[/
 / Copyright (c) 2003-2019 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:read_write_operations Requirements on read and write operations]

A ['read operation] is an operation that reads data into a mutable buffer
sequence argument of a type meeting [link boost_asio.reference.MutableBufferSequence
`MutableBufferSequence`] requirements. The mutable buffer sequence specifies
memory where the data should be placed. A read operation shall always fill a
buffer in the sequence completely before proceeding to the next.

A ['write operation] is an operation that writes data from a constant buffer
sequence argument of a type meeting [link boost_asio.reference.ConstBufferSequence
`ConstBufferSequence`] requirements. The constant buffer sequence specifies
memory where the data to be written is located. A write operation shall always
write a buffer in the sequence completely before proceeding to the next.

If a read or write operation is also an [link
boost_asio.reference.asynchronous_operations asynchronous operation], the operation
shall maintain one or more copies of the buffer sequence until such time as the
operation no longer requires access to the memory specified by the buffers in
the sequence. The program shall ensure the memory remains valid until:

[mdash] the last copy of the buffer sequence is destroyed, or

[mdash] the completion handler for the asynchronous operation is invoked,

whichever comes first.

[endsect]
