使用Boost Asio接收文本的最有效方法？

Question

right now i am receiving text in the following way:

    boost::asio::streambuf buffer;           
    std::string text;
    while(true) {   
        try
        {

            boost::asio::read_until(*m_pSocket, buffer, "END");

            text = boost::asio::buffer_cast<const char*>(buffer.data());
            buffer.consume(text.size());

            boost::asio::write(*m_pSocket, boost::asio::buffer(text, text.size()));
            std::cout << text<< std::endl;
        }
        catch (std::exception& e)
        {
            std::cerr << "Exception: " << e.what() << "\n";
            break;
        }       
    }

I just echo received text to the client when the sequence "END" was received. My question:

It seems to me very inefficent to convert that streambuf to a string and then to consume the text signs from it. What is the right way to work with the received data in a nice, clean and efficent way?

Answer 1

All together you will have two copies of the received text: one in the streambuf, the other in the string. The boost::asio::buffer is just a pointer, pointing into the string, and a size.

If sending the pingback directly from the stringbuf is not an option, that is the best you can get. However, I don't see what should be the problem with first sending back the streambuf's content and consuming it afterwards for your internal use.

Your code could look like this then:

boost::asio::streambuf buffer;           
while(true) {   
    try
    {
        auto size = boost::asio::read_until(*m_pSocket, buffer, "END");

        //send back the seuqence:
        auto begin = boost::asio::buffer_cast<const char*>(buffer.data());
        boost::asio::write(*m_pSocket, boost::asio::buffer(begin, size));

        //consume the content...
        std::istream is(&buffer);
        is >> /* whatever fits here... */
    }
    catch (std::exception& e)
    {
        std::cerr << "Exception: " << e.what() << "\n";
        break;
    }       
}

Aside from that, I would not send back the whole sequence. Depending on the average size of the sequences sent, it could be better to calculate a checksum on the fly and send that back instead of the whole sequence.