Detailed Description

template<typename Iterator, typename T>
class QtConcurrent::IterateKernel< Iterator, T >

Definition at line 178 of file qtconcurrentiteratekernel.h.

#include <qtconcurrentiteratekernel.h>

Inheritance diagram for IterateKernel< Iterator, T >:

Public Types
typedef T	ResultType
Public Member Functions
	IterateKernel (Iterator _begin, Iterator _end)
virtual	~IterateKernel ()
virtual bool	runIteration (Iterator it, int index, T *result)
virtual bool	runIterations (Iterator _begin, int beginIndex, int endIndex, T *results)
void	start ()
bool	shouldStartThread ()
ThreadFunctionResult	threadFunction ()
ThreadFunctionResult	forThreadFunction ()
ThreadFunctionResult	whileThreadFunction ()
Public Attributes
const Iterator	begin
const Iterator	end
Iterator	current
QAtomicInt	currentIndex
bool	forIteration
QAtomicInt	iteratorThreads
int	iterationCount
bool	progressReportingEnabled
QAtomicInt	completed

Member Typedef Documentation

typedef T ResultType

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Reimplemented from ThreadEngine< T >.

Reimplemented in FilterKernel< Sequence, KeepFunctor, ReduceFunctor >, FilteredReducedKernel< ReducedResultType, Iterator, KeepFunctor, ReduceFunctor, Reducer >, FilteredEachKernel< Iterator, KeepFunctor >, MappedReducedKernel< ReducedResultType, Iterator, MapFunctor, ReduceFunctor, Reducer >, and MappedEachKernel< Iterator, MapFunctor >.

Definition at line 181 of file qtconcurrentiteratekernel.h.

Constructor & Destructor Documentation

IterateKernel	(	Iterator	_begin,
		Iterator	_end
	)		`[inline]`

Definition at line 183 of file qtconcurrentiteratekernel.h.

        : 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 ( ) [inline, virtual]

Definition at line 203 of file qtconcurrentiteratekernel.h.

{ }

Member Function Documentation

virtual bool runIteration	(	Iterator	it,
		int	index,
		T *	result
	)		`[inline, virtual]`

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Reimplemented in FilteredReducedKernel< ReducedResultType, Iterator, KeepFunctor, ReduceFunctor, Reducer >, MapKernel< Iterator, MapFunctor >, MappedReducedKernel< ReducedResultType, Iterator, MapFunctor, ReduceFunctor, Reducer >, and MappedEachKernel< Iterator, MapFunctor >.

Definition at line 205 of file qtconcurrentiteratekernel.h.

        { Q_UNUSED(it); Q_UNUSED(index); Q_UNUSED(result); return false; }

virtual bool runIterations	(	Iterator	_begin,
		int	beginIndex,
		int	endIndex,
		T *	results
	)		`[inline, virtual]`

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Reimplemented in FilteredReducedKernel< ReducedResultType, Iterator, KeepFunctor, ReduceFunctor, Reducer >, MapKernel< Iterator, MapFunctor >, MappedReducedKernel< ReducedResultType, Iterator, MapFunctor, ReduceFunctor, Reducer >, and MappedEachKernel< Iterator, MapFunctor >.

Definition at line 207 of file qtconcurrentiteratekernel.h.

        { Q_UNUSED(_begin); Q_UNUSED(beginIndex); Q_UNUSED(endIndex); Q_UNUSED(results); return false; }

void start ( ) [inline, virtual]

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Reimplemented from ThreadEngineBase.

Reimplemented in FilteredEachKernel< Iterator, KeepFunctor >.

Definition at line 210 of file qtconcurrentiteratekernel.h.

    {
        progressReportingEnabled = this->isProgressReportingEnabled();
        if (progressReportingEnabled && iterationCount > 0)
            this->setProgressRange(0, iterationCount);
    }

bool shouldStartThread ( ) [inline, virtual]

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Reimplemented from ThreadEngineBase.

Reimplemented in FilterKernel< Sequence, KeepFunctor, ReduceFunctor >, FilteredReducedKernel< ReducedResultType, Iterator, KeepFunctor, ReduceFunctor, Reducer >, and MappedReducedKernel< ReducedResultType, Iterator, MapFunctor, ReduceFunctor, Reducer >.

Definition at line 217 of file qtconcurrentiteratekernel.h.

    {
        if (forIteration)
            return (currentIndex < iterationCount) && !this->shouldThrottleThread();
        else // whileIteration
            return (iteratorThreads == 0);
    }

ThreadFunctionResult threadFunction ( ) [inline, virtual]

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Reimplemented from ThreadEngineBase.

Definition at line 225 of file qtconcurrentiteratekernel.h.

    {
        if (forIteration)
            return this->forThreadFunction();
        else // whileIteration
            return this->whileThreadFunction();
    }

ThreadFunctionResult forThreadFunction ( ) [inline]

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Definition at line 233 of file qtconcurrentiteratekernel.h.

    {
        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 ( ) [inline]

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Definition at line 284 of file qtconcurrentiteratekernel.h.

    {
        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;
    }