server: break up the Server.Serve method into some reusable parts

Updates grpc#75

server.go

@@ -264,49 +264,74 @@ func (s *Server) Serve(lis net.Listener) error {
 		}
 		s.mu.Unlock()
 
+		go s.serveNewHTTP2Transport(c, authInfo)
+	}
+}
+
+func (s *Server) serveNewHTTP2Transport(c net.Conn, authInfo credentials.AuthInfo) {
+	st, err := transport.NewServerTransport("http2", c, s.opts.maxConcurrentStreams, authInfo)
+	if err != nil {
+		s.mu.Lock()
+		s.errorf("NewServerTransport(%q) failed: %v", c.RemoteAddr(), err)
+		s.mu.Unlock()
+		c.Close()
+		grpclog.Println("grpc: Server.Serve failed to create ServerTransport: ", err)
+		return
+	}
+	if !s.addConn(st) {
+		c.Close()
+		return
+	}
+	s.serveStreams(st)
+}
+
+func (s *Server) serveStreams(st transport.ServerTransport) {
+	defer s.removeConn(st)
+	defer st.Close()
+	var wg sync.WaitGroup
+	st.HandleStreams(func(stream *transport.Stream) {
+		wg.Add(1)
 		go func() {
-			st, err := transport.NewServerTransport("http2", c, s.opts.maxConcurrentStreams, authInfo)
-			if err != nil {
-				s.mu.Lock()
-				s.errorf("NewServerTransport(%q) failed: %v", c.RemoteAddr(), err)
-				s.mu.Unlock()
-				c.Close()
-				grpclog.Println("grpc: Server.Serve failed to create ServerTransport: ", err)
-				return
-			}
-			defer st.Close()
-			s.mu.Lock()
-			if s.conns == nil {
-				s.mu.Unlock()
-				return
-			}
-			s.conns[st] = true
-			s.mu.Unlock()
-			var wg sync.WaitGroup
-			st.HandleStreams(func(stream *transport.Stream) {
-				var trInfo *traceInfo
-				if EnableTracing {
-					trInfo = &traceInfo{
-						tr: trace.New("grpc.Recv."+methodFamily(stream.Method()), stream.Method()),
-					}
-					trInfo.firstLine.client = false
-					trInfo.firstLine.remoteAddr = st.RemoteAddr()
-					stream.TraceContext(trInfo.tr)
-					if dl, ok := stream.Context().Deadline(); ok {
-						trInfo.firstLine.deadline = dl.Sub(time.Now())
-					}
-				}
-				wg.Add(1)
-				go func() {
-					s.handleStream(st, stream, trInfo)
-					wg.Done()
-				}()
-			})
-			wg.Wait()
-			s.mu.Lock()
-			delete(s.conns, st)
-			s.mu.Unlock()
+			defer wg.Done()
+			s.handleStream(st, stream, s.traceInfo(st, stream))
 		}()
+	})
+	wg.Wait()
+}
+
+// traceInfo returns a traceInfo and associates it with stream, if tracing is enabled.
+// If tracing is not enabled, it returns nil.
+func (s *Server) traceInfo(st transport.ServerTransport, stream *transport.Stream) (trInfo *traceInfo) {
+	if !EnableTracing {
+		return nil
+	}
+	trInfo = &traceInfo{
+		tr: trace.New("grpc.Recv."+methodFamily(stream.Method()), stream.Method()),
+	}
+	trInfo.firstLine.client = false
+	trInfo.firstLine.remoteAddr = st.RemoteAddr()
+	stream.TraceContext(trInfo.tr)
+	if dl, ok := stream.Context().Deadline(); ok {
+		trInfo.firstLine.deadline = dl.Sub(time.Now())
+	}
+	return trInfo
+}
+
+func (s *Server) addConn(st transport.ServerTransport) bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.conns == nil {
+		return false
+	}
+	s.conns[st] = true
+	return true
+}
+
+func (s *Server) removeConn(st transport.ServerTransport) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.conns != nil {
+		delete(s.conns, st)
 	}
 }