Simplify ring consumer goroutine

Since network.history is now only accessed from the user goroutine, a
lock becomes unnecessary.

downstream.go

@@ -71,6 +71,8 @@ type downstreamConn struct {
 	password    string   // empty after authentication
 	network     *network // can be nil
 
+	ringConsumers map[*network]*RingConsumer
+
 	negociatingCaps bool
 	capVersion      int
 	caps            map[string]bool
@@ -90,6 +92,7 @@ func newDownstreamConn(srv *Server, netConn net.Conn, id uint64) *downstreamConn
 		logger:        &prefixLogger{srv.Logger, fmt.Sprintf("downstream %q: ", netConn.RemoteAddr())},
 		outgoing:      make(chan *irc.Message, 64),
 		closed:        make(chan struct{}),
+		ringConsumers: make(map[*network]*RingConsumer),
 		caps:          make(map[string]bool),
 		ourMessages:   make(map[*irc.Message]struct{}),
 	}
@@ -722,9 +725,7 @@ func (dc *downstreamConn) runNetwork(net *network, loadHistory bool) {
 
 	var seqPtr *uint64
 	if loadHistory {
-		net.lock.Lock()
 		seq, ok := net.history[dc.clientName]
-		net.lock.Unlock()
 		if ok {
 			seqPtr = &seq
 		}
@@ -735,20 +736,18 @@ func (dc *downstreamConn) runNetwork(net *network, loadHistory bool) {
 	serverTimeEnabled := dc.caps["server-time"]
 
 	consumer, ch := net.ring.NewConsumer(seqPtr)
-	go func() {
-		for {
-			var closed bool
-			select {
-			case _, ok := <-ch:
-				if !ok {
-					closed = true
-					break
-				}
 
+	if _, ok := dc.ringConsumers[net]; ok {
+		panic("network has been added twice")
+	}
+	dc.ringConsumers[net] = consumer
+
+	go func() {
+		for range ch {
 			uc := net.upstream()
 			if uc == nil {
 				dc.logger.Printf("ignoring messages for upstream %q: upstream is disconnected", net.Addr)
-					break
+				continue
 			}
 
 			for {
@@ -793,21 +792,7 @@ func (dc *downstreamConn) runNetwork(net *network, loadHistory bool) {
 				dc.SendMessage(msg)
 				consumer.Consume()
 			}
-			case <-dc.closed:
-				closed = true
 		}
-			if closed {
-				break
-			}
-		}
-
-		// TODO: close the consumer from the user goroutine, so we don't need
-		// that net.history lock
-		seq := consumer.Close()
-
-		net.lock.Lock()
-		net.history[dc.clientName] = seq
-		net.lock.Unlock()
 	}()
 }
 

user.go

@@ -41,9 +41,10 @@ type network struct {
 	ring    *Ring
 	stopped chan struct{}
 
+	history map[string]uint64
+
 	lock sync.Mutex
 	conn *upstreamConn
-	history map[string]uint64
 }
 
 func newNetwork(user *user, record *Network) *network {
@@ -235,6 +236,12 @@ func (u *user) run() {
 			})
 		case eventDownstreamDisconnected:
 			dc := e.dc
+
+			for net, rc := range dc.ringConsumers {
+				seq := rc.Close()
+				net.history[dc.clientName] = seq
+			}
+
 			for i := range u.downstreamConns {
 				if u.downstreamConns[i] == dc {
 					u.downstreamConns = append(u.downstreamConns[:i], u.downstreamConns[i+1:]...)