我正在全面查看的示例是:
我正在全面查看的示例是:
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <boost/shared_ptr.hpp>
#include <iostream>
#include <vector>
using boost::asio::ip::tcp;
// A reference-counted non-modifiable buffer class.
class shared_const_buffer
{
public:
// Construct from a std::string.
explicit shared_const_buffer(const std::string& data)
: data_(new std::vector<char>(data.begin(), data.end())),
buffer_(boost::asio::buffer(*data_))
{
}
// Implement the ConstBufferSequence requirements.
typedef boost::asio::const_buffer value_type;
typedef const boost::asio::const_buffer* const_iterator;
const boost::asio::const_buffer* begin() const { return &buffer_; }
const boost::asio::const_buffer* end() const { return &buffer_ + 1; }
private:
boost::shared_ptr<std::vector<char> > data_;
boost::asio::const_buffer buffer_;
};
class session
: public boost::enable_shared_from_this<session>
{
public:
session(boost::asio::io_service& io_service)
: socket_(io_service)
{
}
tcp::socket& socket()
{
return socket_;
}
void start()
{
using namespace std; // For time_t, time and ctime.
time_t now = time(0);
shared_const_buffer buffer(ctime(&now));
boost::asio::async_write(socket_, buffer,
boost::bind(&session::handle_write, shared_from_this()));
}
void handle_write()
{
}
private:
// The socket used to communicate with the client.
tcp::socket socket_;
};
typedef boost::shared_ptr<session> session_ptr;
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_ptr 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_ptr new_session,
const boost::system::error_code& error)
{
if (!error)
{
new_session->start();
}
new_session.reset(new session(io_service_));
acceptor_.async_accept(new_session->socket(),
boost::bind(&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
}
private:
boost::asio::io_service& io_service_;
tcp::acceptor acceptor_;
};
int main(int argc, char* argv[])
{
try
{
if (argc != 2)
{
std::cerr << "Usage: reference_counted <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;
}
我是一名Java程序员,正在尝试理解boost asio的工作原理,有些问题需要帮助。我的问题如下:
In these lines:
const boost::asio::const_buffer* begin() const { return &buffer_; } const boost::asio::const_buffer* end() const { return &buffer_ + 1; }
this
shared_const_buffer
is use toasync_write
later, so I think it should implement some kind of buffer but I don't see any inherit signature. So definebegin()
andend()
are enough?And in these lines:
shared_const_buffer buffer(ctime(&now)); boost::asio::async_write(socket_, buffer, boost::bind(&session::handle_write, shared_from_this()));
share_const_buffer
hasdata_
is a shared pointer, but not itself, how isbuffer
valid untilasync_write
actually writes the data?