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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. ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #ifndef QTCONCURRENT_REDUCEKERNEL_H #define QTCONCURRENT_REDUCEKERNEL_H #include #ifndef QT_NO_CONCURRENT #include #include #include #include #include #include #include QT_BEGIN_NAMESPACE namespace QtConcurrent { #ifndef Q_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 // Q_QDOC enum ReduceOption { UnorderedReduce = 0x1, OrderedReduce = 0x2, SequentialReduce = 0x4 // ParallelReduce = 0x8 }; Q_DECLARE_FLAGS(ReduceOptions, ReduceOption) Q_DECLARE_OPERATORS_FOR_FLAGS(ReduceOptions) #ifndef Q_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 //Q_QDOC } // namespace QtConcurrent QT_END_NAMESPACE #endif // QT_NO_CONCURRENT #endif