC: make(chan struct{}, 1),
 		closeC:         make(chan struct{}),
 		doneC:          make(chan struct{}),
 		backoff: &backoff.ExponentialBackOff{
@@ -99,9 +103,13 @@ func (a *PeriodicalAnnouncer) Stats() Stats {
 }
 
 func (a *PeriodicalAnnouncer) NeedMorePeers(val bool) {
+	a.mNeedMorePeers.Lock()
+	a.needMorePeers = val
+	a.mNeedMorePeers.Unlock()
 	select {
-	case a.needMorePeersC <- val:
+	case a.needMorePeersC <- struct{}{}:
 	case <-a.doneC:
+	default:
 	}
 }
 
@@ -112,8 +120,6 @@ func (a *PeriodicalAnnouncer) Run() {
 	timer := time.NewTimer(math.MaxInt64)
 	defer timer.Stop()
 
-	var needMorePeers bool
-
 	ca := newCancelableAnnouncer(a.Tracker, a.requests, a.newPeers)
 	defer ca.Cancel()
 
@@ -136,20 +142,27 @@ func (a *PeriodicalAnnouncer) Run() {
 			a.lastError = nil
 			a.status = Working
 			a.backoff.Reset()
+			a.mNeedMorePeers.RLock()
+			needMorePeers := a.needMorePeers
+			a.mNeedMorePeers.RUnlock()
 			if needMorePeers {
 				timer.Reset(a.minInterval)
 			} else {
 				timer.Reset(a.interval)
 			}
 		case a.lastError = <-ca.ErrorC:
 			ca.announcing = false
+			a.lastAnnounce = time.Now()
 			a.status = NotWorking
 			a.log.Debugln("announce error:", a.lastError)
 			timer.Reset(a.backoff.NextBackOff())
-		case needMorePeers = <-a.needMorePeersC:
+		case <-a.needMorePeersC:
 			if ca.announcing {
 				break
 			}
+			a.mNeedMorePeers.RLock()
+			needMorePeers := a.needMorePeers
+			a.mNeedMorePeers.RUnlock()
 			if needMorePeers {
 				timer.Reset(time.Until(a.lastAnnounce.Add(a.minInterval)))
 			} else {