ceph/src/boost/libs/asio/include/boost/asio/detail/buffer_resize_guard.hpp

   1 //
   2 // detail/buffer_resize_guard.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP
  12 #define BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/config.hpp>
  19 #include <boost/asio/detail/limits.hpp>
  20
  21 #include <boost/asio/detail/push_options.hpp>
  22
  23 namespace boost {
  24 namespace asio {
  25 namespace detail {
  26
  27 // Helper class to manage buffer resizing in an exception safe way.
  28 template <typename Buffer>
  29 class buffer_resize_guard
  30 {
  31 public:
  32   // Constructor.
  33   buffer_resize_guard(Buffer& buffer)
  34     : buffer_(buffer),
  35       old_size_(buffer.size())
  36   {
  37   }
  38
  39   // Destructor rolls back the buffer resize unless commit was called.
  40   ~buffer_resize_guard()
  41   {
  42     if (old_size_ != (std::numeric_limits<size_t>::max)())
  43     {
  44       buffer_.resize(old_size_);
  45     }
  46   }
  47
  48   // Commit the resize transaction.
  49   void commit()
  50   {
  51     old_size_ = (std::numeric_limits<size_t>::max)();
  52   }
  53
  54 private:
  55   // The buffer being managed.
  56   Buffer& buffer_;
  57
  58   // The size of the buffer at the time the guard was constructed.
  59   size_t old_size_;
  60 };
  61
  62 } // namespace detail
  63 } // namespace asio
  64 } // namespace boost
  65
  66 #include <boost/asio/detail/pop_options.hpp>
  67
  68 #endif // BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP