提升ASIO套接字读取N个字节不多也不少,等到它们到来或超时异常？

Question

根据示例创建一个简单的TCP服务器,但仍然没有得到如何创建一个读取一定数量字节的套接字,如果没有足够的将等待.我需要这不是异步操作.

#include <iostream>
#include <boost/asio.hpp>

#ifdef _WIN32
#include "Windows.h"
#endif

using namespace boost::asio::ip;
using namespace std;

int main(){
    int m_nPort = 12345;
    boost::asio::io_service io_service;
    tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), m_nPort));

    cout << "Waiting for connection..." << endl;

    tcp::socket socket(io_service);
    acceptor.accept(socket);
    cout << "connection accepted" << endl;
    try
    {
        socket.send(boost::asio::buffer("Start sending me data\r\n"));
    }
    catch(exception &e)
    {
        cerr << e.what() << endl; //"The parameter is incorrect" exception
    }
}

如何接收10000个字节并执行它直到所有10000到达或1000毫秒超时并抛出异常？

Answer 1

Boost 1.47.0刚刚引入了一个超时功能basic_socket_iostream,即expires_at和expires_from_now方法.

以下是基于您的代码段的示例:

#include <iostream>
#include <boost/asio.hpp>

using namespace boost::asio::ip;
using namespace std;

int main(){
    int m_nPort = 12345;
    boost::asio::io_service io_service;
    tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), m_nPort));

    cout << "Waiting for connection..." << endl;

    tcp::iostream stream;
    acceptor.accept(*stream.rdbuf());
    cout << "Connection accepted" << endl;
    try
    {
        stream << "Start sending me data\r\n";

        // Set timeout in 5 seconds from now
        stream.expires_from_now(boost::posix_time::seconds(5));

        // Try to read 12 bytes before timeout
        char buffer[12];
        stream.read(buffer, 12);

        // Print buffer if fully received
        if (stream) // false if read timed out or other error
        {
            cout.write(buffer, 12);
            cout << endl;
        }
    }
    catch(exception &e)
    {
        cerr << e.what() << endl;
    }
}

这个程序适用于Linux.

请注意,我并不是主张使用超时而不是使用截止时间计时器的异步操作.由你来决定.我只想表明可以实现超时basic_socket_iostream.