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Mutex.h
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1 /*
2 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of NVIDIA CORPORATION nor the names of its
13 * contributors may be used to endorse or promote products derived
14 * from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
20 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
21 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
23 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
24 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #ifndef MUTEX_H
30 #define MUTEX_H
31
32 #include <pthread.h>
33
34 #include "Error.h"
35
36 namespace ArgusSamples
37 {
38
39 class ConditionVariable;
40
41 /**
42 * Mutex
43 */
44 class Mutex
45 {
46 public:
47 Mutex();
48 ~Mutex();
49
50 /**
51 * Create the underlying mutex. This method must be called before any other methods.
52 */
53 bool initialize();
54
55 /**
56 * Destroy the underlying mutex. After this call, this object can no longer be used
57 * (until and unless a future call to @c initialize()). Calling this method if the
58 * object is not initialized generates no error, but silently returns.
59 */
60 bool shutdown();
61
62 /**
63 * Lock the mutex. This method is declared @c const for convenience.
64 */
65 bool lock() const;
66
67 /**
68 * Unlock the mutex. This method is declared @c const for convenience.
69 */
70 bool unlock() const;
71
72 private:
73 bool m_initialized;
74 /**
75 * pthread mutex, this is 'mutable' so that 'const' functions can be used.
76 */
77 mutable pthread_mutex_t m_mutex;
78
79 /**
80 * Hide copy constructor and assignment operator
81 */
82 Mutex(Mutex &other);
83 const Mutex& operator = (const Mutex&);
84
85 friend class ConditionVariable;
86
87 pthread_mutex_t* getPThreadMutex() const
88 {
89 return &m_mutex;
90 }
91 };
92
93 /**
94 * An RAII-style class for acquiring a Mutex.
95 * The mutex is acquired in the constructor and released in the destructor.
96 * This class is NOT to be subclassed.
97 */
98 class ScopedMutex
99 {
100 public:
101 explicit ScopedMutex(Mutex& mutex)
102 : m_mutex(&mutex)
103 , m_isLocked(false)
104 {
105 m_isLocked = m_mutex->lock();
106 }
107
108 ~ScopedMutex()
109 {
110 if (m_isLocked)
111 m_mutex->unlock();
112 }
113
114 bool expectLocked() const
115 {
116 if (!m_isLocked)
117 ORIGINATE_ERROR("Expected mutex to be locked");
118 return true;
119 }
120
121 private:
122 Mutex *m_mutex;
123 bool m_isLocked;
124
125 /**
126 * Hide default/copy constructor and assignment operator
127 */
128 ScopedMutex();
129 ScopedMutex(ScopedMutex &other);
130 ScopedMutex& operator = (const ScopedMutex&);
131 };
132
133 } // namespace ArgusSamples
134
135 #endif // MUTEX_H