boost :: asio :: async_read循环无限与零字节的接收数据

Question

我想写基于IO_Service的异步TCP客户端，其中Async_write工作正常，但async_read在无限循环中运行。在我尝试纠正这个问题的过程中，我发现在所有其他情况下，async_read只是停止接收数据，直到我停止服务器时才会收到任何内容。以下是发布我的查询之前我尝试的代码和链接。

我试过的建议是exactly as mine，2，3and但在所有的情况下，我async_read处理程序不读什么。在一个也是唯一的情况下，它开始无限循环，当我设置缓冲区为boost::asio::mutable_buffer bytes;在其他情况下，我已经尝试boost::array<char, 512> bytes;,boost::asio::streambuf bytes;和char bytes[512];其中未引发async_read处理程序。

经历了所有这些解决方案后，我现在感到困惑：它可能是缓冲区的问题吗？在通过阅读 之前，我需要初始化吗？

请指导。

ScalableSocket::ScalableSocket() 
{ 
    //ctor 

    using namespace boost::asio; 
    service = boost::make_shared<io_service>(); 
    work = boost::make_shared<io_service::work>(*service); 
    strand = boost::make_shared<io_service::strand>(*service); 
    worker_threads = boost::make_shared<boost::thread_group>(); 



     worker_threads->create_thread(boost::bind(&ScalableSocket::WorkerThread,this)); 


    resolver = boost::make_shared<boost::asio::ip::tcp::resolver> (*service); 

    tcp_socket= boost::make_shared<boost::asio::ip::tcp::socket> (*service); 

    boost::asio::ip::tcp::resolver::query q(boost::asio::ip::tcp::v4(),"192.168.100.96","9602"); 

    boost::asio::ip::tcp::resolver::iterator it = resolver->resolve(q); 

    boost::asio::async_connect(*tcp_socket,it,boost::bind(&ScalableSocket::connect_handler,this,boost::asio::placeholders::error)); 

    tcp_socket->set_option(boost::asio::ip::tcp::no_delay(true)); 

} 

ScalableSocket::~ScalableSocket() 
{ 
    //dtor 

} 

void ScalableSocket::PublishPost() 
{ 
    strand->post(boost::bind(&ScalableSocket::OnSend,this)); 
} 


void ScalableSocket::OnSend() 
{ 


    boost::array<char, 6> a = { 'a', 'b', 'c', 'd', 'e' }; 

    boost::asio::async_write(*tcp_socket,boost::asio::buffer(a), 
            boost::bind(&ScalableSocket::write_handler, this, boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); 



} 

void ScalableSocket::WorkerThread() 
{ 
    while(true) 
    { 
     try 
     { 
      boost::system::error_code ec; 
      service->run(ec); 
      if(ec) 
      { 
       ///LOGE(ec); 
      } 
      break; 
     } 
     catch(std::exception & ex) 
     { 
      ///LOGE(ex.what()); 
     } 
    } 
} 

void ScalableSocket::connect_handler(const boost::system::error_code &ec) 
{ 
    if (!ec) 
    { 

    PublishPost(); 




/* boost::asio::async_read(*tcp_socket, 
           boost::asio::buffer(bytes), 
           boost::bind(&ScalableSocket::read_handler, this, 
              boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); 
*/ 

     ///https://stackoverflow.com/questions/4527443/problems-using-boostasioasync-read 

     boost::shared_ptr<boost::array<char, 512>> buf(new boost::array<char, 512>); 


     boost::asio::async_read(*tcp_socket,boost::asio::buffer(*buf), 
           boost::bind(&ScalableSocket::read_handler, this,buf, 
           boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); 

    } 
    else 
    { 
     cout<<" Some error connecting to Exchange "<< ec.message()<<endl; 

    } 

} 


void ScalableSocket::OnTimer(const boost::system::error_code &ec) 
{ 
    if(!ec) 
    { 
     printf("\n\n Heartbeat event raised sending KeepAlive to exchange \n\n"); 
     PublishPost(); 
     HeartBeatTimer->async_wait(boost::bind(&ScalableSocket::OnTimer,this, boost::asio::placeholders::error)); 
    } 
} 

void ScalableSocket::recvData() 
{ 
    boost::system::error_code error; 
    boost::array<char, 1024> buf; 

    //for(;;) 
    { 
     size_t len = tcp_socket->read_some(boost::asio::buffer(buf), error); 

     cout<<"\n Recv data size is "<<len; 

    } 
} 

void ScalableSocket::read_handler(boost::shared_ptr<boost::array<char, 512>> buf,const boost::system::error_code &ec,std::size_t bytes_transferred) 
{ 


    if (!ec)//&& bytes_transferred > 0) 
    { 

     ///recvData(); /// If i enable this code during infinite loop it start getting data that means socket has no issue 

     cout << " Data size recieved "<< bytes_transferred<<endl; 




      boost::asio::async_read(*tcp_socket,boost::asio::buffer(*buf), 
           boost::bind(&ScalableSocket::read_handler, this,buf, 
           boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); 
    } 
    else 
    { 
     /// Some issue with socket publish error , inform user and reconnect 
     cout<<" Some error reading data from Exchange "<< ec.message()<<endl; 

    } 
} 

void ScalableSocket::write_handler(const boost::system::error_code& error,std::size_t bytes_transferred) 
{ 
    if(!error) 
    { 
     /// data Sent successfully 
     cout<< " Data sent size "<< bytes_transferred<<endl; 

    } 
    else 
    { 
     cout<<" Some error sending data to Exchange "<< error.message()<<endl; 
    } 

} 

Answer 1

asnyc_read不会“回归” /调用处理程序，直到给定的缓冲区完全充满。

asnyc_read_some将在读取一些字节后返回。这可能是你正在寻找的功能。

请记住用asnyc_read_some正确处理收到的数据。如果发送512字节，则可能会以几次读取为准，具体取决于机器。