[/
 / Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 /
 / Distributed under the Boost Software License, Version 1.0. (See accompanying
 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 /]

[section:reactor Reactor-Style Operations]

Sometimes a program must be integrated with a third-party library that wants to
perform the I/O operations itself. To facilitate this, Boost.Asio includes
synchronous and asynchronous operations that may be used to wait for a socket
to become ready to read, ready to write, or to have a pending error condition.

As an example, to perform a non-blocking read something like the following may
be used:

  ip::tcp::socket socket(my_io_context);
  ...
  socket.non_blocking(true);
  ...
  socket.async_wait(ip::tcp::socket::wait_read, read_handler);
  ...
  void read_handler(boost::system::error_code ec)
  {
    if (!ec)
    {
      std::vector<char> buf(socket.available());
      socket.read_some(buffer(buf));
    }
  }
  
These operations are supported for sockets on all platforms, and for the POSIX
stream-oriented descriptor classes.

[heading See Also]

[link boost_asio.reference.basic_socket.wait basic_socket::wait()],
[link boost_asio.reference.basic_socket.async_wait basic_socket::async_wait()],
[link boost_asio.reference.basic_socket.non_blocking basic_socket::non_blocking()],
[link boost_asio.reference.basic_socket.native_non_blocking basic_socket::native_non_blocking()],
[link boost_asio.examples.cpp03_examples.nonblocking nonblocking example].

[endsect]