Merge pull request #4940 from jroweboy/presentation-thread

Split Presentation thread from Render thread

src/core/frontend/emu_window.cpp

@@ -10,6 +10,8 @@
 
 namespace Frontend {
 
+GraphicsContext::~GraphicsContext() = default;
+
 class EmuWindow::TouchState : public Input::Factory<Input::TouchDevice>,
                               public std::enable_shared_from_this<TouchState> {
 public:

src/core/frontend/emu_window.h

@@ -12,6 +12,61 @@
 
 namespace Frontend {
 
+struct Frame;
+/**
+ * For smooth Vsync rendering, we want to always present the latest frame that the core generates,
+ * but also make sure that rendering happens at the pace that the frontend dictates. This is a
+ * helper class that the renderer can define to sync frames between the render thread and the
+ * presentation thread
+ */
+class TextureMailbox {
+public:
+    virtual ~TextureMailbox() = default;
+
+    /**
+     * Recreate the render objects attached to this frame with the new specified width/height
+     */
+    virtual void ReloadRenderFrame(Frontend::Frame* frame, u32 width, u32 height) = 0;
+
+    /**
+     * Recreate the presentation objects attached to this frame with the new specified width/height
+     */
+    virtual void ReloadPresentFrame(Frontend::Frame* frame, u32 width, u32 height) = 0;
+
+    /**
+     * Render thread calls this to get an available frame to present
+     */
+    virtual Frontend::Frame* GetRenderFrame() = 0;
+
+    /**
+     * Render thread calls this after draw commands are done to add to the presentation mailbox
+     */
+    virtual void ReleaseRenderFrame(Frame* frame) = 0;
+
+    /**
+     * Presentation thread calls this to get the latest frame available to present. If there is no
+     * frame available after timeout, returns the previous frame. If there is no previous frame it
+     * returns nullptr
+     */
+    virtual Frontend::Frame* TryGetPresentFrame(int timeout_ms) = 0;
+};
+
+/**
+ * Represents a graphics context that can be used for background computation or drawing. If the
+ * graphics backend doesn't require the context, then the implementation of these methods can be
+ * stubs
+ */
+class GraphicsContext {
+public:
+    virtual ~GraphicsContext();
+
+    /// Makes the graphics context current for the caller thread
+    virtual void MakeCurrent() = 0;
+
+    /// Releases (dunno if this is the "right" word) the context from the caller thread
+    virtual void DoneCurrent() = 0;
+};
+
 /**
  * Abstraction class used to provide an interface between emulation code and the frontend
  * (e.g. SDL, QGLWidget, GLFW, etc...).
@@ -30,7 +85,7 @@ namespace Frontend {
  * - DO NOT TREAT THIS CLASS AS A GUI TOOLKIT ABSTRACTION LAYER. That's not what it is. Please
  *   re-read the upper points again and think about it if you don't see this.
  */
-class EmuWindow {
+class EmuWindow : public GraphicsContext {
 public:
     /// Data structure to store emuwindow configuration
     struct WindowConfig {
@@ -40,17 +95,21 @@ public:
         std::pair<unsigned, unsigned> min_client_area_size;
     };
 
-    /// Swap buffers to display the next frame
-    virtual void SwapBuffers() = 0;
-
     /// Polls window events
     virtual void PollEvents() = 0;
 
-    /// Makes the graphics context current for the caller thread
-    virtual void MakeCurrent() = 0;
-
-    /// Releases (dunno if this is the "right" word) the GLFW context from the caller thread
-    virtual void DoneCurrent() = 0;
+    /**
+     * Returns a GraphicsContext that the frontend provides that is shared with the emu window. This
+     * context can be used from other threads for background graphics computation. If the frontend
+     * is using a graphics backend that doesn't need anything specific to run on a different thread,
+     * then it can use a stubbed implemenation for GraphicsContext.
+     *
+     * If the return value is null, then the core should assume that the frontend cannot provide a
+     * Shared Context
+     */
+    virtual std::unique_ptr<GraphicsContext> CreateSharedContext() const {
+        return nullptr;
+    }
 
     /**
      * Signal that a touch pressed event has occurred (e.g. mouse click pressed)
@@ -102,6 +161,8 @@ public:
      */
     void UpdateCurrentFramebufferLayout(unsigned width, unsigned height);
 
+    std::unique_ptr<TextureMailbox> mailbox = nullptr;
+
 protected:
     EmuWindow();
     virtual ~EmuWindow();
@@ -131,15 +192,6 @@ protected:
         framebuffer_layout = layout;
     }
 
-    /**
-     * Update internal client area size with the given parameter.
-     * @note EmuWindow implementations will usually use this in window resize event handlers.
-     */
-    void NotifyClientAreaSizeChanged(const std::pair<unsigned, unsigned>& size) {
-        client_area_width = size.first;
-        client_area_height = size.second;
-    }
-
 private:
     /**
      * Handler called when the minimal client area was requested to be changed via SetConfig.
@@ -152,9 +204,6 @@ private:
 
     Layout::FramebufferLayout framebuffer_layout; ///< Current framebuffer layout
 
-    unsigned client_area_width;  ///< Current client width, should be set by window impl.
-    unsigned client_area_height; ///< Current client height, should be set by window impl.
-
     WindowConfig config;        ///< Internal configuration (changes pending for being applied in
                                 /// ProcessConfigurationChanges)
     WindowConfig active_config; ///< Internal active configuration

src/core/frontend/scope_acquire_context.cpp

@@ -0,0 +1,17 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/frontend/emu_window.h"
+#include "core/frontend/scope_acquire_context.h"
+
+namespace Frontend {
+
+ScopeAcquireContext::ScopeAcquireContext(Frontend::GraphicsContext& context) : context{context} {
+    context.MakeCurrent();
+}
+ScopeAcquireContext::~ScopeAcquireContext() {
+    context.DoneCurrent();
+}
+
+} // namespace Frontend

src/core/frontend/scope_acquire_context.h

@@ -0,0 +1,23 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+
+namespace Frontend {
+
+class GraphicsContext;
+
+/// Helper class to acquire/release window context within a given scope
+class ScopeAcquireContext : NonCopyable {
+public:
+    explicit ScopeAcquireContext(Frontend::GraphicsContext& context);
+    ~ScopeAcquireContext();
+
+private:
+    Frontend::GraphicsContext& context;
+};
+
+} // namespace Frontend