From 82fa80a6b28ea5a4d3e245f531fea22a689c7ad3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Trond=20Kjern=C3=A5sen?= <trond@trolltech.com>
Date: Thu, 11 Mar 2010 15:52:37 +0100
Subject: Made QGLTextureCache::instance() threadsafe.

Reviewed-by: Tom Cooksey
---
 src/opengl/qgl.cpp | 27 +++++++--------------------
 src/opengl/qgl_p.h |  1 -
 2 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 7839191..c6ecef6 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -1688,14 +1688,12 @@ typedef void (*_qt_image_cleanup_hook_64)(qint64);
 extern Q_GUI_EXPORT _qt_pixmap_cleanup_hook_64 qt_pixmap_cleanup_hook_64;
 extern Q_GUI_EXPORT _qt_image_cleanup_hook_64 qt_image_cleanup_hook_64;
 
-static QGLTextureCache *qt_gl_texture_cache = 0;
+
+Q_GLOBAL_STATIC(QGLTextureCache, qt_gl_texture_cache)
 
 QGLTextureCache::QGLTextureCache()
     : m_cache(64*1024) // cache ~64 MB worth of textures - this is not accurate though
 {
-    Q_ASSERT(qt_gl_texture_cache == 0);
-    qt_gl_texture_cache = this;
-
     QImagePixmapCleanupHooks::instance()->addPixmapDataModificationHook(cleanupTexturesForPixampData);
     QImagePixmapCleanupHooks::instance()->addPixmapDataDestructionHook(cleanupBeforePixmapDestruction);
     QImagePixmapCleanupHooks::instance()->addImageHook(cleanupTexturesForCacheKey);
@@ -1703,8 +1701,7 @@ QGLTextureCache::QGLTextureCache()
 
 QGLTextureCache::~QGLTextureCache()
 {
-    qt_gl_texture_cache = 0;
-
+    Q_ASSERT(size() == 0);
     QImagePixmapCleanupHooks::instance()->removePixmapDataModificationHook(cleanupTexturesForPixampData);
     QImagePixmapCleanupHooks::instance()->removePixmapDataDestructionHook(cleanupBeforePixmapDestruction);
     QImagePixmapCleanupHooks::instance()->removeImageHook(cleanupTexturesForCacheKey);
@@ -1754,22 +1751,14 @@ void QGLTextureCache::removeContextTextures(QGLContext* ctx)
     }
 }
 
-QGLTextureCache* QGLTextureCache::instance()
-{
-    if (!qt_gl_texture_cache)
-        qt_gl_texture_cache = new QGLTextureCache;
-
-    return qt_gl_texture_cache;
-}
-
 /*
   a hook that removes textures from the cache when a pixmap/image
   is deref'ed
 */
 void QGLTextureCache::cleanupTexturesForCacheKey(qint64 cacheKey)
 {
-    instance()->remove(cacheKey);
-    Q_ASSERT(instance()->getTexture(cacheKey) == 0);
+    qt_gl_texture_cache()->remove(cacheKey);
+    Q_ASSERT(qt_gl_texture_cache()->getTexture(cacheKey) == 0);
 }
 
 
@@ -1791,10 +1780,9 @@ void QGLTextureCache::cleanupBeforePixmapDestruction(QPixmapData* pmd)
 #endif
 }
 
-void QGLTextureCache::deleteIfEmpty()
+QGLTextureCache *QGLTextureCache::instance()
 {
-    if (instance()->size() == 0)
-        delete instance();
+    return qt_gl_texture_cache();
 }
 
 // DDS format structure
@@ -1960,7 +1948,6 @@ QGLContext::~QGLContext()
 {
     // remove any textures cached in this context
     QGLTextureCache::instance()->removeContextTextures(this);
-    QGLTextureCache::deleteIfEmpty(); // ### thread safety
 
     d_ptr->group->cleanupResources(this);
 
diff --git a/src/opengl/qgl_p.h b/src/opengl/qgl_p.h
index ed34f79..5e524a7 100644
--- a/src/opengl/qgl_p.h
+++ b/src/opengl/qgl_p.h
@@ -532,7 +532,6 @@ public:
     bool remove(QGLContext *ctx, GLuint textureId);
     void removeContextTextures(QGLContext *ctx);
     static QGLTextureCache *instance();
-    static void deleteIfEmpty();
     static void cleanupTexturesForCacheKey(qint64 cacheKey);
     static void cleanupTexturesForPixampData(QPixmapData* pixmap);
     static void cleanupBeforePixmapDestruction(QPixmapData* pixmap);
-- 
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