mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-19 04:57:53 +00:00
136 lines
2.9 KiB
C++
136 lines
2.9 KiB
C++
/*
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* Copyright (c)2019 ZeroTier, Inc.
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file in the project's root directory.
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*
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* Change Date: 2025-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2.0 of the Apache License.
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*/
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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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SharedPtr() : _ptr((T *)0) {}
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SharedPtr(T *obj) : _ptr(obj) { ++obj->__refCount; }
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SharedPtr(const SharedPtr &sp) : _ptr(sp._getAndInc()) {}
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~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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