--- /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/random_shuffle.h
+ * @brief Parallel implementation of std::random_shuffle().
+ * This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Johannes Singler.
+
+#ifndef _GLIBCXX_PARALLEL_RANDOM_SHUFFLE_H
+#define _GLIBCXX_PARALLEL_RANDOM_SHUFFLE_H 1
+
+#include <limits>
+#include <bits/stl_numeric.h>
+#include <parallel/parallel.h>
+#include <parallel/random_number.h>
+
+namespace __gnu_parallel
+{
+ /** @brief Type to hold the index of a bin.
+ *
+ * Since many variables of this type are allocated, it should be
+ * chosen as small as possible.
+ */
+ typedef unsigned short _BinIndex;
+
+ /** @brief Data known to every thread participating in
+ __gnu_parallel::__parallel_random_shuffle(). */
+ template<typename _RAIter>
+ struct _DRandomShufflingGlobalData
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ /** @brief Begin iterator of the __source. */
+ _RAIter& _M_source;
+
+ /** @brief Temporary arrays for each thread. */
+ _ValueType** _M_temporaries;
+
+ /** @brief Two-dimensional array to hold the thread-bin distribution.
+ *
+ * Dimensions (_M_num_threads + 1) __x (_M_num_bins + 1). */
+ _DifferenceType** _M_dist;
+
+ /** @brief Start indexes of the threads' __chunks. */
+ _DifferenceType* _M_starts;
+
+ /** @brief Number of the thread that will further process the
+ corresponding bin. */
+ _ThreadIndex* _M_bin_proc;
+
+ /** @brief Number of bins to distribute to. */
+ int _M_num_bins;
+
+ /** @brief Number of bits needed to address the bins. */
+ int _M_num_bits;
+
+ /** @brief Constructor. */
+ _DRandomShufflingGlobalData(_RAIter& __source)
+ : _M_source(__source) { }
+ };
+
+ /** @brief Local data for a thread participating in
+ __gnu_parallel::__parallel_random_shuffle().
+ */
+ template<typename _RAIter, typename _RandomNumberGenerator>
+ struct _DRSSorterPU
+ {
+ /** @brief Number of threads participating in total. */
+ int _M_num_threads;
+
+ /** @brief Begin index for bins taken care of by this thread. */
+ _BinIndex _M_bins_begin;
+
+ /** @brief End index for bins taken care of by this thread. */
+ _BinIndex __bins_end;
+
+ /** @brief Random _M_seed for this thread. */
+ uint32_t _M_seed;
+
+ /** @brief Pointer to global data. */
+ _DRandomShufflingGlobalData<_RAIter>* _M_sd;
+ };
+
+ /** @brief Generate a random number in @c [0,2^__logp).
+ * @param __logp Logarithm (basis 2) of the upper range __bound.
+ * @param __rng Random number generator to use.
+ */
+ template<typename _RandomNumberGenerator>
+ inline int
+ __random_number_pow2(int __logp, _RandomNumberGenerator& __rng)
+ { return __rng.__genrand_bits(__logp); }
+
+ /** @brief Random shuffle code executed by each thread.
+ * @param __pus Array of thread-local data records. */
+ template<typename _RAIter, typename _RandomNumberGenerator>
+ void
+ __parallel_random_shuffle_drs_pu(_DRSSorterPU<_RAIter,
+ _RandomNumberGenerator>* __pus)
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ _ThreadIndex __iam = omp_get_thread_num();
+ _DRSSorterPU<_RAIter, _RandomNumberGenerator>* __d = &__pus[__iam];
+ _DRandomShufflingGlobalData<_RAIter>* __sd = __d->_M_sd;
+
+ // Indexing: _M_dist[bin][processor]
+ _DifferenceType __length = (__sd->_M_starts[__iam + 1]
+ - __sd->_M_starts[__iam]);
+ _BinIndex* __oracles = new _BinIndex[__length];
+ _DifferenceType* __dist = new _DifferenceType[__sd->_M_num_bins + 1];
+ _BinIndex* __bin_proc = new _BinIndex[__sd->_M_num_bins];
+ _ValueType** __temporaries = new _ValueType*[__d->_M_num_threads];
+
+ // Compute oracles and count appearances.
+ for (_BinIndex __b = 0; __b < __sd->_M_num_bins + 1; ++__b)
+ __dist[__b] = 0;
+ int __num_bits = __sd->_M_num_bits;
+
+ _RandomNumber __rng(__d->_M_seed);
+
+ // First main loop.
+ for (_DifferenceType __i = 0; __i < __length; ++__i)
+ {
+ _BinIndex __oracle = __random_number_pow2(__num_bits, __rng);
+ __oracles[__i] = __oracle;
+
+ // To allow prefix (partial) sum.
+ ++(__dist[__oracle + 1]);
+ }
+
+ for (_BinIndex __b = 0; __b < __sd->_M_num_bins + 1; ++__b)
+ __sd->_M_dist[__b][__iam + 1] = __dist[__b];
+
+# pragma omp barrier
+
+# pragma omp single
+ {
+ // Sum up bins, __sd->_M_dist[__s + 1][__d->_M_num_threads] now
+ // contains the total number of items in bin __s
+ for (_BinIndex __s = 0; __s < __sd->_M_num_bins; ++__s)
+ __gnu_sequential::partial_sum(__sd->_M_dist[__s + 1],
+ __sd->_M_dist[__s + 1]
+ + __d->_M_num_threads + 1,
+ __sd->_M_dist[__s + 1]);
+ }
+
+# pragma omp barrier
+
+ _SequenceIndex __offset = 0, __global_offset = 0;
+ for (_BinIndex __s = 0; __s < __d->_M_bins_begin; ++__s)
+ __global_offset += __sd->_M_dist[__s + 1][__d->_M_num_threads];
+
+# pragma omp barrier
+
+ for (_BinIndex __s = __d->_M_bins_begin; __s < __d->__bins_end; ++__s)
+ {
+ for (int __t = 0; __t < __d->_M_num_threads + 1; ++__t)
+ __sd->_M_dist[__s + 1][__t] += __offset;
+ __offset = __sd->_M_dist[__s + 1][__d->_M_num_threads];
+ }
+
+ __sd->_M_temporaries[__iam] = static_cast<_ValueType*>
+ (::operator new(sizeof(_ValueType) * __offset));
+
+# pragma omp barrier
+
+ // Draw local copies to avoid false sharing.
+ for (_BinIndex __b = 0; __b < __sd->_M_num_bins + 1; ++__b)
+ __dist[__b] = __sd->_M_dist[__b][__iam];
+ for (_BinIndex __b = 0; __b < __sd->_M_num_bins; ++__b)
+ __bin_proc[__b] = __sd->_M_bin_proc[__b];
+ for (_ThreadIndex __t = 0; __t < __d->_M_num_threads; ++__t)
+ __temporaries[__t] = __sd->_M_temporaries[__t];
+
+ _RAIter __source = __sd->_M_source;
+ _DifferenceType __start = __sd->_M_starts[__iam];
+
+ // Distribute according to oracles, second main loop.
+ for (_DifferenceType __i = 0; __i < __length; ++__i)
+ {
+ _BinIndex __target_bin = __oracles[__i];
+ _ThreadIndex __target_p = __bin_proc[__target_bin];
+
+ // Last column [__d->_M_num_threads] stays unchanged.
+ ::new(&(__temporaries[__target_p][__dist[__target_bin + 1]++]))
+ _ValueType(*(__source + __i + __start));
+ }
+
+ delete[] __oracles;
+ delete[] __dist;
+ delete[] __bin_proc;
+ delete[] __temporaries;
+
+# pragma omp barrier
+
+ // Shuffle bins internally.
+ for (_BinIndex __b = __d->_M_bins_begin; __b < __d->__bins_end; ++__b)
+ {
+ _ValueType* __begin =
+ (__sd->_M_temporaries[__iam]
+ + (__b == __d->_M_bins_begin
+ ? 0 : __sd->_M_dist[__b][__d->_M_num_threads])),
+ *__end = (__sd->_M_temporaries[__iam]
+ + __sd->_M_dist[__b + 1][__d->_M_num_threads]);
+
+ __sequential_random_shuffle(__begin, __end, __rng);
+ std::copy(__begin, __end, __sd->_M_source + __global_offset
+ + (__b == __d->_M_bins_begin
+ ? 0 : __sd->_M_dist[__b][__d->_M_num_threads]));
+ }
+
+ for (_SequenceIndex __i = 0; __i < __offset; ++__i)
+ __sd->_M_temporaries[__iam][__i].~_ValueType();
+ ::operator delete(__sd->_M_temporaries[__iam]);
+ }
+
+ /** @brief Round up to the next greater power of 2.
+ * @param __x _Integer to round up */
+ template<typename _Tp>
+ _Tp
+ __round_up_to_pow2(_Tp __x)
+ {
+ if (__x <= 1)
+ return 1;
+ else
+ return (_Tp)1 << (__rd_log2(__x - 1) + 1);
+ }
+
+ /** @brief Main parallel random shuffle step.
+ * @param __begin Begin iterator of sequence.
+ * @param __end End iterator of sequence.
+ * @param __n Length of sequence.
+ * @param __num_threads Number of threads to use.
+ * @param __rng Random number generator to use.
+ */
+ template<typename _RAIter, typename _RandomNumberGenerator>
+ void
+ __parallel_random_shuffle_drs(_RAIter __begin, _RAIter __end,
+ typename std::iterator_traits
+ <_RAIter>::difference_type __n,
+ _ThreadIndex __num_threads,
+ _RandomNumberGenerator& __rng)
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ _GLIBCXX_CALL(__n)
+
+ const _Settings& __s = _Settings::get();
+
+ if (__num_threads > __n)
+ __num_threads = static_cast<_ThreadIndex>(__n);
+
+ _BinIndex __num_bins, __num_bins_cache;
+
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_L1
+ // Try the L1 cache first.
+
+ // Must fit into L1.
+ __num_bins_cache =
+ std::max<_DifferenceType>(1, __n / (__s.L1_cache_size_lb
+ / sizeof(_ValueType)));
+ __num_bins_cache = __round_up_to_pow2(__num_bins_cache);
+
+ // No more buckets than TLB entries, power of 2
+ // Power of 2 and at least one element per bin, at most the TLB size.
+ __num_bins = std::min<_DifferenceType>(__n, __num_bins_cache);
+
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_TLB
+ // 2 TLB entries needed per bin.
+ __num_bins = std::min<_DifferenceType>(__s.TLB_size / 2, __num_bins);
+#endif
+ __num_bins = __round_up_to_pow2(__num_bins);
+
+ if (__num_bins < __num_bins_cache)
+ {
+#endif
+ // Now try the L2 cache
+ // Must fit into L2
+ __num_bins_cache = static_cast<_BinIndex>
+ (std::max<_DifferenceType>(1, __n / (__s.L2_cache_size
+ / sizeof(_ValueType))));
+ __num_bins_cache = __round_up_to_pow2(__num_bins_cache);
+
+ // No more buckets than TLB entries, power of 2.
+ __num_bins = static_cast<_BinIndex>
+ (std::min(__n, static_cast<_DifferenceType>(__num_bins_cache)));
+ // Power of 2 and at least one element per bin, at most the TLB size.
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_TLB
+ // 2 TLB entries needed per bin.
+ __num_bins = std::min(static_cast<_DifferenceType>(__s.TLB_size / 2),
+ __num_bins);
+#endif
+ __num_bins = __round_up_to_pow2(__num_bins);
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_L1
+ }
+#endif
+
+ __num_bins = __round_up_to_pow2(
+ std::max<_BinIndex>(__num_threads, __num_bins));
+
+ if (__num_threads <= 1)
+ {
+ _RandomNumber __derived_rng(
+ __rng(std::numeric_limits<uint32_t>::max()));
+ __sequential_random_shuffle(__begin, __end, __derived_rng);
+ return;
+ }
+
+ _DRandomShufflingGlobalData<_RAIter> __sd(__begin);
+ _DRSSorterPU<_RAIter, _RandomNumber >* __pus;
+ _DifferenceType* __starts;
+
+# pragma omp parallel num_threads(__num_threads)
+ {
+ _ThreadIndex __num_threads = omp_get_num_threads();
+# pragma omp single
+ {
+ __pus = new _DRSSorterPU<_RAIter, _RandomNumber>[__num_threads];
+
+ __sd._M_temporaries = new _ValueType*[__num_threads];
+ __sd._M_dist = new _DifferenceType*[__num_bins + 1];
+ __sd._M_bin_proc = new _ThreadIndex[__num_bins];
+ for (_BinIndex __b = 0; __b < __num_bins + 1; ++__b)
+ __sd._M_dist[__b] = new _DifferenceType[__num_threads + 1];
+ for (_BinIndex __b = 0; __b < (__num_bins + 1); ++__b)
+ {
+ __sd._M_dist[0][0] = 0;
+ __sd._M_dist[__b][0] = 0;
+ }
+ __starts = __sd._M_starts = new _DifferenceType[__num_threads + 1];
+ int __bin_cursor = 0;
+ __sd._M_num_bins = __num_bins;
+ __sd._M_num_bits = __rd_log2(__num_bins);
+
+ _DifferenceType __chunk_length = __n / __num_threads,
+ __split = __n % __num_threads,
+ __start = 0;
+ _DifferenceType __bin_chunk_length = __num_bins / __num_threads,
+ __bin_split = __num_bins % __num_threads;
+ for (_ThreadIndex __i = 0; __i < __num_threads; ++__i)
+ {
+ __starts[__i] = __start;
+ __start += (__i < __split
+ ? (__chunk_length + 1) : __chunk_length);
+ int __j = __pus[__i]._M_bins_begin = __bin_cursor;
+
+ // Range of bins for this processor.
+ __bin_cursor += (__i < __bin_split
+ ? (__bin_chunk_length + 1)
+ : __bin_chunk_length);
+ __pus[__i].__bins_end = __bin_cursor;
+ for (; __j < __bin_cursor; ++__j)
+ __sd._M_bin_proc[__j] = __i;
+ __pus[__i]._M_num_threads = __num_threads;
+ __pus[__i]._M_seed = __rng(std::numeric_limits<uint32_t>::max());
+ __pus[__i]._M_sd = &__sd;
+ }
+ __starts[__num_threads] = __start;
+ } //single
+ // Now shuffle in parallel.
+ __parallel_random_shuffle_drs_pu(__pus);
+ } // parallel
+
+ delete[] __starts;
+ delete[] __sd._M_bin_proc;
+ for (int __s = 0; __s < (__num_bins + 1); ++__s)
+ delete[] __sd._M_dist[__s];
+ delete[] __sd._M_dist;
+ delete[] __sd._M_temporaries;
+
+ delete[] __pus;
+ }
+
+ /** @brief Sequential cache-efficient random shuffle.
+ * @param __begin Begin iterator of sequence.
+ * @param __end End iterator of sequence.
+ * @param __rng Random number generator to use.
+ */
+ template<typename _RAIter, typename _RandomNumberGenerator>
+ void
+ __sequential_random_shuffle(_RAIter __begin, _RAIter __end,
+ _RandomNumberGenerator& __rng)
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ _DifferenceType __n = __end - __begin;
+ const _Settings& __s = _Settings::get();
+
+ _BinIndex __num_bins, __num_bins_cache;
+
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_L1
+ // Try the L1 cache first, must fit into L1.
+ __num_bins_cache = std::max<_DifferenceType>
+ (1, __n / (__s.L1_cache_size_lb / sizeof(_ValueType)));
+ __num_bins_cache = __round_up_to_pow2(__num_bins_cache);
+
+ // No more buckets than TLB entries, power of 2
+ // Power of 2 and at least one element per bin, at most the TLB size
+ __num_bins = std::min(__n, (_DifferenceType)__num_bins_cache);
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_TLB
+ // 2 TLB entries needed per bin
+ __num_bins = std::min((_DifferenceType)__s.TLB_size / 2, __num_bins);
+#endif
+ __num_bins = __round_up_to_pow2(__num_bins);
+
+ if (__num_bins < __num_bins_cache)
+ {
+#endif
+ // Now try the L2 cache, must fit into L2.
+ __num_bins_cache = static_cast<_BinIndex>
+ (std::max<_DifferenceType>(1, __n / (__s.L2_cache_size
+ / sizeof(_ValueType))));
+ __num_bins_cache = __round_up_to_pow2(__num_bins_cache);
+
+ // No more buckets than TLB entries, power of 2
+ // Power of 2 and at least one element per bin, at most the TLB size.
+ __num_bins = static_cast<_BinIndex>
+ (std::min(__n, static_cast<_DifferenceType>(__num_bins_cache)));
+
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_TLB
+ // 2 TLB entries needed per bin
+ __num_bins = std::min<_DifferenceType>(__s.TLB_size / 2, __num_bins);
+#endif
+ __num_bins = __round_up_to_pow2(__num_bins);
+#if _GLIBCXX_RANDOM_SHUFFLE_CONSIDER_L1
+ }
+#endif
+
+ int __num_bits = __rd_log2(__num_bins);
+
+ if (__num_bins > 1)
+ {
+ _ValueType* __target =
+ static_cast<_ValueType*>(::operator new(sizeof(_ValueType) * __n));
+ _BinIndex* __oracles = new _BinIndex[__n];
+ _DifferenceType* __dist0 = new _DifferenceType[__num_bins + 1],
+ * __dist1 = new _DifferenceType[__num_bins + 1];
+
+ for (int __b = 0; __b < __num_bins + 1; ++__b)
+ __dist0[__b] = 0;
+
+ _RandomNumber __bitrng(__rng(0xFFFFFFFF));
+
+ for (_DifferenceType __i = 0; __i < __n; ++__i)
+ {
+ _BinIndex __oracle = __random_number_pow2(__num_bits, __bitrng);
+ __oracles[__i] = __oracle;
+
+ // To allow prefix (partial) sum.
+ ++(__dist0[__oracle + 1]);
+ }
+
+ // Sum up bins.
+ __gnu_sequential::partial_sum(__dist0, __dist0 + __num_bins + 1,
+ __dist0);
+
+ for (int __b = 0; __b < __num_bins + 1; ++__b)
+ __dist1[__b] = __dist0[__b];
+
+ // Distribute according to oracles.
+ for (_DifferenceType __i = 0; __i < __n; ++__i)
+ ::new(&(__target[(__dist0[__oracles[__i]])++]))
+ _ValueType(*(__begin + __i));
+
+ for (int __b = 0; __b < __num_bins; ++__b)
+ __sequential_random_shuffle(__target + __dist1[__b],
+ __target + __dist1[__b + 1], __rng);
+
+ // Copy elements back.
+ std::copy(__target, __target + __n, __begin);
+
+ delete[] __dist0;
+ delete[] __dist1;
+ delete[] __oracles;
+
+ for (_DifferenceType __i = 0; __i < __n; ++__i)
+ __target[__i].~_ValueType();
+ ::operator delete(__target);
+ }
+ else
+ __gnu_sequential::random_shuffle(__begin, __end, __rng);
+ }
+
+ /** @brief Parallel random public call.
+ * @param __begin Begin iterator of sequence.
+ * @param __end End iterator of sequence.
+ * @param __rng Random number generator to use.
+ */
+ template<typename _RAIter, typename _RandomNumberGenerator>
+ inline void
+ __parallel_random_shuffle(_RAIter __begin, _RAIter __end,
+ _RandomNumberGenerator __rng = _RandomNumber())
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+ _DifferenceType __n = __end - __begin;
+ __parallel_random_shuffle_drs(__begin, __end, __n,
+ __get_max_threads(), __rng);
+ }
+}
+
+#endif /* _GLIBCXX_PARALLEL_RANDOM_SHUFFLE_H */
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