From 994f4977810749c0b597e7a7531a02d907967a68 Mon Sep 17 00:00:00 2001
From: comex <comexk@gmail.com>
Date: Sun, 22 Nov 2020 16:05:18 -0500
Subject: Overhaul EmuWindow::PollEvents to fix yuzu-cmd calling SDL_PollEvents
 off main thread

EmuWindow::PollEvents was called from the GPU thread (or the CPU thread
in sync-GPU mode) when swapping buffers.  It had three implementations:

- In GRenderWindow, it didn't actually poll events, just set a flag and
  emit a signal to indicate that a frame was displayed.

- In EmuWindow_SDL2_Hide, it did nothing.

- In EmuWindow_SDL2, it did call SDL_PollEvents, but this is wrong
  because SDL_PollEvents is supposed to be called on the thread that set
  up video - in this case, the main thread, which was sleeping in a
  busyloop (regardless of whether sync-GPU was enabled).  On macOS this
  causes a crash.

To fix this:

- Rename EmuWindow::PollEvents to OnFrameDisplayed, and give it a
  default implementation that does nothing.

- In EmuWindow_SDL2, do not override OnFrameDisplayed, but instead have
  the main thread call SDL_WaitEvent in a loop.
---
 src/yuzu_cmd/emu_window/emu_window_sdl2.cpp | 100 ++++++++++++++--------------
 1 file changed, 51 insertions(+), 49 deletions(-)

(limited to 'src/yuzu_cmd/emu_window/emu_window_sdl2.cpp')

diff --git a/src/yuzu_cmd/emu_window/emu_window_sdl2.cpp b/src/yuzu_cmd/emu_window/emu_window_sdl2.cpp
index 521209622..c4a4a36be 100644
--- a/src/yuzu_cmd/emu_window/emu_window_sdl2.cpp
+++ b/src/yuzu_cmd/emu_window/emu_window_sdl2.cpp
@@ -121,62 +121,64 @@ void EmuWindow_SDL2::Fullscreen() {
     SDL_MaximizeWindow(render_window);
 }
 
-void EmuWindow_SDL2::PollEvents() {
+void EmuWindow_SDL2::WaitEvent() {
+    // Called on main thread
     SDL_Event event;
 
-    // SDL_PollEvent returns 0 when there are no more events in the event queue
-    while (SDL_PollEvent(&event)) {
-        switch (event.type) {
-        case SDL_WINDOWEVENT:
-            switch (event.window.event) {
-            case SDL_WINDOWEVENT_SIZE_CHANGED:
-            case SDL_WINDOWEVENT_RESIZED:
-            case SDL_WINDOWEVENT_MAXIMIZED:
-            case SDL_WINDOWEVENT_RESTORED:
-                OnResize();
-                break;
-            case SDL_WINDOWEVENT_MINIMIZED:
-            case SDL_WINDOWEVENT_EXPOSED:
-                is_shown = event.window.event == SDL_WINDOWEVENT_EXPOSED;
-                OnResize();
-                break;
-            case SDL_WINDOWEVENT_CLOSE:
-                is_open = false;
-                break;
-            }
-            break;
-        case SDL_KEYDOWN:
-        case SDL_KEYUP:
-            OnKeyEvent(static_cast<int>(event.key.keysym.scancode), event.key.state);
-            break;
-        case SDL_MOUSEMOTION:
-            // ignore if it came from touch
-            if (event.button.which != SDL_TOUCH_MOUSEID)
-                OnMouseMotion(event.motion.x, event.motion.y);
-            break;
-        case SDL_MOUSEBUTTONDOWN:
-        case SDL_MOUSEBUTTONUP:
-            // ignore if it came from touch
-            if (event.button.which != SDL_TOUCH_MOUSEID) {
-                OnMouseButton(event.button.button, event.button.state, event.button.x,
-                              event.button.y);
-            }
-            break;
-        case SDL_FINGERDOWN:
-            OnFingerDown(event.tfinger.x, event.tfinger.y);
-            break;
-        case SDL_FINGERMOTION:
-            OnFingerMotion(event.tfinger.x, event.tfinger.y);
+    if (!SDL_WaitEvent(&event)) {
+        LOG_CRITICAL(Frontend, "SDL_WaitEvent failed: {}", SDL_GetError());
+        exit(1);
+    }
+
+    switch (event.type) {
+    case SDL_WINDOWEVENT:
+        switch (event.window.event) {
+        case SDL_WINDOWEVENT_SIZE_CHANGED:
+        case SDL_WINDOWEVENT_RESIZED:
+        case SDL_WINDOWEVENT_MAXIMIZED:
+        case SDL_WINDOWEVENT_RESTORED:
+            OnResize();
             break;
-        case SDL_FINGERUP:
-            OnFingerUp();
+        case SDL_WINDOWEVENT_MINIMIZED:
+        case SDL_WINDOWEVENT_EXPOSED:
+            is_shown = event.window.event == SDL_WINDOWEVENT_EXPOSED;
+            OnResize();
             break;
-        case SDL_QUIT:
+        case SDL_WINDOWEVENT_CLOSE:
             is_open = false;
             break;
-        default:
-            break;
         }
+        break;
+    case SDL_KEYDOWN:
+    case SDL_KEYUP:
+        OnKeyEvent(static_cast<int>(event.key.keysym.scancode), event.key.state);
+        break;
+    case SDL_MOUSEMOTION:
+        // ignore if it came from touch
+        if (event.button.which != SDL_TOUCH_MOUSEID)
+            OnMouseMotion(event.motion.x, event.motion.y);
+        break;
+    case SDL_MOUSEBUTTONDOWN:
+    case SDL_MOUSEBUTTONUP:
+        // ignore if it came from touch
+        if (event.button.which != SDL_TOUCH_MOUSEID) {
+            OnMouseButton(event.button.button, event.button.state, event.button.x, event.button.y);
+        }
+        break;
+    case SDL_FINGERDOWN:
+        OnFingerDown(event.tfinger.x, event.tfinger.y);
+        break;
+    case SDL_FINGERMOTION:
+        OnFingerMotion(event.tfinger.x, event.tfinger.y);
+        break;
+    case SDL_FINGERUP:
+        OnFingerUp();
+        break;
+    case SDL_QUIT:
+        is_open = false;
+        break;
+    default:
+        break;
     }
 
     const u32 current_time = SDL_GetTicks();
-- 
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