Merge pull request #1689 from fjl/discover-ignore-temp-errors

p2p, p2p/discover: small fixes

p2p/discover/node.go

@@ -48,6 +48,10 @@ type Node struct {
 	// In those tests, the content of sha will not actually correspond
 	// with ID.
 	sha common.Hash
+
+	// whether this node is currently being pinged in order to replace
+	// it in a bucket
+	contested bool
 }
 
 func newNode(id NodeID, ip net.IP, udpPort, tcpPort uint16) *Node {

p2p/discover/table.go

@@ -455,24 +455,31 @@ func (tab *Table) ping(id NodeID, addr *net.UDPAddr) error {
 func (tab *Table) add(new *Node) {
 	b := tab.buckets[logdist(tab.self.sha, new.sha)]
 	tab.mutex.Lock()
+	defer tab.mutex.Unlock()
 	if b.bump(new) {
-		tab.mutex.Unlock()
 		return
 	}
 	var oldest *Node
 	if len(b.entries) == bucketSize {
 		oldest = b.entries[bucketSize-1]
+		if oldest.contested {
+			// The node is already being replaced, don't attempt
+			// to replace it.
+			return
+		}
+		oldest.contested = true
 		// Let go of the mutex so other goroutines can access
 		// the table while we ping the least recently active node.
 		tab.mutex.Unlock()
-		if err := tab.ping(oldest.ID, oldest.addr()); err == nil {
+		err := tab.ping(oldest.ID, oldest.addr())
+		tab.mutex.Lock()
+		oldest.contested = false
+		if err == nil {
 			// The node responded, don't replace it.
 			return
 		}
-		tab.mutex.Lock()
 	}
 	added := b.replace(new, oldest)
-	tab.mutex.Unlock()
 	if added && tab.nodeAddedHook != nil {
 		tab.nodeAddedHook(new)
 	}

p2p/discover/udp.go

@@ -458,6 +458,10 @@ func encodePacket(priv *ecdsa.PrivateKey, ptype byte, req interface{}) ([]byte,
 	return packet, nil
 }
 
+type tempError interface {
+	Temporary() bool
+}
+
 // readLoop runs in its own goroutine. it handles incoming UDP packets.
 func (t *udp) readLoop() {
 	defer t.conn.Close()
@@ -467,7 +471,13 @@ func (t *udp) readLoop() {
 	buf := make([]byte, 1280)
 	for {
 		nbytes, from, err := t.conn.ReadFromUDP(buf)
-		if err != nil {
+		if tempErr, ok := err.(tempError); ok && tempErr.Temporary() {
+			// Ignore temporary read errors.
+			glog.V(logger.Debug).Infof("Temporary read error: %v", err)
+			continue
+		} else if err != nil {
+			// Shut down the loop for permament errors.
+			glog.V(logger.Debug).Infof("Read error: %v", err)
 			return
 		}
 		t.handlePacket(from, buf[:nbytes])

p2p/server.go

@@ -542,6 +542,10 @@ func (srv *Server) encHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn)
 	}
 }
 
+type tempError interface {
+	Temporary() bool
+}
+
 // listenLoop runs in its own goroutine and accepts
 // inbound connections.
 func (srv *Server) listenLoop() {
@@ -561,16 +565,31 @@ func (srv *Server) listenLoop() {
 	}
 
 	for {
+		// Wait for a handshake slot before accepting.
 		<-slots
-		fd, err := srv.listener.Accept()
-		if err != nil {
-			return
-		}
-		mfd := newMeteredConn(fd, true)
 
-		glog.V(logger.Debug).Infof("Accepted conn %v\n", mfd.RemoteAddr())
+		var (
+			fd  net.Conn
+			err error
+		)
+		for {
+			fd, err = srv.listener.Accept()
+			if tempErr, ok := err.(tempError); ok && tempErr.Temporary() {
+				glog.V(logger.Debug).Infof("Temporary read error: %v", err)
+				continue
+			} else if err != nil {
+				glog.V(logger.Debug).Infof("Read error: %v", err)
+				return
+			}
+			break
+		}
+		fd = newMeteredConn(fd, true)
+		glog.V(logger.Debug).Infof("Accepted conn %v\n", fd.RemoteAddr())
+
+		// Spawn the handler. It will give the slot back when the connection
+		// has been established.
 		go func() {
-			srv.setupConn(mfd, inboundConn, nil)
+			srv.setupConn(fd, inboundConn, nil)
 			slots <- struct{}{}
 		}()
 	}