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////////////////////////////////////////////////////////////////////////////////
//
// RefCount.hh (completely deprecated since not thread-safe)
//
// produced: 05/02/98 jr
// last change: 05/02/98 jr
//
////////////////////////////////////////////////////////////////////////////////
#ifndef REFCOUNT_HH
#define REFCOUNT_HH
#include <memory>
#include <atomic>
namespace topcom {
// reference counter must be atomic for multi-threading:
typedef std::atomic<unsigned long> refcount_type;
// typedef unsigned long refcount_type;
class RefCount {
private:
refcount_type _refcount;
public:
inline void pick_reference();
inline void drop_reference();
inline RefCount();
inline RefCount(const RefCount&);
inline ~RefCount();
inline const refcount_type& refcount() const;
};
inline void RefCount::pick_reference() {
++_refcount;
#ifdef REFCOUNT_DEBUG
std::cout << "pick_reference(): refcount = " << _refcount
<< " to address " << this << std::endl;
#endif
}
inline void RefCount::drop_reference() {
--_refcount;
#ifdef REFCOUNT_DEBUG
std::cout << "drop_reference(): refcount = " << _refcount
<< " to address " << this << std::endl;
#endif
}
inline RefCount::RefCount() : _refcount(0) {}
inline RefCount::RefCount(const RefCount&) : _refcount(0) {}
inline RefCount::~RefCount() {}
inline const refcount_type& RefCount::refcount() const {
return _refcount;
}
template <class T>
class SmartPtr {
private:
class RefCountData : public RefCount {
public:
T _data;
public:
RefCountData() : RefCount(), _data() {}
RefCountData(const RefCountData& rcd) : RefCount(rcd), _data(rcd._data) {}
RefCountData(const T& obj) : RefCount(), _data(obj) {}
~RefCountData() {}
};
private:
// typedef std::simple_alloc<RefCountData, std::alloc> data_allocator;
std::allocator<RefCountData> data_allocator;
private:
RefCountData* _bufptr;
private:
RefCountData* _ptr;
public:
// constructors:
inline SmartPtr();
inline SmartPtr(const SmartPtr&);
inline SmartPtr(const T&);
// destructor:
inline ~SmartPtr();
// assignment:
inline SmartPtr& operator=(const SmartPtr&);
// static nullpointer:
inline static SmartPtr& smartnullptr();
// casts:
inline operator bool() const;
// accessors:
inline const refcount_type refcount() const;
// operators:
inline const T* operator->() const;
inline T* operator->();
inline const T& operator*() const;
inline T& operator*();
inline const bool operator==(const SmartPtr& p) const;
inline const bool operator!=(const SmartPtr& p) const;
};
// constructors:
template <class T>
inline SmartPtr<T>::SmartPtr() : _ptr(NULL) {
#ifdef CONSTRUCTOR_DEBUG
std::cout << "SmartPtr<T>::SmartPtr()" << std::endl;
#endif
}
template <class T>
inline SmartPtr<T>::SmartPtr(const SmartPtr& p) : _ptr(p._ptr) {
#ifdef CONSTRUCTOR_DEBUG
std::cout << "SmartPtr<T>::SmartPtr(const SmartPtr&)" << std::endl;
#endif
if (_ptr) {
_ptr->pick_reference();
}
}
template <class T>
inline SmartPtr<T>::SmartPtr(const T& obj) {
#ifdef CONSTRUCTOR_DEBUG
std::cout << "SmartPtr<T>::SmartPtr(const T&)" << std::endl;
#endif
_ptr = data_allocator.allocate(1);
std::allocator_traits<std::allocator<RefCountData> >::construct(data_allocator, _ptr, obj);
_ptr->pick_reference();
}
// destructor:
template <class T>
inline SmartPtr<T>::~SmartPtr() {
#ifdef CONSTRUCTOR_DEBUG
std::cout << "SmartPtr<T>::~SmartPtr()" << std::endl;
#endif
if (_ptr) {
if (_ptr->refcount() == 1) {
#ifdef REFCOUNT_DEBUG
std::cout << "DESTROY " << _ptr->_data << std::endl;
#endif
std::allocator_traits<std::allocator<RefCountData> >::destroy(data_allocator, _ptr);
data_allocator.deallocate(_ptr, 1);
_ptr = NULL;
}
else {
_ptr->drop_reference();
}
}
}
// assignment:
template <class T>
inline SmartPtr<T>& SmartPtr<T>::operator=(const SmartPtr& p) {
#ifdef CONSTRUCTOR_DEBUG
std::cout << "SmartPtr<T>::operator=(const SmartPtr&)" << std::endl;
#endif
if (_ptr) {
if (_ptr->refcount() == 1) {
std::allocator_traits<std::allocator<RefCountData> >::destroy(data_allocator, _ptr);
data_allocator.deallocate(_ptr, 1);
_ptr = NULL;
}
else {
_ptr->drop_reference();
}
}
_ptr = p._ptr;
if (_ptr) {
_ptr->pick_reference();
}
return *this;
}
// casts:
template <class T>
inline SmartPtr<T>::operator bool() const {
return (_ptr != NULL);
}
// accessors:
template <class T>
inline const refcount_type SmartPtr<T>::refcount() const {
return _ptr->refcount();
}
// static nullpointer:
template <class T>
inline SmartPtr<T>& SmartPtr<T>::smartnullptr() {
static SmartPtr<T> smartnullptr;
return smartnullptr;
}
// operators:
template <class T>
inline const T* SmartPtr<T>::operator->() const {
return &_ptr->_data;
}
template <class T>
inline T* SmartPtr<T>::operator->() {
if (_ptr) {
if (_ptr->refcount() > 1) {
#ifdef DEBUG
std::cout << "T* SmartPtr<T>::operator->(): copy for overwrite" << std::endl;
#endif
_ptr->drop_reference();
_bufptr = _ptr;
_ptr = data_allocator.allocate(1);
std::allocator_traits<std::allocator<RefCountData> >::construct(data_allocator, _ptr, *_bufptr);
_ptr->pick_reference();
}
}
return &_ptr->_data;
}
template <class T>
inline const T& SmartPtr<T>::operator*() const {
return std::ref(_ptr->_data);
}
template <class T>
inline T& SmartPtr<T>::operator*() {
if (_ptr) {
if (_ptr->refcount() > 1) {
#ifdef DEBUG
std::cout << "T& SmartPtr<T>::operator*(): copy for overwrite" << std::endl;
#endif
_ptr->drop_reference();
_bufptr = _ptr;
_ptr = data_allocator.allocate(1);
std::allocator_traits<std::allocator<RefCountData> >::construct(data_allocator, _ptr, *_bufptr);
_ptr->pick_reference();
}
}
return std::ref(_ptr->_data);
}
template <class T>
inline const bool SmartPtr<T>::operator==(const SmartPtr<T>& p) const {
return (_ptr == p._ptr);
}
template <class T>
inline const bool SmartPtr<T>::operator!=(const SmartPtr<T>& p) const {
return (!(*this == p));
}
}; // namespace topcom
#endif
// eof RefCount.hh
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