Alessandro Bonazzi
8c43d5cf2f
Files correlati : cg0.exe cg0700a.msk cg0700b.msk cg3.exe cg4.exe Bug : Commento: Merge 1.0 libraries
122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2015 The Qt Company Ltd.
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** Contact: http://www.qt.io/licensing/
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**
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** This file is part of the test suite of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see http://www.qt.io/terms-conditions. For further
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** information use the contact form at http://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 or version 3 as published by the Free
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** Software Foundation and appearing in the file LICENSE.LGPLv21 and
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** LICENSE.LGPLv3 included in the packaging of this file. Please review the
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** following information to ensure the GNU Lesser General Public License
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** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
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** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** As a special exception, The Qt Company gives you certain additional
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** rights. These rights are described in The Qt Company LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qplatformdefs.h"
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#include "qthreadonce.h"
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#ifndef QT_NO_THREAD
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#include "qmutex.h"
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Q_GLOBAL_STATIC_WITH_ARGS(QMutex, onceInitializationMutex, (QMutex::Recursive))
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enum QOnceExtra {
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MustRunCode = 0x01,
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MustUnlockMutex = 0x02
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};
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/*!
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\internal
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Initialize the Q_ONCE structure.
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Q_ONCE consists of two variables:
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- a static POD QOnceControl::ControlVariable (it's a QBasicAtomicInt)
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- an automatic QOnceControl that controls the former
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The POD is initialized to 0.
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When QOnceControl's constructor starts, it'll lock the global
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initialization mutex. It'll then check if it's the first to up
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the control variable and will take note.
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The QOnceControl's destructor will unlock the global
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initialization mutex.
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*/
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QOnceControl::QOnceControl(QBasicAtomicInt *control)
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{
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d = 0;
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gv = control;
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// check if code has already run once
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if (*gv == 2) {
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// uncontended case: it has already initialized
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// no waiting
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return;
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}
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// acquire the path
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onceInitializationMutex()->lock();
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extra = MustUnlockMutex;
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if (gv->testAndSetAcquire(0, 1)) {
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// path acquired, we're the first
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extra |= MustRunCode;
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}
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}
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QOnceControl::~QOnceControl()
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{
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if (mustRunCode())
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// code wasn't run!
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gv->testAndSetRelease(1, 0);
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else
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gv->testAndSetRelease(1, 2);
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if (extra & MustUnlockMutex)
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onceInitializationMutex()->unlock();
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}
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/*!
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\internal
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Returns true if the initialization code must be run.
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Obviously, the initialization code must be run only once...
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*/
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bool QOnceControl::mustRunCode()
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{
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return extra & MustRunCode;
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}
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void QOnceControl::done()
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{
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extra &= ~MustRunCode;
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}
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#endif // QT_NO_THREAD
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