refactor: remove the unused struct io_engine (#512)

src/core/core/service_engine.cpp

@@ -45,25 +45,21 @@ bool service_node::rpc_register_handler(task_code code,
                                         const char *extra_name,
                                         const rpc_request_handler &h)
 {
-    return _node_io.rpc->register_rpc_handler(code, extra_name, h);
+    return _rpc->register_rpc_handler(code, extra_name, h);
 }
 
 bool service_node::rpc_unregister_handler(dsn::task_code rpc_code)
 {
-    return _node_io.rpc->unregister_rpc_handler(rpc_code);
+    return _rpc->unregister_rpc_handler(rpc_code);
 }
 
-error_code service_node::init_io_engine()
+error_code service_node::init_rpc_engine()
 {
     // init rpc engine
-    _node_io.rpc = make_unique<rpc_engine>(this);
-    return ERR_OK;
-}
+    _rpc = make_unique<rpc_engine>(this);
 
-error_code service_node::start_io_engine_in_main()
-{
     // start rpc engine
-    return _node_io.rpc->start(_app_spec);
+    return _rpc->start(_app_spec);
 }
 
 dsn::error_code service_node::start_app()
@@ -116,13 +112,11 @@ error_code service_node::start()
     _computation->create(_app_spec.pools);
     dassert(!_computation->is_started(), "task engine must not be started at this point");
 
-    err = init_io_engine();
+    // init rpc
+    err = init_rpc_engine();
     if (err != ERR_OK)
         return err;
 
-    // start io engines (only timer, disk and rpc), others are started in app start task
-    start_io_engine_in_main();
-
     // start task engine
     _computation->start();
     dassert(_computation->is_started(), "task engine must be started at this point");
@@ -134,7 +128,7 @@ error_code service_node::start()
     }
 
     // start rpc serving
-    _node_io.rpc->start_serving();
+    _rpc->start_serving();
 
     return err;
 }

src/core/core/service_engine.h

@@ -60,18 +60,12 @@ class timer_service;
 //
 class service_node
 {
-public:
-    struct io_engine
-    {
-        std::unique_ptr<rpc_engine> rpc;
-    };
-
 public:
     explicit service_node(service_app_spec &app_spec);
 
     ~service_node();
 
-    rpc_engine *rpc() const { return _node_io.rpc.get(); }
+    rpc_engine *rpc() const { return _rpc.get(); }
     task_engine *computation() const { return _computation.get(); }
 
     void get_runtime_info(const std::string &indent,
@@ -100,15 +94,14 @@ class service_node
     service_app_spec _app_spec;
 
     std::unique_ptr<task_engine> _computation;
-    io_engine _node_io;
+    std::unique_ptr<rpc_engine> _rpc;
 
 private:
     // the service entity is initialized after the engine
     // is initialized, so this should be call in start()
     void init_service_app();
 
-    error_code init_io_engine();
-    error_code start_io_engine_in_main();
+    error_code init_rpc_engine();
 };
 
 typedef std::map<int, std::shared_ptr<service_node>> service_nodes_by_app_id;