From Frashud Lashkari, "I was getting "Unsupported wrapper class..." error messages when attempting to load osgb models simultaneously from multiple threads. I believe the problem is caused by un-synchronized access to the global osgDB::ObjectWrapperManager class. I've attached a change that adds a mutex to the class and uses it when accessing the internal wrapper/compress maps. This appears to fix the issues I was having."

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14880 16af8721-9629-0410-8352-f15c8da7e697

include/osgDB/ObjectWrapper

@@ -15,6 +15,7 @@
 #ifndef OSGDB_OBJECTWRAPPER
 #define OSGDB_OBJECTWRAPPER
 
+#include <OpenThreads/ReentrantMutex>
 #include <osgDB/Serializer>
 #include <osg/ScriptEngine>
 
@@ -169,6 +170,8 @@ protected:
     ObjectWrapperManager();
     virtual ~ObjectWrapperManager();
 
+    OpenThreads::ReentrantMutex _wrapperMutex;
+
     WrapperMap _wrappers;
     CompressorMap _compressors;