--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009, 2010, 2011 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/find.h
+ * @brief Parallel implementation base for std::find(), std::equal()
+ * and related functions.
+ * This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Felix Putze and Johannes Singler.
+
+#ifndef _GLIBCXX_PARALLEL_FIND_H
+#define _GLIBCXX_PARALLEL_FIND_H 1
+
+#include <bits/stl_algobase.h>
+
+#include <parallel/features.h>
+#include <parallel/parallel.h>
+#include <parallel/compatibility.h>
+#include <parallel/equally_split.h>
+
+namespace __gnu_parallel
+{
+ /**
+ * @brief Parallel std::find, switch for different algorithms.
+ * @param __begin1 Begin iterator of first sequence.
+ * @param __end1 End iterator of first sequence.
+ * @param __begin2 Begin iterator of second sequence. Must have same
+ * length as first sequence.
+ * @param __pred Find predicate.
+ * @param __selector _Functionality (e. g. std::find_if(), std::equal(),...)
+ * @return Place of finding in both sequences.
+ */
+ template<typename _RAIter1,
+ typename _RAIter2,
+ typename _Pred,
+ typename _Selector>
+ inline std::pair<_RAIter1, _RAIter2>
+ __find_template(_RAIter1 __begin1, _RAIter1 __end1,
+ _RAIter2 __begin2, _Pred __pred, _Selector __selector)
+ {
+ switch (_Settings::get().find_algorithm)
+ {
+ case GROWING_BLOCKS:
+ return __find_template(__begin1, __end1, __begin2, __pred,
+ __selector, growing_blocks_tag());
+ case CONSTANT_SIZE_BLOCKS:
+ return __find_template(__begin1, __end1, __begin2, __pred,
+ __selector, constant_size_blocks_tag());
+ case EQUAL_SPLIT:
+ return __find_template(__begin1, __end1, __begin2, __pred,
+ __selector, equal_split_tag());
+ default:
+ _GLIBCXX_PARALLEL_ASSERT(false);
+ return std::make_pair(__begin1, __begin2);
+ }
+ }
+
+#if _GLIBCXX_FIND_EQUAL_SPLIT
+
+ /**
+ * @brief Parallel std::find, equal splitting variant.
+ * @param __begin1 Begin iterator of first sequence.
+ * @param __end1 End iterator of first sequence.
+ * @param __begin2 Begin iterator of second sequence. Second __sequence
+ * must have same length as first sequence.
+ * @param __pred Find predicate.
+ * @param __selector _Functionality (e. g. std::find_if(), std::equal(),...)
+ * @return Place of finding in both sequences.
+ */
+ template<typename _RAIter1,
+ typename _RAIter2,
+ typename _Pred,
+ typename _Selector>
+ std::pair<_RAIter1, _RAIter2>
+ __find_template(_RAIter1 __begin1, _RAIter1 __end1,
+ _RAIter2 __begin2, _Pred __pred,
+ _Selector __selector, equal_split_tag)
+ {
+ _GLIBCXX_CALL(__end1 - __begin1)
+
+ typedef std::iterator_traits<_RAIter1> _TraitsType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+ typedef typename _TraitsType::value_type _ValueType;
+
+ _DifferenceType __length = __end1 - __begin1;
+ _DifferenceType __result = __length;
+ _DifferenceType* __borders;
+
+ omp_lock_t __result_lock;
+ omp_init_lock(&__result_lock);
+
+ _ThreadIndex __num_threads = __get_max_threads();
+# pragma omp parallel num_threads(__num_threads)
+ {
+# pragma omp single
+ {
+ __num_threads = omp_get_num_threads();
+ __borders = new _DifferenceType[__num_threads + 1];
+ __equally_split(__length, __num_threads, __borders);
+ } //single
+
+ _ThreadIndex __iam = omp_get_thread_num();
+ _DifferenceType __start = __borders[__iam],
+ __stop = __borders[__iam + 1];
+
+ _RAIter1 __i1 = __begin1 + __start;
+ _RAIter2 __i2 = __begin2 + __start;
+ for (_DifferenceType __pos = __start; __pos < __stop; ++__pos)
+ {
+# pragma omp flush(__result)
+ // Result has been set to something lower.
+ if (__result < __pos)
+ break;
+
+ if (__selector(__i1, __i2, __pred))
+ {
+ omp_set_lock(&__result_lock);
+ if (__pos < __result)
+ __result = __pos;
+ omp_unset_lock(&__result_lock);
+ break;
+ }
+ ++__i1;
+ ++__i2;
+ }
+ } //parallel
+
+ omp_destroy_lock(&__result_lock);
+ delete[] __borders;
+
+ return std::pair<_RAIter1, _RAIter2>(__begin1 + __result,
+ __begin2 + __result);
+ }
+
+#endif
+
+#if _GLIBCXX_FIND_GROWING_BLOCKS
+
+ /**
+ * @brief Parallel std::find, growing block size variant.
+ * @param __begin1 Begin iterator of first sequence.
+ * @param __end1 End iterator of first sequence.
+ * @param __begin2 Begin iterator of second sequence. Second __sequence
+ * must have same length as first sequence.
+ * @param __pred Find predicate.
+ * @param __selector _Functionality (e. g. std::find_if(), std::equal(),...)
+ * @return Place of finding in both sequences.
+ * @see __gnu_parallel::_Settings::find_sequential_search_size
+ * @see __gnu_parallel::_Settings::find_scale_factor
+ *
+ * There are two main differences between the growing blocks and
+ * the constant-size blocks variants.
+ * 1. For GB, the block size grows; for CSB, the block size is fixed.
+ * 2. For GB, the blocks are allocated dynamically;
+ * for CSB, the blocks are allocated in a predetermined manner,
+ * namely spacial round-robin.
+ */
+ template<typename _RAIter1,
+ typename _RAIter2,
+ typename _Pred,
+ typename _Selector>
+ std::pair<_RAIter1, _RAIter2>
+ __find_template(_RAIter1 __begin1, _RAIter1 __end1,
+ _RAIter2 __begin2, _Pred __pred, _Selector __selector,
+ growing_blocks_tag)
+ {
+ _GLIBCXX_CALL(__end1 - __begin1)
+
+ typedef std::iterator_traits<_RAIter1> _TraitsType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+ typedef typename _TraitsType::value_type _ValueType;
+
+ const _Settings& __s = _Settings::get();
+
+ _DifferenceType __length = __end1 - __begin1;
+
+ _DifferenceType
+ __sequential_search_size = std::min<_DifferenceType>
+ (__length, __s.find_sequential_search_size);
+
+ // Try it sequentially first.
+ std::pair<_RAIter1, _RAIter2>
+ __find_seq_result = __selector._M_sequential_algorithm
+ (__begin1, __begin1 + __sequential_search_size,
+ __begin2, __pred);
+
+ if (__find_seq_result.first != (__begin1 + __sequential_search_size))
+ return __find_seq_result;
+
+ // Index of beginning of next free block (after sequential find).
+ _DifferenceType __next_block_start = __sequential_search_size;
+ _DifferenceType __result = __length;
+
+ omp_lock_t __result_lock;
+ omp_init_lock(&__result_lock);
+
+ const float __scale_factor = __s.find_scale_factor;
+
+ _ThreadIndex __num_threads = __get_max_threads();
+# pragma omp parallel shared(__result) num_threads(__num_threads)
+ {
+# pragma omp single
+ __num_threads = omp_get_num_threads();
+
+ // Not within first __k elements -> start parallel.
+ _ThreadIndex __iam = omp_get_thread_num();
+
+ _DifferenceType __block_size =
+ std::max<_DifferenceType>(1, __scale_factor * __next_block_start);
+ _DifferenceType __start = __fetch_and_add<_DifferenceType>
+ (&__next_block_start, __block_size);
+
+ // Get new block, update pointer to next block.
+ _DifferenceType __stop =
+ std::min<_DifferenceType>(__length, __start + __block_size);
+
+ std::pair<_RAIter1, _RAIter2> __local_result;
+
+ while (__start < __length)
+ {
+# pragma omp flush(__result)
+ // Get new value of result.
+ if (__result < __start)
+ {
+ // No chance to find first element.
+ break;
+ }
+
+ __local_result = __selector._M_sequential_algorithm
+ (__begin1 + __start, __begin1 + __stop,
+ __begin2 + __start, __pred);
+
+ if (__local_result.first != (__begin1 + __stop))
+ {
+ omp_set_lock(&__result_lock);
+ if ((__local_result.first - __begin1) < __result)
+ {
+ __result = __local_result.first - __begin1;
+
+ // Result cannot be in future blocks, stop algorithm.
+ __fetch_and_add<_DifferenceType>(&__next_block_start,
+ __length);
+ }
+ omp_unset_lock(&__result_lock);
+ }
+
+ _DifferenceType __block_size =
+ std::max<_DifferenceType>(1, __scale_factor * __next_block_start);
+
+ // Get new block, update pointer to next block.
+ __start = __fetch_and_add<_DifferenceType>(&__next_block_start,
+ __block_size);
+ __stop =
+ std::min<_DifferenceType>(__length, __start + __block_size);
+ }
+ } //parallel
+
+ omp_destroy_lock(&__result_lock);
+
+ // Return iterator on found element.
+ return
+ std::pair<_RAIter1, _RAIter2>(__begin1 + __result,
+ __begin2 + __result);
+ }
+
+#endif
+
+#if _GLIBCXX_FIND_CONSTANT_SIZE_BLOCKS
+
+ /**
+ * @brief Parallel std::find, constant block size variant.
+ * @param __begin1 Begin iterator of first sequence.
+ * @param __end1 End iterator of first sequence.
+ * @param __begin2 Begin iterator of second sequence. Second __sequence
+ * must have same length as first sequence.
+ * @param __pred Find predicate.
+ * @param __selector _Functionality (e. g. std::find_if(), std::equal(),...)
+ * @return Place of finding in both sequences.
+ * @see __gnu_parallel::_Settings::find_sequential_search_size
+ * @see __gnu_parallel::_Settings::find_block_size
+ * There are two main differences between the growing blocks and the
+ * constant-size blocks variants.
+ * 1. For GB, the block size grows; for CSB, the block size is fixed.
+ * 2. For GB, the blocks are allocated dynamically; for CSB, the
+ * blocks are allocated in a predetermined manner, namely spacial
+ * round-robin.
+ */
+ template<typename _RAIter1,
+ typename _RAIter2,
+ typename _Pred,
+ typename _Selector>
+ std::pair<_RAIter1, _RAIter2>
+ __find_template(_RAIter1 __begin1, _RAIter1 __end1,
+ _RAIter2 __begin2, _Pred __pred, _Selector __selector,
+ constant_size_blocks_tag)
+ {
+ _GLIBCXX_CALL(__end1 - __begin1)
+ typedef std::iterator_traits<_RAIter1> _TraitsType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+ typedef typename _TraitsType::value_type _ValueType;
+
+ const _Settings& __s = _Settings::get();
+
+ _DifferenceType __length = __end1 - __begin1;
+
+ _DifferenceType __sequential_search_size = std::min<_DifferenceType>
+ (__length, __s.find_sequential_search_size);
+
+ // Try it sequentially first.
+ std::pair<_RAIter1, _RAIter2>
+ __find_seq_result = __selector._M_sequential_algorithm
+ (__begin1, __begin1 + __sequential_search_size, __begin2, __pred);
+
+ if (__find_seq_result.first != (__begin1 + __sequential_search_size))
+ return __find_seq_result;
+
+ _DifferenceType __result = __length;
+ omp_lock_t __result_lock;
+ omp_init_lock(&__result_lock);
+
+ // Not within first __sequential_search_size elements -> start parallel.
+
+ _ThreadIndex __num_threads = __get_max_threads();
+# pragma omp parallel shared(__result) num_threads(__num_threads)
+ {
+# pragma omp single
+ __num_threads = omp_get_num_threads();
+
+ _ThreadIndex __iam = omp_get_thread_num();
+ _DifferenceType __block_size = __s.find_initial_block_size;
+
+ // First element of thread's current iteration.
+ _DifferenceType __iteration_start = __sequential_search_size;
+
+ // Where to work (initialization).
+ _DifferenceType __start = __iteration_start + __iam * __block_size;
+ _DifferenceType __stop = std::min<_DifferenceType>(__length,
+ __start
+ + __block_size);
+
+ std::pair<_RAIter1, _RAIter2> __local_result;
+
+ while (__start < __length)
+ {
+ // Get new value of result.
+# pragma omp flush(__result)
+ // No chance to find first element.
+ if (__result < __start)
+ break;
+
+ __local_result = __selector._M_sequential_algorithm
+ (__begin1 + __start, __begin1 + __stop,
+ __begin2 + __start, __pred);
+
+ if (__local_result.first != (__begin1 + __stop))
+ {
+ omp_set_lock(&__result_lock);
+ if ((__local_result.first - __begin1) < __result)
+ __result = __local_result.first - __begin1;
+ omp_unset_lock(&__result_lock);
+ // Will not find better value in its interval.
+ break;
+ }
+
+ __iteration_start += __num_threads * __block_size;
+
+ // Where to work.
+ __start = __iteration_start + __iam * __block_size;
+ __stop = std::min<_DifferenceType>(__length,
+ __start + __block_size);
+ }
+ } //parallel
+
+ omp_destroy_lock(&__result_lock);
+
+ // Return iterator on found element.
+ return std::pair<_RAIter1, _RAIter2>(__begin1 + __result,
+ __begin2 + __result);
+ }
+#endif
+} // end namespace
+
+#endif /* _GLIBCXX_PARALLEL_FIND_H */
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