[/
 / 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:asynchronous_socket_operations Requirements on asynchronous socket operations]

In this library, ['asynchronous socket operations] are those member functions
having prefix `async_`.

For an object `s`, a program may initiate asynchronous socket operations such
that there are multiple simultaneously outstanding asynchronous operations.

When there are multiple outstanding asynchronous [link
boost_asio.reference.read_write_operations read operations] on `s`:

[mdash] having no argument `flags` of type `socket_base::message_flags`, or

[mdash] having an argument `flags` of type `socket_base::message_flags` but
where `(flags & socket_base::message_out_of_band) == 0`

then the `buffers` are filled in the order in which these operations were
issued. The order of invocation of the completion handlers for these operations
is unspecified.

When there are multiple outstanding asynchronous [link
boost_asio.reference.read_write_operations read operations] on `s` having an argument
`flags` of type `socket_base::message_flags` where `(flags &
socket_base::message_out_of_band) != 0` then the `buffers` are filled in the
order in which these operations were issued.

When there are multiple outstanding asynchronous [link
boost_asio.reference.read_write_operations write operations] on `s`, the `buffers`
are transmitted in the order in which these operations were issued. The order
of invocation of the completion handlers for these operations is unspecified.

[endsect]