以下代码基于http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/example/echo/async_tcp_echo_server.cpp的boost文档示例。我只是稍微更改了一下,以便我可以在不同的线程中运行服务器,并在运行几秒后退出。
此代码按预期工作。当客户端连接并发送一些文本时,副本将回显给客户端。
只有一个问题。有一个类session
的实例永远不会被删除。如果运行代码,则可以看到构造函数和析构函数被调用的次数。它始终是最后一个session
实例,不会被删除。
想知道是否有一种简单的方法来解决这个问题。也许我可以使用smart_ptr类。
请注意,我必须使用boost库1.46。我发现其他一些例子都是基于较新的库版本。但是这些示例不能在较旧的boost库下编译。问候。
#include <cstdlib>
#include <iostream>
#include <vector>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/thread.hpp>
using boost::asio::ip::tcp;
class session
{
public:
session(boost::asio::io_service& io_service)
: socket_(io_service)
{
char buf[100]; sprintf(buf, "%p", this);
std::cout << "Session created: " << buf << std::endl;
}
~session() {
char buf[100]; sprintf(buf, "%p", this);
std::cout << "Session destroyed: " << buf << std::endl;
}
tcp::socket& socket()
{
return socket_;
}
void start()
{
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));
}
void handle_read(const boost::system::error_code& error,
size_t bytes_transferred)
{
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));
}
~server() {
}
void handle_accept(session* new_session,
const boost::system::error_code& error)
{
if (!error)
{
new_session->start(); // ownership passed
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
{
std::cout << "Error in HA: " << error.message() << std::endl;
}
}
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;
}
*/
static void serverThread(boost::asio::io_service* io_service) {
server s(*io_service, 5000);
io_service->run();
}
int main(int argc, char* argv[])
{
boost::asio::io_service io_service;
boost::thread t(serverThread, &io_service);
::sleep(10);
io_service.stop();
t.join();
std::cout << "Quitting" << std::endl;
return 0;
}
答案 0 :(得分:1)
未被删除的那个是传递给异步接受处理程序的那个,即handler_accept
。我会建议大量使用智能指针。 shared_ptr
在这里是一个很好的候选人:
#include <cstdlib>
#include <iostream>
#include <vector>
#include <thread>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <memory>
using boost::asio::ip::tcp;
class session: public std::enable_shared_from_this<session>
{
public:
session(boost::asio::io_service& io_service)
: socket_(io_service)
{
char buf[100]; sprintf(buf, "%p", this);
std::cout << "Session created: " << buf << std::endl;
}
~session() {
char buf[100]; sprintf(buf, "%p", this);
std::cout << "Session destroyed: " << buf << std::endl;
}
tcp::socket& socket()
{
return socket_;
}
void start()
{
socket_.async_read_some(boost::asio::buffer(data_, max_length),
boost::bind(&session::handle_read, shared_from_this(),
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
void handle_read(const boost::system::error_code& error,
size_t bytes_transferred)
{
if (!error)
{
boost::asio::async_write(socket_,
boost::asio::buffer(data_, bytes_transferred),
boost::bind(&session::handle_write, shared_from_this(),
boost::asio::placeholders::error));
}
}
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, shared_from_this(),
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
}
private:
tcp::socket socket_;
enum { max_length = 1024 };
char data_[max_length];
};
using session_ptr = std::shared_ptr<session>;
class server
{
public:
server(boost::asio::io_service& io_service, short port)
: io_service_(io_service),
acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
{
auto new_session = std::make_shared<session>(io_service_);
acceptor_.async_accept(new_session->socket(),
boost::bind(&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
}
~server() {
}
void handle_accept(session_ptr new_session,
const boost::system::error_code& error)
{
if (!error)
{
new_session->start(); // ownership passed
new_session.reset();
new_session = std::make_shared<session>(io_service_);
acceptor_.async_accept(new_session->socket(),
boost::bind(&server::handle_accept, this, new_session,
boost::asio::placeholders::error));
}
else
{
std::cout << "Error in HA: " << error.message() << std::endl;
}
}
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;
}
*/
static void serverThread(boost::asio::io_service* io_service) {
server s(*io_service, 5000);
io_service->run();
}
int main(int argc, char* argv[])
{
boost::asio::io_service io_service;
std::thread t(serverThread, &io_service);
::sleep(10);
io_service.stop();
t.join();
std::cout << "Quitting" << std::endl;
return 0;
}
我使用了c ++ 11功能,即std::thread
和std::shared_ptr
。 std::enable_shared_from_this
使您能够创建shared_ptr
this
对象。在session
类的异步函数调用中查看它是如何使用的。
另外,看一下代码,我觉得你打算在调用io_service::stop
后调用一些错误代码来处理处理程序?不,事实并非如此。它将简单地调用scheduler::shutdown
,它只会破坏异步处理程序,而不是别的。