ceph/src/boost/libs/asio/doc/requirements/SyncRandomAccessReadDevice.qbk

   1 [/
   2  / Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   3  /
   4  / Distributed under the Boost Software License, Version 1.0. (See accompanying
   5  / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6  /]
   7
   8 [section:SyncRandomAccessReadDevice Buffer-oriented synchronous random-access
   9 read device requirements]
  10
  11 In the table below, `a` denotes a synchronous random-access read device object,
  12 `o` denotes an offset of type `boost::uint64_t`, `mb` denotes an object
  13 satisfying [link boost_asio.reference.MutableBufferSequence mutable buffer sequence]
  14 requirements, and `ec` denotes an object of type `error_code`.
  15
  16 [table Buffer-oriented synchronous random-access read device requirements
  17   [[operation] [type] [semantics, pre/post-conditions]]
  18   [
  19     [`a.read_some_at(o, mb);`]
  20     [`size_t`]
  21     [Equivalent to:
  22      ``
  23        error_code ec;
  24        size_t s = a.read_some_at(o, mb, ec);
  25        if (ec) throw system_error(ec);
  26        return s;
  27      ``]
  28   ]
  29   [
  30     [`a.read_some_at(o, mb, ec);`]
  31     [`size_t`]
  32     [
  33       Reads one or more bytes of data from the device `a` at offset `o`.\n
  34       \n
  35       The mutable buffer sequence `mb` specifies memory where the data should
  36       be placed. The `read_some_at` operation shall always fill a buffer in the
  37       sequence completely before proceeding to the next.\n
  38       \n
  39       If successful, returns the number of bytes read and sets `ec` such that
  40       `!ec` is true. If an error occurred, returns `0` and sets `ec` such that
  41       `!!ec` is true.\n
  42       \n
  43       If the total size of all buffers in the sequence `mb` is `0`, the
  44       function shall return `0` immediately.
  45     ]
  46   ]
  47 ]
  48
  49 [endsect]