mirror of
https://github.com/zerotier/ZeroTierOne.git
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100 lines
2.9 KiB
C++
100 lines
2.9 KiB
C++
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/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ZT_LOCKINGPTR_HPP
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#define ZT_LOCKINGPTR_HPP
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#include "Mutex.hpp"
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namespace ZeroTier {
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/**
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* A simple pointer that locks and holds a mutex until destroyed
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*
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* Care must be taken when using this. It's not very sophisticated and does
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* not handle being copied except for the simple return use case. When it is
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* copied it hands off the mutex to the copy and clears it in the original,
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* meaning that the mutex is unlocked when the last LockingPtr<> in a chain
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* of such handoffs is destroyed. If this chain of handoffs "forks" (more than
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* one copy is made) then non-determinism may ensue.
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*
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* This does not delete or do anything else with the pointer. It also does not
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* take care of locking the lock. That must be done beforehand.
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*/
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template<typename T>
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class LockingPtr
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{
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public:
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LockingPtr() :
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_ptr((T *)0),
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_lock((Mutex *)0)
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{
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}
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LockingPtr(T *obj,Mutex *lock) :
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_ptr(obj),
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_lock(lock)
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{
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}
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LockingPtr(const LockingPtr &p) :
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_ptr(p._ptr),
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_lock(p._lock)
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{
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const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
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}
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~LockingPtr()
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{
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if (_lock)
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_lock->unlock();
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}
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inline LockingPtr &operator=(const LockingPtr &p)
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{
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_ptr = p._ptr;
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_lock = p._lock;
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const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
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return *this;
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}
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inline operator bool() const throw() { return (_ptr != (T *)0); }
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inline T &operator*() const throw() { return *_ptr; }
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inline T *operator->() const throw() { return _ptr; }
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/**
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* @return Raw pointer to held object
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*/
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inline T *ptr() const throw() { return _ptr; }
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inline bool operator==(const LockingPtr &sp) const throw() { return (_ptr == sp._ptr); }
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inline bool operator!=(const LockingPtr &sp) const throw() { return (_ptr != sp._ptr); }
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inline bool operator>(const LockingPtr &sp) const throw() { return (_ptr > sp._ptr); }
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inline bool operator<(const LockingPtr &sp) const throw() { return (_ptr < sp._ptr); }
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inline bool operator>=(const LockingPtr &sp) const throw() { return (_ptr >= sp._ptr); }
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inline bool operator<=(const LockingPtr &sp) const throw() { return (_ptr <= sp._ptr); }
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private:
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T *_ptr;
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Mutex *_lock;
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};
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} // namespace ZeroTier
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#endif
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