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| 1 | +/* | |
| 2 | + * This file is part of mpv. | |
| 3 | + * | |
| 4 | + * mpv is free software; you can redistribute it and/or | |
| 5 | + * modify it under the terms of the GNU Lesser General Public | |
| 6 | + * License as published by the Free Software Foundation; either | |
| 7 | + * version 2.1 of the License, or (at your option) any later version. | |
| 8 | + * | |
| 9 | + * mpv is distributed in the hope that it will be useful, | |
| 10 | + * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 | + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 | + * GNU Lesser General Public License for more details. | |
| 13 | + * | |
| 14 | + * You should have received a copy of the GNU Lesser General Public | |
| 15 | + * License along with mpv. If not, see <http://www.gnu.org/licenses/>. | |
| 16 | + */ | |
| 17 | + | |
| 18 | +#include <pthread.h> | |
| 19 | + | |
| 20 | +#include "common/common.h" | |
| 21 | + | |
| 22 | +#include "thread_pool.h" | |
| 23 | + | |
| 24 | +struct work { | |
| 25 | + void (*fn)(void *ctx); | |
| 26 | + void *fn_ctx; | |
| 27 | +}; | |
| 28 | + | |
| 29 | +struct mp_thread_pool { | |
| 30 | + pthread_t *threads; | |
| 31 | + int num_threads; | |
| 32 | + | |
| 33 | + pthread_mutex_t lock; | |
| 34 | + pthread_cond_t wakeup; | |
| 35 | + | |
| 36 | + // --- the following fields are protected by lock | |
| 37 | + bool terminate; | |
| 38 | + struct work *work; | |
| 39 | + int num_work; | |
| 40 | +}; | |
| 41 | + | |
| 42 | +static void *worker_thread(void *arg) | |
| 43 | +{ | |
| 44 | + struct mp_thread_pool *pool = arg; | |
| 45 | + | |
| 46 | + pthread_mutex_lock(&pool->lock); | |
| 47 | + while (1) { | |
| 48 | + while (!pool->num_work && !pool->terminate) | |
| 49 | + pthread_cond_wait(&pool->wakeup, &pool->lock); | |
| 50 | + | |
| 51 | + if (!pool->num_work && pool->terminate) | |
| 52 | + break; | |
| 53 | + | |
| 54 | + assert(pool->num_work > 0); | |
| 55 | + struct work work = pool->work[pool->num_work - 1]; | |
| 56 | + pool->num_work -= 1; | |
| 57 | + | |
| 58 | + pthread_mutex_unlock(&pool->lock); | |
| 59 | + work.fn(work.fn_ctx); | |
| 60 | + pthread_mutex_lock(&pool->lock); | |
| 61 | + } | |
| 62 | + assert(pool->num_work == 0); | |
| 63 | + pthread_mutex_unlock(&pool->lock); | |
| 64 | + | |
| 65 | + return NULL; | |
| 66 | +} | |
| 67 | + | |
| 68 | +static void thread_pool_dtor(void *ctx) | |
| 69 | +{ | |
| 70 | + struct mp_thread_pool *pool = ctx; | |
| 71 | + | |
| 72 | + pthread_mutex_lock(&pool->lock); | |
| 73 | + pool->terminate = true; | |
| 74 | + pthread_cond_broadcast(&pool->wakeup); | |
| 75 | + pthread_mutex_unlock(&pool->lock); | |
| 76 | + | |
| 77 | + for (int n = 0; n < pool->num_threads; n++) | |
| 78 | + pthread_join(pool->threads[n], NULL); | |
| 79 | + | |
| 80 | + assert(pool->num_work == 0); | |
| 81 | + pthread_cond_destroy(&pool->wakeup); | |
| 82 | + pthread_mutex_destroy(&pool->lock); | |
| 83 | +} | |
| 84 | + | |
| 85 | +// Create a thread pool with the given number of worker threads. This can return | |
| 86 | +// NULL if the worker threads could not be created. The thread pool can be | |
| 87 | +// destroyed with talloc_free(pool), or indirectly with talloc_free(ta_parent). | |
| 88 | +// If there are still work items on freeing, it will block until all work items | |
| 89 | +// are done, and the threads terminate. | |
| 90 | +struct mp_thread_pool *mp_thread_pool_create(void *ta_parent, int threads) | |
| 91 | +{ | |
| 92 | + assert(threads > 0); | |
| 93 | + | |
| 94 | + struct mp_thread_pool *pool = talloc_zero(ta_parent, struct mp_thread_pool); | |
| 95 | + talloc_set_destructor(pool, thread_pool_dtor); | |
| 96 | + | |
| 97 | + pthread_mutex_init(&pool->lock, NULL); | |
| 98 | + pthread_cond_init(&pool->wakeup, NULL); | |
| 99 | + | |
| 100 | + for (int n = 0; n < threads; n++) { | |
| 101 | + pthread_t thread; | |
| 102 | + if (pthread_create(&thread, NULL, worker_thread, pool)) { | |
| 103 | + talloc_free(pool); | |
| 104 | + return NULL; | |
| 105 | + } | |
| 106 | + MP_TARRAY_APPEND(pool, pool->threads, pool->num_threads, thread); | |
| 107 | + } | |
| 108 | + | |
| 109 | + return pool; | |
| 110 | +} | |
| 111 | + | |
| 112 | +// Queue a function to be run on a worker thread: fn(fn_ctx) | |
| 113 | +// If no worker thread is currently available, it's appended to a list in memory | |
| 114 | +// with unbounded size. This function always returns immediately. | |
| 115 | +// Concurrent queue calls are allowed, as long as it does not overlap with | |
| 116 | +// pool destruction. | |
| 117 | +void mp_thread_pool_queue(struct mp_thread_pool *pool, void (*fn)(void *ctx), | |
| 118 | + void *fn_ctx) | |
| 119 | +{ | |
| 120 | + pthread_mutex_lock(&pool->lock); | |
| 121 | + struct work work = {fn, fn_ctx}; | |
| 122 | + MP_TARRAY_INSERT_AT(pool, pool->work, pool->num_work, 0, work); | |
| 123 | + pthread_cond_signal(&pool->wakeup); | |
| 124 | + pthread_mutex_unlock(&pool->lock); | |
| 125 | +} | |
| @@ -0,0 +1,10 @@ | ||
| 1 | +#ifndef MPV_MP_THREAD_POOL_H | |
| 2 | +#define MPV_MP_THREAD_POOL_H | |
| 3 | + | |
| 4 | +struct mp_thread_pool; | |
| 5 | + | |
| 6 | +struct mp_thread_pool *mp_thread_pool_create(void *ta_parent, int threads); | |
| 7 | +void mp_thread_pool_queue(struct mp_thread_pool *pool, void (*fn)(void *ctx), | |
| 8 | + void *fn_ctx); | |
| 9 | + | |
| 10 | +#endif | |