Question

我是boost :: asio的初学者，所以请帮助我。

我需要编写单线程TCP服务器。服务器应接受客户端连接并连续从客户端套接字读取输入数据。服务器应定期向客户端发送数据。所以我遇到了一些问题 - 所有例子都描述了我们总是有循环的情况

async_receive（）
on_receive（） - ＆gt; ASYNC_WRITE（）
on_write（） - ＆gt;转到1：）

所以我决定使用timer来检查要发送到套接字的数据。

我写了测试服务器，并且有非常奇怪的行为 - 如果客户端连接，执行某些操作并且使用一些时间增量一个接一个地断开连接，它可以正常工作。但如果所有客户端同时断开连接我都有计时器处理程序尝试使用已经DESTROYED对象的成员类时的情况（锁定关键部分）。

我无法描述为什么！请帮忙！

[此视频展示了如何复制]（http://www.youtube.com/watch?v=NMWkD7rqf7Y&feature=youtu.be“1080p”）

谢谢！

#include <boost/none.hpp>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>

#include <iostream>




using namespace boost::asio;
using namespace boost::posix_time;



class CIncommingConnection ;
typedef boost::shared_ptr<CIncommingConnection> CIncommingConnectionPtr;


struct IIncomingServer
{
    virtual  void OnData(CIncommingConnectionPtr pConn, const char *pData, size_t bytes) = 0;
    virtual  void OnConnected(CIncommingConnectionPtr pConn) = 0;
    virtual  void OnDisconnected(const boost::system::error_code& err, CIncommingConnectionPtr pConn) = 0;
};



class CAutoLock
{
public:
    CAutoLock(CRITICAL_SECTION &cs)  :
      m_cs(cs)
    {
        ::EnterCriticalSection(&m_cs);
    }

   ~CAutoLock()
   {
       ::LeaveCriticalSection(&m_cs);
   }

private:
    CRITICAL_SECTION &m_cs;
};

class CIncommingConnection :  public boost::enable_shared_from_this<CIncommingConnection>                      
                             ,boost::noncopyable 
{
public:

    CIncommingConnection(const std::string sPeerName, boost::asio::io_service  &service, IIncomingServer *pServer) :
     m_service(service)
    ,sock_(service)
    ,m_sPeerName(sPeerName) 
    ,m_pServer(pServer)
    ,m_timer(service)
    {
        ::InitializeCriticalSection(&m_cs);

        std::cout << "CIncommingConnection()"  << std::endl ;
    }


    ~CIncommingConnection()
    {
        std::cout << "CIncommingConnection()~"  << std::endl ;
        ::DeleteCriticalSection(&m_cs);
    }


    ip::tcp::socket & sock()
    {
        return sock_;
    }



    void start()
    {
        m_pServer->OnConnected(shared_from_this());
        do_read();
        wait_for_outgoingdata();
    }


private:

    void stop()
    {      
        sock_.close();
        m_timer.cancel();
    }



    void do_read()
    {
        sock_.async_receive(buffer(read_buffer_), boost::bind(&CIncommingConnection::handler_read, this, _1, _2) );
    }



    void do_error(const boost::system::error_code& error)
    {
        CIncommingConnectionPtr pConn = shared_from_this();

        stop() ;

        m_pServer->OnDisconnected(error, pConn);
    }



    void handler_read(const boost::system::error_code& error, std::size_t bytes)
    {
        if (error)
        {
            do_error(error);
            return ;
        }

        CIncommingConnectionPtr pConn = shared_from_this() ;

        m_pServer->OnData(pConn, read_buffer_, bytes);

        do_read();
    }



    void wait_for_outgoingdata()
    {
        m_timer.expires_from_now( boost::posix_time::millisec( 100 ) );
        m_timer.async_wait( boost::bind( &CIncommingConnection::on_output_queue_timer, this, _1 ) );
    }



    void on_output_queue_timer(const boost::system::error_code& error)
    {
        if (error == boost::asio::error::operation_aborted)
        {
            return ;
        }

        CAutoLock oLock(m_cs);

        if (!m_sOutBuf.empty())
            sock_.async_send(buffer(m_sOutBuf), boost::bind(&CIncommingConnection::handler_write, this, _1, _2) );
        else
            wait_for_outgoingdata();
    }


    void handler_write(const boost::system::error_code& error, std::size_t bytes)
    {    
        if (error)
            return ;


        if (bytes)
        {
            m_sOutBuf = m_sOutBuf.substr(bytes, m_sOutBuf.length()-bytes);
        }

        wait_for_outgoingdata();
    }



private:
    ip::tcp::socket sock_;

    enum { max_msg = 1024 };
    char read_buffer_[max_msg];
    char write_buffer_[max_msg];


    boost::asio::io_service        &m_service ;   
    std::string                     m_sPeerName ;
    std::string                     m_sOutBuf;
    CRITICAL_SECTION                m_cs ;
    IIncomingServer                *m_pServer;
    boost::asio::deadline_timer     m_timer;
};






class CIncomingServer :   public boost::enable_shared_from_this<CIncomingServer>                      
                         , public IIncomingServer
                         , boost::noncopyable 
{

public:

    CIncomingServer(boost::asio::io_service  &service,
        unsigned int port,
        bool bAllowManyConnections,
        const std::string sPeerName) :

      m_acceptor (service, ip::tcp::endpoint(ip::tcp::v4(), port), false)
     ,m_sPeerName(sPeerName)
     ,m_port(port) 
     ,m_service(service)
     ,m_timer(service)
     ,m_bAllowManyConnections(bAllowManyConnections)
    {
    }



    ~CIncomingServer()
    {
    }



    void run()
    {
        CIncommingConnectionPtr pConn (new CIncommingConnection(m_sPeerName, m_service, this));
        m_clients.push_back( pConn );


        m_acceptor.async_accept(pConn->sock(), boost::bind(&CIncomingServer::handle_accept, this, _1));

        m_timer.expires_from_now( boost::posix_time::millisec( 500 ) );
        m_timer.async_wait( boost::bind( &CIncomingServer::on_timer, this ) );
    }




private:

    void handle_accept(const boost::system::error_code & err)
    {
        m_clients.back()->start();

        CIncommingConnectionPtr pConnNew (new CIncommingConnection(m_sPeerName, m_service, this));
        m_clients.push_back( pConnNew );

        m_acceptor.async_accept(pConnNew->sock(), boost::bind(&CIncomingServer::handle_accept, this,  _1));
    }


    //IIncomingServer
    virtual  void OnData(CIncommingConnectionPtr pConn, const char *pData, size_t bytes)
    {
        std::cout << "Data received" << std::endl ;
    }


    virtual  void OnConnected(CIncommingConnectionPtr pConn)
    {
        std::cout << "Client connected" << std::endl ;
    }


    virtual  void OnDisconnected(const boost::system::error_code& err, CIncommingConnectionPtr pConn)
    {
        std::cout << "Client disconnected" << std::endl ;

        auto it = std::find(m_clients.begin(), m_clients.end(), pConn) ;
        if (it != m_clients.end())
        {
            m_clients.erase(it);
        }

    }



    void on_timer()
    {
        //if (NeedTerminate())
        //{
        //    m_service.stop();
        //    return ;
        //}

        m_timer.expires_from_now( boost::posix_time::millisec( 500 ) );
        m_timer.async_wait( boost::bind( &CIncomingServer::on_timer, this ) );
    }



private:
    ip::tcp::acceptor  m_acceptor ;

    std::vector<CIncommingConnectionPtr> m_clients;
    std::string m_sPeerName ;
    unsigned int m_port ;
    boost::asio::io_service       &m_service ;
    boost::asio::deadline_timer    m_timer;
    bool                           m_bAllowManyConnections; 
};


int _tmain(int argc, _TCHAR* argv[])
{

    boost::asio::io_service  service ;


    boost::shared_ptr<CIncomingServer> pServer;

    try
    {
        pServer.reset( new CIncomingServer(service, 8000,  false, "BS Server"));        
        pServer->run();
    }
    catch (const boost::system::system_error &err)
    {
        std::cout << "Error : " << err.what() << std::endl ;
        return 0 ;
    }

    service.run();

    return 0 ;


}

Answer 1

长话短说：您应该将完成处理程序绑定到从shared_from_this()返回的shared_ptr，而不是简单this（所谓的shared_from_this成语）。这样可以确保正确自动管理连接对象的生命周期。

从技术上讲，现在发生以下情况：do_error导致2个操作发生：

计时器取消（即异步操作）删除
CIncommingConnectionPtr（同步操作）。

在第（2）点，连接被破坏，因为没有其他shared_ptr持有它。现在是timer completion handler comes ......崩溃！

boost :: asio如何从客户端异步读取数据并定期写入数据（如果有的话）

1 个答案: