skip dialing based on last time dialed

p2p/pex/pex_reactor.go

@@ -63,7 +63,7 @@ type PEXReactor struct {
 	requestsSent         *cmn.CMap // ID->struct{}: unanswered send requests
 	lastReceivedRequests *cmn.CMap // ID->time.Time: last time peer requested from us
 
-	attemptsToDial sync.Map // dial address (string) -> number of attempts (int) to dial (for exponential backoff)
+	attemptsToDial sync.Map // address (string) -> {number of attempts (int), last time dialed (time.Time)}
 }
 
 // PEXReactorConfig holds reactor specific configuration data.
@@ -76,6 +76,11 @@ type PEXReactorConfig struct {
 	Seeds []string
 }
 
+type _attemptsToDial struct {
+	number     int
+	lastDialed time.Time
+}
+
 // NewPEXReactor creates new PEX reactor.
 func NewPEXReactor(b AddrBook, config *PEXReactorConfig) *PEXReactor {
 	r := &PEXReactor{
@@ -367,7 +372,12 @@ func (r *PEXReactor) ensurePeers() {
 }
 
 func (r *PEXReactor) dialPeer(addr *p2p.NetAddress) {
-	attempts := r.AttemptsToDial(addr)
+	var attempts int
+	var lastDialed time.Time
+	if lAttempts, attempted := r.attemptsToDial.Load(addr.DialString()); attempted {
+		attempts = lAttempts.(_attemptsToDial).number
+		lastDialed = lAttempts.(_attemptsToDial).lastDialed
+	}
 
 	if attempts > maxAttemptsToDial {
 		r.Logger.Error("Reached max attempts to dial", "addr", addr, "attempts", attempts)
@@ -376,11 +386,14 @@ func (r *PEXReactor) dialPeer(addr *p2p.NetAddress) {
 	}
 
 	// exponential backoff if it's not our first attempt to dial given address
-	if attempts != 0 {
+	if attempts > 0 {
 		jitterSeconds := time.Duration(rand.Float64() * float64(time.Second)) // 1s == (1e9 ns)
 		backoffDuration := jitterSeconds + ((1 << uint(attempts)) * time.Second)
-		r.Logger.Debug("Sleeping before dialing", "addr", addr, "dur", backoffDuration)
-		time.Sleep(backoffDuration)
+		sinceLastDialed := time.Now().Sub(lastDialed)
+		if sinceLastDialed < backoffDuration {
+			r.Logger.Debug("Too early to dial", "addr", addr, "backoff_duration", backoffDuration, "last_dialed", lastDialed, "time_since", sinceLastDialed)
+			return
+		}
 	}
 
 	err := r.Switch.DialPeerWithAddress(addr, false)
@@ -393,7 +406,7 @@ func (r *PEXReactor) dialPeer(addr *p2p.NetAddress) {
 			r.book.MarkAttempt(addr)
 		}
 		// record attempt
-		r.attemptsToDial.Store(addr.DialString(), attempts+1)
+		r.attemptsToDial.Store(addr.DialString(), _attemptsToDial{attempts + 1, time.Now()})
 	} else {
 		// cleanup any history
 		r.attemptsToDial.Delete(addr.DialString())
@@ -440,9 +453,9 @@ func (r *PEXReactor) dialSeeds() {
 // AttemptsToDial returns the number of attempts to dial specific address. It
 // returns 0 if never attempted or successfully connected.
 func (r *PEXReactor) AttemptsToDial(addr *p2p.NetAddress) int {
-	attempts, attempted := r.attemptsToDial.Load(addr.DialString())
+	lAttempts, attempted := r.attemptsToDial.Load(addr.DialString())
 	if attempted {
-		return attempts.(int)
+		return lAttempts.(_attemptsToDial).number
 	} else {
 		return 0
 	}

p2p/pex/pex_reactor_test.go

@@ -282,10 +282,13 @@ func TestPEXReactorDialPeer(t *testing.T) {
 	// 1st unsuccessful attempt
 	pexR.dialPeer(addr)
 
+	assert.Equal(t, 1, pexR.AttemptsToDial(addr))
+
 	// 2nd unsuccessful attempt
 	pexR.dialPeer(addr)
 
-	assert.Equal(t, 2, pexR.AttemptsToDial(addr))
+	// must be skipped because it is too early
+	assert.Equal(t, 1, pexR.AttemptsToDial(addr))
 }
 
 type mockPeer struct {