shared_ptr_tencent.cpp

#include <iostream>
#include <mutex>
#include <thread>
using namespace std;

// https://cloud.tencent.com/developer/article/1688444

template <class T>
class Shared_Ptr {
  public:
    Shared_Ptr(T *ptr = nullptr)
        : _pPtr(ptr), _pRefCount(new int(1)), _pMutex(new mutex) {}
    ~Shared_Ptr() { Release(); }
    Shared_Ptr(const Shared_Ptr<T> &sp)
        : _pPtr(sp._pPtr), _pRefCount(sp._pRefCount), _pMutex(sp._pMutex) {
        AddRefCount();
    }
    Shared_Ptr<T> &operator=(const Shared_Ptr<T> &sp) {
        // if (this != &sp)
        if (_pPtr != sp._pPtr) {
            // 释放管理的旧资源
            Release();
            // 共享管理新对象的资源，并增加引用计数
            _pPtr = sp._pPtr;
            _pRefCount = sp._pRefCount;
            _pMutex = sp._pMutex;
            AddRefCount();
        }
        return *this;
    }
    T &operator*() { return *_pPtr; }
    T *operator->() { return _pPtr; }
    int UseCount() { return *_pRefCount; }
    T *Get() { return _pPtr; }
    void AddRefCount() {
        _pMutex->lock();
        ++(*_pRefCount);
        _pMutex->unlock();
    }

  private:
    void Release() {
        bool deleteflag = false;
        _pMutex->lock();
        if (--(*_pRefCount) == 0) {
            delete _pRefCount;
            delete _pPtr;
            deleteflag = true;
        }
        _pMutex->unlock();
        if (deleteflag == true)
            delete _pMutex;
    }

  private:
    int *_pRefCount;
    T *_pPtr;
    mutex *_pMutex;
};