diff -r 000000000000 -r 1918ee327afb src/corelib/concurrent/qtconcurrentiteratekernel.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/corelib/concurrent/qtconcurrentiteratekernel.h	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,343 @@
+/****************************************************************************
+**
+** 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 QTCONCURRENT_ITERATEKERNEL_H
+#define QTCONCURRENT_ITERATEKERNEL_H
+
+#include <QtCore/qglobal.h>
+
+#ifndef QT_NO_CONCURRENT
+
+#include <QtCore/qatomic.h>
+#include <QtCore/qtconcurrentmedian.h>
+#include <QtCore/qtconcurrentthreadengine.h>
+
+#ifndef QT_NO_STL
+#  include <iterator>
+#endif
+
+QT_BEGIN_HEADER
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Core)
+
+#ifndef qdoc
+
+namespace QtConcurrent {
+
+#ifndef QT_NO_STL
+    using std::advance;
+#else
+    template <typename It, typename T>
+    void advance(It &it, T value)
+    {
+        it+=value;
+    }
+#endif
+
+/*
+    The BlockSizeManager class manages how many iterations a thread should
+    reserve and process at a time. This is done by measuring the time spent
+    in the user code versus the control part code, and then increasing
+    the block size if the ratio between them is to small. The block size
+    management is done on the basis of the median of several timing measuremens,
+    and it is done induvidualy for each thread.
+*/
+class Q_CORE_EXPORT BlockSizeManager
+{
+public:
+    BlockSizeManager(int iterationCount);
+    void timeBeforeUser();
+    void timeAfterUser();
+    int blockSize();
+private:
+    inline bool blockSizeMaxed()
+    {
+        return (m_blockSize >= maxBlockSize);
+    }
+
+    const int maxBlockSize;
+    qint64 beforeUser;
+    qint64 afterUser;
+    Median<double> controlPartElapsed;
+    Median<double> userPartElapsed;
+    int m_blockSize;
+};
+
+template <typename T>
+class ResultReporter
+{
+public:
+    ResultReporter(ThreadEngine<T> *_threadEngine)
+    :threadEngine(_threadEngine)
+    {
+
+    }
+
+    void reserveSpace(int resultCount)
+    {
+        currentResultCount = resultCount;
+        vector.resize(qMax(resultCount, vector.count()));
+    }
+
+    void reportResults(int begin)
+    {
+        const int useVectorThreshold = 4; // Tunable parameter.
+        if (currentResultCount > useVectorThreshold) {
+            vector.resize(currentResultCount);
+            threadEngine->reportResults(vector, begin);
+        } else {
+            for (int i = 0; i < currentResultCount; ++i)
+                threadEngine->reportResult(&vector.at(i), begin + i);
+        }
+    }
+
+    inline T * getPointer()
+    {
+        return vector.data();
+    }
+
+    int currentResultCount;
+    ThreadEngine<T> *threadEngine;
+    QVector<T> vector;
+};
+
+template <>
+class ResultReporter<void>
+{
+public:
+    inline ResultReporter(ThreadEngine<void> *) { }
+    inline void reserveSpace(int) { };
+    inline void reportResults(int) { };
+    inline void * getPointer() { return 0; }
+};
+
+#ifndef QT_NO_STL
+inline bool selectIteration(std::bidirectional_iterator_tag)
+{
+    return false; // while
+}
+
+inline bool selectIteration(std::forward_iterator_tag)
+{
+    return false; // while
+}
+
+inline bool selectIteration(std::random_access_iterator_tag)
+{
+    return true; // for
+}
+#else
+// no stl support, always use while iteration
+template <typename T>
+inline bool selectIteration(T)
+{
+    return false; // while
+}
+#endif
+
+template <typename Iterator, typename T>
+class IterateKernel : public ThreadEngine<T>
+{
+public:
+    typedef T ResultType;
+
+    IterateKernel(Iterator _begin, Iterator _end)
+#if defined (QT_NO_STL)
+        : begin(_begin), end(_end), current(_begin), currentIndex(0),
+           forIteration(false), progressReportingEnabled(true)
+#elif !defined(QT_NO_PARTIAL_TEMPLATE_SPECIALIZATION)
+        : begin(_begin), end(_end), current(_begin), currentIndex(0),
+           forIteration(selectIteration(typename std::iterator_traits<Iterator>::iterator_category())), progressReportingEnabled(true)
+#else
+        : begin(_begin), end(_end), currentIndex(0),
+          forIteration(selectIteration(std::iterator_category(_begin))), progressReportingEnabled(true)
+#endif
+    {
+#if defined (QT_NO_STL)
+       iterationCount = 0;
+#else
+        iterationCount =  forIteration ? std::distance(_begin, _end) : 0;
+
+#endif
+    }
+
+    virtual ~IterateKernel() { }
+
+    virtual bool runIteration(Iterator it, int index , T *result)
+        { Q_UNUSED(it); Q_UNUSED(index); Q_UNUSED(result); return false; }
+    virtual bool runIterations(Iterator _begin, int beginIndex, int endIndex, T *results)
+        { Q_UNUSED(_begin); Q_UNUSED(beginIndex); Q_UNUSED(endIndex); Q_UNUSED(results); return false; }
+
+    void start()
+    {
+        progressReportingEnabled = this->isProgressReportingEnabled();
+        if (progressReportingEnabled && iterationCount > 0)
+            this->setProgressRange(0, iterationCount);
+    }
+
+    bool shouldStartThread()
+    {
+        if (forIteration)
+            return (currentIndex < iterationCount) && !this->shouldThrottleThread();
+        else // whileIteration
+            return (iteratorThreads == 0);
+    }
+
+    ThreadFunctionResult threadFunction()
+    {
+        if (forIteration)
+            return this->forThreadFunction();
+        else // whileIteration
+            return this->whileThreadFunction();
+    }
+
+    ThreadFunctionResult forThreadFunction()
+    {
+        BlockSizeManager blockSizeManager(iterationCount);
+        ResultReporter<T> resultReporter(this);
+
+        for(;;) {
+            if (this->isCanceled())
+                break;
+
+            const int currentBlockSize = blockSizeManager.blockSize();
+
+            if (currentIndex >= iterationCount)
+                break;
+
+            // Atomically reserve a block of iterationCount for this thread.
+            const int beginIndex = currentIndex.fetchAndAddRelease(currentBlockSize);
+            const int endIndex = qMin(beginIndex + currentBlockSize, iterationCount);
+
+            if (beginIndex >= endIndex) {
+                // No more work
+                break;
+            }
+
+            this->waitForResume(); // (only waits if the qfuture is paused.)
+
+            if (shouldStartThread())
+                this->startThread();
+
+            const int finalBlockSize = endIndex - beginIndex; // block size adjusted for possible end-of-range
+            resultReporter.reserveSpace(finalBlockSize);
+
+            // Call user code with the current iteration range.
+            blockSizeManager.timeBeforeUser();
+            const bool resultsAvailable = this->runIterations(begin, beginIndex, endIndex, resultReporter.getPointer());
+            blockSizeManager.timeAfterUser();
+
+            if (resultsAvailable)
+                resultReporter.reportResults(beginIndex);
+
+            // Report progress if progress reporting enabled.
+            if (progressReportingEnabled) {
+                completed.fetchAndAddAcquire(finalBlockSize);
+                this->setProgressValue(this->completed);
+            }
+
+            if (this->shouldThrottleThread())
+                return ThrottleThread;
+        }
+        return ThreadFinished;
+    }
+
+    ThreadFunctionResult whileThreadFunction()
+    {
+        if (iteratorThreads.testAndSetAcquire(0, 1) == false)
+            return ThreadFinished;
+
+        ResultReporter<T> resultReporter(this);
+        resultReporter.reserveSpace(1);
+
+        while (current != end) {
+            // The following two lines breaks support for input iterators according to
+            // the sgi docs: dereferencing prev after calling ++current is not allowed
+            // on input iterators. (prev is dereferenced inside user.runIteration())
+            Iterator prev = current;
+            ++current;
+            int index = currentIndex.fetchAndAddRelaxed(1);
+            iteratorThreads.testAndSetRelease(1, 0);
+
+            this->waitForResume(); // (only waits if the qfuture is paused.)
+
+            if (shouldStartThread())
+                this->startThread();
+
+            const bool resultAavailable = this->runIteration(prev, index, resultReporter.getPointer());
+            if (resultAavailable)
+                resultReporter.reportResults(index);
+
+            if (this->shouldThrottleThread())
+                return ThrottleThread;
+
+            if (iteratorThreads.testAndSetAcquire(0, 1) == false)
+                return ThreadFinished;
+        }
+
+        return ThreadFinished;
+    }
+
+
+public:
+    const Iterator begin;
+    const Iterator end;
+    Iterator current;
+    QAtomicInt currentIndex;
+    bool forIteration;
+    QAtomicInt iteratorThreads;
+    int iterationCount;
+
+    bool progressReportingEnabled;
+    QAtomicInt completed;
+};
+
+} // namespace QtConcurrent
+
+#endif //qdoc
+
+QT_END_NAMESPACE
+QT_END_HEADER
+
+#endif // QT_NO_CONCURRENT
+
+#endif