mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-24 23:26:41 +00:00
149 lines
3.7 KiB
C++
149 lines
3.7 KiB
C++
/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2019 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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* --
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*
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* You can be released from the requirements of the license by purchasing
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* a commercial license. Buying such a license is mandatory as soon as you
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* develop commercial closed-source software that incorporates or links
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* directly against ZeroTier software without disclosing the source code
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* of your own application.
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*/
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#ifndef ZT_SHAREDPTR_HPP
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#define ZT_SHAREDPTR_HPP
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#include "Mutex.hpp"
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#include "AtomicCounter.hpp"
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namespace ZeroTier {
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/**
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* Simple zero-overhead introspective reference counted pointer
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*
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* This is an introspective shared pointer. Classes that need to be reference
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* counted must list this as a 'friend' and must have a private instance of
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* AtomicCounter called __refCount.
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*/
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template<typename T>
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class SharedPtr
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{
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public:
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inline SharedPtr() : _ptr((T *)0) {}
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inline SharedPtr(T *obj) : _ptr(obj) { ++obj->__refCount; }
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inline SharedPtr(const SharedPtr &sp) : _ptr(sp._getAndInc()) {}
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inline ~SharedPtr()
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{
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if (_ptr) {
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if (--_ptr->__refCount <= 0)
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delete _ptr;
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}
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}
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inline SharedPtr &operator=(const SharedPtr &sp)
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{
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if (_ptr != sp._ptr) {
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T *p = sp._getAndInc();
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if (_ptr) {
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if (--_ptr->__refCount <= 0)
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delete _ptr;
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}
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_ptr = p;
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}
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return *this;
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}
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/**
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* Set to a naked pointer and increment its reference count
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*
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* This assumes this SharedPtr is NULL and that ptr is not a 'zombie.' No
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* checks are performed.
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*
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* @param ptr Naked pointer to assign
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*/
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inline void set(T *ptr)
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{
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zero();
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++ptr->__refCount;
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_ptr = ptr;
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}
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/**
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* Swap with another pointer 'for free' without ref count overhead
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*
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* @param with Pointer to swap with
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*/
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inline void swap(SharedPtr &with)
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{
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T *tmp = _ptr;
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_ptr = with._ptr;
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with._ptr = tmp;
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}
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inline operator bool() const { return (_ptr != (T *)0); }
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inline T &operator*() const { return *_ptr; }
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inline T *operator->() const { 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 { return _ptr; }
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/**
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* Set this pointer to NULL
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*/
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inline void zero()
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{
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if (_ptr) {
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if (--_ptr->__refCount <= 0)
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delete _ptr;
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_ptr = (T *)0;
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}
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}
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/**
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* @return Number of references according to this object's ref count or 0 if NULL
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*/
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inline int references()
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{
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if (_ptr)
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return _ptr->__refCount.load();
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return 0;
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}
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inline bool operator==(const SharedPtr &sp) const { return (_ptr == sp._ptr); }
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inline bool operator!=(const SharedPtr &sp) const { return (_ptr != sp._ptr); }
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inline bool operator>(const SharedPtr &sp) const { return (_ptr > sp._ptr); }
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inline bool operator<(const SharedPtr &sp) const { return (_ptr < sp._ptr); }
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inline bool operator>=(const SharedPtr &sp) const { return (_ptr >= sp._ptr); }
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inline bool operator<=(const SharedPtr &sp) const { return (_ptr <= sp._ptr); }
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private:
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inline T *_getAndInc() const
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{
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if (_ptr)
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++_ptr->__refCount;
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return _ptr;
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}
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T *_ptr;
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};
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} // namespace ZeroTier
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#endif
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