Fix recorded render time when glXSwapBuffers() blocks

If glXSwapBuffers() blocks, the render loop will also record how long
kwin was blocked. Obviously, we don't want that.

composite.cpp

@@ -659,15 +659,10 @@ void Compositor::handleFrameRequested(RenderLoop *renderLoop)
         kwinApp()->platform()->createOpenGLSafePoint(Platform::OpenGLSafePoint::PreFrame);
     }
 
-    const std::chrono::milliseconds presentTime =
-            std::chrono::duration_cast<std::chrono::milliseconds>(renderLoop->nextPresentationTimestamp());
-
     const QRegion repaints = m_scene->repaints(screenId);
     m_scene->resetRepaints(screenId);
 
-    renderLoop->beginFrame();
-    m_scene->paint(screenId, repaints, windows, presentTime);
-    renderLoop->endFrame();
+    m_scene->paint(screenId, repaints, windows, renderLoop);
 
     if (m_framesToTestForSafety > 0) {
         if (m_scene->compositingType() & OpenGLCompositing) {

plugins/scenes/opengl/scene_opengl.cpp

@@ -33,6 +33,7 @@
 #include "lanczosfilter.h"
 #include "main.h"
 #include "overlaywindow.h"
+#include "renderloop.h"
 #include "screens.h"
 #include "cursor.h"
 #include "decorations/decoratedclient.h"
@@ -602,7 +603,7 @@ void SceneOpenGL::aboutToStartPainting(int screenId, const QRegion &damage)
 }
 
 void SceneOpenGL::paint(int screenId, const QRegion &damage, const QList<Toplevel *> &toplevels,
-                        std::chrono::milliseconds presentTime)
+                        RenderLoop *renderLoop)
 {
     if (m_resetOccurred) {
         return; // A graphics reset has occurred, do nothing.
@@ -639,9 +640,10 @@ void SceneOpenGL::paint(int screenId, const QRegion &damage, const QList<Topleve
     } else {
         int mask = 0;
         updateProjectionMatrix();
+        renderLoop->beginFrame();
 
         paintScreen(&mask, damage.intersected(geo), repaint, &update, &valid,
-                    presentTime, projectionMatrix(), geo, scaling);   // call generic implementation
+                    renderLoop, projectionMatrix(), geo, scaling);   // call generic implementation
         paintCursor(valid);
 
         if (!GLPlatform::instance()->isGLES() && screenId == -1) {
@@ -659,6 +661,8 @@ void SceneOpenGL::paint(int screenId, const QRegion &damage, const QList<Topleve
             }
         }
 
+        renderLoop->endFrame();
+
         GLVertexBuffer::streamingBuffer()->endOfFrame();
         m_backend->endFrame(screenId, valid, update);
         GLVertexBuffer::streamingBuffer()->framePosted();

plugins/scenes/opengl/scene_opengl.h

@@ -36,7 +36,7 @@ public:
     ~SceneOpenGL() override;
     bool initFailed() const override;
     void paint(int screenId, const QRegion &damage, const QList<Toplevel *> &windows,
-               std::chrono::milliseconds presentTime) override;
+               RenderLoop *renderLoop) override;
     Scene::EffectFrame *createEffectFrame(EffectFrameImpl *frame) override;
     Shadow *createShadow(Toplevel *toplevel) override;
     void screenGeometryChanged(const QSize &size) override;

plugins/scenes/qpainter/scene_qpainter.cpp

@@ -14,6 +14,7 @@
 #include "deleted.h"
 #include "effects.h"
 #include "main.h"
+#include "renderloop.h"
 #include "screens.h"
 #include "toplevel.h"
 #include "platform.h"
@@ -81,7 +82,7 @@ void SceneQPainter::paintGenericScreen(int mask, const ScreenPaintData &data)
 }
 
 void SceneQPainter::paint(int screenId, const QRegion &_damage, const QList<Toplevel *> &toplevels,
-                          std::chrono::milliseconds presentTime)
+                          RenderLoop *renderLoop)
 {
     Q_ASSERT(kwinApp()->platform()->isPerScreenRenderingEnabled());
     painted_screen = screenId;
@@ -100,15 +101,17 @@ void SceneQPainter::paint(int screenId, const QRegion &_damage, const QList<Topl
     const QRect geometry = screens()->geometry(screenId);
     QImage *buffer = m_backend->bufferForScreen(screenId);
     if (buffer && !buffer->isNull()) {
+        renderLoop->beginFrame();
         m_painter->begin(buffer);
         m_painter->setWindow(geometry);
 
         QRegion updateRegion, validRegion;
         paintScreen(&mask, damage.intersected(geometry), QRegion(), &updateRegion, &validRegion,
-                    presentTime);
+                    renderLoop);
         paintCursor(updateRegion);
 
         m_painter->end();
+        renderLoop->endFrame();
         m_backend->endFrame(screenId, mask, updateRegion);
     }
 

plugins/scenes/qpainter/scene_qpainter.h

@@ -26,7 +26,7 @@ public:
     ~SceneQPainter() override;
     OverlayWindow* overlayWindow() const override;
     void paint(int screenId, const QRegion &damage, const QList<Toplevel *> &windows,
-               std::chrono::milliseconds presentTime) override;
+               RenderLoop *renderLoop) override;
     void paintGenericScreen(int mask, const ScreenPaintData &data) override;
     CompositingType compositingType() const override;
     bool initFailed() const override;

plugins/scenes/xrender/scene_xrender.cpp

@@ -23,6 +23,7 @@
 #include "main.h"
 #include "overlaywindow.h"
 #include "platform.h"
+#include "renderloop.h"
 #include "screens.h"
 #include "xcbutils.h"
 #include "decorations/decoratedclient.h"
@@ -76,7 +77,7 @@ bool SceneXrender::initFailed() const
 
 // the entry point for painting
 void SceneXrender::paint(int screenId, const QRegion &damage, const QList<Toplevel *> &toplevels,
-                         std::chrono::milliseconds presentTime)
+                         RenderLoop *renderLoop)
 {
     painted_screen = screenId;
 
@@ -84,7 +85,9 @@ void SceneXrender::paint(int screenId, const QRegion &damage, const QList<Toplev
 
     int mask = 0;
     QRegion updateRegion, validRegion;
-    paintScreen(&mask, damage, QRegion(), &updateRegion, &validRegion, presentTime);
+    renderLoop->beginFrame();
+    paintScreen(&mask, damage, QRegion(), &updateRegion, &validRegion, renderLoop);
+    renderLoop->endFrame();
 
     m_backend->showOverlay();
 

plugins/scenes/xrender/scene_xrender.h

@@ -33,7 +33,7 @@ public:
         return XRenderCompositing;
     }
     void paint(int screenId, const QRegion &damage, const QList<Toplevel *> &windows,
-               std::chrono::milliseconds presentTime) override;
+               RenderLoop *renderLoop) override;
     Scene::EffectFrame *createEffectFrame(EffectFrameImpl *frame) override;
     Shadow *createShadow(Toplevel *toplevel) override;
     void screenGeometryChanged(const QSize &size) override;

scene.cpp

@@ -146,8 +146,7 @@ void Scene::reallocRepaints()
 
 // returns mask and possibly modified region
 void Scene::paintScreen(int* mask, const QRegion &damage, const QRegion &repaint,
-                        QRegion *updateRegion, QRegion *validRegion,
-                        std::chrono::milliseconds presentTime,
+                        QRegion *updateRegion, QRegion *validRegion, RenderLoop *renderLoop,
                         const QMatrix4x4 &projection, const QRect &outputGeometry,
                         qreal screenScale)
 {
@@ -155,6 +154,9 @@ void Scene::paintScreen(int* mask, const QRegion &damage, const QRegion &repaint
     const QRegion displayRegion(0, 0, screenSize.width(), screenSize.height());
     *mask = (damage == displayRegion) ? 0 : PAINT_SCREEN_REGION;
 
+    const std::chrono::milliseconds presentTime =
+            std::chrono::duration_cast<std::chrono::milliseconds>(renderLoop->nextPresentationTimestamp());
+
     if (Q_UNLIKELY(presentTime < m_expectedPresentTimestamp)) {
         qCDebug(KWIN_CORE, "Provided presentation timestamp is invalid: %ld (current: %ld)",
                 presentTime.count(), m_expectedPresentTimestamp.count());

scene.h

@@ -39,6 +39,7 @@ class Deleted;
 class EffectFrameImpl;
 class EffectWindowImpl;
 class OverlayWindow;
+class RenderLoop;
 class Shadow;
 class WindowPixmap;
 class GLTexture;
@@ -75,7 +76,7 @@ public:
     // returns the time since the last vblank signal - if there's one
     // ie. "what of this frame is lost to painting"
     virtual void paint(int screenId, const QRegion &damage, const QList<Toplevel *> &windows,
-                       std::chrono::milliseconds presentTime) = 0;
+                       RenderLoop *renderLoop) = 0;
 
     /**
      * Adds the Toplevel to the Scene.
@@ -208,8 +209,7 @@ protected:
     void clearStackingOrder();
     // shared implementation, starts painting the screen
     void paintScreen(int *mask, const QRegion &damage, const QRegion &repaint,
-                     QRegion *updateRegion, QRegion *validRegion,
-                     std::chrono::milliseconds presentTime,
+                     QRegion *updateRegion, QRegion *validRegion, RenderLoop *renderLoop,
                      const QMatrix4x4 &projection = QMatrix4x4(),
                      const QRect &outputGeometry = QRect(), qreal screenScale = 1.0);
     // Render cursor texture in case hardware cursor is disabled/non-applicable