Adding LockingPtr class to Loki project.

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@370 7ec92016-0320-0410-acc4-a06ded1c099a

include/loki/LockingPtr.h

@@ -0,0 +1,90 @@
+////////////////////////////////////////////////////////////////////////////////
+// The Loki Library
+// Copyright (c) 2001 by Andrei Alexandrescu
+// This code is from the article:
+//     "Generic<Programming>: volatile — Multithreaded Programmer’s Best Friend
+//     Volatile-Correctness or How to Have Your Compiler Detect Race Conditions
+//     for You" by Alexandrescu, Andrei.
+//     Published in the February 2001 issue of the C/C++ Users Journal.
+//     http://www.cuj.com/documents/s=7998/cujcexp1902alexandr/
+// Prepared for Loki library by Richard Sposato
+////////////////////////////////////////////////////////////////////////////////
+
+// $Header$
+
+
+#ifndef LOKI_LOCKING_PTR_INC_
+#define LOKI_LOCKING_PTR_INC_
+
+namespace Loki
+{
+
+    /** @class LockingPtr
+     Locks a volatile object and casts away volatility so that the object
+     can be safely used in a single-threaded region of code.
+     Original version of LockingPtr had only one template - for the shared
+     object, but not the mutex type.  This version allows users to specify a
+     the mutex type as a LockingPolicy class.  The only requirements for a
+     LockingPolicy class are to provide Lock and Unlock methods.
+     */
+    template < typename SharedObject, typename LockingPolicy >
+    class LockingPtr
+    {
+    public:
+
+        /** Constructor locks mutex associated with an object.
+         @param obj Reference to object.
+         @param mtx Mutex used to control thread access to object.
+         */
+        LockingPtr( volatile SharedObject & object, LockingPolicy & mutex )
+           : pObject_( const_cast< SharedObject * >( &object ) ),
+            pMutex_( &mutex )
+        {
+            mutex.Lock();
+        }
+
+        /// Destructor unlocks the mutex.
+        ~LockingPtr()
+        {
+            pMutex_->Unlock();
+        }
+
+        /// Star-operator dereferences pointer.
+        T & operator * ()
+        {
+            return *pObject_;
+        }
+
+        /// Point-operator returns pointer to object.
+        T * operator -> ()
+        {
+            return pObject_;
+        }
+
+    private:
+
+        /// Default constructor is not implemented.
+        LockingPtr();
+
+        /// Copy-constructor is not implemented.
+        LockingPtr( const LockingPtr & );
+
+        /// Copy-assignment-operator is not implemented.
+        LockingPtr & operator = ( const LockingPtr & );
+
+        /// Pointer to the shared object.
+        SharedObject * pObject_;
+
+        /// Pointer to the mutex.
+        LockingPolicy * pMutex_;
+
+    }; // end class LockingPtr
+
+} // namespace Loki
+
+#endif  // end file guardian
+
+// $Log$
+// Revision 1.1  2005/11/19 22:00:23  rich_sposato
+// Adding LockingPtr class to Loki project.
+//