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

   1 //
   2 // detail/thread_info_base.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2018 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   struct default_tag
  33   {
  34     enum { mem_index = 0 };
  35   };
  36
  37   struct awaitee_tag
  38   {
  39     enum { mem_index = 1 };
  40   };
  41
  42   thread_info_base()
  43   {
  44     for (int i = 0; i < max_mem_index; ++i)
  45       reusable_memory_[i] = 0;
  46   }
  47
  48   ~thread_info_base()
  49   {
  50     for (int i = 0; i < max_mem_index; ++i)
  51       if (reusable_memory_[i])
  52         ::operator delete(reusable_memory_[i]);
  53   }
  54
  55   static void* allocate(thread_info_base* this_thread, std::size_t size)
  56   {
  57     return allocate(default_tag(), this_thread, size);
  58   }
  59
  60   static void deallocate(thread_info_base* this_thread,
  61       void* pointer, std::size_t size)
  62   {
  63     deallocate(default_tag(), this_thread, pointer, size);
  64   }
  65
  66   template <typename Purpose>
  67   static void* allocate(Purpose, thread_info_base* this_thread,
  68       std::size_t size)
  69   {
  70     std::size_t chunks = (size + chunk_size - 1) / chunk_size;
  71
  72     if (this_thread && this_thread->reusable_memory_[Purpose::mem_index])
  73     {
  74       void* const pointer = this_thread->reusable_memory_[Purpose::mem_index];
  75       this_thread->reusable_memory_[Purpose::mem_index] = 0;
  76
  77       unsigned char* const mem = static_cast<unsigned char*>(pointer);
  78       if (static_cast<std::size_t>(mem[0]) >= chunks)
  79       {
  80         mem[size] = mem[0];
  81         return pointer;
  82       }
  83
  84       ::operator delete(pointer);
  85     }
  86
  87     void* const pointer = ::operator new(chunks * chunk_size + 1);
  88     unsigned char* const mem = static_cast<unsigned char*>(pointer);
  89     mem[size] = (chunks <= UCHAR_MAX) ? static_cast<unsigned char>(chunks) : 0;
  90     return pointer;
  91   }
  92
  93   template <typename Purpose>
  94   static void deallocate(Purpose, thread_info_base* this_thread,
  95       void* pointer, std::size_t size)
  96   {
  97     if (size <= chunk_size * UCHAR_MAX)
  98     {
  99       if (this_thread && this_thread->reusable_memory_[Purpose::mem_index] == 0)
 100       {
 101         unsigned char* const mem = static_cast<unsigned char*>(pointer);
 102         mem[0] = mem[size];
 103         this_thread->reusable_memory_[Purpose::mem_index] = pointer;
 104         return;
 105       }
 106     }
 107
 108     ::operator delete(pointer);
 109   }
 110
 111 private:
 112   enum { chunk_size = 4 };
 113   enum { max_mem_index = 2 };
 114   void* reusable_memory_[max_mem_index];
 115 };
 116
 117 } // namespace detail
 118 } // namespace asio
 119 } // namespace boost
 120
 121 #include <boost/asio/detail/pop_options.hpp>
 122
 123 #endif // BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP