Implement a simple caching algorithm for shader programs.

When the number of programs held in the cache exceeds a threshold, the
least frequantly used programs get deleted. This also covers programs
with custom snippets of code. As a conequence, when a
QGLCustomShaderStage gets deleted, any programs using that code will
(eventually) be freed.

Reviewed-By: Samuel Rødal

1 files changed, 11 insertions, 2 deletions

diff --git a/src/opengl/gl2paintengineex/qglengineshadermanager_p.h b/src/opengl/gl2paintengineex/qglengineshadermanager_p.h
index fd73b44..59e50d0 100644
--- a/src/opengl/gl2paintengineex/qglengineshadermanager_p.h
+++ b/src/opengl/gl2paintengineex/qglengineshadermanager_p.h
@@ -366,13 +366,22 @@ private:
     QGLSharedResourceGuard ctxGuard;
     QGLShaderProgram *blitShaderProg;
     QGLShaderProgram *simpleShaderProg;
-    QList<QGLEngineShaderProg> cachedPrograms;
+    QList<QGLEngineShaderProg*> cachedPrograms;
 
     static const char* qShaderSnippets[TotalSnippetCount];
 };
 
-struct QGLEngineShaderProg
+
+class QGLEngineShaderProg
 {
+public:
+    QGLEngineShaderProg() : program(0) {}
+
+    ~QGLEngineShaderProg() {
+        if (program)
+            delete program;
+    }
+
     QGLEngineSharedShaders::SnippetName mainVertexShader;
     QGLEngineSharedShaders::SnippetName positionVertexShader;
     QGLEngineSharedShaders::SnippetName mainFragShader;