libcxx/src/mutex_destructor.cpp

   1 //===----------------------------------------------------------------------===//
   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
  31 class _LIBCPP_EXPORTED_FROM_ABI mutex
  32 {
  33     __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
  34
  35 public:
  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
  44 mutex::~mutex() noexcept
  45 {
  46     __libcpp_mutex_destroy(&__m_);
  47 }
  48
  49 #endif // !_LIBCPP_HAS_NO_THREADS
  50 _LIBCPP_END_NAMESPACE_STD