fix handling of keepAliveTimer and blocked state in link.go

src/yggdrasil/link.go

@@ -387,19 +387,14 @@ func (intf *link) notifySending(size int) {
 	intf.Act(&intf.writer, func() {
 		intf.isSending = true
 		intf.sendTimer = time.AfterFunc(sendTime, intf.notifyBlockedSend)
-		intf._cancelStallTimer()
+		if intf.keepAliveTimer != nil {
+			intf.keepAliveTimer.Stop()
+			intf.keepAliveTimer = nil
+		}
 		intf.peer.notifyBlocked(intf)
 	})
 }
 
-// we just sent something, so cancel any pending timer to send keep-alive traffic
-func (intf *link) _cancelStallTimer() {
-	if intf.stallTimer != nil {
-		intf.stallTimer.Stop()
-		intf.stallTimer = nil
-	}
-}
-
 // This gets called from a time.AfterFunc, and notifies the switch that we appear
 // to have gotten blocked on a write, so the switch should start routing traffic
 // through other links, if alternatives exist
@@ -441,11 +436,13 @@ func (intf *link) _notifyIdle() {
 // Set the peer as stalled, to prevent them from returning to the switch until a read succeeds
 func (intf *link) notifyStalled() {
 	intf.Act(nil, func() { // Sent from a time.AfterFunc
-		if intf.stallTimer != nil && !intf.blocked {
+		if intf.stallTimer != nil {
 			intf.stallTimer.Stop()
 			intf.stallTimer = nil
-			intf.blocked = true
-			intf.links.core.switchTable.blockPeer(intf, intf.peer.port)
+			if !intf.blocked {
+				intf.blocked = true
+				intf.links.core.switchTable.blockPeer(intf, intf.peer.port)
+			}
 		}
 	})
 }
@@ -480,9 +477,9 @@ func (intf *link) notifyRead(size int) {
 // We need to send keep-alive traffic now
 func (intf *link) notifyDoKeepAlive() {
 	intf.Act(nil, func() { // Sent from a time.AfterFunc
-		if intf.stallTimer != nil {
-			intf.stallTimer.Stop()
-			intf.stallTimer = nil
+		if intf.keepAliveTimer != nil {
+			intf.keepAliveTimer.Stop()
+			intf.keepAliveTimer = nil
 			intf.writer.sendFrom(nil, [][]byte{nil}) // Empty keep-alive traffic
 		}
 	})