OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
6807f08628
gcc/libstdc++-v3/include/parallel/multiseq_selection.h
Jakub Jelinek cbe34bb5ed Update copyright years. 
From-SVN: r243994
2017-01-01 13:07:43 +01:00

645 lines
22 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// -*- C++ -*-
// Copyright (C) 2007-2017 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file parallel/multiseq_selection.h
* @brief Functions to find elements of a certain global __rank in
* multiple sorted sequences. Also serves for splitting such
* sequence sets.
*
* The algorithm description can be found in
*
* P. J. Varman, S. D. Scheufler, B. R. Iyer, and G. R. Ricard.
* Merging Multiple Lists on Hierarchical-Memory Multiprocessors.
* Journal of Parallel and Distributed Computing, 12(2):171–177, 1991.
*
* This file is a GNU parallel extension to the Standard C++ Library.
*/
// Written by Johannes Singler.
#ifndef _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H
#define _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H 1
#include <vector>
#include <queue>
#include <bits/stl_algo.h>
namespace __gnu_parallel
{
/** @brief Compare __a pair of types lexicographically, ascending. */
template<typename _T1, typename _T2, typename _Compare>
class _Lexicographic
: public std::binary_function<std::pair<_T1, _T2>,
std::pair<_T1, _T2>, bool>
{
private:
_Compare& _M_comp;
public:
_Lexicographic(_Compare& __comp) : _M_comp(__comp) { }
bool
operator()(const std::pair<_T1, _T2>& __p1,
const std::pair<_T1, _T2>& __p2) const
{
if (_M_comp(__p1.first, __p2.first))
return true;
if (_M_comp(__p2.first, __p1.first))
return false;
// Firsts are equal.
return __p1.second < __p2.second;
}
};
/** @brief Compare __a pair of types lexicographically, descending. */
template<typename _T1, typename _T2, typename _Compare>
class _LexicographicReverse : public std::binary_function<_T1, _T2, bool>
{
private:
_Compare& _M_comp;
public:
_LexicographicReverse(_Compare& __comp) : _M_comp(__comp) { }
bool
operator()(const std::pair<_T1, _T2>& __p1,
const std::pair<_T1, _T2>& __p2) const
{
if (_M_comp(__p2.first, __p1.first))
return true;
if (_M_comp(__p1.first, __p2.first))
return false;
// Firsts are equal.
return __p2.second < __p1.second;
}
};
/**
* @brief Splits several sorted sequences at a certain global __rank,
* resulting in a splitting point for each sequence.
* The sequences are passed via a sequence of random-access
* iterator pairs, none of the sequences may be empty. If there
* are several equal elements across the split, the ones on the
* __left side will be chosen from sequences with smaller number.
* @param __begin_seqs Begin of the sequence of iterator pairs.
* @param __end_seqs End of the sequence of iterator pairs.
* @param __rank The global rank to partition at.
* @param __begin_offsets A random-access __sequence __begin where the
* __result will be stored in. Each element of the sequence is an
* iterator that points to the first element on the greater part of
* the respective __sequence.
* @param __comp The ordering functor, defaults to std::less<_Tp>.
*/
template<typename _RanSeqs, typename _RankType, typename _RankIterator,
typename _Compare>
void
multiseq_partition(_RanSeqs __begin_seqs, _RanSeqs __end_seqs,
_RankType __rank,
_RankIterator __begin_offsets,
_Compare __comp = std::less<
typename std::iterator_traits<typename
std::iterator_traits<_RanSeqs>::value_type::
first_type>::value_type>()) // std::less<_Tp>
{
_GLIBCXX_CALL(__end_seqs - __begin_seqs)
typedef typename std::iterator_traits<_RanSeqs>::value_type::first_type
_It;
typedef typename std::iterator_traits<_RanSeqs>::difference_type
_SeqNumber;
typedef typename std::iterator_traits<_It>::difference_type
_DifferenceType;
typedef typename std::iterator_traits<_It>::value_type _ValueType;
_Lexicographic<_ValueType, _SeqNumber, _Compare> __lcomp(__comp);
_LexicographicReverse<_ValueType, _SeqNumber, _Compare> __lrcomp(__comp);
// Number of sequences, number of elements in total (possibly
// including padding).
_DifferenceType __m = std::distance(__begin_seqs, __end_seqs), __nn = 0,
__nmax, __n, __r;
for (_SeqNumber __i = 0; __i < __m; __i++)
{
__nn += std::distance(__begin_seqs[__i].first,
__begin_seqs[__i].second);
_GLIBCXX_PARALLEL_ASSERT(
std::distance(__begin_seqs[__i].first,
__begin_seqs[__i].second) > 0);
}
if (__rank == __nn)
{
for (_SeqNumber __i = 0; __i < __m; __i++)
__begin_offsets[__i] = __begin_seqs[__i].second; // Very end.
// Return __m - 1;
return;
}
_GLIBCXX_PARALLEL_ASSERT(__m != 0);
_GLIBCXX_PARALLEL_ASSERT(__nn != 0);
_GLIBCXX_PARALLEL_ASSERT(__rank >= 0);
_GLIBCXX_PARALLEL_ASSERT(__rank < __nn);
_DifferenceType* __ns = new _DifferenceType[__m];
_DifferenceType* __a = new _DifferenceType[__m];
_DifferenceType* __b = new _DifferenceType[__m];
_DifferenceType __l;
__ns[0] = std::distance(__begin_seqs[0].first, __begin_seqs[0].second);
__nmax = __ns[0];
for (_SeqNumber __i = 0; __i < __m; __i++)
{
__ns[__i] = std::distance(__begin_seqs[__i].first,
__begin_seqs[__i].second);
__nmax = std::max(__nmax, __ns[__i]);
}
__r = __rd_log2(__nmax) + 1;
// Pad all lists to this length, at least as long as any ns[__i],
// equality iff __nmax = 2^__k - 1.
__l = (1ULL << __r) - 1;
for (_SeqNumber __i = 0; __i < __m; __i++)
{
__a[__i] = 0;
__b[__i] = __l;
}
__n = __l / 2;
// Invariants:
// 0 <= __a[__i] <= __ns[__i], 0 <= __b[__i] <= __l
#define __S(__i) (__begin_seqs[__i].first)
// Initial partition.
std::vector<std::pair<_ValueType, _SeqNumber> > __sample;
for (_SeqNumber __i = 0; __i < __m; __i++)
if (__n < __ns[__i]) //__sequence long enough
__sample.push_back(std::make_pair(__S(__i)[__n], __i));
__gnu_sequential::sort(__sample.begin(), __sample.end(), __lcomp);
for (_SeqNumber __i = 0; __i < __m; __i++) //conceptual infinity
if (__n >= __ns[__i]) //__sequence too short, conceptual infinity
__sample.push_back(
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
_DifferenceType __localrank = __rank / __l;
_SeqNumber __j;
for (__j = 0;
__j < __localrank && ((__n + 1) <= __ns[__sample[__j].second]);
++__j)
__a[__sample[__j].second] += __n + 1;
for (; __j < __m; __j++)
__b[__sample[__j].second] -= __n + 1;
// Further refinement.
while (__n > 0)
{
__n /= 2;
_SeqNumber __lmax_seq = -1; // to avoid warning
const _ValueType* __lmax = 0; // impossible to avoid the warning?
for (_SeqNumber __i = 0; __i < __m; __i++)
{
if (__a[__i] > 0)
{
if (!__lmax)
{
__lmax = &(__S(__i)[__a[__i] - 1]);
__lmax_seq = __i;
}
else
{
// Max, favor rear sequences.
if (!__comp(__S(__i)[__a[__i] - 1], *__lmax))
{
__lmax = &(__S(__i)[__a[__i] - 1]);
__lmax_seq = __i;
}
}
}
}
_SeqNumber __i;
for (__i = 0; __i < __m; __i++)
{
_DifferenceType __middle = (__b[__i] + __a[__i]) / 2;
if (__lmax && __middle < __ns[__i] &&
__lcomp(std::make_pair(__S(__i)[__middle], __i),
std::make_pair(*__lmax, __lmax_seq)))
__a[__i] = std::min(__a[__i] + __n + 1, __ns[__i]);
else
__b[__i] -= __n + 1;
}
_DifferenceType __leftsize = 0;
for (_SeqNumber __i = 0; __i < __m; __i++)
__leftsize += __a[__i] / (__n + 1);
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
if (__skew > 0)
{
// Move to the left, find smallest.
std::priority_queue<std::pair<_ValueType, _SeqNumber>,
std::vector<std::pair<_ValueType, _SeqNumber> >,
_LexicographicReverse<_ValueType, _SeqNumber, _Compare> >
__pq(__lrcomp);
for (_SeqNumber __i = 0; __i < __m; __i++)
if (__b[__i] < __ns[__i])
__pq.push(std::make_pair(__S(__i)[__b[__i]], __i));
for (; __skew != 0 && !__pq.empty(); --__skew)
{
_SeqNumber __source = __pq.top().second;
__pq.pop();
__a[__source]
= std::min(__a[__source] + __n + 1, __ns[__source]);
__b[__source] += __n + 1;
if (__b[__source] < __ns[__source])
__pq.push(
std::make_pair(__S(__source)[__b[__source]], __source));
}
}
else if (__skew < 0)
{
// Move to the right, find greatest.
std::priority_queue<std::pair<_ValueType, _SeqNumber>,
std::vector<std::pair<_ValueType, _SeqNumber> >,
_Lexicographic<_ValueType, _SeqNumber, _Compare> >
__pq(__lcomp);
for (_SeqNumber __i = 0; __i < __m; __i++)
if (__a[__i] > 0)
__pq.push(std::make_pair(__S(__i)[__a[__i] - 1], __i));
for (; __skew != 0; ++__skew)
{
_SeqNumber __source = __pq.top().second;
__pq.pop();
__a[__source] -= __n + 1;
__b[__source] -= __n + 1;
if (__a[__source] > 0)
__pq.push(std::make_pair(
__S(__source)[__a[__source] - 1], __source));
}
}
}
// Postconditions:
// __a[__i] == __b[__i] in most cases, except when __a[__i] has been
// clamped because of having reached the boundary
// Now return the result, calculate the offset.
// Compare the keys on both edges of the border.
// Maximum of left edge, minimum of right edge.
_ValueType* __maxleft = 0;
_ValueType* __minright = 0;
for (_SeqNumber __i = 0; __i < __m; __i++)
{
if (__a[__i] > 0)
{
if (!__maxleft)
__maxleft = &(__S(__i)[__a[__i] - 1]);
else
{
// Max, favor rear sequences.
if (!__comp(__S(__i)[__a[__i] - 1], *__maxleft))
__maxleft = &(__S(__i)[__a[__i] - 1]);
}
}
if (__b[__i] < __ns[__i])
{
if (!__minright)
__minright = &(__S(__i)[__b[__i]]);
else
{
// Min, favor fore sequences.
if (__comp(__S(__i)[__b[__i]], *__minright))
__minright = &(__S(__i)[__b[__i]]);
}
}
}
_SeqNumber __seq = 0;
for (_SeqNumber __i = 0; __i < __m; __i++)
__begin_offsets[__i] = __S(__i) + __a[__i];
delete[] __ns;
delete[] __a;
delete[] __b;
}
/**
* @brief Selects the element at a certain global __rank from several
* sorted sequences.
*
* The sequences are passed via a sequence of random-access
* iterator pairs, none of the sequences may be empty.
* @param __begin_seqs Begin of the sequence of iterator pairs.
* @param __end_seqs End of the sequence of iterator pairs.
* @param __rank The global rank to partition at.
* @param __offset The rank of the selected element in the global
* subsequence of elements equal to the selected element. If the
* selected element is unique, this number is 0.
* @param __comp The ordering functor, defaults to std::less.
*/
template<typename _Tp, typename _RanSeqs, typename _RankType,
typename _Compare>
_Tp
multiseq_selection(_RanSeqs __begin_seqs, _RanSeqs __end_seqs,
_RankType __rank,
_RankType& __offset, _Compare __comp = std::less<_Tp>())
{
_GLIBCXX_CALL(__end_seqs - __begin_seqs)
typedef typename std::iterator_traits<_RanSeqs>::value_type::first_type
_It;
typedef typename std::iterator_traits<_RanSeqs>::difference_type
_SeqNumber;
typedef typename std::iterator_traits<_It>::difference_type
_DifferenceType;
_Lexicographic<_Tp, _SeqNumber, _Compare> __lcomp(__comp);
_LexicographicReverse<_Tp, _SeqNumber, _Compare> __lrcomp(__comp);
// Number of sequences, number of elements in total (possibly
// including padding).
_DifferenceType __m = std::distance(__begin_seqs, __end_seqs);
_DifferenceType __nn = 0;
_DifferenceType __nmax, __n, __r;
for (_SeqNumber __i = 0; __i < __m; __i++)
__nn += std::distance(__begin_seqs[__i].first,
__begin_seqs[__i].second);
if (__m == 0 || __nn == 0 || __rank < 0 || __rank >= __nn)
{
// result undefined if there is no data or __rank is outside bounds
throw std::exception();
}
_DifferenceType* __ns = new _DifferenceType[__m];
_DifferenceType* __a = new _DifferenceType[__m];
_DifferenceType* __b = new _DifferenceType[__m];
_DifferenceType __l;
__ns[0] = std::distance(__begin_seqs[0].first, __begin_seqs[0].second);
__nmax = __ns[0];
for (_SeqNumber __i = 0; __i < __m; ++__i)
{
__ns[__i] = std::distance(__begin_seqs[__i].first,
__begin_seqs[__i].second);
__nmax = std::max(__nmax, __ns[__i]);
}
__r = __rd_log2(__nmax) + 1;
// Pad all lists to this length, at least as long as any ns[__i],
// equality iff __nmax = 2^__k - 1
__l = __round_up_to_pow2(__r) - 1;
for (_SeqNumber __i = 0; __i < __m; ++__i)
{
__a[__i] = 0;
__b[__i] = __l;
}
__n = __l / 2;
// Invariants:
// 0 <= __a[__i] <= __ns[__i], 0 <= __b[__i] <= __l
#define __S(__i) (__begin_seqs[__i].first)
// Initial partition.
std::vector<std::pair<_Tp, _SeqNumber> > __sample;
for (_SeqNumber __i = 0; __i < __m; __i++)
if (__n < __ns[__i])
__sample.push_back(std::make_pair(__S(__i)[__n], __i));
__gnu_sequential::sort(__sample.begin(), __sample.end(),
__lcomp, sequential_tag());
// Conceptual infinity.
for (_SeqNumber __i = 0; __i < __m; __i++)
if (__n >= __ns[__i])
__sample.push_back(
std::make_pair(__S(__i)[0] /*__dummy element*/, __i));
_DifferenceType __localrank = __rank / __l;
_SeqNumber __j;
for (__j = 0;
__j < __localrank && ((__n + 1) <= __ns[__sample[__j].second]);
++__j)
__a[__sample[__j].second] += __n + 1;
for (; __j < __m; ++__j)
__b[__sample[__j].second] -= __n + 1;
// Further refinement.
while (__n > 0)
{
__n /= 2;
const _Tp* __lmax = 0;
for (_SeqNumber __i = 0; __i < __m; ++__i)
{
if (__a[__i] > 0)
{
if (!__lmax)
__lmax = &(__S(__i)[__a[__i] - 1]);
else
{
if (__comp(*__lmax, __S(__i)[__a[__i] - 1])) //max
__lmax = &(__S(__i)[__a[__i] - 1]);
}
}
}
_SeqNumber __i;
for (__i = 0; __i < __m; __i++)
{
_DifferenceType __middle = (__b[__i] + __a[__i]) / 2;
if (__lmax && __middle < __ns[__i]
&& __comp(__S(__i)[__middle], *__lmax))
__a[__i] = std::min(__a[__i] + __n + 1, __ns[__i]);
else
__b[__i] -= __n + 1;
}
_DifferenceType __leftsize = 0;
for (_SeqNumber __i = 0; __i < __m; ++__i)
__leftsize += __a[__i] / (__n + 1);
_DifferenceType __skew = __rank / (__n + 1) - __leftsize;
if (__skew > 0)
{
// Move to the left, find smallest.
std::priority_queue<std::pair<_Tp, _SeqNumber>,
std::vector<std::pair<_Tp, _SeqNumber> >,
_LexicographicReverse<_Tp, _SeqNumber, _Compare> >
__pq(__lrcomp);
for (_SeqNumber __i = 0; __i < __m; ++__i)
if (__b[__i] < __ns[__i])
__pq.push(std::make_pair(__S(__i)[__b[__i]], __i));
for (; __skew != 0 && !__pq.empty(); --__skew)
{
_SeqNumber __source = __pq.top().second;
__pq.pop();
__a[__source]
= std::min(__a[__source] + __n + 1, __ns[__source]);
__b[__source] += __n + 1;
if (__b[__source] < __ns[__source])
__pq.push(
std::make_pair(__S(__source)[__b[__source]], __source));
}
}
else if (__skew < 0)
{
// Move to the right, find greatest.
std::priority_queue<std::pair<_Tp, _SeqNumber>,
std::vector<std::pair<_Tp, _SeqNumber> >,
_Lexicographic<_Tp, _SeqNumber, _Compare> > __pq(__lcomp);
for (_SeqNumber __i = 0; __i < __m; ++__i)
if (__a[__i] > 0)
__pq.push(std::make_pair(__S(__i)[__a[__i] - 1], __i));
for (; __skew != 0; ++__skew)
{
_SeqNumber __source = __pq.top().second;
__pq.pop();
__a[__source] -= __n + 1;
__b[__source] -= __n + 1;
if (__a[__source] > 0)
__pq.push(std::make_pair(
__S(__source)[__a[__source] - 1], __source));
}
}
}
// Postconditions:
// __a[__i] == __b[__i] in most cases, except when __a[__i] has been
// clamped because of having reached the boundary
// Now return the result, calculate the offset.
// Compare the keys on both edges of the border.
// Maximum of left edge, minimum of right edge.
bool __maxleftset = false, __minrightset = false;
// Impossible to avoid the warning?
_Tp __maxleft, __minright;
for (_SeqNumber __i = 0; __i < __m; ++__i)
{
if (__a[__i] > 0)
{
if (!__maxleftset)
{
__maxleft = __S(__i)[__a[__i] - 1];
__maxleftset = true;
}
else
{
// Max.
if (__comp(__maxleft, __S(__i)[__a[__i] - 1]))
__maxleft = __S(__i)[__a[__i] - 1];
}
}
if (__b[__i] < __ns[__i])
{
if (!__minrightset)
{
__minright = __S(__i)[__b[__i]];
__minrightset = true;
}
else
{
// Min.
if (__comp(__S(__i)[__b[__i]], __minright))
__minright = __S(__i)[__b[__i]];
}
}
}
// Minright is the __splitter, in any case.
if (!__maxleftset || __comp(__minright, __maxleft))
{
// Good luck, everything is split unambiguously.
__offset = 0;
}
else
{
// We have to calculate an offset.
__offset = 0;
for (_SeqNumber __i = 0; __i < __m; ++__i)
{
_DifferenceType lb
= std::lower_bound(__S(__i), __S(__i) + __ns[__i],
__minright,
__comp) - __S(__i);
__offset += __a[__i] - lb;
}
}
delete[] __ns;
delete[] __a;
delete[] __b;
return __minright;
}
}
#undef __S
#endif /* _GLIBCXX_PARALLEL_MULTISEQ_SELECTION_H */
Reference in New Issue View Git Blame Copy Permalink