c++ 协程编程

#include <boost/asio/io_service.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/asio/steady_timer.hpp>
#include <boost/asio/write.hpp>
#include <iostream>
#include <memory>


using boost::asio::ip::tcp;


class session : public std::enable_shared_from_this<session>
{
public:
explicit session(tcp::socket socket)
: socket_(std::move(socket)),
timer_(socket_.get_io_service()),
strand_(socket_.get_io_service())
{
}


void go()
{
auto self(shared_from_this());


// 使用strand创建协程
boost::asio::spawn(strand_,
[this, self](boost::asio::yield_context yield)
{
try
{
char data[128];
for (;;)
{
timer_.expires_from_now(std::chrono::seconds(5));
std::size_t n = socket_.async_read_some(boost::asio::buffer(data), yield);
boost::asio::async_write(socket_, boost::asio::buffer(data, n), yield);
}
}
catch (std::exception& e)
{
socket_.close();
timer_.cancel();
}
});


// 使用strand创建协程
boost::asio::spawn(strand_,
[this, self](boost::asio::yield_context yield)
{
while (socket_.is_open())
{
boost::system::error_code ignored_ec;
timer_.async_wait(yield[ignored_ec]);
if (timer_.expires_from_now() <= std::chrono::seconds(0))
socket_.close();
}
});
}


private:
tcp::socket socket_;
boost::asio::steady_timer timer_;
boost::asio::io_service::strand strand_;
};


int main(int argc, char* argv[])
{
try
{
if (argc != 2)
{
std::cerr << "Usage: echo_server <port>\n";
return 1;
}


boost::asio::io_service io_service;


// 使用io_service创建协程
boost::asio::spawn(io_service,
[&](boost::asio::yield_context yield)
{
tcp::acceptor acceptor(io_service,
tcp::endpoint(tcp::v4(), std::atoi(argv[1])));


for (;;)
{
boost::system::error_code ec;
tcp::socket socket(io_service);
acceptor.async_accept(socket, yield[ec]);
if (!ec) std::make_shared<session>(std::move(socket))->go();
}
});


io_service.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}


return 0;

}