unique_lock.h
Go to the documentation of this file.
// std::unique_lock implementation -*- C++ -*-
// Copyright (C) 2008-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file bits/unique_lock.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{mutex}
*/
#ifndef _GLIBCXX_UNIQUE_LOCK_H
#define _GLIBCXX_UNIQUE_LOCK_H 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <chrono>
#include <bits/move.h> // for std::swap
#include <bits/std_mutex.h> // for std::defer_lock_t
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/** @brief A movable scoped lock type.
*
* A unique_lock controls mutex ownership within a scope. Ownership of the
* mutex can be delayed until after construction and can be transferred
* to another unique_lock by move construction or move assignment. If a
* mutex lock is owned when the destructor runs ownership will be released.
*
* @ingroup mutexes
*/
template<typename _Mutex>
class unique_lock
{
public:
typedef _Mutex mutex_type;
unique_lock() noexcept
: _M_device(0), _M_owns(false)
{ }
explicit unique_lock(mutex_type& __m)
: _M_device(std::__addressof(__m)), _M_owns(false)
{
lock();
_M_owns = true;
}
unique_lock(mutex_type& __m, defer_lock_t) noexcept
: _M_device(std::__addressof(__m)), _M_owns(false)
{ }
unique_lock(mutex_type& __m, try_to_lock_t)
: _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
{ }
unique_lock(mutex_type& __m, adopt_lock_t) noexcept
: _M_device(std::__addressof(__m)), _M_owns(true)
{
// XXX calling thread owns mutex
}
template<typename _Clock, typename _Duration>
unique_lock(mutex_type& __m,
const chrono::time_point<_Clock, _Duration>& __atime)
: _M_device(std::__addressof(__m)),
_M_owns(_M_device->try_lock_until(__atime))
{ }
template<typename _Rep, typename _Period>
unique_lock(mutex_type& __m,
const chrono::duration<_Rep, _Period>& __rtime)
: _M_device(std::__addressof(__m)),
_M_owns(_M_device->try_lock_for(__rtime))
{ }
~unique_lock()
{
if (_M_owns)
unlock();
}
unique_lock(const unique_lock&) = delete;
unique_lock& operator=(const unique_lock&) = delete;
unique_lock(unique_lock&& __u) noexcept
: _M_device(__u._M_device), _M_owns(__u._M_owns)
{
__u._M_device = 0;
__u._M_owns = false;
}
unique_lock& operator=(unique_lock&& __u) noexcept
{
if(_M_owns)
unlock();
unique_lock(std::move(__u)).swap(*this);
__u._M_device = 0;
__u._M_owns = false;
return *this;
}
void
lock()
{
if (!_M_device)
__throw_system_error(int(errc::operation_not_permitted));
else if (_M_owns)
__throw_system_error(int(errc::resource_deadlock_would_occur));
else
{
_M_device->lock();
_M_owns = true;
}
}
bool
try_lock()
{
if (!_M_device)
__throw_system_error(int(errc::operation_not_permitted));
else if (_M_owns)
__throw_system_error(int(errc::resource_deadlock_would_occur));
else
{
_M_owns = _M_device->try_lock();
return _M_owns;
}
}
template<typename _Clock, typename _Duration>
bool
try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
{
if (!_M_device)
__throw_system_error(int(errc::operation_not_permitted));
else if (_M_owns)
__throw_system_error(int(errc::resource_deadlock_would_occur));
else
{
_M_owns = _M_device->try_lock_until(__atime);
return _M_owns;
}
}
template<typename _Rep, typename _Period>
bool
try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
{
if (!_M_device)
__throw_system_error(int(errc::operation_not_permitted));
else if (_M_owns)
__throw_system_error(int(errc::resource_deadlock_would_occur));
else
{
_M_owns = _M_device->try_lock_for(__rtime);
return _M_owns;
}
}
void
unlock()
{
if (!_M_owns)
__throw_system_error(int(errc::operation_not_permitted));
else if (_M_device)
{
_M_device->unlock();
_M_owns = false;
}
}
void
swap(unique_lock& __u) noexcept
{
std::swap(_M_device, __u._M_device);
std::swap(_M_owns, __u._M_owns);
}
mutex_type*
release() noexcept
{
mutex_type* __ret = _M_device;
_M_device = 0;
_M_owns = false;
return __ret;
}
bool
owns_lock() const noexcept
{ return _M_owns; }
explicit operator bool() const noexcept
{ return owns_lock(); }
mutex_type*
mutex() const noexcept
{ return _M_device; }
private:
mutex_type* _M_device;
bool _M_owns;
};
/// Swap overload for unique_lock objects.
/// @relates unique_lock
template<typename _Mutex>
inline void
swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
{ __x.swap(__y); }
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11
#endif // _GLIBCXX_UNIQUE_LOCK_H
c++0x_warning.h
move.h
std_mutex.h
std::__addressof
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:428
std
ISO C++ entities toplevel namespace is std.
std::chrono::duration
chrono::duration represents a distance between two points in time
Definition: chrono:460
std::chrono::time_point
chrono::time_point represents a point in time as measured by a clock
Definition: chrono:873
std::mutex
The standard mutex type.
Definition: std_mutex.h:84
std::defer_lock_t
Do not acquire ownership of the mutex.
Definition: std_mutex.h:199
std::try_to_lock_t
Try to acquire ownership of the mutex without blocking.
Definition: std_mutex.h:202
std::adopt_lock_t
Assume the calling thread has already obtained mutex ownership and manage it.
Definition: std_mutex.h:206
std::unique_lock
A movable scoped lock type.
Definition: unique_lock.h:58
std::unique_lock::swap
void swap(unique_lock< _Mutex > &__x, unique_lock< _Mutex > &__y) noexcept
Swap overload for unique_lock objects.
Definition: unique_lock.h:236
chrono