Question

经过很长一段时间后，我相信我的代码存在的问题是我对同一个对象有多个智能指针引用，导致该对象被多个智能指针删除。我尽可能地压缩代码而不会忽略程序的想法。

目前，我得到的错误是seg。故障。我相信我的双引用会在这一行创建。

newProtocol->SetCPU(CPUPtr(this));

我的问题是对同一个对象的双重引用，如果是，我该如何解决？

#include <iostream>
#include <map>
using namespace std;

#include "boost/weak_ptr.hpp"
#include <boost/shared_ptr.hpp>

class TCPProtocol;
class CPU;
class TCPConnection;

typedef boost::shared_ptr<TCPProtocol> TCPProtocolPtr;
typedef boost::shared_ptr<CPU> CPUPtr;
typedef boost::shared_ptr<TCPConnection> TCPConnectionPtr;


class Protocol
{
    public:
    string GetName() const;
    string _name;
};

class TCPProtocol : public Protocol
{
    public:
        static TCPProtocolPtr Create(){return(TCPProtocolPtr(new TCPProtocol()));}
        static TCPProtocolPtr Create(const TCPProtocol &Protocol
        {
            return(TCPProtocolPtr(new TCPProtocol(Protocol)));
        }
        void SetCPU(boost::shared_ptr<CPU> CPU){ _CPU = CPU; }

    protected:
        boost::weak_ptr<CPU> _CPU;
};

class CPU
{
    public:
    typedef std::map<std::string, TCPProtocolPtr> ProtocolMap;

    public:
        CPU(const CPU& obj);
        CPU(TCPConnectionPtr connection){}
        static CPUPtr Create(const TCPConnectionPtr connection)
        {
            return(CPUPtr(new CPU(connection)));
        }
        void AddProtocol(const TCPProtocolPtr ProtocolPtr);
        void SetCPU(boost::shared_ptr<CPU> CPU);
        ProtocolMap Protocols();
        const ProtocolMap Protocols() const;
        ProtocolMap _Protocols;
};

 class TCPConnection
 {
      public:
          static TCPConnectionPtr Create()
          {
              return(TCPConnectionPtr(new TCPConnection()));
          }
          void SetVersion(int version){ _version = version; }       

      private: 
          int _version;
};

int main()
{
    //Create a connection to an CPU
    TCPConnectionPtr CPUConnection = TCPConnection::Create();

    //Define needed connection parameters
    CPUConnection->SetVersion(123);

    //Create an CPU
    CPUPtr CPU = CPU::Create(CPUConnection);

    //Create an instance of TCPProtocol
    TCPProtocolPtr ProtocolPtr = TCPProtocol::Create();

    //Add the protocol to the CPU
    CPU->AddProtocol(ProtocolPtr);
}

CPU::CPU(const CPU& obj) 
{
    //Iterate through rhs map and insert its pairs into the lhs map
    for(ProtocolMap::const_iterator i = obj._Protocols.begin(); 
         i != obj._Protocols.end(); ++i)
    {
        TCPProtocolPtr p = TCPProtocol::Create();
        *p = *(i->second);
        AddProtocol(p);
    }
}

void CPU::AddProtocol(const TCPProtocolPtr ProtocolPtr)
{
    TCPProtocolPtr newProtocol = TCPProtocol::Create(*ProtocolPtr);
    std::string name = newProtocol->_name;
    newProtocol->SetCPU(CPUPtr(this));
    _Protocols[name] = newProtocol;

}

Answer 1

在R. Martinho Fernandes的评论中提示后，我使用了

boost::enable_shared_from_this<CPU>

摆脱双重引用。我更新的代码部分如下所示。

我公开继承自boost::enable_shared_from_this<>并创建了一个名为share的方法，该方法将返回对象的引用并保持引用计数正确。

class CPU : public boost::enable_shared_from_this<CPU>
{
   ...
   boost::shared_ptr<CPU> Share()
   {
       return shared_from_this();
   }
};

void CPU::AddProtocol(const TCPProtocolPtr ProtocolPtr)
{
   ...
    newProtocol->SetCPU(CPUPtr(this));
    _Protocols[name] = newProtocol;

}

对同一对象的多个智能指针引用

1 个答案: