/**************************************************************************** ** ** Copyright (C) 2012 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. ** ** $QT_BEGIN_LICENSE:LGPL$ ** 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. ** ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #ifndef QTCONCURRENT_REDUCEKERNEL_H #define QTCONCURRENT_REDUCEKERNEL_H #include #ifndef QT_NO_CONCURRENT #include #include #include #include #include #include #include QT_BEGIN_HEADER QT_BEGIN_NAMESPACE QT_MODULE(Core) namespace QtConcurrent { #ifndef qdoc /* The ReduceQueueStartLimit and ReduceQueueThrottleLimit constants limit the reduce queue size for MapReduce. When the number of reduce blocks in the queue exceeds ReduceQueueStartLimit, MapReduce won't start any new threads, and when it exceeds ReduceQueueThrottleLimit running threads will be stopped. */ enum { ReduceQueueStartLimit = 20, ReduceQueueThrottleLimit = 30 }; // IntermediateResults holds a block of intermediate results from a // map or filter functor. The begin/end offsets indicates the origin // and range of the block. template class IntermediateResults { public: int begin, end; QVector vector; }; #endif // qdoc enum ReduceOption { UnorderedReduce = 0x1, OrderedReduce = 0x2, SequentialReduce = 0x4 // ParallelReduce = 0x8 }; Q_DECLARE_FLAGS(ReduceOptions, ReduceOption) Q_DECLARE_OPERATORS_FOR_FLAGS(ReduceOptions) #ifndef qdoc // supports both ordered and out-of-order reduction template class ReduceKernel { typedef QMap > ResultsMap; const ReduceOptions reduceOptions; QMutex mutex; int progress, resultsMapSize, threadCount; ResultsMap resultsMap; bool canReduce(int begin) const { return (((reduceOptions & UnorderedReduce) && progress == 0) || ((reduceOptions & OrderedReduce) && progress == begin)); } void reduceResult(ReduceFunctor &reduce, ReduceResultType &r, const IntermediateResults &result) { for (int i = 0; i < result.vector.size(); ++i) { reduce(r, result.vector.at(i)); } } void reduceResults(ReduceFunctor &reduce, ReduceResultType &r, ResultsMap &map) { typename ResultsMap::iterator it = map.begin(); while (it != map.end()) { reduceResult(reduce, r, it.value()); ++it; } } public: ReduceKernel(ReduceOptions _reduceOptions) : reduceOptions(_reduceOptions), progress(0), resultsMapSize(0), threadCount(QThreadPool::globalInstance()->maxThreadCount()) { } void runReduce(ReduceFunctor &reduce, ReduceResultType &r, const IntermediateResults &result) { QMutexLocker locker(&mutex); if (!canReduce(result.begin)) { ++resultsMapSize; resultsMap.insert(result.begin, result); return; } if (reduceOptions & UnorderedReduce) { // UnorderedReduce progress = -1; // reduce this result locker.unlock(); reduceResult(reduce, r, result); locker.relock(); // reduce all stored results as well while (!resultsMap.isEmpty()) { ResultsMap resultsMapCopy = resultsMap; resultsMap.clear(); locker.unlock(); reduceResults(reduce, r, resultsMapCopy); locker.relock(); resultsMapSize -= resultsMapCopy.size(); } progress = 0; } else { // reduce this result locker.unlock(); reduceResult(reduce, r, result); locker.relock(); // OrderedReduce progress += result.end - result.begin; // reduce as many other results as possible typename ResultsMap::iterator it = resultsMap.begin(); while (it != resultsMap.end()) { if (it.value().begin != progress) break; locker.unlock(); reduceResult(reduce, r, it.value()); locker.relock(); --resultsMapSize; progress += it.value().end - it.value().begin; it = resultsMap.erase(it); } } } // final reduction void finish(ReduceFunctor &reduce, ReduceResultType &r) { reduceResults(reduce, r, resultsMap); } inline bool shouldThrottle() { return (resultsMapSize > (ReduceQueueThrottleLimit * threadCount)); } inline bool shouldStartThread() { return (resultsMapSize <= (ReduceQueueStartLimit * threadCount)); } }; template struct SequenceHolder2 : public Base { SequenceHolder2(const Sequence &_sequence, Functor1 functor1, Functor2 functor2, ReduceOptions reduceOptions) : Base(_sequence.begin(), _sequence.end(), functor1, functor2, reduceOptions), sequence(_sequence) { } Sequence sequence; void finish() { Base::finish(); // Clear the sequence to make sure all temporaries are destroyed // before finished is signaled. sequence = Sequence(); } }; #endif //qdoc } // namespace QtConcurrent QT_END_NAMESPACE QT_END_HEADER #endif // QT_NO_CONCURRENT #endif