Added osgDB::ReentrantMutex is prep for making osgDB::Registry single threaded.

VisualStudio/osgDB/osgDB.dsp

@@ -155,6 +155,10 @@ SOURCE=..\..\Src\osgDB\Registry.cpp
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\Src\osgDB\ReentrantMutex.cpp
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\src\osgDB\SharedStateManager.cpp
 # End Source File
 # Begin Source File
@@ -239,6 +243,10 @@ SOURCE=..\..\Include\osgDB\Registry
 # End Source File
 # Begin Source File
 
+SOURCE=..\..\Include\osgDB\ReentrantMutex
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\Include\osgDB\SharedStateManager
 # End Source File
 # Begin Source File

include/osgDB/ReentrantMutex

@@ -0,0 +1,51 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
+ *
+ * This library is open source and may be redistributed and/or modified under  
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+ * OpenSceneGraph Public License for more details.
+*/
+
+#ifndef OSGDB_REENTRANTMUTEX
+#define OSGDB_REENTRANTMUTEX
+
+#include <OpenThreads/Thread>
+#include <OpenThreads/Mutex>
+
+#include <osgDB/Export>
+
+namespace osgDB {
+
+class OSGDB_EXPORT ReentrantMutex : public OpenThreads::Mutex
+{
+    public:
+
+        ReentrantMutex();
+
+        virtual ~ReentrantMutex();
+
+        virtual int lock();
+
+        virtual int unlock();
+
+        virtual int trylock();
+
+    private:
+
+        ReentrantMutex(const ReentrantMutex &):Mutex() {}
+
+        ReentrantMutex &operator=(const ReentrantMutex &) {return *(this);}
+        
+        OpenThreads::Thread* _threadHoldingMutex;
+        unsigned int         _lockCount;
+
+};
+
+}
+
+#endif

src/osgDB/GNUmakefile

@@ -9,6 +9,7 @@ CXXFILES =\
 	FileUtils.cpp\
 	ReadFile.cpp\
 	ReaderWriter.cpp\
+	ReentrantMutex.cpp\
 	Registry.cpp\
 	Version.cpp\
 	WriteFile.cpp\