1// -*- C++ -*-
2
3// Copyright (C) 2007-2022 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the terms
7// of the GNU General Public License as published by the Free Software
8// Foundation; either version 3, or (at your option) any later
9// version.
10
11// This library is distributed in the hope that it will be useful, but
12// WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14// General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/**
26 * @file parallel/tags.h
27 * @brief Tags for compile-time selection.
28 *  This file is a GNU parallel extension to the Standard C++ Library.
29 */
30
31// Written by Johannes Singler and Felix Putze.
32
33#ifndef _GLIBCXX_PARALLEL_TAGS_H
34#define _GLIBCXX_PARALLEL_TAGS_H 1
35
36#include <omp.h>
37#include <parallel/types.h>
38
39namespace __gnu_parallel
40{
41  /** @brief Forces sequential execution at compile time. */
42  struct sequential_tag { };
43
44  /** @brief Recommends parallel execution at compile time,
45   *  optionally using a user-specified number of threads. */
46  struct parallel_tag
47  {
48    private:
49      _ThreadIndex _M_num_threads;
50
51    public:
52      /** @brief Default constructor. Use default number of threads. */
53      parallel_tag()
54      { _M_num_threads = 0; }
55
56      /** @brief Default constructor. Recommend number of threads to use.
57       *  @param __num_threads Desired number of threads. */
58      parallel_tag(_ThreadIndex __num_threads)
59      { _M_num_threads = __num_threads; }
60
61      /** @brief Find out desired number of threads.
62       *  @return Desired number of threads. */
63      _ThreadIndex __get_num_threads()
64      {
65        if(_M_num_threads == 0)
66          return omp_get_max_threads();
67        else
68          return _M_num_threads;
69      }
70
71      /** @brief Set the desired number of threads.
72       *  @param __num_threads Desired number of threads. */
73      void set_num_threads(_ThreadIndex __num_threads)
74      { _M_num_threads = __num_threads; }
75  };
76
77  /** @brief Recommends parallel execution using the
78      default parallel algorithm. */
79  struct default_parallel_tag : public parallel_tag
80  {
81    default_parallel_tag() { }
82    default_parallel_tag(_ThreadIndex __num_threads)
83    : parallel_tag(__num_threads) { }
84  };
85
86  /** @brief Recommends parallel execution using dynamic
87      load-balancing at compile time. */
88  struct balanced_tag : public parallel_tag { };
89
90  /** @brief Recommends parallel execution using static
91      load-balancing at compile time. */
92  struct unbalanced_tag : public parallel_tag { };
93
94  /** @brief Recommends parallel execution using OpenMP dynamic
95      load-balancing at compile time. */
96  struct omp_loop_tag : public parallel_tag { };
97
98  /** @brief Recommends parallel execution using OpenMP static
99      load-balancing at compile time. */
100  struct omp_loop_static_tag : public parallel_tag { };
101
102
103  /** @brief Base class for for std::find() variants. */
104  struct find_tag { };
105
106
107  /** @brief Forces parallel merging
108   *  with exact splitting, at compile time. */
109  struct exact_tag : public parallel_tag
110  {
111    exact_tag() { }
112    exact_tag(_ThreadIndex __num_threads)
113    : parallel_tag(__num_threads) { }
114  };
115
116  /** @brief Forces parallel merging
117   *  with exact splitting, at compile time. */
118  struct sampling_tag : public parallel_tag
119  {
120    sampling_tag() { }
121    sampling_tag(_ThreadIndex __num_threads)
122    : parallel_tag(__num_threads) { }
123  };
124
125
126  /** @brief Forces parallel sorting using multiway mergesort
127   *  at compile time. */
128  struct multiway_mergesort_tag : public parallel_tag
129  {
130    multiway_mergesort_tag() { }
131    multiway_mergesort_tag(_ThreadIndex __num_threads)
132    : parallel_tag(__num_threads) { }
133  };
134
135  /** @brief Forces parallel sorting using multiway mergesort
136   *  with exact splitting at compile time. */
137  struct multiway_mergesort_exact_tag : public parallel_tag
138  {
139    multiway_mergesort_exact_tag() { }
140    multiway_mergesort_exact_tag(_ThreadIndex __num_threads)
141    : parallel_tag(__num_threads) { }
142  };
143
144  /** @brief Forces parallel sorting using multiway mergesort
145   *  with splitting by sampling at compile time. */
146  struct multiway_mergesort_sampling_tag : public parallel_tag
147  {
148    multiway_mergesort_sampling_tag() { }
149    multiway_mergesort_sampling_tag(_ThreadIndex __num_threads)
150    : parallel_tag(__num_threads) { }
151  };
152
153  /** @brief Forces parallel sorting using unbalanced quicksort
154   *  at compile time. */
155  struct quicksort_tag : public parallel_tag
156  {
157    quicksort_tag() { }
158    quicksort_tag(_ThreadIndex __num_threads)
159    : parallel_tag(__num_threads) { }
160  };
161
162  /** @brief Forces parallel sorting using balanced quicksort
163   *  at compile time. */
164  struct balanced_quicksort_tag : public parallel_tag
165  {
166    balanced_quicksort_tag() { }
167    balanced_quicksort_tag(_ThreadIndex __num_threads)
168    : parallel_tag(__num_threads) { }
169  };
170
171
172  /** @brief Selects the growing block size variant for std::find().
173      @see _GLIBCXX_FIND_GROWING_BLOCKS */
174  struct growing_blocks_tag : public find_tag { };
175
176  /** @brief Selects the constant block size variant for std::find().
177      @see _GLIBCXX_FIND_CONSTANT_SIZE_BLOCKS */
178  struct constant_size_blocks_tag : public find_tag { };
179
180  /** @brief Selects the equal splitting variant for std::find().
181      @see _GLIBCXX_FIND_EQUAL_SPLIT */
182  struct equal_split_tag : public find_tag { };
183}
184
185#endif /* _GLIBCXX_PARALLEL_TAGS_H */
186