| Absolute File Name: | /home/qt/qt5_coco/qt5/qtbase/src/corelib/thread/qthreadstorage.cpp |
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| 1 | /**************************************************************************** | - |
| 2 | ** | - |
| 3 | ** Copyright (C) 2016 The Qt Company Ltd. | - |
| 4 | ** Contact: https://www.qt.io/licensing/ | - |
| 5 | ** | - |
| 6 | ** This file is part of the QtCore module of the Qt Toolkit. | - |
| 7 | ** | - |
| 8 | ** $QT_BEGIN_LICENSE:LGPL$ | - |
| 9 | ** Commercial License Usage | - |
| 10 | ** Licensees holding valid commercial Qt licenses may use this file in | - |
| 11 | ** accordance with the commercial license agreement provided with the | - |
| 12 | ** Software or, alternatively, in accordance with the terms contained in | - |
| 13 | ** a written agreement between you and The Qt Company. For licensing terms | - |
| 14 | ** and conditions see https://www.qt.io/terms-conditions. For further | - |
| 15 | ** information use the contact form at https://www.qt.io/contact-us. | - |
| 16 | ** | - |
| 17 | ** GNU Lesser General Public License Usage | - |
| 18 | ** Alternatively, this file may be used under the terms of the GNU Lesser | - |
| 19 | ** General Public License version 3 as published by the Free Software | - |
| 20 | ** Foundation and appearing in the file LICENSE.LGPL3 included in the | - |
| 21 | ** packaging of this file. Please review the following information to | - |
| 22 | ** ensure the GNU Lesser General Public License version 3 requirements | - |
| 23 | ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. | - |
| 24 | ** | - |
| 25 | ** GNU General Public License Usage | - |
| 26 | ** Alternatively, this file may be used under the terms of the GNU | - |
| 27 | ** General Public License version 2.0 or (at your option) the GNU General | - |
| 28 | ** Public license version 3 or any later version approved by the KDE Free | - |
| 29 | ** Qt Foundation. The licenses are as published by the Free Software | - |
| 30 | ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 | - |
| 31 | ** included in the packaging of this file. Please review the following | - |
| 32 | ** information to ensure the GNU General Public License requirements will | - |
| 33 | ** be met: https://www.gnu.org/licenses/gpl-2.0.html and | - |
| 34 | ** https://www.gnu.org/licenses/gpl-3.0.html. | - |
| 35 | ** | - |
| 36 | ** $QT_END_LICENSE$ | - |
| 37 | ** | - |
| 38 | ****************************************************************************/ | - |
| 39 | - | |
| 40 | #include "qthreadstorage.h" | - |
| 41 | - | |
| 42 | #ifndef QT_NO_THREAD | - |
| 43 | #include "qthread.h" | - |
| 44 | #include "qthread_p.h" | - |
| 45 | #include "qmutex.h" | - |
| 46 | - | |
| 47 | #include <string.h> | - |
| 48 | - | |
| 49 | QT_BEGIN_NAMESPACE | - |
| 50 | - | |
| 51 | // #define THREADSTORAGE_DEBUG | - |
| 52 | #ifdef THREADSTORAGE_DEBUG | - |
| 53 | # define DEBUG_MSG qtsDebug | - |
| 54 | - | |
| 55 | # include <stdio.h> | - |
| 56 | # include <stdarg.h> | - |
| 57 | void qtsDebug(const char *fmt, ...) | - |
| 58 | { | - |
| 59 | va_list va; | - |
| 60 | va_start(va, fmt); | - |
| 61 | - | |
| 62 | fprintf(stderr, "QThreadStorage: "); | - |
| 63 | vfprintf(stderr, fmt, va); | - |
| 64 | fprintf(stderr, "\n"); | - |
| 65 | - | |
| 66 | va_end(va); | - |
| 67 | } | - |
| 68 | #else | - |
| 69 | # define DEBUG_MSG if(false)qDebug | - |
| 70 | #endif | - |
| 71 | - | |
| 72 | static QBasicMutex destructorsMutex; | - |
| 73 | typedef QVector<void (*)(void *)> DestructorMap; | - |
| 74 | Q_GLOBAL_STATIC(DestructorMap, destructors) | - |
| 75 | - | |
| 76 | QThreadStorageData::QThreadStorageData(void (*func)(void *)) | - |
| 77 | { | - |
| 78 | QMutexLocker locker(&destructorsMutex); | - |
| 79 | DestructorMap *destr = destructors(); | - |
| 80 | if (!destr) { | - |
| 81 | /* | - |
| 82 | the destructors vector has already been destroyed, yet a new | - |
| 83 | QThreadStorage is being allocated. this can only happen during global | - |
| 84 | destruction, at which point we assume that there is only one thread. | - |
| 85 | in order to keep QThreadStorage working, we need somewhere to store | - |
| 86 | the data, best place we have in this situation is at the tail of the | - |
| 87 | current thread's tls vector. the destructor is ignored, since we have | - |
| 88 | no where to store it, and no way to actually call it. | - |
| 89 | */ | - |
| 90 | QThreadData *data = QThreadData::current(); | - |
| 91 | id = data->tls.count(); | - |
| 92 | DEBUG_MSG("QThreadStorageData: Allocated id %d, destructor %p cannot be stored", id, func); dead code: QMessageLogger(__FILE__, 92, __PRETTY_FUNCTION__).debug("QThreadStorageData: Allocated id %d, destructor %p cannot be stored", id, func); | - |
| 93 | return; | - |
| 94 | } | - |
| 95 | for (id = 0; id < destr->count(); id++) { | - |
| 96 | if (destr->at(id) == 0) | - |
| 97 | break; | - |
| 98 | } | - |
| 99 | if (id == destr->count()) { | - |
| 100 | destr->append(func); | - |
| 101 | } else { | - |
| 102 | (*destr)[id] = func; | - |
| 103 | } | - |
| 104 | DEBUG_MSG("QThreadStorageData: Allocated id %d, destructor %p", id, func); dead code: QMessageLogger(__FILE__, 104, __PRETTY_FUNCTION__).debug("QThreadStorageData: Allocated id %d, destructor %p", id, func); | - |
| 105 | } | - |
| 106 | - | |
| 107 | QThreadStorageData::~QThreadStorageData() | - |
| 108 | { | - |
| 109 | DEBUG_MSG("QThreadStorageData: Released id %d", id); dead code: QMessageLogger(__FILE__, 109, __PRETTY_FUNCTION__).debug("QThreadStorageData: Released id %d", id); | - |
| 110 | QMutexLocker locker(&destructorsMutex); | - |
| 111 | if (destructors()) | - |
| 112 | (*destructors())[id] = 0; | - |
| 113 | } | - |
| 114 | - | |
| 115 | void **QThreadStorageData::get() const | - |
| 116 | { | - |
| 117 | QThreadData *data = QThreadData::current(); | - |
| 118 | if (!data) { | - |
| 119 | qWarning("QThreadStorage::get: QThreadStorage can only be used with threads started with QThread"); | - |
| 120 | return 0; | - |
| 121 | } | - |
| 122 | QVector<void *> &tls = data->tls; | - |
| 123 | if (tls.size() <= id) | - |
| 124 | tls.resize(id + 1); | - |
| 125 | void **v = &tls[id]; | - |
| 126 | - | |
| 127 | DEBUG_MSG("QThreadStorageData: Returning storage %d, data %p, for thread %p", dead code: QMessageLogger(__FILE__, 127, __PRETTY_FUNCTION__).debug("QThreadStorageData: Returning storage %d, data %p, for thread %p", id, *v, data->thread.load()); | - |
| 128 | id, dead code: QMessageLogger(__FILE__, 127, __PRETTY_FUNCTION__).debug("QThreadStorageData: Returning storage %d, data %p, for thread %p", id, *v, data->thread.load()); | - |
| 129 | *v, dead code: QMessageLogger(__FILE__, 127, __PRETTY_FUNCTION__).debug("QThreadStorageData: Returning storage %d, data %p, for thread %p", id, *v, data->thread.load()); | - |
| 130 | data->thread.load()); dead code: QMessageLogger(__FILE__, 127, __PRETTY_FUNCTION__).debug("QThreadStorageData: Returning storage %d, data %p, for thread %p", id, *v, data->thread.load()); | - |
| 131 | - | |
| 132 | return *v ? v : 0; | - |
| 133 | } | - |
| 134 | - | |
| 135 | void **QThreadStorageData::set(void *p) | - |
| 136 | { | - |
| 137 | QThreadData *data = QThreadData::current(); | - |
| 138 | if (!data) { | - |
| 139 | qWarning("QThreadStorage::set: QThreadStorage can only be used with threads started with QThread"); | - |
| 140 | return 0; | - |
| 141 | } | - |
| 142 | QVector<void *> &tls = data->tls; | - |
| 143 | if (tls.size() <= id) | - |
| 144 | tls.resize(id + 1); | - |
| 145 | - | |
| 146 | void *&value = tls[id]; | - |
| 147 | // delete any previous data | - |
| 148 | if (value != 0) { | - |
| 149 | DEBUG_MSG("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p", dead code: QMessageLogger(__FILE__, 149, __PRETTY_FUNCTION__).debug("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p", id, value, data->thread.load()); | - |
| 150 | id, dead code: QMessageLogger(__FILE__, 149, __PRETTY_FUNCTION__).debug("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p", id, value, data->thread.load()); | - |
| 151 | value, dead code: QMessageLogger(__FILE__, 149, __PRETTY_FUNCTION__).debug("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p", id, value, data->thread.load()); | - |
| 152 | data->thread.load()); dead code: QMessageLogger(__FILE__, 149, __PRETTY_FUNCTION__).debug("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p", id, value, data->thread.load()); | - |
| 153 | - | |
| 154 | QMutexLocker locker(&destructorsMutex); | - |
| 155 | DestructorMap *destr = destructors(); | - |
| 156 | void (*destructor)(void *) = destr ? destr->value(id) : 0; | - |
| 157 | locker.unlock(); | - |
| 158 | - | |
| 159 | void *q = value; | - |
| 160 | value = 0; | - |
| 161 | - | |
| 162 | if (destructor) | - |
| 163 | destructor(q); | - |
| 164 | } | - |
| 165 | - | |
| 166 | // store new data | - |
| 167 | value = p; | - |
| 168 | DEBUG_MSG("QThreadStorageData: Set storage %d for thread %p to %p", id, data->thread.load(), p); dead code: QMessageLogger(__FILE__, 168, __PRETTY_FUNCTION__).debug("QThreadStorageData: Set storage %d for thread %p to %p", id, data->thread.load(), p); | - |
| 169 | return &value; | - |
| 170 | } | - |
| 171 | - | |
| 172 | void QThreadStorageData::finish(void **p) | - |
| 173 | { | - |
| 174 | QVector<void *> *tls = reinterpret_cast<QVector<void *> *>(p); | - |
| 175 | if (!tls || tls->isEmpty() || !destructors()) | - |
| 176 | return; // nothing to do | - |
| 177 | - | |
| 178 | DEBUG_MSG("QThreadStorageData: Destroying storage for thread %p", QThread::currentThread()); dead code: QMessageLogger(__FILE__, 178, __PRETTY_FUNCTION__).debug("QThreadStorageData: Destroying storage for thread %p", QThread::currentThread()); | - |
| 179 | while (!tls->isEmpty()) { | - |
| 180 | void *&value = tls->last(); | - |
| 181 | void *q = value; | - |
| 182 | value = 0; | - |
| 183 | int i = tls->size() - 1; | - |
| 184 | tls->resize(i); | - |
| 185 | - | |
| 186 | if (!q) { | - |
| 187 | // data already deleted | - |
| 188 | continue; | - |
| 189 | } | - |
| 190 | - | |
| 191 | QMutexLocker locker(&destructorsMutex); | - |
| 192 | void (*destructor)(void *) = destructors()->value(i); | - |
| 193 | locker.unlock(); | - |
| 194 | - | |
| 195 | if (!destructor) { | - |
| 196 | if (QThread::currentThread()) | - |
| 197 | qWarning("QThreadStorage: Thread %p exited after QThreadStorage %d destroyed", | - |
| 198 | QThread::currentThread(), i); | - |
| 199 | continue; | - |
| 200 | } | - |
| 201 | destructor(q); //crash here might mean the thread exited after qthreadstorage was destroyed | - |
| 202 | - | |
| 203 | if (tls->size() > i) { | - |
| 204 | //re reset the tls in case it has been recreated by its own destructor. | - |
| 205 | (*tls)[i] = 0; | - |
| 206 | } | - |
| 207 | } | - |
| 208 | tls->clear(); | - |
| 209 | } | - |
| 210 | - | |
| 211 | /*! | - |
| 212 | \class QThreadStorage | - |
| 213 | \inmodule QtCore | - |
| 214 | \brief The QThreadStorage class provides per-thread data storage. | - |
| 215 | - | |
| 216 | \threadsafe | - |
| 217 | - | |
| 218 | \ingroup thread | - |
| 219 | - | |
| 220 | QThreadStorage is a template class that provides per-thread data | - |
| 221 | storage. | - |
| 222 | - | |
| 223 | The setLocalData() function stores a single thread-specific value | - |
| 224 | for the calling thread. The data can be accessed later using | - |
| 225 | localData(). | - |
| 226 | - | |
| 227 | The hasLocalData() function allows the programmer to determine if | - |
| 228 | data has previously been set using the setLocalData() function. | - |
| 229 | This is also useful for lazy initializiation. | - |
| 230 | - | |
| 231 | If T is a pointer type, QThreadStorage takes ownership of the data | - |
| 232 | (which must be created on the heap with \c new) and deletes it when | - |
| 233 | the thread exits, either normally or via termination. | - |
| 234 | - | |
| 235 | For example, the following code uses QThreadStorage to store a | - |
| 236 | single cache for each thread that calls the cacheObject() and | - |
| 237 | removeFromCache() functions. The cache is automatically | - |
| 238 | deleted when the calling thread exits. | - |
| 239 | - | |
| 240 | \snippet threads/threads.cpp 7 | - |
| 241 | \snippet threads/threads.cpp 8 | - |
| 242 | \snippet threads/threads.cpp 9 | - |
| 243 | - | |
| 244 | \section1 Caveats | - |
| 245 | - | |
| 246 | \list | - |
| 247 | - | |
| 248 | \li The QThreadStorage destructor does not delete per-thread data. | - |
| 249 | QThreadStorage only deletes per-thread data when the thread exits | - |
| 250 | or when setLocalData() is called multiple times. | - |
| 251 | - | |
| 252 | \li QThreadStorage can be used to store data for the \c main() | - |
| 253 | thread. QThreadStorage deletes all data set for the \c main() | - |
| 254 | thread when QApplication is destroyed, regardless of whether or | - |
| 255 | not the \c main() thread has actually finished. | - |
| 256 | - | |
| 257 | \endlist | - |
| 258 | - | |
| 259 | \sa QThread | - |
| 260 | */ | - |
| 261 | - | |
| 262 | /*! | - |
| 263 | \fn QThreadStorage::QThreadStorage() | - |
| 264 | - | |
| 265 | Constructs a new per-thread data storage object. | - |
| 266 | */ | - |
| 267 | - | |
| 268 | /*! | - |
| 269 | \fn QThreadStorage::~QThreadStorage() | - |
| 270 | - | |
| 271 | Destroys the per-thread data storage object. | - |
| 272 | - | |
| 273 | Note: The per-thread data stored is not deleted. Any data left | - |
| 274 | in QThreadStorage is leaked. Make sure that all threads using | - |
| 275 | QThreadStorage have exited before deleting the QThreadStorage. | - |
| 276 | - | |
| 277 | \sa hasLocalData() | - |
| 278 | */ | - |
| 279 | - | |
| 280 | /*! | - |
| 281 | \fn bool QThreadStorage::hasLocalData() const | - |
| 282 | - | |
| 283 | If T is a pointer type, returns \c true if the calling thread has | - |
| 284 | non-zero data available. | - |
| 285 | - | |
| 286 | If T is a value type, returns whether the data has already been | - |
| 287 | constructed by calling setLocalData or localData. | - |
| 288 | - | |
| 289 | \sa localData() | - |
| 290 | */ | - |
| 291 | - | |
| 292 | /*! | - |
| 293 | \fn T &QThreadStorage::localData() | - |
| 294 | - | |
| 295 | Returns a reference to the data that was set by the calling | - |
| 296 | thread. | - |
| 297 | - | |
| 298 | If no data has been set, this will create a default constructed | - |
| 299 | instance of type T. | - |
| 300 | - | |
| 301 | \sa hasLocalData() | - |
| 302 | */ | - |
| 303 | - | |
| 304 | /*! | - |
| 305 | \fn const T QThreadStorage::localData() const | - |
| 306 | \overload | - |
| 307 | - | |
| 308 | Returns a copy of the data that was set by the calling thread. | - |
| 309 | - | |
| 310 | \sa hasLocalData() | - |
| 311 | */ | - |
| 312 | - | |
| 313 | /*! | - |
| 314 | \fn void QThreadStorage::setLocalData(T data) | - |
| 315 | - | |
| 316 | Sets the local data for the calling thread to \a data. It can be | - |
| 317 | accessed later using the localData() functions. | - |
| 318 | - | |
| 319 | If T is a pointer type, QThreadStorage takes ownership of the data | - |
| 320 | and deletes it automatically either when the thread exits (either | - |
| 321 | normally or via termination) or when setLocalData() is called again. | - |
| 322 | - | |
| 323 | \sa localData(), hasLocalData() | - |
| 324 | */ | - |
| 325 | - | |
| 326 | #endif // QT_NO_THREAD | - |
| 327 | - | |
| 328 | QT_END_NAMESPACE | - |
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