boost::asio::async_read_until问题
我试图从boost asio中修改回送服务器示例，在尝试使用boost::asio::async_read_until时遇到了问题。下面是代码：
#include <cstdlib>
#include <iostream>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
using boost::asio::ip::tcp;
class session
{
public:
session(boost::asio::io_service& io_service)
: socket_(io_service)
{
}
tcp::socket& socket()
{
return socket_;
}
void start()
{
std::cout<<"starting"<<std::endl;
boost::asio::async_read_until(socket_, boost::asio::buffer(data_, max_length), ' ',
boost::bind(&session::handle_read, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
void handle_read(const boost::system::error_code& error,
size_t bytes_transferred)
{
std::cout<<"handling read"<<std::endl;
if (!error)
{
boost::asio::async_write(socket_,
boost::asio::buffer(data_, bytes_transferred),
boost::bind(&session::handle_write, this,
boost::asio::placeholders::error));
}
else
{
delete this;
}
}
void handle_write(const boost::system::error_code& error)
{
if (!error)
{
/*
socket_.async_read_some(boost::asio::buffer(data_, max_length),
boost::bind(&session::handle_read, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
*/ }
else
{
delete this;
}
}
private:
tcp::socket socket_;
enum { max_length = 1024 };
char data_[max_length];
};
class server
{
public:
server(boost::asio::io_service& io_service, short port)
: io_service_(io_service),
acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
{
session* new_session = new session(io_service_);
acceptor_.async_accept(new_session->socket(),
boost::bind(&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
}
void handle_accept(session* new_session,
const boost::system::error_code& error)
{
if (!error)
{
new_session->start();
new_session = new session(io_service_);
acceptor_.async_accept(new_session->socket(),
boost::bind(&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
}
else
{
delete new_session;
}
}
private:
boost::asio::io_service& io_service_;
tcp::acceptor acceptor_;
};
int main(int argc, char* argv[])
{
try
{
if (argc != 2)
{
std::cerr << "Usage: async_tcp_echo_server <port>\n";
return 1;
}
boost::asio::io_service io_service;
using namespace std; // For atoi.
server s(io_service, atoi(argv[1]));
io_service.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}问题是，当我试图编译时，我得到了一个奇怪的错误：
‘async_read_until(boost::asio::basic_stream_socket : server.cpp:在成员函数‘void：：start()’：server.cpp:27: server.cpp:27:不匹配调用server.cpp:27 >&、boost::asio::mutable_buffers_1、char、boost::_bi::bind_t、boost::_bi::list3、boost::arg<1> ()()、boost::arg<2> ()(>)‘
有人能解释一下发生了什么事吗？据我所知，async_read_until的参数是正确的。
谢谢!
回答 3
Stack Overflow用户
发布于 2010-06-17 01:51:15
async_read_until的第二个参数应该是将数据读入的streambuf对象。简单地说，您需要通过引用传递boost::asio::streambuf，而不是按值传递boost::asio::buffer。
Stack Overflow用户
发布于 2019-09-01 18:32:05
没有必要使用streambufs。有些重载可以接受动态缓冲区。动态是关键，因为read_until意味着需要一个缓冲区，它可以根据被叫者的判断来增加其大小。因此，您只需将对boost::asio::buffer的调用替换为boost::asio::dynamic_buffer，并在std::string或std::vector<char>上调用它。
...
void start()
{
std::cout<<"starting"<<std::endl;
boost::asio::async_read_until(
socket_, boost::asio::dynamic_buffer(data_), ' ',
boost::bind(&session::handle_read, this,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
...
private:
tcp::socket socket_;
std::string data_;
// or
//std::vector<char> data_;
};我也会摆脱boost::bind，因为这是一个过度杀戮和使用lambda (尽可能多地使用它们)。
[this](const boost::system::error_code& error, size_t bytes_transferred) {
handle_read(error, bytes_transferred);
}Stack Overflow用户
发布于 2016-12-07 16:29:13
const (In)正确性也可能导致这类错误消息。
https://stackoverflow.com/questions/3058310
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