Where Online Learning is simpler!

The C and C++ Include Header Files

/usr/include/c++/13/bits/unique_lock.h


$ cat -n /usr/include/c++/13/bits/unique_lock.h

     1	// std::unique_lock implementation -*- C++ -*-
     2	
     3	// Copyright (C) 2008-2023 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 <bits/chrono.h>
    40	#include <bits/move.h> // for std::swap
    41	#include <bits/std_mutex.h> // for std::defer_lock_t
    42	
    43	namespace std _GLIBCXX_VISIBILITY(default)
    44	{
    45	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    46	
    47	  /** @brief A movable scoped lock type.
    48	   *
    49	   * A unique_lock controls mutex ownership within a scope. Ownership of the
    50	   * mutex can be delayed until after construction and can be transferred
    51	   * to another unique_lock by move construction or move assignment. If a
    52	   * mutex lock is owned when the destructor runs ownership will be released.
    53	   *
    54	   * @headerfile mutex
    55	   * @ingroup mutexes
    56	   * @since C++11
    57	   */
    58	  template<typename _Mutex>
    59	    class unique_lock
    60	    {
    61	    public:
    62	      typedef _Mutex mutex_type;
    63	
    64	      unique_lock() noexcept
    65	      : _M_device(0), _M_owns(false)
    66	      { }
    67	
    68	      explicit unique_lock(mutex_type& __m)
    69	      : _M_device(std::__addressof(__m)), _M_owns(false)
    70	      {
    71		lock();
    72		_M_owns = true;
    73	      }
    74	
    75	      unique_lock(mutex_type& __m, defer_lock_t) noexcept
    76	      : _M_device(std::__addressof(__m)), _M_owns(false)
    77	      { }
    78	
    79	      unique_lock(mutex_type& __m, try_to_lock_t)
    80	      : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
    81	      { }
    82	
    83	      unique_lock(mutex_type& __m, adopt_lock_t) noexcept
    84	      : _M_device(std::__addressof(__m)), _M_owns(true)
    85	      {
    86		// XXX calling thread owns mutex
    87	      }
    88	
    89	      template<typename _Clock, typename _Duration>
    90		unique_lock(mutex_type& __m,
    91			    const chrono::time_point<_Clock, _Duration>& __atime)
    92		: _M_device(std::__addressof(__m)),
    93		  _M_owns(_M_device->try_lock_until(__atime))
    94		{ }
    95	
    96	      template<typename _Rep, typename _Period>
    97		unique_lock(mutex_type& __m,
    98			    const chrono::duration<_Rep, _Period>& __rtime)
    99		: _M_device(std::__addressof(__m)),
   100		  _M_owns(_M_device->try_lock_for(__rtime))
   101		{ }
   102	
   103	      ~unique_lock()
   104	      {
   105		if (_M_owns)
   106		  unlock();
   107	      }
   108	
   109	      unique_lock(const unique_lock&) = delete;
   110	      unique_lock& operator=(const unique_lock&) = delete;
   111	
   112	      unique_lock(unique_lock&& __u) noexcept
   113	      : _M_device(__u._M_device), _M_owns(__u._M_owns)
   114	      {
   115		__u._M_device = 0;
   116		__u._M_owns = false;
   117	      }
   118	
   119	      unique_lock& operator=(unique_lock&& __u) noexcept
   120	      {
   121		if(_M_owns)
   122		  unlock();
   123	
   124		unique_lock(std::move(__u)).swap(*this);
   125	
   126		__u._M_device = 0;
   127		__u._M_owns = false;
   128	
   129		return *this;
   130	      }
   131	
   132	      void
   133	      lock()
   134	      {
   135		if (!_M_device)
   136		  __throw_system_error(int(errc::operation_not_permitted));
   137		else if (_M_owns)
   138		  __throw_system_error(int(errc::resource_deadlock_would_occur));
   139		else
   140		  {
   141		    _M_device->lock();
   142		    _M_owns = true;
   143		  }
   144	      }
   145	
   146	      _GLIBCXX_NODISCARD
   147	      bool
   148	      try_lock()
   149	      {
   150		if (!_M_device)
   151		  __throw_system_error(int(errc::operation_not_permitted));
   152		else if (_M_owns)
   153		  __throw_system_error(int(errc::resource_deadlock_would_occur));
   154		else
   155		  {
   156		    _M_owns = _M_device->try_lock();
   157		    return _M_owns;
   158		  }
   159	      }
   160	
   161	      template<typename _Clock, typename _Duration>
   162		_GLIBCXX_NODISCARD
   163		bool
   164		try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
   165		{
   166		  if (!_M_device)
   167		    __throw_system_error(int(errc::operation_not_permitted));
   168		  else if (_M_owns)
   169		    __throw_system_error(int(errc::resource_deadlock_would_occur));
   170		  else
   171		    {
   172		      _M_owns = _M_device->try_lock_until(__atime);
   173		      return _M_owns;
   174		    }
   175		}
   176	
   177	      template<typename _Rep, typename _Period>
   178		_GLIBCXX_NODISCARD
   179		bool
   180		try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
   181		{
   182		  if (!_M_device)
   183		    __throw_system_error(int(errc::operation_not_permitted));
   184		  else if (_M_owns)
   185		    __throw_system_error(int(errc::resource_deadlock_would_occur));
   186		  else
   187		    {
   188		      _M_owns = _M_device->try_lock_for(__rtime);
   189		      return _M_owns;
   190		    }
   191		 }
   192	
   193	      void
   194	      unlock()
   195	      {
   196		if (!_M_owns)
   197		  __throw_system_error(int(errc::operation_not_permitted));
   198		else if (_M_device)
   199		  {
   200		    _M_device->unlock();
   201		    _M_owns = false;
   202		  }
   203	      }
   204	
   205	      void
   206	      swap(unique_lock& __u) noexcept
   207	      {
   208		std::swap(_M_device, __u._M_device);
   209		std::swap(_M_owns, __u._M_owns);
   210	      }
   211	
   212	      mutex_type*
   213	      release() noexcept
   214	      {
   215		mutex_type* __ret = _M_device;
   216		_M_device = 0;
   217		_M_owns = false;
   218		return __ret;
   219	      }
   220	
   221	      _GLIBCXX_NODISCARD
   222	      bool
   223	      owns_lock() const noexcept
   224	      { return _M_owns; }
   225	
   226	      explicit operator bool() const noexcept
   227	      { return owns_lock(); }
   228	
   229	      _GLIBCXX_NODISCARD
   230	      mutex_type*
   231	      mutex() const noexcept
   232	      { return _M_device; }
   233	
   234	    private:
   235	      mutex_type*	_M_device;
   236	      bool		_M_owns;
   237	    };
   238	
   239	  /// Swap overload for unique_lock objects.
   240	  /// @relates unique_lock
   241	  template<typename _Mutex>
   242	    inline void
   243	    swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
   244	    { __x.swap(__y); }
   245	
   246	_GLIBCXX_END_NAMESPACE_VERSION
   247	} // namespace
   248	
   249	#endif // C++11
   250	#endif // _GLIBCXX_UNIQUE_LOCK_H