libstdc++-v3/include/bits/unique_lock.h

   1 // std::unique_lock implementation -*- C++ -*-
   2
   3 // Copyright (C) 2008-2020 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/unique_lock.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{mutex}
  28  */
  29
  30 #ifndef _GLIBCXX_UNIQUE_LOCK_H
  31 #define _GLIBCXX_UNIQUE_LOCK_H 1
  32
  33 #pragma GCC system_header
  34
  35 #if __cplusplus < 201103L
  36 # include <bits/c++0x_warning.h>
  37 #else
  38
  39 #include <chrono>
  40 #include <bits/move.h> // for std::swap
  41
  42 namespace std _GLIBCXX_VISIBILITY(default)
  43 {
  44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  45
  46   /** @brief A movable scoped lock type.
  47    *
  48    * A unique_lock controls mutex ownership within a scope. Ownership of the
  49    * mutex can be delayed until after construction and can be transferred
  50    * to another unique_lock by move construction or move assignment. If a
  51    * mutex lock is owned when the destructor runs ownership will be released.
  52    *
  53    * @ingroup mutexes
  54    */
  55   template<typename _Mutex>
  56     class unique_lock
  57     {
  58     public:
  59       typedef _Mutex mutex_type;
  60
  61       unique_lock() noexcept
  62       : _M_device(0), _M_owns(false)
  63       { }
  64
  65       explicit unique_lock(mutex_type& __m)
  66       : _M_device(std::__addressof(__m)), _M_owns(false)
  67       {
  68         lock();
  69         _M_owns = true;
  70       }
  71
  72       unique_lock(mutex_type& __m, defer_lock_t) noexcept
  73       : _M_device(std::__addressof(__m)), _M_owns(false)
  74       { }
  75
  76       unique_lock(mutex_type& __m, try_to_lock_t)
  77       : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
  78       { }
  79
  80       unique_lock(mutex_type& __m, adopt_lock_t) noexcept
  81       : _M_device(std::__addressof(__m)), _M_owns(true)
  82       {
  83         // XXX calling thread owns mutex
  84       }
  85
  86       template<typename _Clock, typename _Duration>
  87         unique_lock(mutex_type& __m,
  88                     const chrono::time_point<_Clock, _Duration>& __atime)
  89         : _M_device(std::__addressof(__m)),
  90           _M_owns(_M_device->try_lock_until(__atime))
  91         { }
  92
  93       template<typename _Rep, typename _Period>
  94         unique_lock(mutex_type& __m,
  95                     const chrono::duration<_Rep, _Period>& __rtime)
  96         : _M_device(std::__addressof(__m)),
  97           _M_owns(_M_device->try_lock_for(__rtime))
  98         { }
  99
 100       ~unique_lock()
 101       {
 102         if (_M_owns)
 103           unlock();
 104       }
 105
 106       unique_lock(const unique_lock&) = delete;
 107       unique_lock& operator=(const unique_lock&) = delete;
 108
 109       unique_lock(unique_lock&& __u) noexcept
 110       : _M_device(__u._M_device), _M_owns(__u._M_owns)
 111       {
 112         __u._M_device = 0;
 113         __u._M_owns = false;
 114       }
 115
 116       unique_lock& operator=(unique_lock&& __u) noexcept
 117       {
 118         if(_M_owns)
 119           unlock();
 120
 121         unique_lock(std::move(__u)).swap(*this);
 122
 123         __u._M_device = 0;
 124         __u._M_owns = false;
 125
 126         return *this;
 127       }
 128
 129       void
 130       lock()
 131       {
 132         if (!_M_device)
 133           __throw_system_error(int(errc::operation_not_permitted));
 134         else if (_M_owns)
 135           __throw_system_error(int(errc::resource_deadlock_would_occur));
 136         else
 137           {
 138             _M_device->lock();
 139             _M_owns = true;
 140           }
 141       }
 142
 143       bool
 144       try_lock()
 145       {
 146         if (!_M_device)
 147           __throw_system_error(int(errc::operation_not_permitted));
 148         else if (_M_owns)
 149           __throw_system_error(int(errc::resource_deadlock_would_occur));
 150         else
 151           {
 152             _M_owns = _M_device->try_lock();
 153             return _M_owns;
 154           }
 155       }
 156
 157       template<typename _Clock, typename _Duration>
 158         bool
 159         try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
 160         {
 161           if (!_M_device)
 162             __throw_system_error(int(errc::operation_not_permitted));
 163           else if (_M_owns)
 164             __throw_system_error(int(errc::resource_deadlock_would_occur));
 165           else
 166             {
 167               _M_owns = _M_device->try_lock_until(__atime);
 168               return _M_owns;
 169             }
 170         }
 171
 172       template<typename _Rep, typename _Period>
 173         bool
 174         try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
 175         {
 176           if (!_M_device)
 177             __throw_system_error(int(errc::operation_not_permitted));
 178           else if (_M_owns)
 179             __throw_system_error(int(errc::resource_deadlock_would_occur));
 180           else
 181             {
 182               _M_owns = _M_device->try_lock_for(__rtime);
 183               return _M_owns;
 184             }
 185          }
 186
 187       void
 188       unlock()
 189       {
 190         if (!_M_owns)
 191           __throw_system_error(int(errc::operation_not_permitted));
 192         else if (_M_device)
 193           {
 194             _M_device->unlock();
 195             _M_owns = false;
 196           }
 197       }
 198
 199       void
 200       swap(unique_lock& __u) noexcept
 201       {
 202         std::swap(_M_device, __u._M_device);
 203         std::swap(_M_owns, __u._M_owns);
 204       }
 205
 206       mutex_type*
 207       release() noexcept
 208       {
 209         mutex_type* __ret = _M_device;
 210         _M_device = 0;
 211         _M_owns = false;
 212         return __ret;
 213       }
 214
 215       bool
 216       owns_lock() const noexcept
 217       { return _M_owns; }
 218
 219       explicit operator bool() const noexcept
 220       { return owns_lock(); }
 221
 222       mutex_type*
 223       mutex() const noexcept
 224       { return _M_device; }
 225
 226     private:
 227       mutex_type*       _M_device;
 228       bool              _M_owns;
 229     };
 230
 231   /// Swap overload for unique_lock objects.
 232   /// @relates unique_lock
 233   template<typename _Mutex>
 234     inline void
 235     swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
 236     { __x.swap(__y); }
 237
 238 _GLIBCXX_END_NAMESPACE_VERSION
 239 } // namespace
 240
 241 #endif // C++11
 242 #endif // _GLIBCXX_UNIQUE_LOCK_H