socket通信框架——boost asio

boost asio是一个封装了基本socket的跨平台通信框架。它支持异步访问，并支持tcp的自动封闭控制等操作。

一个简单的通信协议可以为：

header	body
body长	数据

通过boost::asio接收的话，即可为：

void receive_header()
{
  auto keep_alive(shared_from_this());
  auto asbuf = boost::asio::buffer(msg->header(), msg->header_length());
  auto on_header_received = [this, keep_alive]
    (boost::system::error_code ec, std::size_t length)
  {
    if (!ec && buffer->decode_header())
    {
      receive_body();
    }
  };

  boost::asio::async_read(socket_id, asbuf, on_header_received);
}

void receive_body()
{
  auto keep_alive(shared_from_this());
  auto asbuf = boost::asio::buffer(msg->body(), msg->body_length());
  auto on_body_received = [this, keep_alive]
    (boost::system::error_code ec, std::size_t length)
  {
    if (!ecode && msg->body_length())
    {
      // do something
    }
    receive_header();
  }

  boost::asio::async_read(socket_id, asbuf, on_body_received);
}

而一个简单的发送数据端可为：

void send(Message msg)
{
  boost::system::error_code ec;
  std::uint32_t posted = 0;
  std::uint32_t rest = msg.length();

  msg.encode_header();

  do 
  {
    auto asbuf = boost::asio::buffer(msg.data() + posted, rest);
    posted = _socket.write_some(asbuf, ec);
    if (ec)
    {
      break;
    }
    rest -= posted;
  } while (rest > 0);
}

资料参考：

https://www.cnblogs.com/fnlingnzb-learner/p/10408812.html