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// -*- C++ -*-
//=============================================================================
/**
* @file True_RefCount_Policy.h
*
* Header file for TAO's true reference count policy (unrelated to
* CORBA policies).
*
* @author Ossama Othman <ossama@dre.vanderbilt.edu>
*/
//=============================================================================
#ifndef TAO_TRUE_REFCOUNT_POLICY_H
#define TAO_TRUE_REFCOUNT_POLICY_H
#include /**/ "ace/pre.h"
#include "tao/AnyTypeCode/TAO_AnyTypeCode_Export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "tao/orbconf.h"
#include "ace/Thread_Mutex.h"
#if defined (ACE_HAS_CPP11)
# include <atomic>
#else
# include "ace/Atomic_Op.h"
#endif /* ACE_HAS_CPP11 */
TAO_BEGIN_VERSIONED_NAMESPACE_DECL
namespace TAO
{
/**
* @class True_RefCount_Policy
*
* @brief True reference counting policy.
*
* This class is intended to be used as a "policy" argument to a
* host class template that requires true/functional reference
* counting. That class would then inherit privately from it like
* so:
*
* @code
* template <class RefCountPolicy>
* class MyHostClass : private RefCountPolicy
* {
* public:
* void my_add_ref (void) { this->RefCountPolicy::add_ref (); }
* void my_remove_ref (void) { this->RefCountPolicy::remove_ref (); }
* };
* @endcode
*
* and use it like so:
*
* @code
* typedef MyHostClass<TAO::True_RefCount_Policy> MyRefCountedClass;
* MyRefCountedClass * p = new MyRefCountedClass;
* ...
* p->my_remove_ref ();
* @endcode
*
* @note Ideally, the host class should declare a protected
* destructor to enforce proper memory management through the
* reference counting mechanism, i.e. to prevent clients from
* calling @c operator @c delete() directly on the host class
* object.
*/
class TAO_AnyTypeCode_Export True_RefCount_Policy
{
public:
/// Increase the reference count on this object.
void add_ref (void);
/// Decrease the reference count on this object.
/**
* Decrease the reference count on this object. Once the
* reference count drops to zero, call @c operator @c delete()
* on this object.
*/
void remove_ref (void);
protected:
/// Constructor.
/**
* @note This constructor is protected since it not meant to be
* instantiated/used as a standalone object.
*/
True_RefCount_Policy (void);
/// Destructor.
/**
* @note The destructor must be virtual to ensure that subclass
* destructors are called when the reference count drops to
* zero, i.e. when @c remove_ref() calls @c operator
* @c delete @c this.
*/
virtual ~True_RefCount_Policy (void);
private:
/// Reference counter.
#if defined (ACE_HAS_CPP11)
std::atomic<uint32_t> refcount_;
#else
ACE_Atomic_Op<TAO_SYNCH_MUTEX, unsigned long> refcount_;
#endif /* ACE_HAS_CPP11 */
};
} // End namespace TAO
TAO_END_VERSIONED_NAMESPACE_DECL
#ifdef __ACE_INLINE__
# include "tao/AnyTypeCode/True_RefCount_Policy.inl"
#endif /* __ACE_INLINE__ */
#include /**/ "ace/post.h"
#endif /* TAO_TRUE_REFCOUNT_POLICY_H */
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