Does boost :: asio increase excessive heap allocation or am I mistaken?

Question

#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()
    {
        socket_.async_read_some(boost::asio::buffer(data_, max_length - 1),
            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)
        {
            data_[bytes_transferred] = '\0';
            if(NULL != strstr(data_, "quit"))
            {
                this->socket().shutdown(boost::asio::ip::tcp::socket::shutdown_both);
                this->socket().close(); // how to make this dispatch "handle_read()" with a "disconnected" flag?
            }
            else
            {
                boost::asio::async_write(socket_,
                    boost::asio::buffer(data_, bytes_transferred),
                    boost::bind(&session::handle_write, this,
                    boost::asio::placeholders::error));

                socket_.async_read_some(boost::asio::buffer(data_, max_length - 1),
                    boost::bind(&session::handle_read, this,
                    boost::asio::placeholders::error,
                    boost::asio::placeholders::bytes_transferred));
            }
        }
        else
        {
            delete this;
        }
    }

    void handle_write(const boost::system::error_code& error)
    {
        if (!error)
        {
            //
        }
        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));
    }

    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;
}

While experimenting with boost :: asio, I noticed that the async_write () / async_read_some () calls use the C ++ keyword "new".

In addition, emphasizing this echo server with a client (1 connection) that sends, for example, 100,000 times some data, the use of this program in memory is getting higher and higher.

What's happening? Will he allocate memory for each call? Or I'm wrong? Ask, because it does not look like the server application will allocate anything. Can I process it with, say, a memory pool?

Another side question :

. "this- > socket(). close();"?
, , , . , . ?

(:

Answer 1

, - - ...

boost:: asio , ++ "" , "new.cpp" @function "void * __ CRTDECL new (size_t size) _THROW1 (_STD bad_alloc)". , MSVC 2008.

:

, BP, .
( ) ( ) ( , "" , ), / .
"" .
BP "" handle_read().
to is async_write() ( MSVC).
F5 () "" - async_read_some() .

: 'new'!!!!!! , !

, , - , "" , : "".
: ".......\boost_1_43_0\libs\asio\example\allocation \".

( ) ;
async_write() async_read_some() "".

, , , , , ; , , .

make_custom_alloc_handler() < --- ?
shared_from_this()??
, "session" "handler_allocator allocator_". "" ?! "", - ?

:

//
// server.cpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2010 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <cstdlib>
#include <iostream>
#include <boost/aligned_storage.hpp>
#include <boost/array.hpp>
#include <boost/bind.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/asio.hpp>

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

// Class to manage the memory to be used for handler-based custom allocation.
// It contains a single block of memory which may be returned for allocation
// requests. If the memory is in use when an allocation request is made, the
// allocator delegates allocation to the global heap.
class handler_allocator
    : private boost::noncopyable
{
public:
    handler_allocator()
        : in_use_(false)
    {
    }

    void* allocate(std::size_t size)
    {
        if (!in_use_ && size < storage_.size)
        {
            in_use_ = true;
            return storage_.address();
        }
        else
        {
            return ::operator new(size);
        }
    }

    void deallocate(void* pointer)
    {
        if (pointer == storage_.address())
        {
            in_use_ = false;
        }
        else
        {
            ::operator delete(pointer);
        }
    }

private:
    // Storage space used for handler-based custom memory allocation.
    boost::aligned_storage<1024> storage_;

    // Whether the handler-based custom allocation storage has been used.
    bool in_use_;
};

// Wrapper class template for handler objects to allow handler memory
// allocation to be customised. Calls to operator() are forwarded to the
// encapsulated handler.
template <typename Handler>
class custom_alloc_handler
{
public:
    custom_alloc_handler(handler_allocator& a, Handler h)
        : allocator_(a),
        handler_(h)
    {
    }

    template <typename Arg1>
    void operator()(Arg1 arg1)
    {
        handler_(arg1);
    }

    template <typename Arg1, typename Arg2>
    void operator()(Arg1 arg1, Arg2 arg2)
    {
        handler_(arg1, arg2);
    }

    friend void* asio_handler_allocate(std::size_t size,
        custom_alloc_handler<Handler>* this_handler)
    {
        return this_handler->allocator_.allocate(size);
    }

    friend void asio_handler_deallocate(void* pointer, std::size_t /*size*/,
        custom_alloc_handler<Handler>* this_handler)
    {
        this_handler->allocator_.deallocate(pointer);
    }

private:
    handler_allocator& allocator_;
    Handler handler_;
};

// Helper function to wrap a handler object to add custom allocation.
template <typename Handler>
inline custom_alloc_handler<Handler> make_custom_alloc_handler(
    handler_allocator& a, Handler h)
{
    return custom_alloc_handler<Handler>(a, h);
}

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()
    {
        socket_.async_read_some(boost::asio::buffer(data_),
            make_custom_alloc_handler(allocator_,
            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),
                make_custom_alloc_handler(allocator_, 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_),
                make_custom_alloc_handler(allocator_,
                boost::bind(&session::handle_read,
                shared_from_this(),
                boost::asio::placeholders::error,
                boost::asio::placeholders::bytes_transferred)));
        }
    }

private:
    // The socket used to communicate with the client.
    tcp::socket socket_;

    // Buffer used to store data received from the client.
    boost::array<char, 1024> data_;

    // The allocator to use for handler-based custom memory allocation.
    handler_allocator allocator_;
};

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: 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;
}

Answer 2

, io_service:: post, boost:: bind, session:: handle_read , .