add send/recv queues for link

tunnel/default.go

@@ -427,7 +427,7 @@ func (t *tun) listen(link *link) {
 		// process anything via the net interface
 		msg := new(transport.Message)
 		if err := link.Recv(msg); err != nil {
-			log.Debugf("Tunnel link %s receive error: %#v", link.Remote(), err)
+			log.Debugf("Tunnel link %s receive error: %v", link.Remote(), err)
 			return
 		}
 

tunnel/link.go

@@ -1,6 +1,7 @@
 package tunnel
 
 import (
+	"io"
 	"sync"
 	"time"
 
@@ -14,6 +15,10 @@ type link struct {
 	sync.RWMutex
 	// stops the link
 	closed chan bool
+	// send queue
+	sendQueue chan *packet
+	// receive queue
+	recvQueue chan *packet
 	// unique id of this link e.g uuid
 	// which we define for ourselves
 	id string
@@ -31,25 +36,37 @@ type link struct {
 	lastKeepAlive time.Time
 	// channels keeps a mapping of channels and last seen
 	channels map[string]time.Time
-
 	// the weighted moving average roundtrip
-	rtt int64
-
+	length int64
 	// weighted moving average of bits flowing
 	rate float64
-
 	// keep an error count on the link
 	errCount int
 }
 
+// packet send over link
+type packet struct {
+	// message to send or received
+	message *transport.Message
+
+	// status returned when sent
+	status chan error
+
+	// receive related error
+	err error
+}
+
 func newLink(s transport.Socket) *link {
 	l := &link{
 		Socket:        s,
 		id:            uuid.New().String(),
-		channels:      make(map[string]time.Time),
-		closed:        make(chan bool),
 		lastKeepAlive: time.Now(),
+		closed:        make(chan bool),
+		channels:      make(map[string]time.Time),
+		sendQueue:     make(chan *packet, 128),
+		recvQueue:     make(chan *packet, 128),
 	}
+	go l.process()
 	go l.expiry()
 	return l
 }
@@ -58,15 +75,51 @@ func (l *link) setRTT(d time.Duration) {
 	l.Lock()
 	defer l.Unlock()
 
-	if l.rtt <= 0 {
-		l.rtt = d.Nanoseconds()
+	if l.length <= 0 {
+		l.length = d.Nanoseconds()
 		return
 	}
 
 	// https://fishi.devtail.io/weblog/2015/04/12/measuring-bandwidth-and-round-trip-time-tcp-connection-inside-application-layer/
-	rtt := 0.8*float64(l.rtt) + 0.2*float64(d.Nanoseconds())
-	// set new rtt
-	l.rtt = int64(rtt)
+	length := 0.8*float64(l.length) + 0.2*float64(d.Nanoseconds())
+	// set new length
+	l.length = int64(length)
+}
+
+// process deals with the send queue
+func (l *link) process() {
+	// receive messages
+	go func() {
+		for {
+			m := new(transport.Message)
+			err := l.recv(m)
+			if err != nil {
+				l.Lock()
+				l.errCount++
+				l.Unlock()
+			}
+
+			// process new received message
+
+			select {
+			case l.recvQueue <- &packet{message: m, err: err}:
+			case <-l.closed:
+				return
+			}
+		}
+	}()
+
+	// send messages
+
+	for {
+		select {
+		case pk := <-l.sendQueue:
+			// send the message
+			pk.status <- l.send(pk.message)
+		case <-l.closed:
+			return
+		}
+	}
 }
 
 // watches the channel expiry
@@ -106,46 +159,7 @@ func (l *link) expiry() {
 	}
 }
 
-// Delay is the current load on the link
-func (l *link) Delay() int64 {
-	return 0
-}
-
-// Current transfer rate as bits per second (lower is better)
-func (l *link) Rate() float64 {
-	l.RLock()
-	defer l.RUnlock()
-	return l.rate
-}
-
-// Length returns the roundtrip time as nanoseconds (lower is better).
-// Returns 0 where no measurement has been taken.
-func (l *link) Length() int64 {
-	l.RLock()
-	defer l.RUnlock()
-
-	return l.rtt
-}
-
-func (l *link) Id() string {
-	l.RLock()
-	defer l.RUnlock()
-
-	return l.id
-}
-
-func (l *link) Close() error {
-	select {
-	case <-l.closed:
-		return nil
-	default:
-		close(l.closed)
-	}
-
-	return nil
-}
-
-func (l *link) Send(m *transport.Message) error {
+func (l *link) send(m *transport.Message) error {
 	dataSent := len(m.Body)
 
 	// set header length
@@ -162,6 +176,15 @@ func (l *link) Send(m *transport.Message) error {
 	l.Lock()
 	defer l.Unlock()
 
+	// there's an error increment the counter and bail
+	if err != nil {
+		l.errCount++
+		return err
+	}
+
+	// reset the counter
+	l.errCount = 0
+
 	// calculate based on data
 	if dataSent > 0 {
 		// measure time taken
@@ -183,17 +206,104 @@ func (l *link) Send(m *transport.Message) error {
 		}
 	}
 
-	// if theres no error reset the counter
-	if err == nil {
-		l.errCount = 0
-	}
-
-	// otherwise increment the counter
-	l.errCount++
-
 	return err
 }
 
+// recv a message on the link
+func (l *link) recv(m *transport.Message) error {
+	if m.Header == nil {
+		m.Header = make(map[string]string)
+	}
+
+	// TODO measure the receive latency if possible
+
+	// receive the transport message
+	return l.Socket.Recv(m)
+}
+
+// Delay is the current load on the link
+func (l *link) Delay() int64 {
+	return int64(len(l.sendQueue) + len(l.recvQueue))
+}
+
+// Current transfer rate as bits per second (lower is better)
+func (l *link) Rate() float64 {
+	l.RLock()
+	defer l.RUnlock()
+
+	return l.rate
+}
+
+// Length returns the roundtrip time as nanoseconds (lower is better).
+// Returns 0 where no measurement has been taken.
+func (l *link) Length() int64 {
+	l.RLock()
+	defer l.RUnlock()
+
+	return l.length
+}
+
+func (l *link) Id() string {
+	l.RLock()
+	defer l.RUnlock()
+
+	return l.id
+}
+
+func (l *link) Close() error {
+	select {
+	case <-l.closed:
+		return nil
+	default:
+		close(l.closed)
+	}
+
+	return nil
+}
+
+// Send sencs a message on the link
+func (l *link) Send(m *transport.Message) error {
+	// create a new packet to send over the link
+	p := &packet{
+		message: m,
+		status:  make(chan error, 1),
+	}
+
+	select {
+	case <-l.closed:
+		return io.EOF
+	case l.sendQueue <- p:
+		// in the send queue
+	}
+
+	// wait for response
+	select {
+	case <-l.closed:
+		return io.EOF
+	case err := <-p.status:
+		return err
+	}
+
+	// never reached
+	return nil
+}
+
+// Accept accepts a message on the socket
+func (l *link) Recv(m *transport.Message) error {
+	select {
+	case <-l.closed:
+		return io.EOF
+	case pk := <-l.recvQueue:
+		// check the packet receive error
+		if pk.err != nil {
+			return pk.err
+		}
+		*m = *pk.message
+	}
+	return nil
+}
+
+// Status can return connected, closed, error
 func (l *link) Status() string {
 	select {
 	case <-l.closed: