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/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2016 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/>.
*/
#ifndef ZT_LOCKINGPTR_HPP
#define ZT_LOCKINGPTR_HPP
#include "Mutex.hpp"
namespace ZeroTier {
/**
* A simple pointer that locks and holds a mutex until destroyed
*
* Care must be taken when using this. It's not very sophisticated and does
* not handle being copied except for the simple return use case. When it is
* copied it hands off the mutex to the copy and clears it in the original,
* meaning that the mutex is unlocked when the last LockingPtr<> in a chain
* of such handoffs is destroyed. If this chain of handoffs "forks" (more than
* one copy is made) then non-determinism may ensue.
*
* This does not delete or do anything else with the pointer. It also does not
* take care of locking the lock. That must be done beforehand.
*/
template<typename T>
class LockingPtr
{
public:
LockingPtr() :
_ptr((T *)0),
_lock((Mutex *)0)
{
}
LockingPtr(T *obj,Mutex *lock) :
_ptr(obj),
_lock(lock)
{
}
LockingPtr(const LockingPtr &p) :
_ptr(p._ptr),
_lock(p._lock)
{
const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
}
~LockingPtr()
{
if (_lock)
_lock->unlock();
}
inline LockingPtr &operator=(const LockingPtr &p)
{
_ptr = p._ptr;
_lock = p._lock;
const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
return *this;
}
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; }
inline bool operator==(const LockingPtr &sp) const throw() { return (_ptr == sp._ptr); }
inline bool operator!=(const LockingPtr &sp) const throw() { return (_ptr != sp._ptr); }
inline bool operator>(const LockingPtr &sp) const throw() { return (_ptr > sp._ptr); }
inline bool operator<(const LockingPtr &sp) const throw() { return (_ptr < sp._ptr); }
inline bool operator>=(const LockingPtr &sp) const throw() { return (_ptr >= sp._ptr); }
inline bool operator<=(const LockingPtr &sp) const throw() { return (_ptr <= sp._ptr); }
private:
T *_ptr;
Mutex *_lock;
};
} // namespace ZeroTier
#endif
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