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

   1 //
   2 // detail/thread_info_base.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2020 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 <boost/asio/detail/config.hpp>
  19 #include <climits>
  20 #include <cstddef>
  21 #include <boost/asio/detail/noncopyable.hpp>
  22
  23 #if defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR) \
  24   && !defined(BOOST_ASIO_NO_EXCEPTIONS)
  25 # include <exception>
  26 # include <boost/asio/multiple_exceptions.hpp>
  27 #endif // defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR)
  28        // && !defined(BOOST_ASIO_NO_EXCEPTIONS)
  29
  30 #include <boost/asio/detail/push_options.hpp>
  31
  32 namespace boost {
  33 namespace asio {
  34 namespace detail {
  35
  36 class thread_info_base
  37   : private noncopyable
  38 {
  39 public:
  40   struct default_tag
  41   {
  42     enum { mem_index = 0 };
  43   };
  44
  45   struct awaitable_frame_tag
  46   {
  47     enum { mem_index = 1 };
  48   };
  49
  50   struct executor_function_tag
  51   {
  52     enum { mem_index = 2 };
  53   };
  54
  55   thread_info_base()
  56 #if defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR) \
  57   && !defined(BOOST_ASIO_NO_EXCEPTIONS)
  58     : has_pending_exception_(0)
  59 #endif // defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR)
  60        // && !defined(BOOST_ASIO_NO_EXCEPTIONS)
  61   {
  62     for (int i = 0; i < max_mem_index; ++i)
  63       reusable_memory_[i] = 0;
  64   }
  65
  66   ~thread_info_base()
  67   {
  68     for (int i = 0; i < max_mem_index; ++i)
  69     {
  70       // The following test for non-null pointers is technically redundant, but
  71       // it is significantly faster when using a tight io_context::poll() loop
  72       // in latency sensitive applications.
  73       if (reusable_memory_[i])
  74         ::operator delete(reusable_memory_[i]);
  75     }
  76   }
  77
  78   static void* allocate(thread_info_base* this_thread, std::size_t size)
  79   {
  80     return allocate(default_tag(), this_thread, size);
  81   }
  82
  83   static void deallocate(thread_info_base* this_thread,
  84       void* pointer, std::size_t size)
  85   {
  86     deallocate(default_tag(), this_thread, pointer, size);
  87   }
  88
  89   template <typename Purpose>
  90   static void* allocate(Purpose, thread_info_base* this_thread,
  91       std::size_t size)
  92   {
  93     std::size_t chunks = (size + chunk_size - 1) / chunk_size;
  94
  95     if (this_thread && this_thread->reusable_memory_[Purpose::mem_index])
  96     {
  97       void* const pointer = this_thread->reusable_memory_[Purpose::mem_index];
  98       this_thread->reusable_memory_[Purpose::mem_index] = 0;
  99
 100       unsigned char* const mem = static_cast<unsigned char*>(pointer);
 101       if (static_cast<std::size_t>(mem[0]) >= chunks)
 102       {
 103         mem[size] = mem[0];
 104         return pointer;
 105       }
 106
 107       ::operator delete(pointer);
 108     }
 109
 110     void* const pointer = ::operator new(chunks * chunk_size + 1);
 111     unsigned char* const mem = static_cast<unsigned char*>(pointer);
 112     mem[size] = (chunks <= UCHAR_MAX) ? static_cast<unsigned char>(chunks) : 0;
 113     return pointer;
 114   }
 115
 116   template <typename Purpose>
 117   static void deallocate(Purpose, thread_info_base* this_thread,
 118       void* pointer, std::size_t size)
 119   {
 120     if (size <= chunk_size * UCHAR_MAX)
 121     {
 122       if (this_thread && this_thread->reusable_memory_[Purpose::mem_index] == 0)
 123       {
 124         unsigned char* const mem = static_cast<unsigned char*>(pointer);
 125         mem[0] = mem[size];
 126         this_thread->reusable_memory_[Purpose::mem_index] = pointer;
 127         return;
 128       }
 129     }
 130
 131     ::operator delete(pointer);
 132   }
 133
 134   void capture_current_exception()
 135   {
 136 #if defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR) \
 137   && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 138     switch (has_pending_exception_)
 139     {
 140     case 0:
 141       has_pending_exception_ = 1;
 142       pending_exception_ = std::current_exception();
 143       break;
 144     case 1:
 145       has_pending_exception_ = 2;
 146       pending_exception_ =
 147         std::make_exception_ptr<multiple_exceptions>(
 148             multiple_exceptions(pending_exception_));
 149       break;
 150     default:
 151       break;
 152     }
 153 #endif // defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR)
 154        // && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 155   }
 156
 157   void rethrow_pending_exception()
 158   {
 159 #if defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR) \
 160   && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 161     if (has_pending_exception_ > 0)
 162     {
 163       has_pending_exception_ = 0;
 164       std::exception_ptr ex(
 165           BOOST_ASIO_MOVE_CAST(std::exception_ptr)(
 166             pending_exception_));
 167       std::rethrow_exception(ex);
 168     }
 169 #endif // defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR)
 170        // && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 171   }
 172
 173 private:
 174   enum { chunk_size = 4 };
 175   enum { max_mem_index = 3 };
 176   void* reusable_memory_[max_mem_index];
 177
 178 #if defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR) \
 179   && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 180   int has_pending_exception_;
 181   std::exception_ptr pending_exception_;
 182 #endif // defined(BOOST_ASIO_HAS_STD_EXCEPTION_PTR)
 183        // && !defined(BOOST_ASIO_NO_EXCEPTIONS)
 184 };
 185
 186 } // namespace detail
 187 } // namespace asio
 188 } // namespace boost
 189
 190 #include <boost/asio/detail/pop_options.hpp>
 191
 192 #endif // BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP