Xds mux unification: introduced unifed mux implementation

envoy/config/grpc_mux.h

@@ -105,6 +105,9 @@ class GrpcMux {
 
   virtual void requestOnDemandUpdate(const std::string& type_url,
                                      const absl::flat_hash_set<std::string>& for_update) PURE;
+
+  // TODO (dmitri-d) remove this when legacy muxes have been removed
+  virtual bool isUnified() const { return false; }
 };
 
 using GrpcMuxPtr = std::unique_ptr<GrpcMux>;

source/common/config/xds_mux/BUILD

@@ -51,3 +51,23 @@ envoy_cc_library(
         "@envoy_api//envoy/service/discovery/v3:pkg_cc_proto",
     ],
 )
+
+envoy_cc_library(
+    name = "grpc_mux_lib",
+    srcs = ["grpc_mux_impl.cc"],
+    hdrs = ["grpc_mux_impl.h"],
+    deps = [
+        ":delta_subscription_state_lib",
+        ":sotw_subscription_state_lib",
+        "//envoy/event:dispatcher_interface",
+        "//envoy/grpc:async_client_interface",
+        "//source/common/config:grpc_stream_lib",
+        "//source/common/config:pausable_ack_queue_lib",
+        "//source/common/config:version_converter_lib",
+        "//source/common/config:watch_map_lib",
+        "//source/common/config:xds_context_params_lib",
+        "//source/common/config:xds_resource_lib",
+        "//source/common/memory:utils_lib",
+        "@envoy_api//envoy/service/discovery/v3:pkg_cc_proto",
+    ],
+)

source/common/config/xds_mux/delta_subscription_state.h

@@ -93,6 +93,20 @@ class DeltaSubscriptionState
   std::set<std::string> names_removed_;
 };
 
+class DeltaSubscriptionStateFactory : public SubscriptionStateFactory<DeltaSubscriptionState> {
+public:
+  DeltaSubscriptionStateFactory(Event::Dispatcher& dispatcher) : dispatcher_(dispatcher) {}
+  ~DeltaSubscriptionStateFactory() override = default;
+  std::unique_ptr<DeltaSubscriptionState>
+  makeSubscriptionState(const std::string& type_url, UntypedConfigUpdateCallbacks& callbacks,
+                        OpaqueResourceDecoder&, const bool wildcard) override {
+    return std::make_unique<DeltaSubscriptionState>(type_url, callbacks, dispatcher_, wildcard);
+  }
+
+private:
+  Event::Dispatcher& dispatcher_;
+};
+
 } // namespace XdsMux
 } // namespace Config
 } // namespace Envoy