diff --git a/include/loki/LockingPtr.h b/include/loki/LockingPtr.h new file mode 100755 index 0000000..0fb406a --- /dev/null +++ b/include/loki/LockingPtr.h @@ -0,0 +1,90 @@ +//////////////////////////////////////////////////////////////////////////////// +// The Loki Library +// Copyright (c) 2001 by Andrei Alexandrescu +// This code is from the article: +// "Generic: 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. +//