Make releaseResources() free the renderer's shader cache

Normally all shader programs from materials are cached in a simple table
that is alive as long as the renderer exists, in practice this means being
tied to the QQuickWindow which is often the entire lifetime of an
application.

Use releaseResources(), which is mostly a no-op on the scenegraph level
at the moment, to free this cache.

Task-number: QTBUG-62392
Change-Id: I279e595874fee1ab4fe0dede0843a3686dea5806
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>

7 files changed, 36 insertions, 3 deletions

diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index edee29584c..d016e79641 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -2914,6 +2914,11 @@ void Renderer::renderRenderNode(Batch *batch)
         glBindFramebuffer(GL_FRAMEBUFFER, prevFbo);
 }
 
+void Renderer::releaseCachedResources()
+{
+    m_shaderManager->invalidated();
+}
+
 class VisualizeShader : public QOpenGLShaderProgram
 {
 public:
diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
index 2c0f8667e8..b0a14d23b9 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
@@ -629,6 +629,7 @@ public:
 protected:
     void nodeChanged(QSGNode *node, QSGNode::DirtyState state) Q_DECL_OVERRIDE;
     void render() Q_DECL_OVERRIDE;
+    void releaseCachedResources() Q_DECL_OVERRIDE;
 
 private:
     enum ClipTypeBit
diff --git a/src/quick/scenegraph/coreapi/qsgrenderer_p.h b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
index 4589685765..d96d893ca5 100644
--- a/src/quick/scenegraph/coreapi/qsgrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
@@ -92,7 +92,8 @@ public:
     QSGNodeUpdater *nodeUpdater() const;
     void setNodeUpdater(QSGNodeUpdater *updater);
     inline QSGMaterialShader::RenderState state(QSGMaterialShader::RenderState::DirtyStates dirty) const;
-    virtual void setCustomRenderMode(const QByteArray &) { };
+    virtual void setCustomRenderMode(const QByteArray &) { }
+    virtual void releaseCachedResources() { }
 
     void clearChangedFlag() { m_changed_emitted = false; }
 
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index bc65dc1bc3..2c73339b7a 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -56,6 +56,7 @@
 #include <QtQuick/QQuickWindow>
 #include <QtQuick/private/qquickwindow_p.h>
 #include <QtQuick/private/qsgcontext_p.h>
+#include <QtQuick/private/qsgrenderer_p.h>
 #include <private/qquickprofiler_p.h>
 
 #if QT_CONFIG(opengl)
@@ -152,7 +153,7 @@ public:
     void update(QQuickWindow *window) { maybeUpdate(window); } // identical for this implementation.
     void handleUpdateRequest(QQuickWindow *);
 
-    void releaseResources(QQuickWindow *) { }
+    void releaseResources(QQuickWindow *) Q_DECL_OVERRIDE;
 
     QAnimationDriver *animationDriver() const { return 0; }
 
@@ -505,6 +506,14 @@ QSGContext *QSGGuiThreadRenderLoop::sceneGraphContext() const
     return sg;
 }
 
+void QSGGuiThreadRenderLoop::releaseResources(QQuickWindow *w)
+{
+    // No full invalidation of the rendercontext, just clear some caches.
+    QQuickWindowPrivate *d = QQuickWindowPrivate::get(w);
+    if (d->renderer)
+        d->renderer->releaseCachedResources();
+}
+
 void QSGGuiThreadRenderLoop::handleUpdateRequest(QQuickWindow *window)
 {
     renderWindow(window);
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index d28a73da20..e0f78a9873 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -406,6 +406,13 @@ bool QSGRenderThread::event(QEvent *e)
                 stopEventProcessing = true;
         } else {
             qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- not releasing because window is still active";
+            if (window) {
+                QQuickWindowPrivate *d = QQuickWindowPrivate::get(window);
+                if (d->renderer) {
+                    qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- requesting renderer to release cached resources";
+                    d->renderer->releaseCachedResources();
+                }
+            }
         }
         waitCondition.wakeOne();
         wm->m_lockedForSync = false;
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop.cpp b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
index e10e52d95e..e33f31f2ac 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -48,6 +48,7 @@
 
 #include <QtQuick/private/qsgcontext_p.h>
 #include <QtQuick/private/qquickwindow_p.h>
+#include <QtQuick/private/qsgrenderer_p.h>
 #include <QtQuick/private/qsgdefaultrendercontext_p.h>
 
 #include <QtQuick/QQuickWindow>
@@ -503,6 +504,15 @@ void QSGWindowsRenderLoop::renderWindow(QQuickWindow *window)
                               QQuickProfiler::SceneGraphRenderLoopSwap);
 }
 
+void QSGWindowsRenderLoop::releaseResources(QQuickWindow *w)
+{
+    // No full invalidation of the rendercontext, just clear some caches.
+    RLDEBUG("releaseResources");
+    QQuickWindowPrivate *d = QQuickWindowPrivate::get(w);
+    if (d->renderer)
+        d->renderer->releaseCachedResources();
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qsgwindowsrenderloop_p.cpp"
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop_p.h b/src/quick/scenegraph/qsgwindowsrenderloop_p.h
index 1940a66af2..a1188fed8a 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop_p.h
+++ b/src/quick/scenegraph/qsgwindowsrenderloop_p.h
@@ -86,7 +86,7 @@ public:
     QSGContext *sceneGraphContext() const override { return m_sg; }
     QSGRenderContext *createRenderContext(QSGContext *) const override;
 
-    void releaseResources(QQuickWindow *) override { }
+    void releaseResources(QQuickWindow *) override;
 
     void render();
     void renderWindow(QQuickWindow *window);