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> 6 ** Contact: https://www.qt.io/licensing/ 7 ** 8 ** This file is part of the QtCore module of the Qt Toolkit. 9 ** 10 ** $QT_BEGIN_LICENSE:LGPL$ 11 ** Commercial License Usage 12 ** Licensees holding valid commercial Qt licenses may use this file in 13 ** accordance with the commercial license agreement provided with the 14 ** Software or, alternatively, in accordance with the terms contained in 15 ** a written agreement between you and The Qt Company. For licensing terms 16 ** and conditions see https://www.qt.io/terms-conditions. For further 17 ** information use the contact form at https://www.qt.io/contact-us. 18 ** 19 ** GNU Lesser General Public License Usage 20 ** Alternatively, this file may be used under the terms of the GNU Lesser 21 ** General Public License version 3 as published by the Free Software 22 ** Foundation and appearing in the file LICENSE.LGPL3 included in the 23 ** packaging of this file. Please review the following information to 24 ** ensure the GNU Lesser General Public License version 3 requirements 25 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 26 ** 27 ** GNU General Public License Usage 28 ** Alternatively, this file may be used under the terms of the GNU 29 ** General Public License version 2.0 or (at your option) the GNU General 30 ** Public license version 3 or any later version approved by the KDE Free 31 ** Qt Foundation. The licenses are as published by the Free Software 32 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 33 ** included in the packaging of this file. Please review the following 34 ** information to ensure the GNU General Public License requirements will 35 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 36 ** https://www.gnu.org/licenses/gpl-3.0.html. 37 ** 38 ** $QT_END_LICENSE$ 39 ** 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 ref()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 } deref()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