ceph/src/boost/boost/asio/detail/thread_info_base.hpp

   1 //
   2 // detail/thread_info_base.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 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_THREAD_INFO_BASE_HPP
  12 #define BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <climits>
  19 #include <cstddef>
  20 #include <boost/asio/detail/noncopyable.hpp>
  21
  22 #include <boost/asio/detail/push_options.hpp>
  23
  24 namespace boost {
  25 namespace asio {
  26 namespace detail {
  27
  28 class thread_info_base
  29   : private noncopyable
  30 {
  31 public:
  32   thread_info_base()
  33     : reusable_memory_(0)
  34   {
  35   }
  36
  37   ~thread_info_base()
  38   {
  39     if (reusable_memory_)
  40       ::operator delete(reusable_memory_);
  41   }
  42
  43   static void* allocate(thread_info_base* this_thread, std::size_t size)
  44   {
  45     std::size_t chunks = (size + chunk_size - 1) / chunk_size;
  46
  47     if (this_thread && this_thread->reusable_memory_)
  48     {
  49       void* const pointer = this_thread->reusable_memory_;
  50       this_thread->reusable_memory_ = 0;
  51
  52       unsigned char* const mem = static_cast<unsigned char*>(pointer);
  53       if (static_cast<std::size_t>(mem[0]) >= chunks)
  54       {
  55         mem[size] = mem[0];
  56         return pointer;
  57       }
  58
  59       ::operator delete(pointer);
  60     }
  61
  62     void* const pointer = ::operator new(chunks * chunk_size + 1);
  63     unsigned char* const mem = static_cast<unsigned char*>(pointer);
  64     mem[size] = (chunks <= UCHAR_MAX) ? static_cast<unsigned char>(chunks) : 0;
  65     return pointer;
  66   }
  67
  68   static void deallocate(thread_info_base* this_thread,
  69       void* pointer, std::size_t size)
  70   {
  71     if (size <= chunk_size * UCHAR_MAX)
  72     {
  73       if (this_thread && this_thread->reusable_memory_ == 0)
  74       {
  75         unsigned char* const mem = static_cast<unsigned char*>(pointer);
  76         mem[0] = mem[size];
  77         this_thread->reusable_memory_ = pointer;
  78         return;
  79       }
  80     }
  81
  82     ::operator delete(pointer);
  83   }
  84
  85 private:
  86   enum { chunk_size = 4 };
  87   void* reusable_memory_;
  88 };
  89
  90 } // namespace detail
  91 } // namespace asio
  92 } // namespace boost
  93
  94 #include <boost/asio/detail/pop_options.hpp>
  95
  96 #endif // BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP