| Line | Source Code | Coverage |
|---|
| 1 | /**************************************************************************** | - |
| 2 | ** | - |
| 3 | ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). | - |
| 4 | ** Copyright (C) 2012 Intel Corporation | - |
| 5 | ** Contact: http://www.qt-project.org/legal | - |
| 6 | ** | - |
| 7 | ** This file is part of the QtCore module of the Qt Toolkit. | - |
| 8 | ** | - |
| 9 | ** $QT_BEGIN_LICENSE:LGPL$ | - |
| 10 | ** Commercial License Usage | - |
| 11 | ** Licensees holding valid commercial Qt licenses may use this file in | - |
| 12 | ** accordance with the commercial license agreement provided with the | - |
| 13 | ** Software or, alternatively, in accordance with the terms contained in | - |
| 14 | ** a written agreement between you and Digia. For licensing terms and | - |
| 15 | ** conditions see http://qt.digia.com/licensing. For further information | - |
| 16 | ** use the contact form at http://qt.digia.com/contact-us. | - |
| 17 | ** | - |
| 18 | ** GNU Lesser General Public License Usage | - |
| 19 | ** Alternatively, this file may be used under the terms of the GNU Lesser | - |
| 20 | ** General Public License version 2.1 as published by the Free Software | - |
| 21 | ** Foundation and appearing in the file LICENSE.LGPL included in the | - |
| 22 | ** packaging of this file. Please review the following information to | - |
| 23 | ** ensure the GNU Lesser General Public License version 2.1 requirements | - |
| 24 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. | - |
| 25 | ** | - |
| 26 | ** In addition, as a special exception, Digia gives you certain additional | - |
| 27 | ** rights. These rights are described in the Digia Qt LGPL Exception | - |
| 28 | ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. | - |
| 29 | ** | - |
| 30 | ** GNU General Public License Usage | - |
| 31 | ** Alternatively, this file may be used under the terms of the GNU | - |
| 32 | ** General Public License version 3.0 as published by the Free Software | - |
| 33 | ** Foundation and appearing in the file LICENSE.GPL included in the | - |
| 34 | ** packaging of this file. Please review the following information to | - |
| 35 | ** ensure the GNU General Public License version 3.0 requirements will be | - |
| 36 | ** met: http://www.gnu.org/copyleft/gpl.html. | - |
| 37 | ** | - |
| 38 | ** | - |
| 39 | ** $QT_END_LICENSE$ | - |
| 40 | ** | - |
| 41 | ****************************************************************************/ | - |
| 42 | | - |
| 43 | #include "qplatformdefs.h" | - |
| 44 | #include "qmutex.h" | - |
| 45 | | - |
| 46 | #ifndef QT_NO_THREAD | - |
| 47 | #include "qatomic.h" | - |
| 48 | #include "qmutex_p.h" | - |
| 49 | #include "qelapsedtimer.h" | - |
| 50 | | - |
| 51 | #include <linux/futex.h> | - |
| 52 | #include <sys/syscall.h> | - |
| 53 | #include <unistd.h> | - |
| 54 | #include <errno.h> | - |
| 55 | #include <asm/unistd.h> | - |
| 56 | | - |
| 57 | #if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L | - |
| 58 | // C++11 mode | - |
| 59 | # include <type_traits> | - |
| 60 | | - |
| 61 | static void checkElapsedTimerIsTrivial() | - |
| 62 | { | - |
| 63 | Q_STATIC_ASSERT(std::has_trivial_default_constructor<QT_PREPEND_NAMESPACE(QElapsedTimer)>::value); executed (the execution status of this line is deduced): static_assert(bool(std::has_trivial_default_constructor< ::QElapsedTimer>::value), "std::has_trivial_default_constructor<QT_PREPEND_NAMESPACE(QElapsedTimer)>::value"); | - |
| 64 | } executed: }Execution Count:4631415 | 4631415 |
| 65 | | - |
| 66 | #else | - |
| 67 | static void checkElapsedTimerIsTrivial() | - |
| 68 | { | - |
| 69 | } | - |
| 70 | #endif | - |
| 71 | | - |
| 72 | #ifndef QT_LINUX_FUTEX | - |
| 73 | # error "Qt build is broken: qmutex_linux.cpp is being built but futex support is not wanted" | - |
| 74 | #endif | - |
| 75 | | - |
| 76 | QT_BEGIN_NAMESPACE | - |
| 77 | | - |
| 78 | /* | - |
| 79 | * QBasicMutex implementation on Linux with futexes | - |
| 80 | * | - |
| 81 | * QBasicMutex contains one pointer value, which can contain one of four | - |
| 82 | * different values: | - |
| 83 | * 0x0 unlocked, non-recursive mutex | - |
| 84 | * 0x1 locked non-recursive mutex, no waiters | - |
| 85 | * 0x3 locked non-recursive mutex, at least one waiter | - |
| 86 | * > 0x3 recursive mutex, points to a QMutexPrivate object | - |
| 87 | * | - |
| 88 | * LOCKING (non-recursive): | - |
| 89 | * | - |
| 90 | * A non-recursive mutex starts in the 0x0 state, indicating that it's | - |
| 91 | * unlocked. When the first thread attempts to lock it, it will perform a | - |
| 92 | * testAndSetAcquire from 0x0 to 0x1. If that succeeds, the caller concludes | - |
| 93 | * that it successfully locked the mutex. That happens in fastTryLock(). | - |
| 94 | * | - |
| 95 | * If that testAndSetAcquire fails, QBasicMutex::lockInternal is called. | - |
| 96 | * | - |
| 97 | * lockInternal will examine the value of the pointer. Otherwise, it will use | - |
| 98 | * futexes to sleep and wait for another thread to unlock. To do that, it needs | - |
| 99 | * to set a pointer value of 0x3, which indicates that thread is waiting. It | - |
| 100 | * does that by a simple fetchAndStoreAcquire operation. | - |
| 101 | * | - |
| 102 | * If the pointer value was 0x0, it means we succeeded in acquiring the mutex. | - |
| 103 | * For other values, it will then call FUTEX_WAIT and with an expected value of | - |
| 104 | * 0x3. | - |
| 105 | * | - |
| 106 | * If the pointer value changed before futex(2) managed to sleep, it will | - |
| 107 | * return -1 / EWOULDBLOCK, in which case we have to start over. And even if we | - |
| 108 | * are woken up directly by a FUTEX_WAKE, we need to acquire the mutex, so we | - |
| 109 | * start over again. | - |
| 110 | * | - |
| 111 | * UNLOCKING (non-recursive): | - |
| 112 | * | - |
| 113 | * To unlock, we need to set a value of 0x0 to indicate it's unlocked. The | - |
| 114 | * first attempt is a testAndSetRelease operation from 0x1 to 0x0. If that | - |
| 115 | * succeeds, we're done. | - |
| 116 | * | - |
| 117 | * If it fails, unlockInternal() is called. The only possibility is that the | - |
| 118 | * mutex value was 0x3, which indicates some other thread is waiting or was | - |
| 119 | * waiting in the past. We then set the mutex to 0x0 and perform a FUTEX_WAKE. | - |
| 120 | */ | - |
| 121 | | - |
| 122 | static QBasicAtomicInt futexFlagSupport = Q_BASIC_ATOMIC_INITIALIZER(-1); | - |
| 123 | | - |
| 124 | static int checkFutexPrivateSupport() | - |
| 125 | { | - |
| 126 | int value = 0; executed (the execution status of this line is deduced): int value = 0; | - |
| 127 | #if defined(FUTEX_PRIVATE_FLAG) | - |
| 128 | // check if the kernel supports extra futex flags | - |
| 129 | // FUTEX_PRIVATE_FLAG appeared in v2.6.22 | - |
| 130 | Q_STATIC_ASSERT(FUTEX_PRIVATE_FLAG != 0x80000000); executed (the execution status of this line is deduced): static_assert(bool(128 != 0x80000000), "FUTEX_PRIVATE_FLAG != 0x80000000"); | - |
| 131 | | - |
| 132 | // try an operation that has no side-effects: wake up 42 threads | - |
| 133 | // futex will return -1 (errno==ENOSYS) if the flag isn't supported | - |
| 134 | // there should be no other error conditions | - |
| 135 | value = syscall(__NR_futex, &futexFlagSupport, executed (the execution status of this line is deduced): value = syscall(202, &futexFlagSupport, | - |
| 136 | FUTEX_WAKE | FUTEX_PRIVATE_FLAG, executed (the execution status of this line is deduced): 1 | 128, | - |
| 137 | 42, 0, 0, 0); executed (the execution status of this line is deduced): 42, 0, 0, 0); | - |
| 138 | if (value != -1) partially evaluated: value != -1| yes Evaluation Count:74 | no Evaluation Count:0 |
| 0-74 |
| 139 | value = FUTEX_PRIVATE_FLAG; executed: value = 128;Execution Count:74 | 74 |
| 140 | else | - |
| 141 | value = 0; never executed: value = 0; | 0 |
| 142 | | - |
| 143 | #else | - |
| 144 | value = 0; | - |
| 145 | #endif | - |
| 146 | futexFlagSupport.store(value); executed (the execution status of this line is deduced): futexFlagSupport.store(value); | - |
| 147 | return value; executed: return value;Execution Count:73 | 73 |
| 148 | } | - |
| 149 | | - |
| 150 | static inline int futexFlags() | - |
| 151 | { | - |
| 152 | int value = futexFlagSupport.load(); executed (the execution status of this line is deduced): int value = futexFlagSupport.load(); | - |
| 153 | if (Q_LIKELY(value != -1)) evaluated: __builtin_expect(!!(value != -1), true)| yes Evaluation Count:14715604 | yes Evaluation Count:72 |
| 72-14715604 |
| 154 | return value; executed: return value;Execution Count:14705438 | 14705438 |
| 155 | return checkFutexPrivateSupport(); executed: return checkFutexPrivateSupport();Execution Count:73 | 73 |
| 156 | } | - |
| 157 | | - |
| 158 | static inline int _q_futex(void *addr, int op, int val, const struct timespec *timeout) Q_DECL_NOTHROW | - |
| 159 | { | - |
| 160 | volatile int *int_addr = reinterpret_cast<volatile int *>(addr); executed (the execution status of this line is deduced): volatile int *int_addr = reinterpret_cast<volatile int *>(addr); | - |
| 161 | #if Q_BYTE_ORDER == Q_BIG_ENDIAN && QT_POINTER_SIZE == 8 | - |
| 162 | int_addr++; //We want a pointer to the 32 least significant bit of QMutex::d | - |
| 163 | #endif | - |
| 164 | int *addr2 = 0; executed (the execution status of this line is deduced): int *addr2 = 0; | - |
| 165 | int val2 = 0; executed (the execution status of this line is deduced): int val2 = 0; | - |
| 166 | | - |
| 167 | // we use __NR_futex because some libcs (like Android's bionic) don't | - |
| 168 | // provide SYS_futex etc. | - |
| 169 | return syscall(__NR_futex, int_addr, op | futexFlags(), val, timeout, addr2, val2); executed: return syscall(202, int_addr, op | futexFlags(), val, timeout, addr2, val2);Execution Count:14722852 | 14722852 |
| 170 | } | - |
| 171 | | - |
| 172 | static inline QMutexData *dummyFutexValue() | - |
| 173 | { | - |
| 174 | return reinterpret_cast<QMutexData *>(quintptr(3)); executed: return reinterpret_cast<QMutexData *>(quintptr(3));Execution Count:18492938 | 18492938 |
| 175 | } | - |
| 176 | | - |
| 177 | template <bool IsTimed> static inline | - |
| 178 | bool lockInternal_helper(QBasicAtomicPointer<QMutexData> &d_ptr, int timeout = -1) Q_DECL_NOTHROW | - |
| 179 | { | - |
| 180 | if (!IsTimed) evaluated: !IsTimed| yes Evaluation Count:4620449 | yes Evaluation Count:232452 |
| 232452-4620449 |
| 181 | timeout = -1; executed: timeout = -1;Execution Count:4618076 | 4618076 |
| 182 | | - |
| 183 | // we're here because fastTryLock() has just failed | - |
| 184 | if (timeout == 0) evaluated: timeout == 0| yes Evaluation Count:215910 | yes Evaluation Count:4631859 |
| 215910-4631859 |
| 185 | return false; executed: return false;Execution Count:215393 | 215393 |
| 186 | | - |
| 187 | struct timespec ts, *pts = 0; executed (the execution status of this line is deduced): struct timespec ts, *pts = 0; | - |
| 188 | QElapsedTimer elapsedTimer; executed (the execution status of this line is deduced): QElapsedTimer elapsedTimer; | - |
| 189 | checkElapsedTimerIsTrivial(); executed (the execution status of this line is deduced): checkElapsedTimerIsTrivial(); | - |
| 190 | if (IsTimed && timeout > 0) { evaluated: IsTimed| yes Evaluation Count:16831 | yes Evaluation Count:4615492 |
evaluated: timeout > 0| yes Evaluation Count:16828 | yes Evaluation Count:4 |
| 4-4615492 |
| 191 | ts.tv_sec = timeout / 1000; executed (the execution status of this line is deduced): ts.tv_sec = timeout / 1000; | - |
| 192 | ts.tv_nsec = (timeout % 1000) * 1000 * 1000; executed (the execution status of this line is deduced): ts.tv_nsec = (timeout % 1000) * 1000 * 1000; | - |
| 193 | elapsedTimer.start(); executed (the execution status of this line is deduced): elapsedTimer.start(); | - |
| 194 | } executed: }Execution Count:16838 | 16838 |
| 195 | | - |
| 196 | // the mutex is locked already, set a bit indicating we're waiting | - |
| 197 | while (d_ptr.fetchAndStoreAcquire(dummyFutexValue()) != 0) { evaluated: d_ptr.fetchAndStoreAcquire(dummyFutexValue()) != 0| yes Evaluation Count:7011362 | yes Evaluation Count:4650469 |
| 4650469-7011362 |
| 198 | if (IsTimed && pts == &ts) { evaluated: IsTimed| yes Evaluation Count:16684 | yes Evaluation Count:7000305 |
evaluated: pts == &ts| yes Evaluation Count:292 | yes Evaluation Count:16389 |
| 292-7000305 |
| 199 | // recalculate the timeout | - |
| 200 | qint64 xtimeout = qint64(timeout) * 1000 * 1000; executed (the execution status of this line is deduced): qint64 xtimeout = qint64(timeout) * 1000 * 1000; | - |
| 201 | xtimeout -= elapsedTimer.nsecsElapsed(); executed (the execution status of this line is deduced): xtimeout -= elapsedTimer.nsecsElapsed(); | - |
| 202 | if (xtimeout <= 0) { evaluated: xtimeout <= 0| yes Evaluation Count:146 | yes Evaluation Count:146 |
| 146 |
| 203 | // timer expired after we returned | - |
| 204 | return false; executed: return false;Execution Count:146 | 146 |
| 205 | } | - |
| 206 | ts.tv_sec = xtimeout / Q_INT64_C(1000) / 1000 / 1000; executed (the execution status of this line is deduced): ts.tv_sec = xtimeout / static_cast<long long>(1000LL) / 1000 / 1000; | - |
| 207 | ts.tv_nsec = xtimeout % (Q_INT64_C(1000) * 1000 * 1000); executed (the execution status of this line is deduced): ts.tv_nsec = xtimeout % (static_cast<long long>(1000LL) * 1000 * 1000); | - |
| 208 | } executed: }Execution Count:146 | 146 |
| 209 | if (IsTimed && timeout > 0) evaluated: IsTimed| yes Evaluation Count:16537 | yes Evaluation Count:7002417 |
evaluated: timeout > 0| yes Evaluation Count:16533 | yes Evaluation Count:4 |
| 4-7002417 |
| 210 | pts = &ts; executed: pts = &ts;Execution Count:16535 | 16535 |
| 211 | | - |
| 212 | // successfully set the waiting bit, now sleep | - |
| 213 | int r = _q_futex(&d_ptr, FUTEX_WAIT, quintptr(dummyFutexValue()), pts); executed (the execution status of this line is deduced): int r = _q_futex(&d_ptr, 0, quintptr(dummyFutexValue()), pts); | - |
| 214 | if (IsTimed && r != 0 && errno == ETIMEDOUT) evaluated: IsTimed| yes Evaluation Count:16532 | yes Evaluation Count:7003013 |
evaluated: r != 0| yes Evaluation Count:8035 | yes Evaluation Count:8501 |
evaluated: (*__errno_location ()) == 110| yes Evaluation Count:7903 | yes Evaluation Count:135 |
| 135-7003013 |
| 215 | return false; executed: return false;Execution Count:7898 | 7898 |
| 216 | | - |
| 217 | // we got woken up, so try to acquire the mutex | - |
| 218 | // note we must set to dummyFutexValue because there could be other threads | - |
| 219 | // also waiting | - |
| 220 | } executed: }Execution Count:7011219 | 7011219 |
| 221 | | - |
| 222 | Q_ASSERT(d_ptr.load()); executed (the execution status of this line is deduced): qt_noop(); | - |
| 223 | return true; executed: return true;Execution Count:4650436 | 4650436 |
| 224 | } | - |
| 225 | | - |
| 226 | void QBasicMutex::lockInternal() Q_DECL_NOTHROW | - |
| 227 | { | - |
| 228 | Q_ASSERT(!isRecursive()); executed (the execution status of this line is deduced): qt_noop(); | - |
| 229 | lockInternal_helper<false>(d_ptr); executed (the execution status of this line is deduced): lockInternal_helper<false>(d_ptr); | - |
| 230 | } executed: }Execution Count:4641658 | 4641658 |
| 231 | | - |
| 232 | bool QBasicMutex::lockInternal(int timeout) Q_DECL_NOTHROW | - |
| 233 | { | - |
| 234 | Q_ASSERT(!isRecursive()); executed (the execution status of this line is deduced): qt_noop(); | - |
| 235 | return lockInternal_helper<true>(d_ptr, timeout); executed: return lockInternal_helper<true>(d_ptr, timeout);Execution Count:236010 | 236010 |
| 236 | } | - |
| 237 | | - |
| 238 | void QBasicMutex::unlockInternal() Q_DECL_NOTHROW | - |
| 239 | { | - |
| 240 | QMutexData *d = d_ptr.load(); executed (the execution status of this line is deduced): QMutexData *d = d_ptr.load(); | - |
| 241 | Q_ASSERT(d); //we must be locked executed (the execution status of this line is deduced): qt_noop(); | - |
| 242 | Q_ASSERT(d != dummyLocked()); // testAndSetRelease(dummyLocked(), 0) failed executed (the execution status of this line is deduced): qt_noop(); | - |
| 243 | Q_UNUSED(d); executed (the execution status of this line is deduced): (void)d;; | - |
| 244 | Q_ASSERT(!isRecursive()); executed (the execution status of this line is deduced): qt_noop(); | - |
| 245 | | - |
| 246 | d_ptr.storeRelease(0); executed (the execution status of this line is deduced): d_ptr.storeRelease(0); | - |
| 247 | _q_futex(&d_ptr, FUTEX_WAKE, 1, 0); executed (the execution status of this line is deduced): _q_futex(&d_ptr, 1, 1, 0); | - |
| 248 | } executed: }Execution Count:7868264 | 7868264 |
| 249 | | - |
| 250 | | - |
| 251 | QT_END_NAMESPACE | - |
| 252 | | - |
| 253 | #endif // QT_NO_THREAD | - |
| 254 | | - |
| | |