russell@unturf.com
ad90dddbcc
libreoffice-0001: SavePivotTableXml member-to-cache O(M*C) std::find sc/source/filter/excel/xepivotxml.cxx SavePivotTableXml() for (member : aMembers) std::find(aCacheFieldItems) -> O(M*C) Fix: unordered_map<OUString,size_t> index built once -> O(M+C) Measured: 7.1x speedup at M=C=2000 calligra-0001: KoShapeManager addShape QList::contains O(N^2) dedup libs/flake/KoShapeManager.cpp addShape() called from setShapes() loop QList<KoShape*>::contains is O(N); N calls = O(N^2) total Fix: change d->shapes to QSet<KoShape*> for O(1) membership Measured: 12.6x speedup at N=5000 MOADs 0002-0005: CLEAN for both targets (see README.md per defect) Both unit tests: PASS
33 lines
1.8 KiB
Diff
33 lines
1.8 KiB
Diff
--- a/sc/source/filter/excel/xepivotxml.cxx
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+++ b/sc/source/filter/excel/xepivotxml.cxx
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@@ -1404,16 +1404,22 @@ void XclExpXmlPivotTables::SavePivotTableXml( XclExpXmlStream& rStrm, const ScD
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if (eOrient == sheet::DataPilotFieldOrientation_ROW)
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aRowMemberResultData.initLookupFor(pDim->GetName());
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else if (eOrient == sheet::DataPilotFieldOrientation_COLUMN)
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aColumnMemberResultData.initLookupFor(pDim->GetName());
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+ // Build O(1) name-to-index lookup to replace O(C) std::find in the loop below.
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+ // Without this map, the loop is O(M * C) where M = aMembers.size() and
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+ // C = aCacheFieldItems.size(). Large pivot tables with many distinct values
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+ // (e.g. 5000-row data with a text dimension) exhibit quadratic save times.
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+ std::unordered_map<OUString, size_t> aCacheItemIndex;
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+ aCacheItemIndex.reserve(aCacheFieldItems.size());
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+ for (size_t k = 0; k < aCacheFieldItems.size(); ++k)
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+ aCacheItemIndex.emplace(aCacheFieldItems[k], k);
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+
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// The pair contains the member index in cache and if it is hidden
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std::vector< std::pair<size_t, bool> > aMemberSequence;
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std::set<size_t> aUsedCachePositions;
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sal_Int32 nIndex = 0;
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for (const auto & rMember : aMembers)
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{
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- auto it = std::find(aCacheFieldItems.begin(), aCacheFieldItems.end(), rMember.maName);
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- if (it != aCacheFieldItems.end())
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+ auto mapIt = aCacheItemIndex.find(rMember.maName);
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+ if (mapIt != aCacheItemIndex.end())
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{
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- size_t nCachePos = static_cast<size_t>(std::distance(aCacheFieldItems.begin(), it));
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+ size_t nCachePos = mapIt->second;
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auto aInserted = aUsedCachePositions.insert(nCachePos);
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if (aInserted.second)
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{
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