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

   1 //
   2 // detail/atomic_count.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2022 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_ATOMIC_COUNT_HPP
  12 #define BOOST_ASIO_DETAIL_ATOMIC_COUNT_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
  20 #if !defined(BOOST_ASIO_HAS_THREADS)
  21 // Nothing to include.
  22 #elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
  23 # include <atomic>
  24 #else // defined(BOOST_ASIO_HAS_STD_ATOMIC)
  25 # include <boost/detail/atomic_count.hpp>
  26 #endif // defined(BOOST_ASIO_HAS_STD_ATOMIC)
  27
  28 namespace boost {
  29 namespace asio {
  30 namespace detail {
  31
  32 #if !defined(BOOST_ASIO_HAS_THREADS)
  33 typedef long atomic_count;
  34 inline void increment(atomic_count& a, long b) { a += b; }
  35 inline void decrement(atomic_count& a, long b) { a -= b; }
  36 inline void ref_count_up(atomic_count& a) { ++a; }
  37 inline bool ref_count_down(atomic_count& a) { return --a == 0; }
  38 #elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
  39 typedef std::atomic<long> atomic_count;
  40 inline void increment(atomic_count& a, long b) { a += b; }
  41 inline void decrement(atomic_count& a, long b) { a -= b; }
  42
  43 inline void ref_count_up(atomic_count& a)
  44 {
  45   a.fetch_add(1, std::memory_order_relaxed);
  46 }
  47
  48 inline bool ref_count_down(atomic_count& a)
  49 {
  50   if (a.fetch_sub(1, std::memory_order_release) == 1)
  51   {
  52     std::atomic_thread_fence(std::memory_order_acquire);
  53     return true;
  54   }
  55   return false;
  56 }
  57 #else // defined(BOOST_ASIO_HAS_STD_ATOMIC)
  58 typedef boost::detail::atomic_count atomic_count;
  59 inline void increment(atomic_count& a, long b) { while (b > 0) ++a, --b; }
  60 inline void decrement(atomic_count& a, long b) { while (b > 0) --a, --b; }
  61 inline void ref_count_up(atomic_count& a) { ++a; }
  62 inline bool ref_count_down(atomic_count& a) { return --a == 0; }
  63 #endif // defined(BOOST_ASIO_HAS_STD_ATOMIC)
  64
  65 } // namespace detail
  66 } // namespace asio
  67 } // namespace boost
  68
  69 #endif // BOOST_ASIO_DETAIL_ATOMIC_COUNT_HPP