ceph/src/boost/boost/atomic/detail/atomic_flag.hpp

   1 /*
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * Copyright (c) 2014 Andrey Semashev
   7  */
   8 /*!
   9  * \file   atomic/detail/atomic_flag.hpp
  10  *
  11  * This header contains interface definition of \c atomic_flag.
  12  */
  13
  14 #ifndef BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_HPP_INCLUDED_
  15 #define BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_HPP_INCLUDED_
  16
  17 #include <boost/assert.hpp>
  18 #include <boost/memory_order.hpp>
  19 #include <boost/atomic/detail/config.hpp>
  20 #include <boost/atomic/detail/operations.hpp>
  21 #if defined(BOOST_ATOMIC_DETAIL_NO_CXX11_ALIGNAS)
  22 #include <boost/type_traits/type_with_alignment.hpp>
  23 #endif
  24
  25 #ifdef BOOST_HAS_PRAGMA_ONCE
  26 #pragma once
  27 #endif
  28
  29 /*
  30  * IMPLEMENTATION NOTE: All interface functions MUST be declared with BOOST_FORCEINLINE,
  31  *                      see comment for convert_memory_order_to_gcc in ops_gcc_atomic.hpp.
  32  */
  33
  34 namespace boost {
  35 namespace atomics {
  36
  37 #if defined(BOOST_ATOMIC_DETAIL_NO_CXX11_CONSTEXPR_UNION_INIT) || defined(BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX)
  38 #define BOOST_ATOMIC_NO_ATOMIC_FLAG_INIT
  39 #else
  40 #define BOOST_ATOMIC_FLAG_INIT {}
  41 #endif
  42
  43 struct atomic_flag
  44 {
  45     typedef atomics::detail::operations< 1u, false > operations;
  46     typedef operations::storage_type storage_type;
  47
  48 #if !defined(BOOST_ATOMIC_DETAIL_NO_CXX11_ALIGNAS)
  49     alignas(operations::storage_alignment) storage_type m_storage;
  50 #else
  51     // Note: Some compilers cannot use constant expressions in alignment attributes, so we have to use the union trick
  52     union
  53     {
  54         storage_type m_storage;
  55         boost::type_with_alignment< operations::storage_alignment >::type m_aligner;
  56     };
  57 #endif
  58
  59     BOOST_FORCEINLINE BOOST_ATOMIC_DETAIL_CONSTEXPR_UNION_INIT atomic_flag() BOOST_NOEXCEPT : m_storage(0u)
  60     {
  61     }
  62
  63     BOOST_FORCEINLINE bool test(memory_order order = memory_order_seq_cst) const volatile BOOST_NOEXCEPT
  64     {
  65         BOOST_ASSERT(order != memory_order_release);
  66         BOOST_ASSERT(order != memory_order_acq_rel);
  67         return !!operations::load(m_storage, order);
  68     }
  69
  70     BOOST_FORCEINLINE bool test_and_set(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
  71     {
  72         return operations::test_and_set(m_storage, order);
  73     }
  74
  75     BOOST_FORCEINLINE void clear(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
  76     {
  77         BOOST_ASSERT(order != memory_order_consume);
  78         BOOST_ASSERT(order != memory_order_acquire);
  79         BOOST_ASSERT(order != memory_order_acq_rel);
  80         operations::clear(m_storage, order);
  81     }
  82
  83     BOOST_DELETED_FUNCTION(atomic_flag(atomic_flag const&))
  84     BOOST_DELETED_FUNCTION(atomic_flag& operator= (atomic_flag const&))
  85 };
  86
  87 } // namespace atomics
  88 } // namespace boost
  89
  90 #endif // BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_HPP_INCLUDED_