fix cef main loop on mac obs-browser (#49)

* update mac-obs-browser to not block main thread (CefRunMessageLoop)
* call CefDoMessageLoopWork instead of CefRunMessageLoop which is a
blocking call
* QoL change for dev: update ExecuteTask/ExecuteSyncTask to check if
invoked on main thread. When debugging slobs, we're on main thread. But when
this code is invoked from SLD, we're running from an async thread. so this
code enables the task to be executed with no thought or care where its been
run from.

Author: sandboxcoder

browser-mac.h

@@ -44,6 +44,8 @@ bool ExecuteNextBrowserTask();
 void ExecuteTask(MessageTask task);
 void ExecuteSyncTask(MessageTask task);
 void DoCefMessageLoop(int ms);
+void DoCefMessageLoopTimer(float ms);
+void StopCefMessageLoopTimer();
 void Process();
 #if 0  // REMOVE_DUPLICATE
 void QueueBrowserTask(CefRefPtr<CefBrowser> browser, BrowserFunc func);

browser-mac.mm

@@ -26,6 +26,7 @@
 
 std::mutex browserTaskMutex;
 std::deque<Task> browserTasks;
+static NSTimer *cefTimer = nil;
 
 bool ExecuteNextBrowserTask()
 {
@@ -45,16 +46,26 @@ bool ExecuteNextBrowserTask()
 
 void ExecuteTask(MessageTask task)
 {
-	dispatch_async(dispatch_get_main_queue(), ^{
+	// Protect against exception if already on main thread
+	if ([NSThread isMainThread]) {
 		task();
-	});
+	} else {
+		dispatch_async(dispatch_get_main_queue(), ^{
+			task();
+		});
+	}
 }
 
 void ExecuteSyncTask(MessageTask task)
 {
-	dispatch_sync(dispatch_get_main_queue(), ^{
+	// Protect against exception if already on main thread
+	if ([NSThread isMainThread]) {
 		task();
-	});
+	} else {
+		dispatch_sync(dispatch_get_main_queue(), ^{
+			task();
+		});
+	}
 }
 
 void DoCefMessageLoop(int)
@@ -64,6 +75,22 @@ void DoCefMessageLoop(int)
 	});
 }
 
+void DoCefMessageLoopTimer(float ms)
+{
+	cefTimer = [NSTimer
+		scheduledTimerWithTimeInterval:ms
+				       repeats:YES
+					 block:^(NSTimer *) {
+						 CefDoMessageLoopWork();
+					 }];
+}
+
+void StopCefMessageLoopTimer()
+{
+	[cefTimer invalidate];
+	cefTimer = nil;
+}
+
 void Process()
 {
 	dispatch_async(dispatch_get_main_queue(), ^{

obs-browser-plugin.cpp

@@ -333,7 +333,8 @@ static obs_data_array_t *browser_source_get_messages(void *data)
 			messages = obs_data_array_create();
 			for (const auto &message : bs->messagesToApp) {
 				obs_data_t *msg_data = obs_data_create();
-				obs_data_set_string(msg_data, "message", message.c_str());
+				obs_data_set_string(msg_data, "message",
+						    message.c_str());
 				obs_data_array_push_back(messages, msg_data);
 				obs_data_release(msg_data);
 			}
@@ -529,15 +530,9 @@ static void BrowserShutdown(void)
 #ifndef ENABLE_BROWSER_QT_LOOP
 static void BrowserManagerThread(obs_data_t *settings)
 {
-#ifdef __APPLE__
-	ExecuteSyncTask([&settings]() {
-#endif
-		BrowserInit(settings);
-		CefRunMessageLoop();
-		BrowserShutdown();
-#ifdef __APPLE__
-	});
-#endif
+	BrowserInit(settings);
+	CefRunMessageLoop();
+	BrowserShutdown();
 }
 #endif
 
@@ -546,6 +541,12 @@ extern "C" EXPORT void obs_browser_initialize(obs_data_t *settings)
 	if (!os_atomic_set_bool(&manager_initialized, true)) {
 #ifdef ENABLE_BROWSER_QT_LOOP
 		BrowserInit(settings);
+#elif __APPLE__
+
+		ExecuteTask([&settings]() {
+			BrowserInit(settings);
+			DoCefMessageLoopTimer(0.01f); // Do not block the main queue so we avoid calling CefRunMessageLoop()
+		});
 #else
 		auto binded_fn = bind(BrowserManagerThread, settings);
 		manager_thread = thread(binded_fn);
@@ -956,6 +957,11 @@ void obs_module_unload(void)
 {
 #ifdef USE_UI_LOOP
 	BrowserShutdown();
+#elif __APPLE__
+	ExecuteSyncTask([]() {
+		StopCefMessageLoopTimer();
+		BrowserShutdown();
+	});
 #else
 	if (manager_thread.joinable()) {
 		while (!QueueCEFTask([]() { CefQuitMessageLoop(); }))