void TcpServiceHandler::writeAsync(unsigned char* data, unsigned int size)
{
    WriteMessagePtr write_msg(new WriteMessage(data, size));

    m_strand.post(boost::bind(&TcpServiceHandler::doWrite,
                              shared_from_this(),
                              write_msg));
}

void TcpServiceHandler::readAsync()
{
    m_strand.post(boost::bind(&TcpServiceHandler::doRead, shared_from_this()));
}

void TcpServiceHandler::doRead()
{
    m_socket.async_read_some(
        asio::buffer(m_read_buffer),
        m_strand.wrap(boost::bind(&TcpServiceHandler::handleRead,
                                  shared_from_this(),
                                  asio::placeholders::error,
                                  asio::placeholders::bytes_transferred)));
}

void TcpTransport::flush() {
    boost::asio::post(m_strand, [this]() {
        // 檢查是否有數(shù)據(jù)正在發(fā)送，如果隊列中存在數(shù)據(jù)，則表示有數(shù)據(jù)正在發(fā)送

        if (m_messages.empty()) {
            // 所有緩沖區(qū)的消息已經(jīng)處理完畢，需要通知外部繼續(xù)處理
            if (m_fn_handle_write_completed) {
                m_fn_handle_write_completed();
            }
        }
    });
}

    boost::asio::post(
        m_io_context,
        [self = derived().shared_from_this(), pack = std::vector<char>(reinterpret_cast<const char *>(data), reinterpret_cast<const char *>(data) + len)]() mutable {
            self->push_send_data(std::move(pack));
        }
    );

[https://github.com/chriskohlhoff/asio/blob/master/asio/src/examples/cpp11/chat/chat_client.cpp](https://github.com/chriskohlhoff/asio/blob/master/asio/src/examples/cpp11/chat/chat_client.cpp)


std::deque<std::string> write_msgs_;

void write(std::string msg)
{
    asio::post(io_context_,
        [this, msg = std::move(msg)]() mutable
        {
          bool write_in_progress = !write_msgs_.empty();
          write_msgs_.push_back(std::move(msg));
          if (!write_in_progress)
          {
            do_write();
          }
        });
}

  void do_write()
  {
    asio::async_write(socket_,
        asio::buffer(write_msgs_.front().data(),
          write_msgs_.front().length()),
        [this](std::error_code ec, std::size_t /*length*/)
        {
          if (!ec)
          {
            write_msgs_.pop_front();
            if (!write_msgs_.empty())
            {
              do_write();
            }
          }
          else
          {
            socket_.close();
          }
        });
  }