Make write error close session as well

internal/multiplex/switchboard.go

@@ -56,22 +56,30 @@ func (sb *switchboard) addConn(conn net.Conn) {
 
 // a pointer to connId is passed here so that the switchboard can reassign it
 func (sb *switchboard) send(data []byte, connId *uint32) (n int, err error) {
+	writeAndRegUsage := func(conn net.Conn, d []byte) (int, error) {
+		n, err = conn.Write(d)
+		if err != nil {
+			sb.close("failed to write to remote " + err.Error())
+			return n, err
+		}
+		sb.AddTx(int64(n))
+		return n, nil
+	}
+
 	sb.Valve.txWait(len(data))
 	sb.connsM.RLock()
 	defer sb.connsM.RUnlock()
-	if sb.strategy == UNIFORM_SPREAD {
-		if atomic.LoadUint32(&sb.broken) == 1 || len(sb.conns) == 0 {
-			return 0, errBrokenSwitchboard
-		}
+	if atomic.LoadUint32(&sb.broken) == 1 || len(sb.conns) == 0 {
+		return 0, errBrokenSwitchboard
+	}
 
+	if sb.strategy == UNIFORM_SPREAD {
 		r := rand.Intn(len(sb.conns))
 		var c int
 		for newConnId := range sb.conns {
 			if r == c {
 				conn, _ := sb.conns[newConnId]
-				n, err = conn.Write(data)
-				sb.AddTx(int64(n))
-				return
+				return writeAndRegUsage(conn, data)
 			}
 			c++
 		}
@@ -80,9 +88,7 @@ func (sb *switchboard) send(data []byte, connId *uint32) (n int, err error) {
 		var conn net.Conn
 		conn, ok := sb.conns[*connId]
 		if ok {
-			n, err = conn.Write(data)
-			sb.AddTx(int64(n))
-			return
+			return writeAndRegUsage(conn, data)
 		} else {
 			// do not call assignRandomConn() here.
 			// we'll have to do connsM.RLock() after we get a new connId from assignRandomConn, in order to
@@ -91,19 +97,13 @@ func (sb *switchboard) send(data []byte, connId *uint32) (n int, err error) {
 			// in particular if newConnId is removed between the RUnlock and RLock, conns[newConnId] will return
 			// a nil pointer. To prevent this we must get newConnId and the reference to conn itself in one single mutex
 			// protection
-			if atomic.LoadUint32(&sb.broken) == 1 || len(sb.conns) == 0 {
-				return 0, errBrokenSwitchboard
-			}
-
 			r := rand.Intn(len(sb.conns))
 			var c int
 			for newConnId := range sb.conns {
 				if r == c {
 					connId = &newConnId
 					conn, _ = sb.conns[newConnId]
-					n, err = conn.Write(data)
-					sb.AddTx(int64(n))
-					return
+					return writeAndRegUsage(conn, data)
 				}
 				c++
 			}
@@ -132,6 +132,14 @@ func (sb *switchboard) assignRandomConn() (uint32, error) {
 	return 0, errBrokenSwitchboard
 }
 
+func (sb *switchboard) close(terminalMsg string) {
+	atomic.StoreUint32(&sb.broken, 1)
+	if !sb.session.IsClosed() {
+		sb.session.SetTerminalMsg(terminalMsg)
+		sb.session.passiveClose()
+	}
+}
+
 // actively triggered by session.Close()
 func (sb *switchboard) closeAll() {
 	sb.connsM.Lock()
@@ -152,11 +160,7 @@ func (sb *switchboard) deplex(connId uint32, conn net.Conn) {
 		if err != nil {
 			log.Debugf("a connection for session %v has closed: %v", sb.session.id, err)
 			go conn.Close()
-			atomic.StoreUint32(&sb.broken, 1)
-			if !sb.session.IsClosed() {
-				sb.session.SetTerminalMsg("a connection has dropped unexpectedly")
-				sb.session.passiveClose()
-			}
+			sb.close("a connection has dropped unexpectedly")
 			return
 		}