Moved OpenThreads directly into OpenSceneGraph/trunk rather than being introduced via svn:externals.

This change has been done to make it easier for OpenSceneGraph users to check out the svn via https 
without any conflicts introduced with a http externals.

include/OpenThreads/ReentrantMutex

@@ -0,0 +1,125 @@
+/* -*-c++-*- OpenThreads - Copyright (C) 1998-2007 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 _OPENTHREADS_REENTRANTMUTEX_
+#define _OPENTHREADS_REENTRANTMUTEX_
+
+#include <OpenThreads/Thread>
+#include <OpenThreads/Mutex>
+#include <OpenThreads/ScopedLock>
+
+namespace OpenThreads {
+
+class ReentrantMutex : public OpenThreads::Mutex
+{
+    public:
+
+        ReentrantMutex():
+            _threadHoldingMutex(0),
+            _lockCount(0) {}
+
+        virtual ~ReentrantMutex() {}
+
+        virtual int lock()
+        {
+            if (_threadHoldingMutex==OpenThreads::Thread::CurrentThread() && _lockCount>0)
+            {
+                OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_lockCountMutex);
+                ++_lockCount;
+                return 0;
+            }
+            else
+            {
+                int result = Mutex::lock();
+                if (result==0)
+                {
+                    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_lockCountMutex);
+
+                    _threadHoldingMutex = OpenThreads::Thread::CurrentThread();
+                    _lockCount = 1;
+                }
+                return result;
+            }
+        }
+
+
+        virtual int unlock()
+        {
+            OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_lockCountMutex);
+        #if 0
+            if (_threadHoldingMutex==OpenThreads::Thread::CurrentThread() && _lockCount>0)
+            {
+                --_lockCount;
+                if (_lockCount<=0)
+                {
+                    _threadHoldingMutex = 0;
+                    return Mutex::unlock();
+                }
+            }
+            else
+            {
+                osg::notify(osg::NOTICE)<<"Error: ReentrantMutex::unlock() - unlocking from the wrong thread."<<std::endl;
+            }
+        #else
+            if (_lockCount>0)
+            {
+                --_lockCount;
+                if (_lockCount<=0)
+                {
+                    _threadHoldingMutex = 0;
+                    return Mutex::unlock();
+                }
+            }
+        #endif    
+            return 0;
+        }
+        
+
+        virtual int trylock()
+        {
+            if (_threadHoldingMutex==OpenThreads::Thread::CurrentThread() && _lockCount>0)
+            {
+                OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_lockCountMutex);
+                ++_lockCount;
+                return 0;
+            }
+            else
+            {
+                int result = Mutex::trylock();
+                if (result==0)
+                {
+                    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_lockCountMutex);
+
+                    _threadHoldingMutex = OpenThreads::Thread::CurrentThread();
+                    _lockCount = 1;
+                }
+                return result;
+            }
+        }
+
+    private:
+
+        ReentrantMutex(const ReentrantMutex&):OpenThreads::Mutex() {}
+
+        ReentrantMutex& operator =(const ReentrantMutex&) { return *(this); }
+        
+        OpenThreads::Thread* _threadHoldingMutex;
+        
+        OpenThreads::Mutex  _lockCountMutex;
+        unsigned int        _lockCount;
+
+};
+
+}
+
+#endif