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| 1 | /* | ||
| 2 | * Copyright (c) 2000-2022 Inria | ||
| 3 | * All rights reserved. | ||
| 4 | * | ||
| 5 | * Redistribution and use in source and binary forms, with or without | ||
| 6 | * modification, are permitted provided that the following conditions are met: | ||
| 7 | * | ||
| 8 | * * Redistributions of source code must retain the above copyright notice, | ||
| 9 | * this list of conditions and the following disclaimer. | ||
| 10 | * * Redistributions in binary form must reproduce the above copyright notice, | ||
| 11 | * this list of conditions and the following disclaimer in the documentation | ||
| 12 | * and/or other materials provided with the distribution. | ||
| 13 | * * Neither the name of the ALICE Project-Team nor the names of its | ||
| 14 | * contributors may be used to endorse or promote products derived from this | ||
| 15 | * software without specific prior written permission. | ||
| 16 | * | ||
| 17 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
| 18 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
| 19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
| 20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE | ||
| 21 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | ||
| 22 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | ||
| 23 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | ||
| 24 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||
| 25 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | ||
| 26 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||
| 27 | * POSSIBILITY OF SUCH DAMAGE. | ||
| 28 | * | ||
| 29 | * Contact: Bruno Levy | ||
| 30 | * | ||
| 31 | * https://www.inria.fr/fr/bruno-levy | ||
| 32 | * | ||
| 33 | * Inria, | ||
| 34 | * Domaine de Voluceau, | ||
| 35 | * 78150 Le Chesnay - Rocquencourt | ||
| 36 | * FRANCE | ||
| 37 | * | ||
| 38 | */ | ||
| 39 | |||
| 40 | #ifndef DELAUNAY_SYNC_H | ||
| 41 | #define DELAUNAY_SYNC_H | ||
| 42 | |||
| 43 | #include <geogram/basic/common.h> | ||
| 44 | #include <geogram/basic/assert.h> | ||
| 45 | #include <atomic> | ||
| 46 | |||
| 47 | // In GARGANTUA mode (64-bit indices), we also enable | ||
| 48 | // more than 127 concurrent threads (16-bits cell status, | ||
| 49 | // that contain owner thread id). | ||
| 50 | #ifdef GARGANTUA | ||
| 51 | #define GEO_CONNECTION_MACHINE | ||
| 52 | #endif | ||
| 53 | |||
| 54 | /** | ||
| 55 | * \file geogram/delaunay/delaunay_sync.h | ||
| 56 | * \brief Synchronization primitives for parallel Delaunay | ||
| 57 | */ | ||
| 58 | |||
| 59 | namespace GEO { | ||
| 60 | |||
| 61 | /** | ||
| 62 | * \brief An array of cell status codes associates to each tetrahedron | ||
| 63 | * in a Delaunay tetrahedralization | ||
| 64 | * \details Each item can be atomically accessed to implement fine-grained | ||
| 65 | * resource control in a multithreaded context. It is used to memorize | ||
| 66 | * for each tetrahedron the thread that owns it as well as a couple of | ||
| 67 | * flags. | ||
| 68 | */ | ||
| 69 | class CellStatusArray { | ||
| 70 | public: | ||
| 71 | #ifdef GEO_CONNECTION_MACHINE | ||
| 72 | // For machines that can run more than 127 concurrent threads | ||
| 73 | typedef uint16_t thread_index_t; | ||
| 74 | typedef uint16_t cell_status_t; | ||
| 75 | static constexpr cell_status_t FREE_CELL = 32767; | ||
| 76 | static constexpr cell_status_t THREAD_MASK = 32767; | ||
| 77 | static constexpr cell_status_t CONFLICT_MASK = 32768; | ||
| 78 | #else | ||
| 79 | typedef uint8_t thread_index_t; | ||
| 80 | typedef uint8_t cell_status_t; | ||
| 81 | static constexpr cell_status_t FREE_CELL = 127; | ||
| 82 | static constexpr cell_status_t THREAD_MASK = 127; | ||
| 83 | static constexpr cell_status_t CONFLICT_MASK = 128; | ||
| 84 | #endif | ||
| 85 | |||
| 86 | static constexpr index_t MAX_THREADS = index_t(THREAD_MASK)-1; | ||
| 87 | |||
| 88 | /** | ||
| 89 | * \brief Creates an empty CellStatusArray | ||
| 90 | */ | ||
| 91 | 5 | CellStatusArray() : cell_status_(nullptr), size_(0), capacity_(0) { | |
| 92 | 5 | } | |
| 93 | |||
| 94 | /** | ||
| 95 | * \brief Creates a CellStatusArray | ||
| 96 | * \param[in] size_in number of cells in the CellStatusArray | ||
| 97 | */ | ||
| 98 | CellStatusArray(index_t size_in) : | ||
| 99 | cell_status_(nullptr), size_(0), capacity_(0) { | ||
| 100 | resize(size_in,size_in); | ||
| 101 | } | ||
| 102 | |||
| 103 | /** | ||
| 104 | * \brief CellStatusArray destructor | ||
| 105 | * \details It is illegal to destroy a CellStatusArray if | ||
| 106 | * - threads are still running | ||
| 107 | * - there exists a cell with a status different from FREE_CELL | ||
| 108 | */ | ||
| 109 | 5 | ~CellStatusArray() { | |
| 110 | 5 | clear(); | |
| 111 | 5 | } | |
| 112 | |||
| 113 | /** | ||
| 114 | * \brief Forbids copy | ||
| 115 | */ | ||
| 116 | CellStatusArray(const CellStatusArray& rhs) = delete; | ||
| 117 | |||
| 118 | /** | ||
| 119 | * \brief Forbids copy | ||
| 120 | */ | ||
| 121 | CellStatusArray& operator=(const CellStatusArray& rhs) = delete; | ||
| 122 | |||
| 123 | /** | ||
| 124 | * \brief Tentatively acquires a cell. | ||
| 125 | * \param[in] cell the index of the cell | ||
| 126 | * \param[in] status the status to be written in the cell if acquisition | ||
| 127 | * is successful, that is, if the current status of the cell is | ||
| 128 | * FREE_CELL | ||
| 129 | * \return FREE_CELL if acquisition was successful, or the id of the | ||
| 130 | * thread that owns \p cell otherwise. | ||
| 131 | */ | ||
| 132 | 168136 | cell_status_t acquire_cell(index_t cell, cell_status_t status) { | |
| 133 |
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168136 | geo_debug_assert(cell < size_); |
| 134 | 168136 | cell_status_t expected = FREE_CELL; | |
| 135 | // strong: acquire_cell is not used in a spinlock-like | ||
| 136 | // spinning loop (so we do not want to have "false negatives") | ||
| 137 | 168136 | cell_status_[cell].compare_exchange_strong( | |
| 138 | expected,status, | ||
| 139 | std::memory_order_acquire,std::memory_order_acquire | ||
| 140 | ); // this one could probably be relaxed ----^ | ||
| 141 | // if compare_exchange was not sucessful, expected contains | ||
| 142 | // the current stored value. | ||
| 143 | 168136 | return (expected & THREAD_MASK); | |
| 144 | } | ||
| 145 | |||
| 146 | /** | ||
| 147 | * \brief Releases a cell | ||
| 148 | * \param[in] cell the index of the cell | ||
| 149 | * \pre the cell is owned by the current thread | ||
| 150 | */ | ||
| 151 | 271027 | void release_cell(index_t cell) { | |
| 152 |
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271027 | geo_debug_assert(cell < size_); |
| 153 | 271027 | cell_status_[cell].store(FREE_CELL, std::memory_order_release); | |
| 154 | 271027 | } | |
| 155 | |||
| 156 | /** | ||
| 157 | * \brief Gets the thread that acquired a cell | ||
| 158 | * \param[in] cell the cell | ||
| 159 | * \return the index of the thread that acquired the cell, or | ||
| 160 | * FREE_CELL if the cell is free | ||
| 161 | */ | ||
| 162 | 3839195 | cell_status_t cell_thread(index_t cell) const { | |
| 163 |
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3839195 | geo_debug_assert(cell < size_); |
| 164 | return ( | ||
| 165 | 3839195 | cell_status_[cell].load(std::memory_order_relaxed) & | |
| 166 | THREAD_MASK | ||
| 167 | 3839195 | ); | |
| 168 | } | ||
| 169 | |||
| 170 | /** | ||
| 171 | * \brief Tests whether a cell is marked as conflict | ||
| 172 | * \param[in] cell the cell | ||
| 173 | * \retval true if \p cell is marked as conflict | ||
| 174 | * \retval false otherwise | ||
| 175 | * \see mark_cell_as_conflict() | ||
| 176 | */ | ||
| 177 | 388261 | bool cell_is_marked_as_conflict(index_t cell) const { | |
| 178 |
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388261 | geo_debug_assert(cell < size_); |
| 179 | return( | ||
| 180 | ( | ||
| 181 | 388261 | cell_status_[cell].load(std::memory_order_relaxed) & | |
| 182 | CONFLICT_MASK | ||
| 183 | 388261 | ) != 0 | |
| 184 | 388261 | ); | |
| 185 | } | ||
| 186 | |||
| 187 | /** | ||
| 188 | * \brief Marks a cell as conflict | ||
| 189 | * \param[in] cell the cell | ||
| 190 | * \pre the cell is owned by the current thread | ||
| 191 | */ | ||
| 192 | 77597 | void mark_cell_as_conflict(index_t cell) { | |
| 193 | // memory_order_relaxed because this function is always called from | ||
| 194 | // a thread that previously acquired the cell. | ||
| 195 | 77597 | cell_status_[cell].fetch_or( | |
| 196 | CONFLICT_MASK, std::memory_order_relaxed | ||
| 197 | ); | ||
| 198 | 77597 | } | |
| 199 | |||
| 200 | /** | ||
| 201 | * \brief Sets the status of a cell | ||
| 202 | * \param[in] cell the index of the cell | ||
| 203 | * \details uses relaxed memory ordering | ||
| 204 | * \pre the cell is owned by the current thread | ||
| 205 | */ | ||
| 206 | 102891 | void set_cell_status(index_t cell, cell_status_t status) { | |
| 207 |
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102891 | geo_debug_assert(cell < size_); |
| 208 | 102891 | cell_status_[cell].store(status, std::memory_order_relaxed); | |
| 209 | 102891 | } | |
| 210 | |||
| 211 | /** | ||
| 212 | * \brief Resizes this CellStatusArray | ||
| 213 | * \param[in] size_in number of cells | ||
| 214 | * \param[in] capacity_in total number of allocated cells | ||
| 215 | * \pre \p capacity_in >= \p size_in and | ||
| 216 | * no concurrent thread is currently running | ||
| 217 | */ | ||
| 218 | 18306 | void resize(index_t size_in, index_t capacity_in) { | |
| 219 |
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18306 | geo_debug_assert(capacity_in >= size_in); |
| 220 |
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18306 | geo_debug_assert(!Process::is_running_threads()); |
| 221 |
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18306 | if(capacity_in > capacity_) { |
| 222 | 10 | capacity_ = capacity_in; | |
| 223 | 10 | std::atomic<cell_status_t>* old_cell_status = cell_status_; | |
| 224 |
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85228 | cell_status_ = new std::atomic<cell_status_t>[capacity_]; |
| 225 |
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85228 | for(index_t i=0; i<capacity_; ++i) { |
| 226 |
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85218 | cell_status_t val = (i < size_) ? |
| 227 | 56812 | old_cell_status[i].load(std::memory_order_relaxed) : | |
| 228 | 56812 | FREE_CELL; | |
| 229 | 85218 | cell_status_[i].store(val, std::memory_order_relaxed); | |
| 230 | } | ||
| 231 |
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10 | delete[] old_cell_status; |
| 232 | } | ||
| 233 | 18306 | size_ = size_in; | |
| 234 | static_assert(std::atomic<cell_status_t>::is_always_lock_free); | ||
| 235 | 18306 | } | |
| 236 | |||
| 237 | /** | ||
| 238 | * \brief Resizes this CellStatusArray | ||
| 239 | * \param[in] size_in number of cells | ||
| 240 | * \pre all cells are free and no concurrent thread is currently running | ||
| 241 | */ | ||
| 242 | 5 | void resize(index_t size_in) { | |
| 243 | 5 | resize(size_in, size_in); | |
| 244 | 5 | } | |
| 245 | |||
| 246 | /** | ||
| 247 | * \brief Reserves additional space | ||
| 248 | * \param[in] new_capacity on exit, this CellStatusArray will have at | ||
| 249 | * least sufficient space for \p new_capacity elements without needing | ||
| 250 | * to reallocate. Size is not modified. Operates like its std::vector | ||
| 251 | * counterpart. | ||
| 252 | */ | ||
| 253 | void reserve(index_t new_capacity) { | ||
| 254 | if(new_capacity > capacity_) { | ||
| 255 | resize(size_, new_capacity); | ||
| 256 | } | ||
| 257 | } | ||
| 258 | |||
| 259 | /** | ||
| 260 | * \brief Increases the size of the array for one additional element | ||
| 261 | * \details capacity is doubled each time additional space is needed | ||
| 262 | */ | ||
| 263 | 18301 | void grow() { | |
| 264 |
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18301 | if(size_+1 >= capacity_) { |
| 265 |
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5 | resize(size_+1, std::max(capacity_*2,size_+1)); |
| 266 | } else { | ||
| 267 | 18296 | resize(size_+1, capacity_); | |
| 268 | } | ||
| 269 | 18301 | } | |
| 270 | |||
| 271 | /** | ||
| 272 | * \brief Gets the size of this CellStatusArray | ||
| 273 | * \return the number of cells | ||
| 274 | */ | ||
| 275 | 18301 | index_t size() const { | |
| 276 | 18301 | return size_; | |
| 277 | } | ||
| 278 | |||
| 279 | /** | ||
| 280 | * \brief Clears this CellStatusArray | ||
| 281 | * \details Deallocates all memory | ||
| 282 | * \pre all the cells are free and no concurrent thread is running | ||
| 283 | */ | ||
| 284 | 5 | void clear() { | |
| 285 |
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5 | geo_debug_assert(!Process::is_running_threads()); |
| 286 | #ifdef GEO_DEBUG | ||
| 287 |
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46712 | for(index_t i=0; i<size_; ++i) { |
| 288 |
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46707 | geo_debug_assert(cell_thread(i) == FREE_CELL); |
| 289 | } | ||
| 290 | #endif | ||
| 291 |
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5 | delete[] cell_status_; |
| 292 | 5 | cell_status_ = nullptr; | |
| 293 | 5 | size_ = 0; | |
| 294 | 5 | capacity_ = 0; | |
| 295 | 5 | } | |
| 296 | |||
| 297 | private: | ||
| 298 | std::atomic<cell_status_t>* cell_status_; | ||
| 299 | index_t size_; | ||
| 300 | index_t capacity_; | ||
| 301 | }; | ||
| 302 | } | ||
| 303 | |||
| 304 | #endif | ||
| 305 |