4a46d84c35
git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@538 7ec92016-0320-0410-acc4-a06ded1c099a
123 lines
3.8 KiB
C++
Executable file
123 lines
3.8 KiB
C++
Executable file
////////////////////////////////////////////////////////////////////////////////
|
||
// 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_
|
||
|
||
#include <loki/ConstPolicy.h>
|
||
|
||
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 = LOKI_DEFAULT_MUTEX,
|
||
template<class> class ConstPolicy = LOKI_DEFAULT_CONSTNESS >
|
||
class LockingPtr
|
||
{
|
||
public:
|
||
|
||
typedef typename ConstPolicy<SharedObject>::Type ConstOrNotType;
|
||
|
||
/** Constructor locks mutex associated with an object.
|
||
@param obj Reference to object.
|
||
@param mtx Mutex used to control thread access to object.
|
||
*/
|
||
LockingPtr( volatile ConstOrNotType & object, LockingPolicy & mutex )
|
||
: pObject_( const_cast< SharedObject * >( &object ) ),
|
||
pMutex_( &mutex )
|
||
{
|
||
mutex.Lock();
|
||
}
|
||
|
||
/// Destructor unlocks the mutex.
|
||
~LockingPtr()
|
||
{
|
||
pMutex_->Unlock();
|
||
}
|
||
|
||
/// Star-operator dereferences pointer.
|
||
ConstOrNotType & operator * ()
|
||
{
|
||
return *pObject_;
|
||
}
|
||
|
||
/// Point-operator returns pointer to object.
|
||
ConstOrNotType * 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.
|
||
ConstOrNotType * pObject_;
|
||
|
||
/// Pointer to the mutex.
|
||
LockingPolicy * pMutex_;
|
||
|
||
}; // end class LockingPtr
|
||
|
||
} // namespace Loki
|
||
|
||
#endif // end file guardian
|
||
|
||
|
||
|
||
// $Log$
|
||
// Revision 1.10 2006/02/20 21:45:40 rich_sposato
|
||
// Removed struct Locking - no longer needed.
|
||
//
|
||
// Revision 1.9 2006/02/19 22:04:28 rich_sposato
|
||
// Moved Const-policy structs from SmartPtr.h to ConstPolicy.h.
|
||
//
|
||
// Revision 1.8 2006/01/30 20:33:01 syntheticpp
|
||
// use policies from SmartPtr.h, clean up
|
||
//
|
||
// Revision 1.7 2006/01/22 13:37:33 syntheticpp
|
||
// use macro LOKI_DEFAULT_MUTEX for Mutex default value, defined in Threads.h
|
||
//
|
||
// Revision 1.6 2006/01/21 14:09:09 syntheticpp
|
||
// replace LockPtr/ConstLockPtr implementation with a template policy based one
|
||
//
|
||
// Revision 1.5 2006/01/21 01:02:12 rich_sposato
|
||
// Added Mutex class to Loki. Made it the default policy class for locking.
|
||
//
|
||
// Revision 1.4 2006/01/19 19:34:19 rich_sposato
|
||
// Added ConstLockingPtr class.
|
||
//
|
||
// Revision 1.3 2006/01/16 18:34:37 rich_sposato
|
||
// Changed return type from LockingPtr to SharedObject.
|
||
//
|
||
// Revision 1.2 2006/01/14 00:20:10 syntheticpp
|
||
// remove c&p error
|
||
//
|
||
// Revision 1.1 2005/11/19 22:00:23 rich_sposato
|
||
// Adding LockingPtr class to Loki project.
|
||
//
|