ceph/src/boost/boost/beast/core/detail/flat_stream.hpp

   1 //
   2 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail 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 // Official repository: https://github.com/boostorg/beast
   8 //
   9
  10 #ifndef BOOST_BEAST_CORE_DETAIL_FLAT_STREAM_HPP
  11 #define BOOST_BEAST_CORE_DETAIL_FLAT_STREAM_HPP
  12
  13 #include <boost/beast/core/buffer_traits.hpp>
  14 #include <boost/asio/buffer.hpp>
  15 #include <cstdlib>
  16
  17 namespace boost {
  18 namespace beast {
  19 namespace detail {
  20
  21 class flat_stream_base
  22 {
  23 public:
  24     // Largest buffer size we will flatten.
  25     // 16KB is the upper limit on reasonably sized HTTP messages.
  26     static std::size_t constexpr max_size = 16 * 1024;
  27
  28     // Largest stack we will use to flatten
  29     static std::size_t constexpr max_stack = 8 * 1024;
  30
  31     struct flatten_result
  32     {
  33         std::size_t size;
  34         bool flatten;
  35     };
  36
  37     // calculates the flatten settings for a buffer sequence
  38     template<class BufferSequence>
  39     static
  40     flatten_result
  41     flatten(
  42         BufferSequence const& buffers, std::size_t limit)
  43     {
  44         flatten_result result{0, false};
  45         auto first = net::buffer_sequence_begin(buffers);
  46         auto last = net::buffer_sequence_end(buffers);
  47         if(first != last)
  48         {
  49             result.size = buffer_bytes(*first);
  50             if(result.size < limit)
  51             {
  52                 auto it = first;
  53                 auto prev = first;
  54                 while(++it != last)
  55                 {
  56                     auto const n = buffer_bytes(*it);
  57                     if(result.size + n > limit)
  58                         break;
  59                     result.size += n;
  60                     prev = it;
  61                 }
  62                 result.flatten = prev != first;
  63             }
  64         }
  65         return result;
  66     }
  67 };
  68
  69 } // detail
  70 } // beast
  71 } // boost
  72
  73 #endif