Boost asio, async_read and acync_write not calling callbacks - c++

Question

I'm encapsulating the boost-asio socket, but I got an issue with it, but neither async_read nor async_write calls their callback function and I don't understand why.
I've tried using async_read_some but had the same issue.
Here's the code I've written so far
#include <iostream>
#include "socket.hpp"
Socket::Socket()
{
boost::asio::ip::tcp::endpoint ep_tmp(boost::asio::ip::tcp::v4(), 4242);
endpoint = ep_tmp;
acceptor = new boost::asio::ip::tcp::acceptor(ios, endpoint);
tcp_socket = new boost::asio::ip::tcp::socket(ios);
acceptor->listen();
}
Socket::~Socket()
{
delete(acceptor);
delete(tcp_socket);
}
void Socket::get_connection()
{
acceptor->async_accept(*tcp_socket, [](const boost::system::error_code &ec)
{
std::cout << "Connection received." << std::endl;
if (ec)
std::cout << "Error " << ec << std::endl;
});
this->exec();
}
void Socket::send(std::string &message)
{
async_write(*tcp_socket, boost::asio::buffer(message),
[](const boost::system::error_code &ec,
std::size_t bytes_transferred)
{
std::cout << "Sending datas." << std::endl;
if (ec)
std::cout << "Error " << ec << std::endl;
else
std::cout << bytes_transferred << " bytes transferred." << std::endl;
});
}
void Socket::receive(void)
{
char *buf;
buf = (char *)malloc(sizeof(char) * 50);
buf = (char *)memset(buf, 0, 50);
async_read(*tcp_socket, boost::asio::buffer(buf, 50),
[](const boost::system::error_code &ec,
std::size_t bytes_transferred)
{
std::cout << "Receiving datas." << std::endl;
if (ec)
std::cout << "Error " << ec << std::endl;
else
std::cout << bytes_transferred
<< " bytes transferred." << std::endl;
});
}
void Socket::exec(void)
{
ios.run();
}
int main()
{
Socket serv;
std::string data_test;
data_test = "Test\n";
serv.get_connection();
serv.send(data_test);
serv.exec();
serv.receive();
serv.exec();
return (0);
}
The malloc bit is temporary until I find a way to do it without using C.
I'd be really thankful if someone could enlighten me on that issue

Answer 1

You have to call io_service::reset before second and later calls to io_service::run. And you probably want to use synchronous API instead, as your current approach absolutely defeats the purpose of asynchronicity.

Answer 2

I'm with yuri: prefer non-async unless you know what you're doing.
It could look like this: http://coliru.stacked-crooked.com/a/523a7828a9aee4b2
#include <boost/asio.hpp>
#include <iostream>
namespace ba = boost::asio;
using ba::ip::tcp;
class Socket {
public:
Socket() { acceptor.listen(); }
void get_connection();
void exec();
void send(std::string const &message);
void receive(void);
private:
ba::io_service ios;
tcp::endpoint endpoint{ tcp::v4(), 4242 };
tcp::acceptor acceptor{ ios, endpoint };
tcp::socket tcp_socket{ ios };
};
void Socket::get_connection() {
acceptor.accept(tcp_socket);
std::cout << "Connection received.\n";
}
void Socket::send(std::string const &message) {
std::cout << "Sending datas.\n";
auto bytes_transferred = ba::write(tcp_socket, ba::buffer(message));
std::cout << bytes_transferred << " bytes transferred.\n";
}
void Socket::receive(void) {
std::cout << "Receiving datas.\n";
char buf[50] = { 0 };
auto bytes_transferred = ba::read(tcp_socket, ba::buffer(buf));
std::cout << bytes_transferred << " bytes transferred.\n";
}
int main() {
Socket serv;
serv.get_connection();
serv.send("Test\n");
serv.receive();
}
If you want async behaviour, you have to manage the lifetimes of each buffer/connection-specific resource. There are many examples of that, e.g. in the docs or here: http://coliru.stacked-crooked.com/a/95e2000e49b4db1d
On the perils of buffer lifetime: client server simple example nonblocking