use the same task runner for platform&render tasks

This fixes the issue where on MacOS the embedder crashes during window resizing.
fixes #133

This dosn't fixes the jankyness during resize.
Follow flutter/flutter#44136 for more info.

Author: pchampio

application.go

@@ -233,14 +233,32 @@ func (a *Application) Run() error {
 	}()
 	a.window.SetUserPointer(unsafe.Pointer(&flutterEnginePointer))
 
+	// Init the engine
+	result := a.engine.Init(unsafe.Pointer(&flutterEnginePointer), a.config.vmArguments)
+	if result != embedder.ResultSuccess {
+		switch result {
+		case embedder.ResultInvalidLibraryVersion:
+			fmt.Printf("go-flutter: engine.Init() returned result code %d (invalid library version)\n", result)
+		case embedder.ResultInvalidArguments:
+			fmt.Printf("go-flutter: engine.Init() returned result code %d (invalid arguments)\n", result)
+		case embedder.ResultInternalInconsistency:
+			fmt.Printf("go-flutter: engine.Init() returned result code %d (internal inconsistency)\n", result)
+		default:
+			fmt.Printf("go-flutter: engine.Init() returned result code %d (unknown result code)\n", result)
+		}
+		os.Exit(1)
+	}
+
 	// Start the engine
-	result := a.engine.Run(unsafe.Pointer(&flutterEnginePointer), a.config.vmArguments)
+	result = a.engine.Run()
 	if result != embedder.ResultSuccess {
 		switch result {
 		case embedder.ResultInvalidLibraryVersion:
 			fmt.Printf("go-flutter: engine.Run() returned result code %d (invalid library version)\n", result)
 		case embedder.ResultInvalidArguments:
 			fmt.Printf("go-flutter: engine.Run() returned result code %d (invalid arguments)\n", result)
+		case embedder.ResultInternalInconsistency:
+			fmt.Printf("go-flutter: engine.Run() returned result code %d (internal inconsistency)\n", result)
 		default:
 			fmt.Printf("go-flutter: engine.Run() returned result code %d (unknown result code)\n", result)
 		}

embedder/embedder.go

@@ -1,7 +1,7 @@
 package embedder
 
 // #include "embedder.h"
-// FlutterEngineResult runFlutter(void *user_data, FlutterEngine *engine, FlutterProjectArgs * Args,
+// FlutterEngineResult initEngine(void *user_data, FlutterEngine *engine, FlutterProjectArgs * Args,
 //						 const char *const * vmArgs, int nVmAgrs);
 // FlutterEngineResult
 // createMessageResponseHandle(FlutterEngine engine, void *user_data,
@@ -28,6 +28,7 @@ const (
 	ResultSuccess               Result = C.kSuccess
 	ResultInvalidLibraryVersion Result = C.kInvalidLibraryVersion
 	ResultInvalidArguments      Result = C.kInvalidArguments
+	ResultInternalInconsistency Result = C.kInternalInconsistency
 	ResultEngineNotRunning      Result = -1
 )
 
@@ -80,8 +81,19 @@ func NewFlutterEngine() *FlutterEngine {
 	return &FlutterEngine{}
 }
 
-// Run launches the Flutter Engine in a background thread.
-func (flu *FlutterEngine) Run(userData unsafe.Pointer, vmArgs []string) Result {
+// Runs an initialized engine in a background thread.
+func (flu *FlutterEngine) Run() Result {
+	if flu.Engine == nil {
+		fmt.Printf("go-flutter: The engine must be ini")
+		return ResultInvalidArguments
+	}
+
+	res := C.FlutterEngineRunInitialized(flu.Engine)
+	return (Result)(res)
+}
+
+// Init the Flutter Engine.
+func (flu *FlutterEngine) Init(userData unsafe.Pointer, vmArgs []string) Result {
 	args := C.FlutterProjectArgs{
 		assets_path:   C.CString(flu.AssetsPath),
 		icu_data_path: C.CString(flu.IcuDataPath),
@@ -94,7 +106,7 @@ func (flu *FlutterEngine) Run(userData unsafe.Pointer, vmArgs []string) Result {
 		C.setArrayString(cVMArgs, C.CString(s), C.int(i))
 	}
 
-	res := C.runFlutter(userData, &flu.Engine, &args, cVMArgs, C.int(len(vmArgs)))
+	res := C.initEngine(userData, &flu.Engine, &args, cVMArgs, C.int(len(vmArgs)))
 	if flu.Engine == nil {
 		return ResultInvalidArguments
 	}

embedder/embedder.h

@@ -24,8 +24,10 @@ void proxy_post_task_callback(FlutterTask task, uint64_t target_time_nanos,
 void proxy_desktop_binary_reply(const uint8_t *data, size_t data_size,
                                 void *user_data);
 
+ static size_t gTaskRunnerIdentifiers = 0;
+
 // C helper
-FlutterEngineResult runFlutter(void *user_data, FlutterEngine *engine,
+FlutterEngineResult initEngine(void *user_data, FlutterEngine *engine,
                                FlutterProjectArgs *Args,
                                const char *const *vmArgs, int nVmAgrs) {
   FlutterRendererConfig config = {};
@@ -45,20 +47,24 @@ FlutterEngineResult runFlutter(void *user_data, FlutterEngine *engine,
   Args->command_line_argv = vmArgs;
   Args->platform_message_callback = proxy_platform_message_callback;
 
-  // Configure task runner interop
+  // Configure a task runner interop
   FlutterTaskRunnerDescription platform_task_runner = {};
   platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
   platform_task_runner.user_data = user_data;
   platform_task_runner.runs_task_on_current_thread_callback =
       proxy_runs_task_on_current_thread_callback;
   platform_task_runner.post_task_callback = proxy_post_task_callback;
+  platform_task_runner.identifier = ++gTaskRunnerIdentifiers;
 
   FlutterCustomTaskRunners custom_task_runners = {};
   custom_task_runners.struct_size = sizeof(FlutterCustomTaskRunners);
+  // Render task and platform task are handled by the same TaskRunner
   custom_task_runners.platform_task_runner = &platform_task_runner;
+  custom_task_runners.render_task_runner = &platform_task_runner;
+
   Args->custom_task_runners = &custom_task_runners;
 
-  return FlutterEngineRun(FLUTTER_ENGINE_VERSION, &config, Args, user_data,
+  return FlutterEngineInitialize(FLUTTER_ENGINE_VERSION, &config, Args, user_data,
                           engine);
 }
 

embedder/embedder_helper.c

@@ -11,7 +11,7 @@ import (
 )
 
 // EventLoop is a event loop for the main thread that allows for delayed task
-// execution.()
+// execution.
 type EventLoop struct {
 	// store the task (event) by their priorities
 	priorityqueue *priorityqueue.PriorityQueue