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// -*- C++ -*-
/**
* @file Refcountable.h
*
* $Id$
*
* @author Pradeep Gore <pradeep@oomworks.com>
*/
#ifndef TAO_Notify_REFCOUNTABLE_H
#define TAO_Notify_REFCOUNTABLE_H
#include /**/ "ace/pre.h"
#include "notify_serv_export.h"
#include "Refcountable_Guard_T.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "tao/orbconf.h"
#include "tao/Basic_Types.h"
#include "ace/Synch_Traits.h"
#include "ace/Thread_Mutex.h"
#include "ace/Atomic_Op.h"
TAO_BEGIN_VERSIONED_NAMESPACE_DECL
/**
* @class TAO_Notify_Refcountable
*
* @brief Thread-safe refounting, calls the <release> method when
* refcount falls to 0.
*
* The refcount is initialized to 0. When an instance of a derived
* class becomes owned by a managed pointer (Refcountable_Guard_T)
* the reference count becomes non-zero. A debug message is printed
* from the destructor if a refcounted is deleted with a non-zero
* refcount.
*
* Instances declared on the stack should always have a refcount of
* zero.
*
* A method that creates or simply returns an instance of Refcountable
* should not increment the reference count. It is the responsibility
* of the client to increment the reference count (take ownership or
* guard against deletion). The client cannot know if the method will
* or will not incr the refcount in its behalf.
*
* Use Refcountable_Guard_T or similar service to guarantee the
* exception safe direct pairing of increments and decrements. Avoid
* calling _incr_refcnt and _decr_refcnt.
*/
class TAO_Notify_Serv_Export TAO_Notify_Refcountable
{
public:
typedef TAO_Notify_Refcountable_Guard_T< TAO_Notify_Refcountable > Ptr;
typedef long Counter;
/// Constuctor
TAO_Notify_Refcountable (void);
/// Destructor
/// public for stack allocated instances
virtual ~TAO_Notify_Refcountable ();
/// This method sigantures deliberately match the RefCounting methods required for ESF Proxy
/// Public for bridge implementations and various guard classes
CORBA::ULong _incr_refcnt (void);
CORBA::ULong _decr_refcnt (void);
protected:
/// The mutex to serialize access to state variables.
TAO_SYNCH_MUTEX lock_;
/// Accessor for debugging.
#ifdef _DEBUG
Counter refcount (void) const;
#endif
private:
/// The release method is called when the refcount reaches 0.
virtual void release (void) = 0;
ACE_Atomic_Op< TAO_SYNCH_MUTEX, Counter > refcount_;
};
TAO_END_VERSIONED_NAMESPACE_DECL
#include /**/ "ace/post.h"
#endif /* TAO_Notify_REFCOUNTABLE_H */
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