--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/auto/qthreadonce/qthreadonce.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,121 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 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.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#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