From f209cb48f9ab9ffb257b0d970a13dc53c206191c Mon Sep 17 00:00:00 2001
From: Simon Praetorius <simon.praetorius@tu-dresden.de>
Date: Sun, 15 Sep 2024 13:31:31 +0200
Subject: [PATCH] Revert "Switch internal data structure in MatrixIndexSet"
This reverts commit c8272a07fa0fd4dc1274612ed5ffb016d4d326c8.
---
dune/istl/matrixindexset.hh | 132 +++++++-----------------------------
1 file changed, 24 insertions(+), 108 deletions(-)
diff --git a/dune/istl/matrixindexset.hh b/dune/istl/matrixindexset.hh
index acc4466b4..10baccf35 100644
--- a/dune/istl/matrixindexset.hh
+++ b/dune/istl/matrixindexset.hh
@@ -5,139 +5,55 @@
#ifndef DUNE_ISTL_MATRIXINDEXSET_HH
#define DUNE_ISTL_MATRIXINDEXSET_HH
-#include <algorithm>
-#include <cstddef>
-#include <cstdint>
-#include <set>
-#include <variant>
#include <vector>
-
-#include <dune/common/overloadset.hh>
+#include <set>
namespace Dune {
- /**
- * \brief Stores the nonzero entries for creating a sparse matrix
- *
- * This stores std::set-like container for the column index
- * of each row. A sorted std::vector is used for this container
- * up to a customizable maxVectorSize. If this size is exceeded,
- * storage of the corresponding row is switched to std::set.
- *
- * The default value for maxVectorSize works well and ensures
- * that the slow std::set fallback is only used for very
- * dense rows.
- */
+ /** \brief Stores the nonzero entries in a sparse matrix */
class MatrixIndexSet
{
- using Index = std::size_t;
-
- // A vector that partly mimics a std::set by staying
- // sorted on insert() and having unique values.
- class FlatSet : public std::vector<Index>
- {
- using Base = std::vector<Index>;
- public:
- using Base::Base;
- using Base::begin;
- using Base::end;
- void insert(const Index& value) {
- auto it = std::lower_bound(begin(), end(), value);
- if ((it == end() or (*it != value)))
- Base::insert(it, value);
- }
- bool contains(const Index& value) const {
- return std::binary_search(begin(), end(), value);
- }
- };
-
- using RowIndexSet = std::variant<FlatSet, std::set<Index>>;
public:
+ typedef std::size_t size_type;
- using size_type = Index;
-
- /**
- * \brief Default value for maxVectorSize
- *
- * This was selected after benchmarking for the worst case
- * of reverse insertion of column indices. In many applications
- * this works well. There's no need to use a different value
- * unless you have many dense rows with more than defaultMaxVectorSize
- * nonzero entries. Even in this case defaultMaxVectorSize may work
- * well and a finding a better value may require careful
- * benchmarking.
- */
- static constexpr size_type defaultMaxVectorSize = 2048;
-
- /**
- * \brief Constructor with custom maxVectorSize
- *
- * \param maxVectorSize Maximal size for stored row vector (default is defaultMaxVectorSize).
- */
- MatrixIndexSet(size_type maxVectorSize=defaultMaxVectorSize) noexcept : rows_(0), cols_(0), maxVectorSize_(maxVectorSize)
+ /** \brief Default constructor */
+ MatrixIndexSet() : rows_(0), cols_(0)
{}
- /**
- * \brief Constructor setting the matrix size
- *
- * \param rows Number of matrix rows
- * \param cols Number of matrix columns
- * \param maxVectorSize Maximal size for stored row vector (default is defaultMaxVectorSize).
- */
- MatrixIndexSet(size_type rows, size_type cols, size_type maxVectorSize=defaultMaxVectorSize) : rows_(rows), cols_(cols), maxVectorSize_(maxVectorSize)
- {
- indices_.resize(rows_, FlatSet());
+ /** \brief Constructor setting the matrix size */
+ MatrixIndexSet(size_type rows, size_type cols) : rows_(rows), cols_(cols) {
+ indices_.resize(rows_);
}
/** \brief Reset the size of an index set */
void resize(size_type rows, size_type cols) {
rows_ = rows;
cols_ = cols;
- indices_.resize(rows_, FlatSet());
+ indices_.resize(rows_);
}
/** \brief Add an index to the index set */
- void add(size_type row, size_type col) {
- return std::visit(Dune::overload(
- // If row is stored as set, call insert directly
- [&](std::set<size_type>& set) {
- set.insert(col);
- },
- // If row is stored as vector only insert directly
- // if maxVectorSize_ is not reached. Otherwise switch
- // to set storage first.
- [&](FlatSet& sortedVector) {
- if (sortedVector.size() < maxVectorSize_)
- sortedVector.insert(col);
- else if (not sortedVector.contains(col))
- {
- std::set<size_type> set(sortedVector.begin(), sortedVector.end());
- set.insert(col);
- indices_[row] = std::move(set);
- }
- }
- ), indices_[row]);
+ void add(size_type i, size_type j) {
+ indices_[i].insert(j);
}
/** \brief Return the number of entries */
size_type size() const {
size_type entries = 0;
for (size_type i=0; i<rows_; i++)
- entries += rowsize(i);
+ entries += indices_[i].size();
+
return entries;
}
/** \brief Return the number of rows */
size_type rows() const {return rows_;}
+
/** \brief Return the number of entries in a given row */
- size_type rowsize(size_type row) const {
- return std::visit([&](const auto& rowIndices) {
- return rowIndices.size();
- }, indices_[row]);
- }
+ size_type rowsize(size_type row) const {return indices_[row].size();}
/** \brief Import all nonzero entries of a sparse matrix into the index set
\tparam MatrixType Needs to be BCRSMatrix<...>
@@ -176,16 +92,17 @@ namespace Dune {
matrix.setSize(rows_, cols_);
matrix.setBuildMode(MatrixType::random);
- for (size_type row=0; row<rows_; row++)
- matrix.setrowsize(row, rowsize(row));
+ for (size_type i=0; i<rows_; i++)
+ matrix.setrowsize(i, indices_[i].size());
matrix.endrowsizes();
- for (size_type row=0; row<rows_; row++) {
- std::visit([&](const auto& rowIndices) {
- for(size_type col : rowIndices)
- matrix.addindex(row, col);
- }, indices_[row]);
+ for (size_type i=0; i<rows_; i++) {
+
+ typename std::set<size_type>::iterator it = indices_[i].begin();
+ for (; it!=indices_[i].end(); ++it)
+ matrix.addindex(i, *it);
+
}
matrix.endindices();
@@ -194,10 +111,9 @@ namespace Dune {
private:
- std::vector<RowIndexSet> indices_;
+ std::vector<std::set<size_type> > indices_;
size_type rows_, cols_;
- size_type maxVectorSize_;
};
--
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