Fix #10271 (crash from race condition in SVG cache when using parallel rendering)

wonder-sk · wonder-sk · commit f3ff3b4fe678 · 2014-06-16T00:36:49.000+07:00
diff --git a/src/core/symbology-ng/qgssvgcache.cpp b/src/core/symbology-ng/qgssvgcache.cpp
@@ -109,6 +109,8 @@ QgsSvgCache::~QgsSvgCache()
 const QImage& QgsSvgCache::svgAsImage( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
                                        double widthScaleFactor, double rasterScaleFactor, bool& fitsInCache )
 {
+  QMutexLocker locker( &mMutex );
+
   fitsInCache = true;
   QgsSvgCacheEntry* currentEntry = cacheEntry( file, size, fill, outline, outlineWidth, widthScaleFactor, rasterScaleFactor );
 
@@ -152,6 +154,8 @@ const QImage& QgsSvgCache::svgAsImage( const QString& file, double size, const Q
 const QPicture& QgsSvgCache::svgAsPicture( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
     double widthScaleFactor, double rasterScaleFactor, bool forceVectorOutput )
 {
+  QMutexLocker locker( &mMutex );
+
   QgsSvgCacheEntry* currentEntry = cacheEntry( file, size, fill, outline, outlineWidth, widthScaleFactor, rasterScaleFactor );
 
   //if current entry picture is 0: cache picture for entry
diff --git a/src/core/symbology-ng/qgssvgcache.h b/src/core/symbology-ng/qgssvgcache.h
@@ -21,6 +21,7 @@
 #include <QColor>
 #include <QMap>
 #include <QMultiHash>
+#include <QMutex>
 #include <QString>
 #include <QUrl>
 
@@ -176,6 +177,9 @@ class CORE_EXPORT QgsSvgCache : public QObject
 
     /** SVG content to be rendered if SVG file was not found. */
     QByteArray mMissingSvg;
+
+    //! Mutex to prevent concurrent access to the class from multiple threads at once (may corrupt the entries otherwise).
+    QMutex mMutex;
 };
 
 #endif // QGSSVGCACHE_H
