diff -r 000000000000 -r 1918ee327afb src/corelib/thread/qreadwritelock.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/corelib/thread/qreadwritelock.h	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,245 @@
+/****************************************************************************
+**
+** 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 QtCore module 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.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QREADWRITELOCK_H
+#define QREADWRITELOCK_H
+
+#include <QtCore/qglobal.h>
+#include <limits.h> // ### Qt 5: remove
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Core)
+
+#ifndef QT_NO_THREAD
+
+struct QReadWriteLockPrivate;
+
+class Q_CORE_EXPORT QReadWriteLock
+{
+public:
+    enum RecursionMode { NonRecursive, Recursive };
+
+    QReadWriteLock(); // ### Qt 5: merge with below
+    QReadWriteLock(RecursionMode recursionMode);
+    ~QReadWriteLock();
+
+    void lockForRead();
+    bool tryLockForRead();
+    bool tryLockForRead(int timeout);
+
+    void lockForWrite();
+    bool tryLockForWrite();
+    bool tryLockForWrite(int timeout);
+
+    void unlock();
+
+private:
+    Q_DISABLE_COPY(QReadWriteLock)
+    QReadWriteLockPrivate *d;
+
+    friend class QWaitCondition;
+};
+
+#if defined(Q_CC_MSVC)
+#pragma warning( push )
+#pragma warning( disable : 4312 ) // ignoring the warning from /Wp64
+#endif
+
+class Q_CORE_EXPORT QReadLocker
+{
+public:
+    inline QReadLocker(QReadWriteLock *readWriteLock);
+
+    inline ~QReadLocker()
+    { unlock(); }
+
+    inline void unlock()
+    {
+        if (q_lock) {
+            if ((q_val & quintptr(1u)) == quintptr(1u)) {
+                q_val &= ~quintptr(1u);
+                q_lock->unlock();
+            }
+        }
+    }
+
+    inline void relock()
+    {
+        if (q_lock) {
+            if ((q_val & quintptr(1u)) == quintptr(0u)) {
+                q_lock->lockForRead();
+                q_val |= quintptr(1u);
+            }
+        }
+    }
+
+    inline QReadWriteLock *readWriteLock() const
+    { return reinterpret_cast<QReadWriteLock *>(q_val & ~quintptr(1u)); }
+
+private:
+    Q_DISABLE_COPY(QReadLocker)
+    union {
+        QReadWriteLock *q_lock;
+        quintptr q_val;
+    };
+};
+
+inline QReadLocker::QReadLocker(QReadWriteLock *areadWriteLock)
+    : q_lock(areadWriteLock)
+{
+    Q_ASSERT_X((q_val & quintptr(1u)) == quintptr(0),
+               "QReadLocker", "QReadWriteLock pointer is misaligned");
+    relock();
+}
+
+class Q_CORE_EXPORT QWriteLocker
+{
+public:
+    inline QWriteLocker(QReadWriteLock *readWriteLock);
+
+    inline ~QWriteLocker()
+    { unlock(); }
+
+    inline void unlock()
+    {
+        if (q_lock) {
+            if ((q_val & quintptr(1u)) == quintptr(1u)) {
+                q_val &= ~quintptr(1u);
+                q_lock->unlock();
+            }
+        }
+    }
+
+    inline void relock()
+    {
+        if (q_lock) {
+            if ((q_val & quintptr(1u)) == quintptr(0u)) {
+                q_lock->lockForWrite();
+                q_val |= quintptr(1u);
+            }
+        }
+    }
+
+    inline QReadWriteLock *readWriteLock() const
+    { return reinterpret_cast<QReadWriteLock *>(q_val & ~quintptr(1u)); }
+
+
+private:
+    Q_DISABLE_COPY(QWriteLocker)
+    union{
+        QReadWriteLock *q_lock;
+        quintptr q_val;
+    };
+};
+
+inline QWriteLocker::QWriteLocker(QReadWriteLock *areadWriteLock)
+    : q_lock(areadWriteLock)
+{
+    Q_ASSERT_X((q_val & quintptr(1u)) == quintptr(0),
+               "QWriteLocker", "QReadWriteLock pointer is misaligned");
+    relock();
+}
+
+#if defined(Q_CC_MSVC)
+#pragma warning( pop )
+#endif
+
+#else // QT_NO_THREAD
+
+class Q_CORE_EXPORT QReadWriteLock
+{
+public:
+    enum RecursionMode { NonRecursive, Recursive };
+    inline explicit QReadWriteLock(RecursionMode = NonRecursive) { }
+    inline ~QReadWriteLock() { }
+
+    static inline void lockForRead() { }
+    static inline bool tryLockForRead() { return true; }
+    static inline bool tryLockForRead(int timeout) { Q_UNUSED(timeout); return true; }
+
+    static inline void lockForWrite() { }
+    static inline bool tryLockForWrite() { return true; }
+    static inline bool tryLockForWrite(int timeout) { Q_UNUSED(timeout); return true; }
+
+    static inline void unlock() { }
+
+private:
+    Q_DISABLE_COPY(QReadWriteLock)
+};
+
+class Q_CORE_EXPORT QReadLocker
+{
+public:
+    inline QReadLocker(QReadWriteLock *) { }
+    inline ~QReadLocker() { }
+
+    static inline void unlock() { }
+    static inline void relock() { }
+    static inline QReadWriteLock *readWriteLock() { return 0; }
+
+private:
+    Q_DISABLE_COPY(QReadLocker)
+};
+
+class Q_CORE_EXPORT QWriteLocker
+{
+public:
+    inline explicit QWriteLocker(QReadWriteLock *) { }
+    inline ~QWriteLocker() { }
+
+    static inline void unlock() { }
+    static inline void relock() { }
+    static inline QReadWriteLock *readWriteLock() { return 0; }
+
+private:
+    Q_DISABLE_COPY(QWriteLocker)
+};
+
+#endif // QT_NO_THREAD
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QREADWRITELOCK_H