diff options
Diffstat (limited to 'libstdc++-v3/include/parallel/balanced_quicksort.h')
| -rw-r--r-- | libstdc++-v3/include/parallel/balanced_quicksort.h | 753 |
1 files changed, 376 insertions, 377 deletions
diff --git a/libstdc++-v3/include/parallel/balanced_quicksort.h b/libstdc++-v3/include/parallel/balanced_quicksort.h index 85e4d699e26..3107d97a45b 100644 --- a/libstdc++-v3/include/parallel/balanced_quicksort.h +++ b/libstdc++-v3/include/parallel/balanced_quicksort.h @@ -57,436 +57,435 @@ namespace __gnu_parallel { -/** @brief Information local to one thread in the parallel quicksort run. */ -template<typename _RAIter> - struct _QSBThreadLocal - { - typedef std::iterator_traits<_RAIter> _TraitsType; - typedef typename _TraitsType::difference_type _DifferenceType; - - /** @brief Continuous part of the sequence, described by an - iterator pair. */ - typedef std::pair<_RAIter, _RAIter> _Piece; - - /** @brief Initial piece to work on. */ - _Piece _M_initial; - - /** @brief Work-stealing queue. */ - _RestrictedBoundedConcurrentQueue<_Piece> _M_leftover_parts; - - /** @brief Number of threads involved in this algorithm. */ - _ThreadIndex _M_num_threads; - - /** @brief Pointer to a counter of elements left over to sort. */ - volatile _DifferenceType* _M_elements_leftover; - - /** @brief The complete sequence to sort. */ - _Piece _M_global; - - /** @brief Constructor. - * @param __queue_size size of the work-stealing queue. */ - _QSBThreadLocal(int __queue_size) : _M_leftover_parts(__queue_size) { } - }; - -/** @brief Balanced quicksort divide step. - * @param __begin Begin iterator of subsequence. - * @param __end End iterator of subsequence. - * @param __comp Comparator. - * @param __num_threads Number of threads that are allowed to work on - * this part. - * @pre @__c (__end-__begin)>=1 */ -template<typename _RAIter, typename _Compare> - typename std::iterator_traits<_RAIter>::difference_type - __qsb_divide(_RAIter __begin, _RAIter __end, - _Compare __comp, _ThreadIndex __num_threads) - { - _GLIBCXX_PARALLEL_ASSERT(__num_threads > 0); - - typedef std::iterator_traits<_RAIter> _TraitsType; - typedef typename _TraitsType::value_type _ValueType; - typedef typename _TraitsType::difference_type _DifferenceType; - - _RAIter __pivot_pos = - __median_of_three_iterators(__begin, __begin + (__end - __begin) / 2, - __end - 1, __comp); + /** @brief Information local to one thread in the parallel quicksort run. */ + template<typename _RAIter> + struct _QSBThreadLocal + { + typedef std::iterator_traits<_RAIter> _TraitsType; + typedef typename _TraitsType::difference_type _DifferenceType; + + /** @brief Continuous part of the sequence, described by an + iterator pair. */ + typedef std::pair<_RAIter, _RAIter> _Piece; + + /** @brief Initial piece to work on. */ + _Piece _M_initial; + + /** @brief Work-stealing queue. */ + _RestrictedBoundedConcurrentQueue<_Piece> _M_leftover_parts; + + /** @brief Number of threads involved in this algorithm. */ + _ThreadIndex _M_num_threads; + + /** @brief Pointer to a counter of elements left over to sort. */ + volatile _DifferenceType* _M_elements_leftover; + + /** @brief The complete sequence to sort. */ + _Piece _M_global; + + /** @brief Constructor. + * @param __queue_size size of the work-stealing queue. */ + _QSBThreadLocal(int __queue_size) : _M_leftover_parts(__queue_size) { } + }; + + /** @brief Balanced quicksort divide step. + * @param __begin Begin iterator of subsequence. + * @param __end End iterator of subsequence. + * @param __comp Comparator. + * @param __num_threads Number of threads that are allowed to work on + * this part. + * @pre @__c (__end-__begin)>=1 */ + template<typename _RAIter, typename _Compare> + typename std::iterator_traits<_RAIter>::difference_type + __qsb_divide(_RAIter __begin, _RAIter __end, + _Compare __comp, _ThreadIndex __num_threads) + { + _GLIBCXX_PARALLEL_ASSERT(__num_threads > 0); + + typedef std::iterator_traits<_RAIter> _TraitsType; + typedef typename _TraitsType::value_type _ValueType; + typedef typename _TraitsType::difference_type _DifferenceType; + + _RAIter __pivot_pos = + __median_of_three_iterators(__begin, __begin + (__end - __begin) / 2, + __end - 1, __comp); #if defined(_GLIBCXX_ASSERTIONS) - // Must be in between somewhere. - _DifferenceType __n = __end - __begin; - - _GLIBCXX_PARALLEL_ASSERT( - (!__comp(*__pivot_pos, *__begin) && - !__comp(*(__begin + __n / 2), *__pivot_pos)) - || (!__comp(*__pivot_pos, *__begin) && - !__comp(*(__end - 1), *__pivot_pos)) - || (!__comp(*__pivot_pos, *(__begin + __n / 2)) && - !__comp(*__begin, *__pivot_pos)) - || (!__comp(*__pivot_pos, *(__begin + __n / 2)) && - !__comp(*(__end - 1), *__pivot_pos)) - || (!__comp(*__pivot_pos, *(__end - 1)) && - !__comp(*__begin, *__pivot_pos)) - || (!__comp(*__pivot_pos, *(__end - 1)) && - !__comp(*(__begin + __n / 2), *__pivot_pos))); + // Must be in between somewhere. + _DifferenceType __n = __end - __begin; + + _GLIBCXX_PARALLEL_ASSERT((!__comp(*__pivot_pos, *__begin) + && !__comp(*(__begin + __n / 2), + *__pivot_pos)) + || (!__comp(*__pivot_pos, *__begin) + && !__comp(*(__end - 1), *__pivot_pos)) + || (!__comp(*__pivot_pos, *(__begin + __n / 2)) + && !__comp(*__begin, *__pivot_pos)) + || (!__comp(*__pivot_pos, *(__begin + __n / 2)) + && !__comp(*(__end - 1), *__pivot_pos)) + || (!__comp(*__pivot_pos, *(__end - 1)) + && !__comp(*__begin, *__pivot_pos)) + || (!__comp(*__pivot_pos, *(__end - 1)) + && !__comp(*(__begin + __n / 2), + *__pivot_pos))); #endif - // Swap pivot value to end. - if (__pivot_pos != (__end - 1)) - std::swap(*__pivot_pos, *(__end - 1)); - __pivot_pos = __end - 1; + // Swap pivot value to end. + if (__pivot_pos != (__end - 1)) + std::swap(*__pivot_pos, *(__end - 1)); + __pivot_pos = __end - 1; - __gnu_parallel::binder2nd<_Compare, _ValueType, _ValueType, bool> - __pred(__comp, *__pivot_pos); + __gnu_parallel::binder2nd<_Compare, _ValueType, _ValueType, bool> + __pred(__comp, *__pivot_pos); - // Divide, returning __end - __begin - 1 in the worst case. - _DifferenceType __split_pos = __parallel_partition( - __begin, __end - 1, __pred, __num_threads); + // Divide, returning __end - __begin - 1 in the worst case. + _DifferenceType __split_pos = __parallel_partition(__begin, __end - 1, + __pred, + __num_threads); - // Swap back pivot to middle. - std::swap(*(__begin + __split_pos), *__pivot_pos); - __pivot_pos = __begin + __split_pos; + // Swap back pivot to middle. + std::swap(*(__begin + __split_pos), *__pivot_pos); + __pivot_pos = __begin + __split_pos; #if _GLIBCXX_ASSERTIONS - _RAIter __r; - for (__r = __begin; __r != __pivot_pos; ++__r) - _GLIBCXX_PARALLEL_ASSERT(__comp(*__r, *__pivot_pos)); - for (; __r != __end; ++__r) - _GLIBCXX_PARALLEL_ASSERT(!__comp(*__r, *__pivot_pos)); + _RAIter __r; + for (__r = __begin; __r != __pivot_pos; ++__r) + _GLIBCXX_PARALLEL_ASSERT(__comp(*__r, *__pivot_pos)); + for (; __r != __end; ++__r) + _GLIBCXX_PARALLEL_ASSERT(!__comp(*__r, *__pivot_pos)); #endif - return __split_pos; - } - -/** @brief Quicksort conquer step. - * @param __tls Array of thread-local storages. - * @param __begin Begin iterator of subsequence. - * @param __end End iterator of subsequence. - * @param __comp Comparator. - * @param __iam Number of the thread processing this function. - * @param __num_threads - * Number of threads that are allowed to work on this part. */ -template<typename _RAIter, typename _Compare> - void - __qsb_conquer(_QSBThreadLocal<_RAIter>** __tls, - _RAIter __begin, _RAIter __end, - _Compare __comp, - _ThreadIndex __iam, _ThreadIndex __num_threads, - bool __parent_wait) - { - typedef std::iterator_traits<_RAIter> _TraitsType; - typedef typename _TraitsType::value_type _ValueType; - typedef typename _TraitsType::difference_type _DifferenceType; - - _DifferenceType __n = __end - __begin; - - if (__num_threads <= 1 || __n <= 1) - { - __tls[__iam]->_M_initial.first = __begin; - __tls[__iam]->_M_initial.second = __end; + return __split_pos; + } - __qsb_local_sort_with_helping(__tls, __comp, __iam, __parent_wait); + /** @brief Quicksort conquer step. + * @param __tls Array of thread-local storages. + * @param __begin Begin iterator of subsequence. + * @param __end End iterator of subsequence. + * @param __comp Comparator. + * @param __iam Number of the thread processing this function. + * @param __num_threads + * Number of threads that are allowed to work on this part. */ + template<typename _RAIter, typename _Compare> + void + __qsb_conquer(_QSBThreadLocal<_RAIter>** __tls, + _RAIter __begin, _RAIter __end, + _Compare __comp, + _ThreadIndex __iam, _ThreadIndex __num_threads, + bool __parent_wait) + { + typedef std::iterator_traits<_RAIter> _TraitsType; + typedef typename _TraitsType::value_type _ValueType; + typedef typename _TraitsType::difference_type _DifferenceType; - return; - } + _DifferenceType __n = __end - __begin; + + if (__num_threads <= 1 || __n <= 1) + { + __tls[__iam]->_M_initial.first = __begin; + __tls[__iam]->_M_initial.second = __end; + + __qsb_local_sort_with_helping(__tls, __comp, __iam, __parent_wait); + + return; + } - // Divide step. - _DifferenceType __split_pos = - __qsb_divide(__begin, __end, __comp, __num_threads); + // Divide step. + _DifferenceType __split_pos = + __qsb_divide(__begin, __end, __comp, __num_threads); #if _GLIBCXX_ASSERTIONS - _GLIBCXX_PARALLEL_ASSERT(0 <= __split_pos && - __split_pos < (__end - __begin)); + _GLIBCXX_PARALLEL_ASSERT(0 <= __split_pos && + __split_pos < (__end - __begin)); #endif - _ThreadIndex __num_threads_leftside = - std::max<_ThreadIndex>(1, std::min<_ThreadIndex>( - __num_threads - 1, __split_pos * __num_threads / __n)); + _ThreadIndex + __num_threads_leftside = std::max<_ThreadIndex> + (1, std::min<_ThreadIndex>(__num_threads - 1, __split_pos + * __num_threads / __n)); -# pragma omp atomic - *__tls[__iam]->_M_elements_leftover -= (_DifferenceType)1; +# pragma omp atomic + *__tls[__iam]->_M_elements_leftover -= (_DifferenceType)1; - // Conquer step. -# pragma omp parallel num_threads(2) - { - bool __wait; - if(omp_get_num_threads() < 2) - __wait = false; - else - __wait = __parent_wait; - -# pragma omp sections - { + // Conquer step. +# pragma omp parallel num_threads(2) + { + bool __wait; + if(omp_get_num_threads() < 2) + __wait = false; + else + __wait = __parent_wait; + +# pragma omp sections + { # pragma omp section - { - __qsb_conquer(__tls, __begin, __begin + __split_pos, __comp, - __iam, - __num_threads_leftside, - __wait); - __wait = __parent_wait; - } - // The pivot_pos is left in place, to ensure termination. + { + __qsb_conquer(__tls, __begin, __begin + __split_pos, __comp, + __iam, __num_threads_leftside, __wait); + __wait = __parent_wait; + } + // The pivot_pos is left in place, to ensure termination. # pragma omp section - { - __qsb_conquer(__tls, __begin + __split_pos + 1, __end, __comp, - __iam + __num_threads_leftside, - __num_threads - __num_threads_leftside, - __wait); - __wait = __parent_wait; - } - } + { + __qsb_conquer(__tls, __begin + __split_pos + 1, __end, __comp, + __iam + __num_threads_leftside, + __num_threads - __num_threads_leftside, __wait); + __wait = __parent_wait; + } + } + } } - } - -/** - * @brief Quicksort step doing load-balanced local sort. - * @param __tls Array of thread-local storages. - * @param __comp Comparator. - * @param __iam Number of the thread processing this function. - */ -template<typename _RAIter, typename _Compare> - void - __qsb_local_sort_with_helping(_QSBThreadLocal<_RAIter>** __tls, - _Compare& __comp, int __iam, bool __wait) - { - typedef std::iterator_traits<_RAIter> _TraitsType; - typedef typename _TraitsType::value_type _ValueType; - typedef typename _TraitsType::difference_type _DifferenceType; - typedef std::pair<_RAIter, _RAIter> _Piece; - - _QSBThreadLocal<_RAIter>& __tl = *__tls[__iam]; - - _DifferenceType __base_case_n = - _Settings::get().sort_qsb_base_case_maximal_n; - if (__base_case_n < 2) - __base_case_n = 2; - _ThreadIndex __num_threads = __tl._M_num_threads; - - // Every thread has its own random number generator. - _RandomNumber __rng(__iam + 1); - - _Piece __current = __tl._M_initial; - - _DifferenceType __elements_done = 0; + + /** + * @brief Quicksort step doing load-balanced local sort. + * @param __tls Array of thread-local storages. + * @param __comp Comparator. + * @param __iam Number of the thread processing this function. + */ + template<typename _RAIter, typename _Compare> + void + __qsb_local_sort_with_helping(_QSBThreadLocal<_RAIter>** __tls, + _Compare& __comp, int __iam, bool __wait) + { + typedef std::iterator_traits<_RAIter> _TraitsType; + typedef typename _TraitsType::value_type _ValueType; + typedef typename _TraitsType::difference_type _DifferenceType; + typedef std::pair<_RAIter, _RAIter> _Piece; + + _QSBThreadLocal<_RAIter>& __tl = *__tls[__iam]; + + _DifferenceType + __base_case_n = _Settings::get().sort_qsb_base_case_maximal_n; + if (__base_case_n < 2) + __base_case_n = 2; + _ThreadIndex __num_threads = __tl._M_num_threads; + + // Every thread has its own random number generator. + _RandomNumber __rng(__iam + 1); + + _Piece __current = __tl._M_initial; + + _DifferenceType __elements_done = 0; #if _GLIBCXX_ASSERTIONS - _DifferenceType __total_elements_done = 0; + _DifferenceType __total_elements_done = 0; #endif - for (;;) - { - // Invariant: __current must be a valid (maybe empty) range. - _RAIter __begin = __current.first, __end = __current.second; - _DifferenceType __n = __end - __begin; - - if (__n > __base_case_n) - { - // Divide. - _RAIter __pivot_pos = __begin + __rng(__n); - - // Swap __pivot_pos value to end. - if (__pivot_pos != (__end - 1)) - std::swap(*__pivot_pos, *(__end - 1)); - __pivot_pos = __end - 1; - - __gnu_parallel::binder2nd - <_Compare, _ValueType, _ValueType, bool> - __pred(__comp, *__pivot_pos); - - // Divide, leave pivot unchanged in last place. - _RAIter __split_pos1, __split_pos2; - __split_pos1 = - __gnu_sequential::partition(__begin, __end - 1, __pred); - - // Left side: < __pivot_pos; __right side: >= __pivot_pos. + for (;;) + { + // Invariant: __current must be a valid (maybe empty) range. + _RAIter __begin = __current.first, __end = __current.second; + _DifferenceType __n = __end - __begin; + + if (__n > __base_case_n) + { + // Divide. + _RAIter __pivot_pos = __begin + __rng(__n); + + // Swap __pivot_pos value to end. + if (__pivot_pos != (__end - 1)) + std::swap(*__pivot_pos, *(__end - 1)); + __pivot_pos = __end - 1; + + __gnu_parallel::binder2nd + <_Compare, _ValueType, _ValueType, bool> + __pred(__comp, *__pivot_pos); + + // Divide, leave pivot unchanged in last place. + _RAIter __split_pos1, __split_pos2; + __split_pos1 = __gnu_sequential::partition(__begin, __end - 1, + __pred); + + // Left side: < __pivot_pos; __right side: >= __pivot_pos. #if _GLIBCXX_ASSERTIONS - _GLIBCXX_PARALLEL_ASSERT(__begin <= __split_pos1 - && __split_pos1 < __end); + _GLIBCXX_PARALLEL_ASSERT(__begin <= __split_pos1 + && __split_pos1 < __end); #endif - // Swap pivot back to middle. - if (__split_pos1 != __pivot_pos) - std::swap(*__split_pos1, *__pivot_pos); - __pivot_pos = __split_pos1; - - // In case all elements are equal, __split_pos1 == 0. - if ((__split_pos1 + 1 - __begin) < (__n >> 7) - || (__end - __split_pos1) < (__n >> 7)) - { - // Very unequal split, one part smaller than one 128th - // elements not strictly larger than the pivot. - __gnu_parallel::__unary_negate<__gnu_parallel::__binder1st - <_Compare, _ValueType, _ValueType, bool>, _ValueType> - __pred(__gnu_parallel::__binder1st - <_Compare, _ValueType, _ValueType, bool>( - __comp, *__pivot_pos)); - - // Find other end of pivot-equal range. - __split_pos2 = __gnu_sequential::partition(__split_pos1 + 1, - __end, __pred); - } - else - // Only skip the pivot. - __split_pos2 = __split_pos1 + 1; - - // Elements equal to pivot are done. - __elements_done += (__split_pos2 - __split_pos1); + // Swap pivot back to middle. + if (__split_pos1 != __pivot_pos) + std::swap(*__split_pos1, *__pivot_pos); + __pivot_pos = __split_pos1; + + // In case all elements are equal, __split_pos1 == 0. + if ((__split_pos1 + 1 - __begin) < (__n >> 7) + || (__end - __split_pos1) < (__n >> 7)) + { + // Very unequal split, one part smaller than one 128th + // elements not strictly larger than the pivot. + __gnu_parallel::__unary_negate<__gnu_parallel::__binder1st + <_Compare, _ValueType, _ValueType, bool>, _ValueType> + __pred(__gnu_parallel::__binder1st + <_Compare, _ValueType, _ValueType, bool> + (__comp, *__pivot_pos)); + + // Find other end of pivot-equal range. + __split_pos2 = __gnu_sequential::partition(__split_pos1 + 1, + __end, __pred); + } + else + // Only skip the pivot. + __split_pos2 = __split_pos1 + 1; + + // Elements equal to pivot are done. + __elements_done += (__split_pos2 - __split_pos1); #if _GLIBCXX_ASSERTIONS - __total_elements_done += (__split_pos2 - __split_pos1); + __total_elements_done += (__split_pos2 - __split_pos1); #endif - // Always push larger part onto stack. - if (((__split_pos1 + 1) - __begin) < (__end - (__split_pos2))) - { - // Right side larger. - if ((__split_pos2) != __end) - __tl._M_leftover_parts.push_front( - std::make_pair(__split_pos2, __end)); - - //__current.first = __begin; //already set anyway - __current.second = __split_pos1; - continue; - } - else - { - // Left side larger. - if (__begin != __split_pos1) - __tl._M_leftover_parts.push_front(std::make_pair(__begin, - __split_pos1)); - - __current.first = __split_pos2; - //__current.second = __end; //already set anyway - continue; - } - } - else - { - __gnu_sequential::sort(__begin, __end, __comp); - __elements_done += __n; + // Always push larger part onto stack. + if (((__split_pos1 + 1) - __begin) < (__end - (__split_pos2))) + { + // Right side larger. + if ((__split_pos2) != __end) + __tl._M_leftover_parts.push_front + (std::make_pair(__split_pos2, __end)); + + //__current.first = __begin; //already set anyway + __current.second = __split_pos1; + continue; + } + else + { + // Left side larger. + if (__begin != __split_pos1) + __tl._M_leftover_parts.push_front(std::make_pair + (__begin, __split_pos1)); + + __current.first = __split_pos2; + //__current.second = __end; //already set anyway + continue; + } + } + else + { + __gnu_sequential::sort(__begin, __end, __comp); + __elements_done += __n; #if _GLIBCXX_ASSERTIONS - __total_elements_done += __n; + __total_elements_done += __n; #endif - // Prefer own stack, small pieces. - if (__tl._M_leftover_parts.pop_front(__current)) - continue; + // Prefer own stack, small pieces. + if (__tl._M_leftover_parts.pop_front(__current)) + continue; -# pragma omp atomic - *__tl._M_elements_leftover -= __elements_done; +# pragma omp atomic + *__tl._M_elements_leftover -= __elements_done; - __elements_done = 0; + __elements_done = 0; #if _GLIBCXX_ASSERTIONS - double __search_start = omp_get_wtime(); + double __search_start = omp_get_wtime(); #endif - // Look for new work. - bool __successfully_stolen = false; - while (__wait && *__tl._M_elements_leftover > 0 - && !__successfully_stolen + // Look for new work. + bool __successfully_stolen = false; + while (__wait && *__tl._M_elements_leftover > 0 + && !__successfully_stolen #if _GLIBCXX_ASSERTIONS - // Possible dead-lock. - && (omp_get_wtime() < (__search_start + 1.0)) + // Possible dead-lock. + && (omp_get_wtime() < (__search_start + 1.0)) #endif - ) - { - _ThreadIndex __victim; - __victim = __rng(__num_threads); - - // Large pieces. - __successfully_stolen = (__victim != __iam) - && __tls[__victim]->_M_leftover_parts.pop_back(__current); - if (!__successfully_stolen) - __yield(); + ) + { + _ThreadIndex __victim; + __victim = __rng(__num_threads); + + // Large pieces. + __successfully_stolen = (__victim != __iam) + && __tls[__victim]->_M_leftover_parts.pop_back(__current); + if (!__successfully_stolen) + __yield(); #if !defined(__ICC) && !defined(__ECC) -# pragma omp flush +# pragma omp flush #endif - } + } #if _GLIBCXX_ASSERTIONS - if (omp_get_wtime() >= (__search_start + 1.0)) - { - sleep(1); - _GLIBCXX_PARALLEL_ASSERT(omp_get_wtime() - < (__search_start + 1.0)); - } + if (omp_get_wtime() >= (__search_start + 1.0)) + { + sleep(1); + _GLIBCXX_PARALLEL_ASSERT(omp_get_wtime() + < (__search_start + 1.0)); + } #endif - if (!__successfully_stolen) - { + if (!__successfully_stolen) + { #if _GLIBCXX_ASSERTIONS - _GLIBCXX_PARALLEL_ASSERT(*__tl._M_elements_leftover == 0); + _GLIBCXX_PARALLEL_ASSERT(*__tl._M_elements_leftover == 0); #endif - return; - } - } - } - } - -/** @brief Top-level quicksort routine. - * @param __begin Begin iterator of sequence. - * @param __end End iterator of sequence. - * @param __comp Comparator. - * @param __num_threads Number of threads that are allowed to work on - * this part. - */ -template<typename _RAIter, typename _Compare> - void - __parallel_sort_qsb(_RAIter __begin, _RAIter __end, - _Compare __comp, - _ThreadIndex __num_threads) - { - _GLIBCXX_CALL(__end - __begin) - - typedef std::iterator_traits<_RAIter> _TraitsType; - typedef typename _TraitsType::value_type _ValueType; - typedef typename _TraitsType::difference_type _DifferenceType; - typedef std::pair<_RAIter, _RAIter> _Piece; - - typedef _QSBThreadLocal<_RAIter> _TLSType; - - _DifferenceType __n = __end - __begin; - - if (__n <= 1) - return; - - // At least one element per processor. - if (__num_threads > __n) - __num_threads = static_cast<_ThreadIndex>(__n); - - // Initialize thread local storage - _TLSType** __tls = new _TLSType*[__num_threads]; - _DifferenceType __queue_size = - __num_threads * (_ThreadIndex)(log2(__n) + 1); - for (_ThreadIndex __t = 0; __t < __num_threads; ++__t) - __tls[__t] = new _QSBThreadLocal<_RAIter>(__queue_size); - - // There can never be more than ceil(log2(__n)) ranges on the stack, - // because - // 1. Only one processor pushes onto the stack - // 2. The largest range has at most length __n - // 3. Each range is larger than half of the range remaining - volatile _DifferenceType _M_elements_leftover = __n; - for (int __i = 0; __i < __num_threads; ++__i) - { - __tls[__i]->_M_elements_leftover = &_M_elements_leftover; - __tls[__i]->_M_num_threads = __num_threads; - __tls[__i]->_M_global = std::make_pair(__begin, __end); - - // Just in case nothing is left to assign. - __tls[__i]->_M_initial = std::make_pair(__end, __end); - } + return; + } + } + } + } - // Main recursion call. - __qsb_conquer( - __tls, __begin, __begin + __n, __comp, 0, __num_threads, true); + /** @brief Top-level quicksort routine. + * @param __begin Begin iterator of sequence. + * @param __end End iterator of sequence. + * @param __comp Comparator. + * @param __num_threads Number of threads that are allowed to work on + * this part. + */ + template<typename _RAIter, typename _Compare> + void + __parallel_sort_qsb(_RAIter __begin, _RAIter __end, + _Compare __comp, _ThreadIndex __num_threads) + { + _GLIBCXX_CALL(__end - __begin) + + typedef std::iterator_traits<_RAIter> _TraitsType; + typedef typename _TraitsType::value_type _ValueType; + typedef typename _TraitsType::difference_type _DifferenceType; + typedef std::pair<_RAIter, _RAIter> _Piece; + + typedef _QSBThreadLocal<_RAIter> _TLSType; + + _DifferenceType __n = __end - __begin; + + if (__n <= 1) + return; + + // At least one element per processor. + if (__num_threads > __n) + __num_threads = static_cast<_ThreadIndex>(__n); + + // Initialize thread local storage + _TLSType** __tls = new _TLSType*[__num_threads]; + _DifferenceType __queue_size = (__num_threads + * (_ThreadIndex)(__rd_log2(__n) + 1)); + for (_ThreadIndex __t = 0; __t < __num_threads; ++__t) + __tls[__t] = new _QSBThreadLocal<_RAIter>(__queue_size); + + // There can never be more than ceil(__rd_log2(__n)) ranges on the + // stack, because + // 1. Only one processor pushes onto the stack + // 2. The largest range has at most length __n + // 3. Each range is larger than half of the range remaining + volatile _DifferenceType __elements_leftover = __n; + for (int __i = 0; __i < __num_threads; ++__i) + { + __tls[__i]->_M_elements_leftover = &__elements_leftover; + __tls[__i]->_M_num_threads = __num_threads; + __tls[__i]->_M_global = std::make_pair(__begin, __end); + + // Just in case nothing is left to assign. + __tls[__i]->_M_initial = std::make_pair(__end, __end); + } + + // Main recursion call. + __qsb_conquer(__tls, __begin, __begin + __n, __comp, 0, + __num_threads, true); #if _GLIBCXX_ASSERTIONS - // All stack must be empty. - _Piece __dummy; - for (int __i = 1; __i < __num_threads; ++__i) - _GLIBCXX_PARALLEL_ASSERT( - !__tls[__i]->_M_leftover_parts.pop_back(__dummy)); + // All stack must be empty. + _Piece __dummy; + for (int __i = 1; __i < __num_threads; ++__i) + _GLIBCXX_PARALLEL_ASSERT( + !__tls[__i]->_M_leftover_parts.pop_back(__dummy)); #endif - for (int __i = 0; __i < __num_threads; ++__i) - delete __tls[__i]; - delete[] __tls; - } + for (int __i = 0; __i < __num_threads; ++__i) + delete __tls[__i]; + delete[] __tls; + } } // namespace __gnu_parallel #endif /* _GLIBCXX_PARALLEL_BALANCED_QUICKSORT_H */ |