set_operations.h
Go to the documentation of this file.
// -*- C++ -*-
// Copyright (C) 2007-2013 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/set_operations.h
* @brief Parallel implementations of set operations for random-access
* iterators.
* This file is a GNU parallel extension to the Standard C++ Library.
*/
// Written by Marius Elvert and Felix Bondarenko.
#ifndef _GLIBCXX_PARALLEL_SET_OPERATIONS_H
#define _GLIBCXX_PARALLEL_SET_OPERATIONS_H 1
#include <omp.h>
#include <parallel/settings.h>
#include <parallel/multiseq_selection.h>
namespace __gnu_parallel
{
template<typename _IIter, typename _OutputIterator>
_OutputIterator
__copy_tail(std::pair<_IIter, _IIter> __b,
std::pair<_IIter, _IIter> __e, _OutputIterator __r)
{
if (__b.first != __e.first)
{
do
{
*__r++ = *__b.first++;
}
while (__b.first != __e.first);
}
else
{
while (__b.second != __e.second)
*__r++ = *__b.second++;
}
return __r;
}
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
struct __symmetric_difference_func
{
typedef std::iterator_traits<_IIter> _TraitsType;
typedef typename _TraitsType::difference_type _DifferenceType;
typedef typename std::pair<_IIter, _IIter> _IteratorPair;
__symmetric_difference_func(_Compare __comp) : _M_comp(__comp) {}
_Compare _M_comp;
_OutputIterator
_M_invoke(_IIter __a, _IIter __b, _IIter __c, _IIter __d,
_OutputIterator __r) const
{
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{
*__r = *__a;
++__a;
++__r;
}
else if (_M_comp(*__c, *__a))
{
*__r = *__c;
++__c;
++__r;
}
else
{
++__a;
++__c;
}
}
return std::copy(__c, __d, std::copy(__a, __b, __r));
}
_DifferenceType
__count(_IIter __a, _IIter __b, _IIter __c, _IIter __d) const
{
_DifferenceType __counter = 0;
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{
++__a;
++__counter;
}
else if (_M_comp(*__c, *__a))
{
++__c;
++__counter;
}
else
{
++__a;
++__c;
}
}
return __counter + (__b - __a) + (__d - __c);
}
_OutputIterator
__first_empty(_IIter __c, _IIter __d, _OutputIterator __out) const
{ return std::copy(__c, __d, __out); }
_OutputIterator
__second_empty(_IIter __a, _IIter __b, _OutputIterator __out) const
{ return std::copy(__a, __b, __out); }
};
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
struct __difference_func
{
typedef std::iterator_traits<_IIter> _TraitsType;
typedef typename _TraitsType::difference_type _DifferenceType;
typedef typename std::pair<_IIter, _IIter> _IteratorPair;
__difference_func(_Compare __comp) : _M_comp(__comp) {}
_Compare _M_comp;
_OutputIterator
_M_invoke(_IIter __a, _IIter __b, _IIter __c, _IIter __d,
_OutputIterator __r) const
{
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{
*__r = *__a;
++__a;
++__r;
}
else if (_M_comp(*__c, *__a))
{ ++__c; }
else
{
++__a;
++__c;
}
}
return std::copy(__a, __b, __r);
}
_DifferenceType
__count(_IIter __a, _IIter __b,
_IIter __c, _IIter __d) const
{
_DifferenceType __counter = 0;
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{
++__a;
++__counter;
}
else if (_M_comp(*__c, *__a))
{ ++__c; }
else
{ ++__a; ++__c; }
}
return __counter + (__b - __a);
}
_OutputIterator
__first_empty(_IIter, _IIter, _OutputIterator __out) const
{ return __out; }
_OutputIterator
__second_empty(_IIter __a, _IIter __b, _OutputIterator __out) const
{ return std::copy(__a, __b, __out); }
};
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
struct __intersection_func
{
typedef std::iterator_traits<_IIter> _TraitsType;
typedef typename _TraitsType::difference_type _DifferenceType;
typedef typename std::pair<_IIter, _IIter> _IteratorPair;
__intersection_func(_Compare __comp) : _M_comp(__comp) {}
_Compare _M_comp;
_OutputIterator
_M_invoke(_IIter __a, _IIter __b, _IIter __c, _IIter __d,
_OutputIterator __r) const
{
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{ ++__a; }
else if (_M_comp(*__c, *__a))
{ ++__c; }
else
{
*__r = *__a;
++__a;
++__c;
++__r;
}
}
return __r;
}
_DifferenceType
__count(_IIter __a, _IIter __b, _IIter __c, _IIter __d) const
{
_DifferenceType __counter = 0;
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{ ++__a; }
else if (_M_comp(*__c, *__a))
{ ++__c; }
else
{
++__a;
++__c;
++__counter;
}
}
return __counter;
}
_OutputIterator
__first_empty(_IIter, _IIter, _OutputIterator __out) const
{ return __out; }
_OutputIterator
__second_empty(_IIter, _IIter, _OutputIterator __out) const
{ return __out; }
};
template<class _IIter, class _OutputIterator, class _Compare>
struct __union_func
{
typedef typename std::iterator_traits<_IIter>::difference_type
_DifferenceType;
__union_func(_Compare __comp) : _M_comp(__comp) {}
_Compare _M_comp;
_OutputIterator
_M_invoke(_IIter __a, const _IIter __b, _IIter __c,
const _IIter __d, _OutputIterator __r) const
{
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{
*__r = *__a;
++__a;
}
else if (_M_comp(*__c, *__a))
{
*__r = *__c;
++__c;
}
else
{
*__r = *__a;
++__a;
++__c;
}
++__r;
}
return std::copy(__c, __d, std::copy(__a, __b, __r));
}
_DifferenceType
__count(_IIter __a, _IIter __b, _IIter __c, _IIter __d) const
{
_DifferenceType __counter = 0;
while (__a != __b && __c != __d)
{
if (_M_comp(*__a, *__c))
{ ++__a; }
else if (_M_comp(*__c, *__a))
{ ++__c; }
else
{
++__a;
++__c;
}
++__counter;
}
__counter += (__b - __a);
__counter += (__d - __c);
return __counter;
}
_OutputIterator
__first_empty(_IIter __c, _IIter __d, _OutputIterator __out) const
{ return std::copy(__c, __d, __out); }
_OutputIterator
__second_empty(_IIter __a, _IIter __b, _OutputIterator __out) const
{ return std::copy(__a, __b, __out); }
};
template<typename _IIter,
typename _OutputIterator,
typename _Operation>
_OutputIterator
__parallel_set_operation(_IIter __begin1, _IIter __end1,
_IIter __begin2, _IIter __end2,
_OutputIterator __result, _Operation __op)
{
_GLIBCXX_CALL((__end1 - __begin1) + (__end2 - __begin2))
typedef std::iterator_traits<_IIter> _TraitsType;
typedef typename _TraitsType::difference_type _DifferenceType;
typedef typename std::pair<_IIter, _IIter> _IteratorPair;
if (__begin1 == __end1)
return __op.__first_empty(__begin2, __end2, __result);
if (__begin2 == __end2)
return __op.__second_empty(__begin1, __end1, __result);
const _DifferenceType __size = (__end1 - __begin1) + (__end2 - __begin2);
const _IteratorPair __sequence[2] = { std::make_pair(__begin1, __end1),
std::make_pair(__begin2, __end2) };
_OutputIterator __return_value = __result;
_DifferenceType *__borders;
_IteratorPair *__block_begins;
_DifferenceType* __lengths;
_ThreadIndex __num_threads =
std::min<_DifferenceType>(__get_max_threads(),
std::min(__end1 - __begin1, __end2 - __begin2));
# pragma omp parallel num_threads(__num_threads)
{
# pragma omp single
{
__num_threads = omp_get_num_threads();
__borders = new _DifferenceType[__num_threads + 2];
__equally_split(__size, __num_threads + 1, __borders);
__block_begins = new _IteratorPair[__num_threads + 1];
// Very __start.
__block_begins[0] = std::make_pair(__begin1, __begin2);
__lengths = new _DifferenceType[__num_threads];
} //single
_ThreadIndex __iam = omp_get_thread_num();
// _Result from multiseq_partition.
_IIter __offset[2];
const _DifferenceType __rank = __borders[__iam + 1];
multiseq_partition(__sequence, __sequence + 2,
__rank, __offset, __op._M_comp);
// allowed to read?
// together
// *(__offset[ 0 ] - 1) == *__offset[ 1 ]
if (__offset[ 0 ] != __begin1 && __offset[1] != __end2
&& !__op._M_comp(*(__offset[0] - 1), *__offset[1])
&& !__op._M_comp(*__offset[1], *(__offset[0] - 1)))
{
// Avoid split between globally equal elements: move one to
// front in first sequence.
--__offset[0];
}
_IteratorPair __block_end = __block_begins[__iam + 1] =
_IteratorPair(__offset[0], __offset[1]);
// Make sure all threads have their block_begin result written out.
# pragma omp barrier
_IteratorPair __block_begin = __block_begins[__iam];
// Begin working for the first block, while the others except
// the last start to count.
if (__iam == 0)
{
// The first thread can copy already.
__lengths[ __iam ] =
__op._M_invoke(__block_begin.first, __block_end.first,
__block_begin.second, __block_end.second,
__result) - __result;
}
else
{
__lengths[ __iam ] =
__op.__count(__block_begin.first, __block_end.first,
__block_begin.second, __block_end.second);
}
// Make sure everyone wrote their lengths.
# pragma omp barrier
_OutputIterator __r = __result;
if (__iam == 0)
{
// Do the last block.
for (_ThreadIndex __i = 0; __i < __num_threads; ++__i)
__r += __lengths[__i];
__block_begin = __block_begins[__num_threads];
// Return the result iterator of the last block.
__return_value =
__op._M_invoke(__block_begin.first, __end1,
__block_begin.second, __end2, __r);
}
else
{
for (_ThreadIndex __i = 0; __i < __iam; ++__i)
__r += __lengths[ __i ];
// Reset begins for copy pass.
__op._M_invoke(__block_begin.first, __block_end.first,
__block_begin.second, __block_end.second, __r);
}
}
return __return_value;
}
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
inline _OutputIterator
__parallel_set_union(_IIter __begin1, _IIter __end1,
_IIter __begin2, _IIter __end2,
_OutputIterator __result, _Compare __comp)
{
return __parallel_set_operation(__begin1, __end1, __begin2, __end2,
__result,
__union_func< _IIter, _OutputIterator,
_Compare>(__comp));
}
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
inline _OutputIterator
__parallel_set_intersection(_IIter __begin1, _IIter __end1,
_IIter __begin2, _IIter __end2,
_OutputIterator __result, _Compare __comp)
{
return __parallel_set_operation(__begin1, __end1, __begin2, __end2,
__result,
__intersection_func<_IIter,
_OutputIterator, _Compare>(__comp));
}
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
inline _OutputIterator
__parallel_set_difference(_IIter __begin1, _IIter __end1,
_IIter __begin2, _IIter __end2,
_OutputIterator __result, _Compare __comp)
{
return __parallel_set_operation(__begin1, __end1, __begin2, __end2,
__result,
__difference_func<_IIter,
_OutputIterator, _Compare>(__comp));
}
template<typename _IIter,
typename _OutputIterator,
typename _Compare>
inline _OutputIterator
__parallel_set_symmetric_difference(_IIter __begin1, _IIter __end1,
_IIter __begin2, _IIter __end2,
_OutputIterator __result,
_Compare __comp)
{
return __parallel_set_operation(__begin1, __end1, __begin2, __end2,
__result,
__symmetric_difference_func<_IIter,
_OutputIterator, _Compare>(__comp));
}
}
#endif /* _GLIBCXX_PARALLEL_SET_OPERATIONS_H */