1 | // std::unique_lock implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2008-2021 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 | #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 | * @ingroup mutexes |
55 | */ |
56 | template<typename _Mutex> |
57 | class unique_lock |
58 | { |
59 | public: |
60 | typedef _Mutex mutex_type; |
61 | |
62 | unique_lock() noexcept |
63 | : _M_device(0), _M_owns(false) |
64 | { } |
65 | |
66 | explicit unique_lock(mutex_type& __m) |
67 | : _M_device(std::__addressof(__m)), _M_owns(false) |
68 | { |
69 | lock(); |
70 | _M_owns = true; |
71 | } |
72 | |
73 | unique_lock(mutex_type& __m, defer_lock_t) noexcept |
74 | : _M_device(std::__addressof(__m)), _M_owns(false) |
75 | { } |
76 | |
77 | unique_lock(mutex_type& __m, try_to_lock_t) |
78 | : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock()) |
79 | { } |
80 | |
81 | unique_lock(mutex_type& __m, adopt_lock_t) noexcept |
82 | : _M_device(std::__addressof(__m)), _M_owns(true) |
83 | { |
84 | // XXX calling thread owns mutex |
85 | } |
86 | |
87 | template<typename _Clock, typename _Duration> |
88 | unique_lock(mutex_type& __m, |
89 | const chrono::time_point<_Clock, _Duration>& __atime) |
90 | : _M_device(std::__addressof(__m)), |
91 | _M_owns(_M_device->try_lock_until(__atime)) |
92 | { } |
93 | |
94 | template<typename _Rep, typename _Period> |
95 | unique_lock(mutex_type& __m, |
96 | const chrono::duration<_Rep, _Period>& __rtime) |
97 | : _M_device(std::__addressof(__m)), |
98 | _M_owns(_M_device->try_lock_for(__rtime)) |
99 | { } |
100 | |
101 | ~unique_lock() |
102 | { |
103 | if (_M_owns) |
104 | unlock(); |
105 | } |
106 | |
107 | unique_lock(const unique_lock&) = delete; |
108 | unique_lock& operator=(const unique_lock&) = delete; |
109 | |
110 | unique_lock(unique_lock&& __u) noexcept |
111 | : _M_device(__u._M_device), _M_owns(__u._M_owns) |
112 | { |
113 | __u._M_device = 0; |
114 | __u._M_owns = false; |
115 | } |
116 | |
117 | unique_lock& operator=(unique_lock&& __u) noexcept |
118 | { |
119 | if(_M_owns) |
120 | unlock(); |
121 | |
122 | unique_lock(std::move(__u)).swap(*this); |
123 | |
124 | __u._M_device = 0; |
125 | __u._M_owns = false; |
126 | |
127 | return *this; |
128 | } |
129 | |
130 | void |
131 | lock() |
132 | { |
133 | if (!_M_device) |
134 | __throw_system_error(int(errc::operation_not_permitted)); |
135 | else if (_M_owns) |
136 | __throw_system_error(int(errc::resource_deadlock_would_occur)); |
137 | else |
138 | { |
139 | _M_device->lock(); |
140 | _M_owns = true; |
141 | } |
142 | } |
143 | |
144 | bool |
145 | try_lock() |
146 | { |
147 | if (!_M_device) |
148 | __throw_system_error(int(errc::operation_not_permitted)); |
149 | else if (_M_owns) |
150 | __throw_system_error(int(errc::resource_deadlock_would_occur)); |
151 | else |
152 | { |
153 | _M_owns = _M_device->try_lock(); |
154 | return _M_owns; |
155 | } |
156 | } |
157 | |
158 | template<typename _Clock, typename _Duration> |
159 | bool |
160 | try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime) |
161 | { |
162 | if (!_M_device) |
163 | __throw_system_error(int(errc::operation_not_permitted)); |
164 | else if (_M_owns) |
165 | __throw_system_error(int(errc::resource_deadlock_would_occur)); |
166 | else |
167 | { |
168 | _M_owns = _M_device->try_lock_until(__atime); |
169 | return _M_owns; |
170 | } |
171 | } |
172 | |
173 | template<typename _Rep, typename _Period> |
174 | bool |
175 | try_lock_for(const chrono::duration<_Rep, _Period>& __rtime) |
176 | { |
177 | if (!_M_device) |
178 | __throw_system_error(int(errc::operation_not_permitted)); |
179 | else if (_M_owns) |
180 | __throw_system_error(int(errc::resource_deadlock_would_occur)); |
181 | else |
182 | { |
183 | _M_owns = _M_device->try_lock_for(__rtime); |
184 | return _M_owns; |
185 | } |
186 | } |
187 | |
188 | void |
189 | unlock() |
190 | { |
191 | if (!_M_owns) |
192 | __throw_system_error(int(errc::operation_not_permitted)); |
193 | else if (_M_device) |
194 | { |
195 | _M_device->unlock(); |
196 | _M_owns = false; |
197 | } |
198 | } |
199 | |
200 | void |
201 | swap(unique_lock& __u) noexcept |
202 | { |
203 | std::swap(_M_device, __u._M_device); |
204 | std::swap(_M_owns, __u._M_owns); |
205 | } |
206 | |
207 | mutex_type* |
208 | release() noexcept |
209 | { |
210 | mutex_type* __ret = _M_device; |
211 | _M_device = 0; |
212 | _M_owns = false; |
213 | return __ret; |
214 | } |
215 | |
216 | bool |
217 | owns_lock() const noexcept |
218 | { return _M_owns; } |
219 | |
220 | explicit operator bool() const noexcept |
221 | { return owns_lock(); } |
222 | |
223 | mutex_type* |
224 | mutex() const noexcept |
225 | { return _M_device; } |
226 | |
227 | private: |
228 | mutex_type* _M_device; |
229 | bool _M_owns; |
230 | }; |
231 | |
232 | /// Swap overload for unique_lock objects. |
233 | /// @relates unique_lock |
234 | template<typename _Mutex> |
235 | inline void |
236 | swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept |
237 | { __x.swap(__y); } |
238 | |
239 | _GLIBCXX_END_NAMESPACE_VERSION |
240 | } // namespace |
241 | |
242 | #endif // C++11 |
243 | #endif // _GLIBCXX_UNIQUE_LOCK_H |
244 | |