Boost C++ 库

Move accept token 是一个 completion token，其完成签名是 void(error_code, typename Protocol::socket) 或 void(error_code, typename Protocol::socket::template rebind_executor<Executor>::other)，适用于 acceptor 类模板的 Protocol 类型。

示例

作为 move accept token 的自由函数

void accept_handler(
    const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
{
  ...
}

Move accept token 函数对象

struct accept_handler
{
  ...
  void operator()(
      const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
  {
    ...
  }
  ...
};

作为 move accept token 的 lambda 表达式

acceptor.async_accept(...,
    [](const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
    {
      ...
    });

使用 std::bind() 将非静态类成员函数适配为 move accept token

void my_class::accept_handler(
    const boost::system::error_code& ec, boost::asio::ip::tcp::socket socket)
{
  ...
}
...
boost::asio::async_accept(...,
    std::bind(&my_class::accept_handler,
      this, std::placeholders::_1,
      std::placeholders::_2));

将 use_future 用作 move accept token

std::future<boost::asio::ip::tcp::socket> f =
  acceptor.async_accept(..., boost::asio::use_future);
...
try
{
  boost::asio::ip::tcp::socket s = f.get();
  ...
}
catch (const system_error& e)
{
  ...
}

将 use_awaitable 用作 move accept token

boost::asio::awaitable<void> my_coroutine()
{
  try
  {
    ...
    boost::asio::ip::tcp::socket s =
      co_await acceptor.async_accept(
          ..., boost::asio::use_awaitable);
    ...
  }
  catch (const system_error& e)
  {
    ...
  }
}