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/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2017 ZeroTier, Inc. https://www.zerotier.com/
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* --
*
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial closed-source software that incorporates or links
* directly against ZeroTier software without disclosing the source code
* of your own application.
*/
#ifndef ZT_SHAREDPTR_HPP
#define ZT_SHAREDPTR_HPP
#include "Mutex.hpp"
#include "AtomicCounter.hpp"
namespace ZeroTier {
/**
* Simple reference counted pointer
*
* This is an introspective shared pointer. Classes that need to be reference
* counted must list this as a 'friend' and must have a private instance of
* AtomicCounter called __refCount. They should also have private destructors,
* since only this class should delete them.
*
* Because this is introspective, it is safe to apply to a naked pointer
* multiple times provided there is always at least one holding SharedPtr.
*
* Once C++11 is ubiquitous, this and a few other things like Thread might get
* torn out for their standard equivalents.
*/
template<typename T>
class SharedPtr
{
public:
SharedPtr()
throw() :
_ptr((T *)0)
{
}
SharedPtr(T *obj)
throw() :
_ptr(obj)
{
++obj->__refCount;
}
SharedPtr(const SharedPtr &sp)
throw() :
_ptr(sp._getAndInc())
{
}
~SharedPtr()
{
if (_ptr) {
if (--_ptr->__refCount <= 0)
delete _ptr;
}
}
inline SharedPtr &operator=(const SharedPtr &sp)
{
if (_ptr != sp._ptr) {
T *p = sp._getAndInc();
if (_ptr) {
if (--_ptr->__refCount <= 0)
delete _ptr;
}
_ptr = p;
}
return *this;
}
/**
* Set to a naked pointer and increment its reference count
*
* This assumes this SharedPtr is NULL and that ptr is not a 'zombie.' No
* checks are performed.
*
* @param ptr Naked pointer to assign
*/
inline void setToUnsafe(T *ptr)
{
++ptr->__refCount;
_ptr = ptr;
}
/**
* Swap with another pointer 'for free' without ref count overhead
*
* @param with Pointer to swap with
*/
inline void swap(SharedPtr &with)
throw()
{
T *tmp = _ptr;
_ptr = with._ptr;
with._ptr = tmp;
}
inline operator bool() const throw() { return (_ptr != (T *)0); }
inline T &operator*() const throw() { return *_ptr; }
inline T *operator->() const throw() { return _ptr; }
/**
* @return Raw pointer to held object
*/
inline T *ptr() const throw() { return _ptr; }
/**
* Set this pointer to NULL
*/
inline void zero()
{
if (_ptr) {
if (--_ptr->__refCount <= 0)
delete _ptr;
_ptr = (T *)0;
}
}
/**
* Set this pointer to NULL if this is the only pointer holding the object
*
* @return True if object was deleted and SharedPtr is now NULL (or was already NULL)
*/
inline bool reclaimIfWeak()
{
if (_ptr) {
if (++_ptr->__refCount <= 2) {
if (--_ptr->__refCount <= 1) {
delete _ptr;
_ptr = (T *)0;
return true;
} else {
return false;
}
} else {
return false;
}
} else {
return true;
}
}
inline bool operator==(const SharedPtr &sp) const throw() { return (_ptr == sp._ptr); }
inline bool operator!=(const SharedPtr &sp) const throw() { return (_ptr != sp._ptr); }
inline bool operator>(const SharedPtr &sp) const throw() { return (_ptr > sp._ptr); }
inline bool operator<(const SharedPtr &sp) const throw() { return (_ptr < sp._ptr); }
inline bool operator>=(const SharedPtr &sp) const throw() { return (_ptr >= sp._ptr); }
inline bool operator<=(const SharedPtr &sp) const throw() { return (_ptr <= sp._ptr); }
private:
inline T *_getAndInc() const
throw()
{
if (_ptr)
++_ptr->__refCount;
return _ptr;
}
T *_ptr;
};
} // namespace ZeroTier
#endif
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