| 1 | /* |
| 2 | * Copyright (c) 2010-2020 The RetroArch team |
| 3 | * Copyright (c) 2017 John Schember <john@nachtimwald.com> |
| 4 | * |
| 5 | * --------------------------------------------------------------------------------------- |
| 6 | * The following license statement only applies to this file (tpool.c). |
| 7 | * --------------------------------------------------------------------------------------- |
| 8 | * |
| 9 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 10 | * of this software and associated documentation files (the "Software"), to deal |
| 11 | * in the Software without restriction, including without limitation the rights |
| 12 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 13 | * copies of the Software, and to permit persons to whom the Software is |
| 14 | * furnished to do so, subject to the following conditions: |
| 15 | * |
| 16 | * The above copyright notice and this permission notice shall be included in |
| 17 | * all copies or substantial portions of the Software. |
| 18 | * |
| 19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 20 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 21 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 22 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 23 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 24 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 25 | * THE SOFTWARE |
| 26 | */ |
| 27 | |
| 28 | #include <stdlib.h> |
| 29 | #include <boolean.h> |
| 30 | |
| 31 | #include <rthreads/rthreads.h> |
| 32 | #include <rthreads/tpool.h> |
| 33 | |
| 34 | /* Work object which will sit in a queue |
| 35 | * waiting for the pool to process it. |
| 36 | * |
| 37 | * It is a singly linked list acting as a FIFO queue. */ |
| 38 | struct tpool_work |
| 39 | { |
| 40 | thread_func_t func; /* Function to be called. */ |
| 41 | void *arg; /* Data to be passed to func. */ |
| 42 | struct tpool_work *next; /* Next work item in the queue. */ |
| 43 | }; |
| 44 | typedef struct tpool_work tpool_work_t; |
| 45 | |
| 46 | struct tpool |
| 47 | { |
| 48 | tpool_work_t *work_first; /* First work item in the work queue. */ |
| 49 | tpool_work_t *work_last; /* Last work item in the work queue. */ |
| 50 | slock_t *work_mutex; /* Mutex protecting inserting and removing work from the work queue. */ |
| 51 | scond_t *work_cond; /* Conditional to signal when there is work to process. */ |
| 52 | scond_t *working_cond; /* Conditional to signal when there is no work processing. |
| 53 | This will also signal when there are no threads running. */ |
| 54 | size_t working_cnt; /* The number of threads processing work (Not waiting for work). */ |
| 55 | size_t thread_cnt; /* Total number of threads within the pool. */ |
| 56 | bool stop; /* Marker to tell the work threads to exit. */ |
| 57 | }; |
| 58 | |
| 59 | static tpool_work_t *tpool_work_create(thread_func_t func, void *arg) |
| 60 | { |
| 61 | tpool_work_t *work; |
| 62 | |
| 63 | if (!func) |
| 64 | return NULL; |
| 65 | |
| 66 | work = (tpool_work_t*)calloc(1, sizeof(*work)); |
| 67 | work->func = func; |
| 68 | work->arg = arg; |
| 69 | work->next = NULL; |
| 70 | return work; |
| 71 | } |
| 72 | |
| 73 | static void tpool_work_destroy(tpool_work_t *work) |
| 74 | { |
| 75 | if (work) |
| 76 | free(work); |
| 77 | } |
| 78 | |
| 79 | /* Pull the first work item out of the queue. */ |
| 80 | static tpool_work_t *tpool_work_get(tpool_t *tp) |
| 81 | { |
| 82 | tpool_work_t *work; |
| 83 | |
| 84 | if (!tp) |
| 85 | return NULL; |
| 86 | |
| 87 | work = tp->work_first; |
| 88 | if (!work) |
| 89 | return NULL; |
| 90 | |
| 91 | if (!work->next) |
| 92 | { |
| 93 | tp->work_first = NULL; |
| 94 | tp->work_last = NULL; |
| 95 | } |
| 96 | else |
| 97 | tp->work_first = work->next; |
| 98 | |
| 99 | return work; |
| 100 | } |
| 101 | |
| 102 | static void tpool_worker(void *arg) |
| 103 | { |
| 104 | tpool_work_t *work = NULL; |
| 105 | tpool_t *tp = (tpool_t*)arg; |
| 106 | |
| 107 | for (;;) |
| 108 | { |
| 109 | slock_lock(tp->work_mutex); |
| 110 | /* Keep running until told to stop. */ |
| 111 | if (tp->stop) |
| 112 | break; |
| 113 | |
| 114 | /* If there is no work in the queue wait in the conditional until |
| 115 | * there is work to take. */ |
| 116 | if (!tp->work_first) |
| 117 | scond_wait(tp->work_cond, tp->work_mutex); |
| 118 | |
| 119 | /* Try to pull work from the queue. */ |
| 120 | work = tpool_work_get(tp); |
| 121 | tp->working_cnt++; |
| 122 | slock_unlock(tp->work_mutex); |
| 123 | |
| 124 | /* Call the work function and let it process. |
| 125 | * |
| 126 | * work can legitimately be NULL. Since multiple threads from the pool |
| 127 | * will wake when there is work, a thread might not get any work. 1 |
| 128 | * piece of work and 2 threads, both will wake but with 1 only work 1 |
| 129 | * will get the work and the other won't. |
| 130 | * |
| 131 | * working_cnt has been increment and work could be NULL. While it's |
| 132 | * not true there is work processing the thread is considered working |
| 133 | * because it's not waiting in the conditional. Pedantic but... |
| 134 | */ |
| 135 | if (work) |
| 136 | { |
| 137 | work->func(work->arg); |
| 138 | tpool_work_destroy(work); |
| 139 | } |
| 140 | |
| 141 | slock_lock(tp->work_mutex); |
| 142 | tp->working_cnt--; |
| 143 | /* Since we're in a lock no work can be added or removed form the queue. |
| 144 | * Also, the working_cnt can't be changed (except the thread holding the lock). |
| 145 | * At this point if there isn't any work processing and if there is no work |
| 146 | * signal this is the case. */ |
| 147 | if (!tp->stop && tp->working_cnt == 0 && !tp->work_first) |
| 148 | scond_signal(tp->working_cond); |
| 149 | slock_unlock(tp->work_mutex); |
| 150 | } |
| 151 | |
| 152 | tp->thread_cnt--; |
| 153 | if (tp->thread_cnt == 0) |
| 154 | scond_signal(tp->working_cond); |
| 155 | slock_unlock(tp->work_mutex); |
| 156 | } |
| 157 | |
| 158 | tpool_t *tpool_create(size_t num) |
| 159 | { |
| 160 | tpool_t *tp; |
| 161 | sthread_t *thread; |
| 162 | size_t i; |
| 163 | |
| 164 | if (num == 0) |
| 165 | num = 2; |
| 166 | |
| 167 | tp = (tpool_t*)calloc(1, sizeof(*tp)); |
| 168 | tp->thread_cnt = num; |
| 169 | |
| 170 | tp->work_mutex = slock_new(); |
| 171 | tp->work_cond = scond_new(); |
| 172 | tp->working_cond = scond_new(); |
| 173 | |
| 174 | tp->work_first = NULL; |
| 175 | tp->work_last = NULL; |
| 176 | |
| 177 | /* Create the requested number of thread and detach them. */ |
| 178 | for (i = 0; i < num; i++) |
| 179 | { |
| 180 | thread = sthread_create(tpool_worker, tp); |
| 181 | sthread_detach(thread); |
| 182 | } |
| 183 | |
| 184 | return tp; |
| 185 | } |
| 186 | |
| 187 | void tpool_destroy(tpool_t *tp) |
| 188 | { |
| 189 | tpool_work_t *work; |
| 190 | tpool_work_t *work2; |
| 191 | |
| 192 | if (!tp) |
| 193 | return; |
| 194 | |
| 195 | /* Take all work out of the queue and destroy it. */ |
| 196 | slock_lock(tp->work_mutex); |
| 197 | work = tp->work_first; |
| 198 | while (work) |
| 199 | { |
| 200 | work2 = work->next; |
| 201 | tpool_work_destroy(work); |
| 202 | work = work2; |
| 203 | } |
| 204 | |
| 205 | /* Tell the worker threads to stop. */ |
| 206 | tp->stop = true; |
| 207 | scond_broadcast(tp->work_cond); |
| 208 | slock_unlock(tp->work_mutex); |
| 209 | |
| 210 | /* Wait for all threads to stop. */ |
| 211 | tpool_wait(tp); |
| 212 | |
| 213 | slock_free(tp->work_mutex); |
| 214 | scond_free(tp->work_cond); |
| 215 | scond_free(tp->working_cond); |
| 216 | |
| 217 | free(tp); |
| 218 | } |
| 219 | |
| 220 | bool tpool_add_work(tpool_t *tp, thread_func_t func, void *arg) |
| 221 | { |
| 222 | tpool_work_t *work; |
| 223 | |
| 224 | if (!tp) |
| 225 | return false; |
| 226 | |
| 227 | work = tpool_work_create(func, arg); |
| 228 | if (!work) |
| 229 | return false; |
| 230 | |
| 231 | slock_lock(tp->work_mutex); |
| 232 | if (!tp->work_first) |
| 233 | { |
| 234 | tp->work_first = work; |
| 235 | tp->work_last = tp->work_first; |
| 236 | } |
| 237 | else |
| 238 | { |
| 239 | tp->work_last->next = work; |
| 240 | tp->work_last = work; |
| 241 | } |
| 242 | |
| 243 | scond_broadcast(tp->work_cond); |
| 244 | slock_unlock(tp->work_mutex); |
| 245 | |
| 246 | return true; |
| 247 | } |
| 248 | |
| 249 | void tpool_wait(tpool_t *tp) |
| 250 | { |
| 251 | if (!tp) |
| 252 | return; |
| 253 | |
| 254 | slock_lock(tp->work_mutex); |
| 255 | |
| 256 | for (;;) |
| 257 | { |
| 258 | /* working_cond is dual use. It signals when we're not stopping but the |
| 259 | * working_cnt is 0 indicating there isn't any work processing. If we |
| 260 | * are stopping it will trigger when there aren't any threads running. */ |
| 261 | if ((!tp->stop && tp->working_cnt != 0) || (tp->stop && tp->thread_cnt != 0)) |
| 262 | scond_wait(tp->working_cond, tp->work_mutex); |
| 263 | else |
| 264 | break; |
| 265 | } |
| 266 | |
| 267 | slock_unlock(tp->work_mutex); |
| 268 | } |