Fix a memory leak in the material shader cache.

There were multiple problems in the implementation of the shader cache:
 1) it was not thread-safe
 2) nothing was ever removed from the hash
 3) since the keys into the hash are the actual shader source code, problem
    #2 would lead to serious memory consumption over time

Change-Id: I20d1fb2074932e23f89edddba12e68ab8adcbff0
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

3 files changed, 12 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index ce3bf7d61d..b7a6475c23 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -52,6 +52,8 @@
 #include <QtQuick/private/qsgcontext_p.h>
 #include <private/qquickprofiler_p.h>
 
+#include <private/qquickshadereffectnode_p.h>
+
 #ifdef Q_OS_WIN
 #  include <QtCore/qt_windows.h>
 #endif
@@ -293,6 +295,8 @@ void QSGGuiThreadRenderLoop::windowDestroyed(QQuickWindow *window)
     if (Q_UNLIKELY(!current))
         qCDebug(QSG_LOG_RENDERLOOP) << "cleanup without an OpenGL context";
 
+    QQuickShaderEffectMaterial::cleanupMaterialCache();
+
     d->cleanupNodesOnShutdown();
     if (m_windows.size() == 0) {
         rc->invalidate();
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index 7b1e24246b..26a0e78254 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -56,6 +56,8 @@
 #include <private/qquickprofiler_p.h>
 #include <private/qqmldebugservice_p.h>
 
+#include <private/qquickshadereffectnode_p.h>
+
 /*
    Overall design:
 
@@ -449,6 +451,8 @@ void QSGRenderThread::invalidateOpenGL(QQuickWindow *window, bool inDestructor,
         qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- cleanup without an OpenGL context";
     }
 
+    QQuickShaderEffectMaterial::cleanupMaterialCache();
+
     // The canvas nodes must be cleaned up regardless if we are in the destructor..
     if (wipeSG) {
         QQuickWindowPrivate *dd = QQuickWindowPrivate::get(window);
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop.cpp b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
index 0e22fa8b7b..309e877dae 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -48,6 +48,8 @@
 
 #include <private/qquickprofiler_p.h>
 
+#include <private/qquickshadereffectnode_p.h>
+
 QT_BEGIN_NAMESPACE
 
 extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha);
@@ -232,6 +234,8 @@ void QSGWindowsRenderLoop::windowDestroyed(QQuickWindow *window)
     if (Q_UNLIKELY(!current))
         qCDebug(QSG_LOG_RENDERLOOP) << "cleanup without an OpenGL context";
 
+    QQuickShaderEffectMaterial::cleanupMaterialCache();
+
     d->cleanupNodesOnShutdown();
     if (m_windows.size() == 0) {
         d->context->invalidate();