1 | /**************************************************************************** |
2 | ** |
3 | ** Copyright (C) 2016 The Qt Company Ltd. |
4 | ** Copyright (C) 2016 Intel Corporation. |
5 | ** Copyright (C) 2012 Olivier Goffart <ogoffart@woboq.com> |
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7 | ** |
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40 | ****************************************************************************/ |
41 | |
42 | #ifndef QMUTEX_P_H |
43 | #define QMUTEX_P_H |
44 | |
45 | // |
46 | // W A R N I N G |
47 | // ------------- |
48 | // |
49 | // This file is not part of the Qt API. It exists for the convenience |
50 | // of qmutex.cpp, qmutex_unix.cpp, and qmutex_win.cpp. This header |
51 | // file may change from version to version without notice, or even be |
52 | // removed. |
53 | // |
54 | // We mean it. |
55 | // |
56 | |
57 | #include <QtCore/private/qglobal_p.h> |
58 | #include <QtCore/qnamespace.h> |
59 | #include <QtCore/qmutex.h> |
60 | #include <QtCore/qatomic.h> |
61 | #include <QtCore/qdeadlinetimer.h> |
62 | |
63 | #if defined(Q_OS_MAC) |
64 | # include <mach/semaphore.h> |
65 | #elif defined(Q_OS_LINUX) && !defined(QT_LINUXBASE) |
66 | // use Linux mutexes everywhere except for LSB builds |
67 | # define QT_LINUX_FUTEX |
68 | #elif defined(Q_OS_UNIX) |
69 | # if _POSIX_VERSION-0 >= 200112L || _XOPEN_VERSION-0 >= 600 |
70 | # include <semaphore.h> |
71 | # define QT_UNIX_SEMAPHORE |
72 | # endif |
73 | #endif |
74 | |
75 | struct timespec; |
76 | |
77 | QT_BEGIN_NAMESPACE |
78 | |
79 | class QMutexData |
80 | { |
81 | public: |
82 | bool recursive; |
83 | QMutexData(QMutex::RecursionMode mode = QMutex::NonRecursive) |
84 | : recursive(mode == QMutex::Recursive) {} |
85 | }; |
86 | |
87 | #if !defined(QT_LINUX_FUTEX) |
88 | class QMutexPrivate : public QMutexData |
89 | { |
90 | public: |
91 | ~QMutexPrivate(); |
92 | QMutexPrivate(); |
93 | |
94 | bool wait(int timeout = -1); |
95 | void wakeUp() noexcept; |
96 | |
97 | // Control the lifetime of the privates |
98 | QAtomicInt refCount; |
99 | int id; |
100 | |
101 | bool ref() { |
102 | Q_ASSERT(refCount.loadRelaxed() >= 0); |
103 | int c; |
104 | do { |
105 | c = refCount.loadRelaxed(); |
106 | if (c == 0) |
107 | return false; |
108 | } while (!refCount.testAndSetRelaxed(c, c + 1)); |
109 | Q_ASSERT(refCount.loadRelaxed() >= 0); |
110 | return true; |
111 | } |
112 | void deref() { |
113 | Q_ASSERT(refCount.loadRelaxed() >= 0); |
114 | if (!refCount.deref()) |
115 | release(); |
116 | Q_ASSERT(refCount.loadRelaxed() >= 0); |
117 | } |
118 | void release(); |
119 | static QMutexPrivate *allocate(); |
120 | |
121 | QAtomicInt waiters; // Number of threads waiting on this mutex. (may be offset by -BigNumber) |
122 | QAtomicInt possiblyUnlocked; /* Boolean indicating that a timed wait timed out. |
123 | When it is true, a reference is held. |
124 | It is there to avoid a race that happens if unlock happens right |
125 | when the mutex is unlocked. |
126 | */ |
127 | enum { BigNumber = 0x100000 }; //Must be bigger than the possible number of waiters (number of threads) |
128 | void derefWaiters(int value) noexcept; |
129 | |
130 | //platform specific stuff |
131 | #if defined(Q_OS_MAC) |
132 | semaphore_t mach_semaphore; |
133 | #elif defined(QT_UNIX_SEMAPHORE) |
134 | sem_t semaphore; |
135 | #elif defined(Q_OS_UNIX) |
136 | bool wakeup; |
137 | pthread_mutex_t mutex; |
138 | pthread_cond_t cond; |
139 | #elif defined(Q_OS_WIN) |
140 | Qt::HANDLE event; |
141 | #endif |
142 | }; |
143 | #endif //QT_LINUX_FUTEX |
144 | |
145 | |
146 | #ifdef Q_OS_UNIX |
147 | // helper functions for qmutex_unix.cpp and qwaitcondition_unix.cpp |
148 | // they are in qwaitcondition_unix.cpp actually |
149 | void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where); |
150 | void qt_abstime_for_timeout(struct timespec *ts, QDeadlineTimer deadline); |
151 | #endif |
152 | |
153 | QT_END_NAMESPACE |
154 | |
155 | #endif // QMUTEX_P_H |
156 | |