Fixed race in Filter Chain (#4728)

xds/internal/server/listener_wrapper.go

@@ -324,12 +324,13 @@ func (l *listenerWrapper) Accept() (net.Conn, error) {
 		// can come it at any time), and connections aren't accepted too often,
 		// so this reinstantation of the Route Configuration is an acceptable
 		// tradeoff for simplicity.
-		if err := fc.ConstructUsableRouteConfiguration(rc); err != nil {
+		vhswi, err := fc.ConstructUsableRouteConfiguration(rc)
+		if err != nil {
 			l.logger.Warningf("route configuration construction: %v", err)
 			conn.Close()
 			continue
 		}
-		return &connWrapper{Conn: conn, filterChain: fc, parent: l, virtualHosts: fc.VirtualHosts}, nil
+		return &connWrapper{Conn: conn, filterChain: fc, parent: l, virtualHosts: vhswi}, nil
 	}
 }
 

xds/internal/xdsclient/filter_chain.go

@@ -67,11 +67,6 @@ type FilterChain struct {
 	//
 	// Only one of RouteConfigName and InlineRouteConfig is set.
 	InlineRouteConfig *RouteConfigUpdate
-
-	// VirtualHosts are the virtual hosts ready to be used in the xds interceptors.
-	// It contains a way to match routes using a matcher and also instantiates
-	// HTTPFilter overrides to simply run incoming RPC's through if they are selected.
-	VirtualHosts []VirtualHostWithInterceptors
 }
 
 // VirtualHostWithInterceptors captures information present in a VirtualHost
@@ -98,17 +93,16 @@ type RouteWithInterceptors struct {
 
 // ConstructUsableRouteConfiguration takes Route Configuration and converts it
 // into matchable route configuration, with instantiated HTTP Filters per route.
-func (f *FilterChain) ConstructUsableRouteConfiguration(config RouteConfigUpdate) error {
+func (f *FilterChain) ConstructUsableRouteConfiguration(config RouteConfigUpdate) ([]VirtualHostWithInterceptors, error) {
 	vhs := make([]VirtualHostWithInterceptors, len(config.VirtualHosts))
 	for _, vh := range config.VirtualHosts {
 		vhwi, err := f.convertVirtualHost(vh)
 		if err != nil {
-			return fmt.Errorf("virtual host construction: %v", err)
+			return nil, fmt.Errorf("virtual host construction: %v", err)
 		}
 		vhs = append(vhs, vhwi)
 	}
-	f.VirtualHosts = vhs
-	return nil
+	return vhs, nil
 }
 
 func (f *FilterChain) convertVirtualHost(virtualHost *VirtualHost) (VirtualHostWithInterceptors, error) {

xds/internal/xdsclient/filter_chain_test.go

@@ -2629,11 +2629,14 @@ func TestHTTPFilterInstantiation(t *testing.T) {
 			fc := FilterChain{
 				HTTPFilters: test.filters,
 			}
-			fc.ConstructUsableRouteConfiguration(test.routeConfig)
+			vhswi, err := fc.ConstructUsableRouteConfiguration(test.routeConfig)
+			if err != nil {
+				t.Fatalf("Error constructing usable route configuration: %v", err)
+			}
 			// Build out list of errors by iterating through the virtual hosts and routes,
 			// and running the filters in route configurations.
 			var errs []string
-			for _, vh := range fc.VirtualHosts {
+			for _, vh := range vhswi {
 				for _, r := range vh.Routes {
 					for _, int := range r.Interceptors {
 						errs = append(errs, int.AllowRPC(context.Background()).Error())