From 7172cfd88974518e58e28f226b3a238bba2bd1c2 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Thu, 14 Jan 2021 19:28:21 -0600
Subject: [PATCH] Properly handle multiple window event flush barriers in
 flight at once

Fixes streaming on macOS Mojave without Metal support
---
 app/streaming/session.cpp | 13 +++++++++----
 app/streaming/session.h   |  2 +-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/app/streaming/session.cpp b/app/streaming/session.cpp
index 261e4423..773a6b70 100644
--- a/app/streaming/session.cpp
+++ b/app/streaming/session.cpp
@@ -380,7 +380,7 @@ Session::Session(NvComputer* computer, NvApp& app, StreamingPreferences *prefere
       m_InputHandler(nullptr),
       m_InputHandlerLock(0),
       m_MouseEmulationRefCount(0),
-      m_FlushingWindowEvents(false),
+      m_FlushingWindowEventsRef(0),
       m_AsyncConnectionSuccess(false),
       m_PortTestResults(0),
       m_OpusDecoder(nullptr),
@@ -1113,7 +1113,7 @@ void Session::flushWindowEvents()
     // Insert a barrier to discard any additional window events.
     // We don't use SDL_FlushEvent() here because it could cause
     // important events to be lost.
-    m_FlushingWindowEvents = true;
+    m_FlushingWindowEventsRef++;
 
     // This event will cause us to set m_FlushingWindowEvents back to false.
     SDL_Event flushEvent = {};
@@ -1343,7 +1343,7 @@ void Session::exec(int displayOriginX, int displayOriginY)
                 SDL_ShowCursor(SDL_ENABLE);
                 break;
             case SDL_CODE_FLUSH_WINDOW_EVENT_BARRIER:
-                m_FlushingWindowEvents = false;
+                m_FlushingWindowEventsRef--;
                 break;
             default:
                 SDL_assert(false);
@@ -1401,8 +1401,13 @@ void Session::exec(int displayOriginX, int displayOriginY)
                 SDL_SetWindowPosition(m_Window, x, y);
             }
 
-            if (m_FlushingWindowEvents) {
+            if (m_FlushingWindowEventsRef > 0) {
                 // Ignore window events for renderer reset if flushing
+                SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                            "Dropping window event during flush: %d (%d %d)",
+                            event.window.event,
+                            event.window.data1,
+                            event.window.data2);
                 break;
             }
 
diff --git a/app/streaming/session.h b/app/streaming/session.h
index 77602810..f372a651 100644
--- a/app/streaming/session.h
+++ b/app/streaming/session.h
@@ -152,7 +152,7 @@ private:
     SdlInputHandler* m_InputHandler;
     SDL_SpinLock m_InputHandlerLock;
     int m_MouseEmulationRefCount;
-    bool m_FlushingWindowEvents;
+    int m_FlushingWindowEventsRef;
 
     bool m_AsyncConnectionSuccess;
     int m_PortTestResults;