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1 | // |
2 | // detail/conditionally_enabled_mutex.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
92f5a8d4 | 5 | // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
b32b8144 FG |
6 | // |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP | |
12 | #define BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | #include <boost/asio/detail/mutex.hpp> | |
20 | #include <boost/asio/detail/noncopyable.hpp> | |
21 | #include <boost/asio/detail/scoped_lock.hpp> | |
22 | ||
23 | #include <boost/asio/detail/push_options.hpp> | |
24 | ||
25 | namespace boost { | |
26 | namespace asio { | |
27 | namespace detail { | |
28 | ||
29 | // Mutex adapter used to conditionally enable or disable locking. | |
30 | class conditionally_enabled_mutex | |
31 | : private noncopyable | |
32 | { | |
33 | public: | |
34 | // Helper class to lock and unlock a mutex automatically. | |
35 | class scoped_lock | |
36 | : private noncopyable | |
37 | { | |
38 | public: | |
39 | // Tag type used to distinguish constructors. | |
40 | enum adopt_lock_t { adopt_lock }; | |
41 | ||
42 | // Constructor adopts a lock that is already held. | |
43 | scoped_lock(conditionally_enabled_mutex& m, adopt_lock_t) | |
44 | : mutex_(m), | |
45 | locked_(m.enabled_) | |
46 | { | |
47 | } | |
48 | ||
49 | // Constructor acquires the lock. | |
50 | explicit scoped_lock(conditionally_enabled_mutex& m) | |
51 | : mutex_(m) | |
52 | { | |
53 | if (m.enabled_) | |
54 | { | |
55 | mutex_.mutex_.lock(); | |
56 | locked_ = true; | |
57 | } | |
58 | else | |
59 | locked_ = false; | |
60 | } | |
61 | ||
62 | // Destructor releases the lock. | |
63 | ~scoped_lock() | |
64 | { | |
65 | if (locked_) | |
66 | mutex_.mutex_.unlock(); | |
67 | } | |
68 | ||
69 | // Explicitly acquire the lock. | |
70 | void lock() | |
71 | { | |
72 | if (mutex_.enabled_ && !locked_) | |
73 | { | |
74 | mutex_.mutex_.lock(); | |
75 | locked_ = true; | |
76 | } | |
77 | } | |
78 | ||
79 | // Explicitly release the lock. | |
80 | void unlock() | |
81 | { | |
82 | if (locked_) | |
83 | { | |
84 | mutex_.unlock(); | |
85 | locked_ = false; | |
86 | } | |
87 | } | |
88 | ||
89 | // Test whether the lock is held. | |
90 | bool locked() const | |
91 | { | |
92 | return locked_; | |
93 | } | |
94 | ||
95 | // Get the underlying mutex. | |
96 | boost::asio::detail::mutex& mutex() | |
97 | { | |
98 | return mutex_.mutex_; | |
99 | } | |
100 | ||
101 | private: | |
102 | friend class conditionally_enabled_event; | |
103 | conditionally_enabled_mutex& mutex_; | |
104 | bool locked_; | |
105 | }; | |
106 | ||
107 | // Constructor. | |
108 | explicit conditionally_enabled_mutex(bool enabled) | |
109 | : enabled_(enabled) | |
110 | { | |
111 | } | |
112 | ||
113 | // Destructor. | |
114 | ~conditionally_enabled_mutex() | |
115 | { | |
116 | } | |
117 | ||
118 | // Determine whether locking is enabled. | |
119 | bool enabled() const | |
120 | { | |
121 | return enabled_; | |
122 | } | |
123 | ||
124 | // Lock the mutex. | |
125 | void lock() | |
126 | { | |
127 | if (enabled_) | |
128 | mutex_.lock(); | |
129 | } | |
130 | ||
131 | // Unlock the mutex. | |
132 | void unlock() | |
133 | { | |
134 | if (enabled_) | |
135 | mutex_.unlock(); | |
136 | } | |
137 | ||
138 | private: | |
139 | friend class scoped_lock; | |
140 | friend class conditionally_enabled_event; | |
141 | boost::asio::detail::mutex mutex_; | |
142 | const bool enabled_; | |
143 | }; | |
144 | ||
145 | } // namespace detail | |
146 | } // namespace asio | |
147 | } // namespace boost | |
148 | ||
149 | #include <boost/asio/detail/pop_options.hpp> | |
150 | ||
151 | #endif // BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP |