Add eventDownstreamDisconnected

This should remove the need for protecting user.downstreamConns with a
mutex.

downstream.go

@@ -310,10 +310,6 @@ func (dc *downstreamConn) Close() error {
 		return fmt.Errorf("downstream connection already closed")
 	}
 
-	if u := dc.user; u != nil {
-		u.removeDownstream(dc)
-	}
-
 	close(dc.closed)
 	return nil
 }
@@ -757,16 +753,9 @@ func (dc *downstreamConn) runNetwork(net *network, loadHistory bool) {
 
 		seq := consumer.Close()
 
-		// TODO: need to take dc.network into account here
-		dc.user.lock.Lock()
-		lastDownstream := len(dc.user.downstreamConns) == 0
-		dc.user.lock.Unlock()
-
-		if lastDownstream {
 		net.lock.Lock()
 		net.history[historyName] = seq
 		net.lock.Unlock()
-		}
 	}()
 }
 

server.go

@@ -123,6 +123,7 @@ func (s *Server) Serve(ln net.Listener) error {
 				if err := dc.readMessages(dc.user.events); err != nil {
 					dc.logger.Print(err)
 				}
+				dc.user.events <- eventDownstreamDisconnected{dc}
 			}
 			dc.Close()
 

user.go

@@ -23,6 +23,10 @@ type eventDownstreamConnected struct {
 	dc *downstreamConn
 }
 
+type eventDownstreamDisconnected struct {
+	dc *downstreamConn
+}
+
 type network struct {
 	Network
 	user *user
@@ -169,6 +173,16 @@ func (u *user) run() {
 			u.lock.Lock()
 			u.downstreamConns = append(u.downstreamConns, dc)
 			u.lock.Unlock()
+		case eventDownstreamDisconnected:
+			dc := e.dc
+			u.lock.Lock()
+			for i := range u.downstreamConns {
+				if u.downstreamConns[i] == dc {
+					u.downstreamConns = append(u.downstreamConns[:i], u.downstreamConns[i+1:]...)
+					break
+				}
+			}
+			u.lock.Unlock()
 		case eventDownstreamMessage:
 			msg, dc := e.msg, e.dc
 			if dc.isClosed() {
@@ -189,17 +203,6 @@ func (u *user) run() {
 	}
 }
 
-func (u *user) removeDownstream(dc *downstreamConn) {
-	u.lock.Lock()
-	for i := range u.downstreamConns {
-		if u.downstreamConns[i] == dc {
-			u.downstreamConns = append(u.downstreamConns[:i], u.downstreamConns[i+1:]...)
-			break
-		}
-	}
-	u.lock.Unlock()
-}
-
 func (u *user) createNetwork(net *Network) (*network, error) {
 	if net.ID != 0 {
 		panic("tried creating an already-existing network")