--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009 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 RandomAccessIterator1,
+ typename RandomAccessIterator2,
+ typename Pred,
+ typename Selector>
+ inline std::pair<RandomAccessIterator1, RandomAccessIterator2>
+ find_template(RandomAccessIterator1 begin1, RandomAccessIterator1 end1,
+ RandomAccessIterator2 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 RandomAccessIterator1,
+ typename RandomAccessIterator2,
+ typename Pred,
+ typename Selector>
+ std::pair<RandomAccessIterator1, RandomAccessIterator2>
+ find_template(RandomAccessIterator1 begin1,
+ RandomAccessIterator1 end1,
+ RandomAccessIterator2 begin2,
+ Pred pred,
+ Selector selector,
+ equal_split_tag)
+ {
+ _GLIBCXX_CALL(end1 - begin1)
+
+ typedef std::iterator_traits<RandomAccessIterator1> traits_type;
+ typedef typename traits_type::difference_type difference_type;
+ typedef typename traits_type::value_type value_type;
+
+ difference_type length = end1 - begin1;
+ difference_type result = length;
+ difference_type* borders;
+
+ omp_lock_t result_lock;
+ omp_init_lock(&result_lock);
+
+ thread_index_t num_threads = get_max_threads();
+# pragma omp parallel num_threads(num_threads)
+ {
+# pragma omp single
+ {
+ num_threads = omp_get_num_threads();
+ borders = new difference_type[num_threads + 1];
+ equally_split(length, num_threads, borders);
+ } //single
+
+ thread_index_t iam = omp_get_thread_num();
+ difference_type start = borders[iam], stop = borders[iam + 1];
+
+ RandomAccessIterator1 i1 = begin1 + start;
+ RandomAccessIterator2 i2 = begin2 + start;
+ for (difference_type 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<RandomAccessIterator1, RandomAccessIterator2>(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_initial_block_size
+ * @see __gnu_parallel::_Settings::find_maximum_block_size
+ * @see __gnu_parallel::_Settings::find_increasing_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 RandomAccessIterator1,
+ typename RandomAccessIterator2,
+ typename Pred,
+ typename Selector>
+ std::pair<RandomAccessIterator1, RandomAccessIterator2>
+ find_template(RandomAccessIterator1 begin1, RandomAccessIterator1 end1,
+ RandomAccessIterator2 begin2, Pred pred, Selector selector,
+ growing_blocks_tag)
+ {
+ _GLIBCXX_CALL(end1 - begin1)
+
+ typedef std::iterator_traits<RandomAccessIterator1> traits_type;
+ typedef typename traits_type::difference_type difference_type;
+ typedef typename traits_type::value_type value_type;
+
+ const _Settings& __s = _Settings::get();
+
+ difference_type length = end1 - begin1;
+
+ difference_type sequential_search_size =
+ std::min<difference_type>(length, __s.find_sequential_search_size);
+
+ // Try it sequentially first.
+ std::pair<RandomAccessIterator1, RandomAccessIterator2> find_seq_result =
+ selector.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).
+ difference_type next_block_start = sequential_search_size;
+ difference_type result = length;
+
+ omp_lock_t result_lock;
+ omp_init_lock(&result_lock);
+
+ thread_index_t 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.
+ thread_index_t iam = omp_get_thread_num();
+
+ difference_type block_size = __s.find_initial_block_size;
+ difference_type start =
+ fetch_and_add<difference_type>(&next_block_start, block_size);
+
+ // Get new block, update pointer to next block.
+ difference_type stop =
+ std::min<difference_type>(length, start + block_size);
+
+ std::pair<RandomAccessIterator1, RandomAccessIterator2> 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.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<difference_type>(&next_block_start, length);
+ }
+ omp_unset_lock(&result_lock);
+ }
+
+ block_size =
+ std::min<difference_type>(block_size * __s.find_increasing_factor,
+ __s.find_maximum_block_size);
+
+ // Get new block, update pointer to next block.
+ start =
+ fetch_and_add<difference_type>(&next_block_start, block_size);
+ stop = ((length < (start + block_size))
+ ? length : (start + block_size));
+ }
+ } //parallel
+
+ omp_destroy_lock(&result_lock);
+
+ // Return iterator on found element.
+ return
+ std::pair<RandomAccessIterator1, RandomAccessIterator2>(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 RandomAccessIterator1,
+ typename RandomAccessIterator2,
+ typename Pred,
+ typename Selector>
+ std::pair<RandomAccessIterator1, RandomAccessIterator2>
+ find_template(RandomAccessIterator1 begin1, RandomAccessIterator1 end1,
+ RandomAccessIterator2 begin2, Pred pred, Selector selector,
+ constant_size_blocks_tag)
+ {
+ _GLIBCXX_CALL(end1 - begin1)
+ typedef std::iterator_traits<RandomAccessIterator1> traits_type;
+ typedef typename traits_type::difference_type difference_type;
+ typedef typename traits_type::value_type value_type;
+
+ const _Settings& __s = _Settings::get();
+
+ difference_type length = end1 - begin1;
+
+ difference_type sequential_search_size = std::min<difference_type>(
+ length, __s.find_sequential_search_size);
+
+ // Try it sequentially first.
+ std::pair<RandomAccessIterator1, RandomAccessIterator2> find_seq_result =
+ selector.sequential_algorithm(begin1, begin1 + sequential_search_size,
+ begin2, pred);
+
+ if (find_seq_result.first != (begin1 + sequential_search_size))
+ return find_seq_result;
+
+ difference_type result = length;
+ omp_lock_t result_lock;
+ omp_init_lock(&result_lock);
+
+ // Not within first sequential_search_size elements -> start parallel.
+
+ thread_index_t num_threads = get_max_threads();
+# pragma omp parallel shared(result) num_threads(num_threads)
+ {
+# pragma omp single
+ num_threads = omp_get_num_threads();
+
+ thread_index_t iam = omp_get_thread_num();
+ difference_type block_size = __s.find_initial_block_size;
+
+ // First element of thread's current iteration.
+ difference_type iteration_start = sequential_search_size;
+
+ // Where to work (initialization).
+ difference_type start = iteration_start + iam * block_size;
+ difference_type stop =
+ std::min<difference_type>(length, start + block_size);
+
+ std::pair<RandomAccessIterator1, RandomAccessIterator2> 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.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<difference_type>(length, start + block_size);
+ }
+ } //parallel
+
+ omp_destroy_lock(&result_lock);
+
+ // Return iterator on found element.
+ return
+ std::pair<RandomAccessIterator1, RandomAccessIterator2>(begin1 + result,
+ begin2 + result);
+ }
+#endif
+} // end namespace
+
+#endif /* _GLIBCXX_PARALLEL_FIND_H */
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