Hi,
I'm trying to figure out how asynchronous reads and writes work in
boost asio by manipulating the echo example. Currently, I have a server that should, when sent a sentence, respond with only the first word. However, the boost::asio::async_write never seems to complete even though the write handler is being called. Can someone please explain what's going on? Here's the code:
#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_, buffer, ' ',
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::ostringstream ss;
// ss<<&buffer;
char* c = new char[bytes_transferred];
//std::string s;
buffer.sgetn(c,bytes_transferred);
std::cout<<"data: "<< c<<" bytes: "<<bytes_transferred<<std::endl;
if (!error)
{
boost::asio::async_write(socket_,
boost::asio::buffer(c,bytes_transferred),
boost::bind(&session::handle_write, this,
boost::asio::placeholders::error));
}
else
{
delete this;
}
}
void handle_write(const boost::system::error_code& error)
{
std::cout<<"handling write"<<std::endl;
if (!error)
{
}
else
{
delete this;
}
}
private:
tcp::socket socket_;
boost::asio::streambuf buffer;
};
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;
}
Thanks!
