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 <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/quick/items/qquickshadereffectnode_p.h b/src/quick/items/qquickshadereffectnode_p.h
index 7e3cf74276..28382c483c 100644
--- a/src/quick/items/qquickshadereffectnode_p.h
+++ b/src/quick/items/qquickshadereffectnode_p.h
@@ -101,6 +101,8 @@ public:
     void updateTextures() const;
     void invalidateTextureProvider(QSGTextureProvider *provider);
 
+    static void cleanupMaterialCache();
+
 protected:
     friend class QQuickCustomMaterialShader;
 
@@ -115,8 +117,6 @@ protected:
 
     QQuickShaderEffectNode *m_node;
     bool m_emittedLogChanged;
-
-    static QHash<QQuickShaderEffectMaterialKey, QSharedPointer<QSGMaterialType> > materialMap;
 };