mutex_destructor.cpp revision 360784 
1//===--------------------- mutex_destructor.cpp ---------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// Define ~mutex.
10//
11// On some platforms ~mutex has been made trivial and the definition is only
12// provided for ABI compatibility.
13//
14// In order to avoid ODR violations within libc++ itself, we need to ensure
15// that *nothing* sees the non-trivial mutex declaration. For this reason
16// we re-declare the entire class in this file instead of using
17// _LIBCPP_BUILDING_LIBRARY to change the definition in the headers.
18
19#include "__config"
20#include "__threading_support"
21
22#if !defined(_LIBCPP_HAS_NO_THREADS)
23#if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION)
24#define NEEDS_MUTEX_DESTRUCTOR
25#endif
26#endif
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30#ifdef NEEDS_MUTEX_DESTRUCTOR
31class _LIBCPP_TYPE_VIS mutex
32{
33    __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
34
35public:
36    _LIBCPP_ALWAYS_INLINE _LIBCPP_INLINE_VISIBILITY
37    constexpr mutex() = default;
38    mutex(const mutex&) = delete;
39    mutex& operator=(const mutex&) = delete;
40    ~mutex() noexcept;
41};
42
43
44mutex::~mutex() _NOEXCEPT
45{
46    __libcpp_mutex_destroy(&__m_);
47}
48
49#endif // !_LIBCPP_HAS_NO_THREADS
50_LIBCPP_END_NAMESPACE_STD
51