diff options
Diffstat (limited to 'tests/auto/corelib/thread/qthreadonce/qthreadonce.cpp')
-rw-r--r-- | tests/auto/corelib/thread/qthreadonce/qthreadonce.cpp | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/tests/auto/corelib/thread/qthreadonce/qthreadonce.cpp b/tests/auto/corelib/thread/qthreadonce/qthreadonce.cpp new file mode 100644 index 0000000000..b23e11b153 --- /dev/null +++ b/tests/auto/corelib/thread/qthreadonce/qthreadonce.cpp @@ -0,0 +1,121 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the test suite of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** GNU Lesser General Public License Usage +** This file may be used under the terms of the GNU Lesser General Public +** License version 2.1 as published by the Free Software Foundation and +** appearing in the file LICENSE.LGPL included in the packaging of this +** file. Please review the following information to ensure the GNU Lesser +** General Public License version 2.1 requirements will be met: +** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU General +** Public License version 3.0 as published by the Free Software Foundation +** and appearing in the file LICENSE.GPL included in the packaging of this +** file. Please review the following information to ensure the GNU General +** Public License version 3.0 requirements will be met: +** http://www.gnu.org/copyleft/gpl.html. +** +** Other Usage +** Alternatively, this file may be used in accordance with the terms and +** conditions contained in a signed written agreement between you and Nokia. +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + + +#include "qplatformdefs.h" +#include "qthreadonce.h" + +#ifndef QT_NO_THREAD +#include "qmutex.h" + +Q_GLOBAL_STATIC_WITH_ARGS(QMutex, onceInitializationMutex, (QMutex::Recursive)) + +enum QOnceExtra { + MustRunCode = 0x01, + MustUnlockMutex = 0x02 +}; + +/*! + \internal + Initialize the Q_ONCE structure. + + Q_ONCE consists of two variables: + - a static POD QOnceControl::ControlVariable (it's a QBasicAtomicInt) + - an automatic QOnceControl that controls the former + + The POD is initialized to 0. + + When QOnceControl's constructor starts, it'll lock the global + initialization mutex. It'll then check if it's the first to up + the control variable and will take note. + + The QOnceControl's destructor will unlock the global + initialization mutex. +*/ +QOnceControl::QOnceControl(QBasicAtomicInt *control) +{ + d = 0; + gv = control; + // check if code has already run once + if (*gv == 2) { + // uncontended case: it has already initialized + // no waiting + return; + } + + // acquire the path + onceInitializationMutex()->lock(); + extra = MustUnlockMutex; + + if (gv->testAndSetAcquire(0, 1)) { + // path acquired, we're the first + extra |= MustRunCode; + } +} + +QOnceControl::~QOnceControl() +{ + if (mustRunCode()) + // code wasn't run! + gv->testAndSetRelease(1, 0); + else + gv->testAndSetRelease(1, 2); + if (extra & MustUnlockMutex) + onceInitializationMutex()->unlock(); +} + +/*! + \internal + Returns true if the initialization code must be run. + + Obviously, the initialization code must be run only once... +*/ +bool QOnceControl::mustRunCode() +{ + return extra & MustRunCode; +} + +void QOnceControl::done() +{ + extra &= ~MustRunCode; +} + +#endif // QT_NO_THREAD |