Boost::asio async_read

gistfile1.cpp

// schedule_read is called o start reading

void connection::connect()
{
    boost::asio::ip::tcp::resolver resolver(_io);
    boost::asio::ip::tcp::resolver::query query(_hostname, std::to_string(_port));
    boost::asio::ip::tcp::resolver::iterator iterator = resolver.resolve(query);
    boost::system::error_code ec;
    boost::asio::connect(_socket, iterator, ec);
    if (ec)
    {
        error("Cannot connect: " + ec.message());
        throw fatal_exception(ec.message());
    }
    schedule_read();
}

connection::connection():
    _socket(_io),
{
// _io is an instance variable
    _thread.reset(new std::thread(boost::bind(&boost::asio::io_service::run, &_io)));
    _worker.reset(new boost::asio::io_service::work(_io));
    connect();
}

void connection::schedule_read()
{
  // _read_buf is a boost::asio::streambuf
    boost::asio::streambuf::mutable_buffers_type mutableBuffer = _read_buf.prepare(1024);
//    _socket.async_read_some(mutableBuffer, boost::bind(&connection::read_handler, this, _1, _2));

    boost::asio::async_read(_socket, mutableBuffer, boost::asio::transfer_at_least(1), boost::bind(&connection::read_handler, this, _1, _2));
}

void connection::read_handler(const boost::system::error_code &ec, std::size_t bytes_read)
{
  // _read_buf is a boost::asio::streambuf
    trace("socket read returns: " + ec.message());
    if (!ec)
    {
        trace(boost::str(boost::format("Read %d bytes") % bytes_read));
        if (bytes_read > 0)
        {
            _read_buf.commit(bytes_read);
            boost::asio::streambuf::const_buffers_type bufs = _read_buf.data();
            std::string data(boost::asio::buffers_begin(bufs), boost::asio::buffers_end(bufs));
            trace(boost::str(boost::format("Connection is %p") % _connection.get()));
            std::size_t size = _connection->parse(data.c_str(), data.size());
            trace(boost::str(boost::format("Consumed %d bytes") % size));
            _read_buf.consume(size);
            trace(boost::str(boost::format("Still on buffer %d bytes") % _read_buf.size()));
        }
        schedule_read();
    }
    else
    {
        if (!_closing)
        {
            throw fatal_exception("Error on connection: " + ec.message());
        }
    }
}