diff options
Diffstat (limited to 'threadpool.c')
| -rw-r--r-- | threadpool.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/threadpool.c b/threadpool.c new file mode 100644 index 0000000..50d8cb7 --- /dev/null +++ b/threadpool.c @@ -0,0 +1,215 @@ +/* + * Copyright 2018 Anton Khirnov <anton@khirnov.net> + * + * This program 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 of the License, or + * (at your option) any later version. + * + * This program 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. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <errno.h> +#include <pthread.h> +#include <stdatomic.h> +#include <stdlib.h> +#include <string.h> +#include <sys/time.h> + +#include "threadpool.h" +#include "worker.h" + +#include <stdio.h> + +#define MIN(x, y) ((x) < (y) ? (x) : (y)) + +struct TPContext { + struct { + Worker *w; + WorkBatch wb; + int have_work; + + pthread_mutex_t work_lock; + pthread_cond_t work_cond; + + atomic_int work_completed; + atomic_int queue_empty; + + unsigned int rand_seed; + } *workers; + unsigned int nb_workers; + + atomic_int finish; + + pthread_mutex_t execute_lock; + + pthread_mutex_t progress_lock; + pthread_cond_t progress_cond; + atomic_int nb_workers_finished; + + atomic_int nb_workers_queue_empty; +}; + +void tp_free(TPContext **pctx) +{ + TPContext *ctx = *pctx; + + if (!ctx) + return; + + atomic_store(&ctx->finish, 1); + + for (unsigned int i = 0; i < ctx->nb_workers; i++) { + pthread_mutex_lock(&ctx->workers[i].work_lock); + pthread_cond_signal(&ctx->workers[i].work_cond); + pthread_mutex_unlock(&ctx->workers[i].work_lock); + + tpi_worker_destroy(&ctx->workers[i].w); + pthread_mutex_destroy(&ctx->workers[i].work_lock); + pthread_cond_destroy(&ctx->workers[i].work_cond); + } + free(ctx->workers); + ctx->nb_workers = 0; + + pthread_mutex_destroy(&ctx->execute_lock); + + free(ctx); + *pctx = NULL; +} + +int tp_init(TPContext **pctx, unsigned int nb_threads) +{ + TPContext *ctx = NULL; + int ret; + + if (!nb_threads) { + ret = -EINVAL; + goto fail; + } + + ctx = calloc(1, sizeof(*ctx)); + if (!ctx) { + ret = -ENOMEM; + goto fail; + } + + pthread_mutex_init(&ctx->execute_lock, NULL); + atomic_store(&ctx->finish, 0); + + ctx->workers = calloc(nb_threads, sizeof(*ctx->workers)); + if (!ctx->workers) { + ret = -ENOMEM; + goto fail; + } + + for (unsigned int i = 0; i < nb_threads; i++) { + struct timeval tv; + + pthread_mutex_init(&ctx->workers[i].work_lock, NULL); + pthread_cond_init(&ctx->workers[i].work_cond, NULL); + + gettimeofday(&tv, NULL); + ctx->workers[i].rand_seed = tv.tv_usec; + + ret = tpi_worker_spawn(&ctx->workers[i].w, i, ctx); + if (ret < 0) + goto fail; + ctx->nb_workers++; + } + + *pctx = ctx; + return 0; + +fail: + tp_free(&ctx); + *pctx = NULL; + return ret; +} + +int tpi_worksource_wait_jobs(TPContext *ctx, unsigned int worker_idx, + WorkBatch *wb) +{ + pthread_mutex_lock(&ctx->progress_lock); + atomic_store(&ctx->workers[worker_idx].work_completed, 1); + atomic_fetch_add(&ctx->nb_workers_finished, 1); + pthread_cond_signal(&ctx->progress_cond); + pthread_mutex_unlock(&ctx->progress_lock); + + pthread_mutex_lock(&ctx->workers[worker_idx].work_lock); + + while (!atomic_load(&ctx->finish) && !ctx->workers[worker_idx].have_work) + pthread_cond_wait(&ctx->workers[worker_idx].work_cond, &ctx->workers[worker_idx].work_lock); + + memcpy(wb, &ctx->workers[worker_idx].wb, sizeof(*wb)); + wb->finish = atomic_load(&ctx->finish); + ctx->workers[worker_idx].have_work = 0; + + pthread_mutex_unlock(&ctx->workers[worker_idx].work_lock); + + return 0; +} + +int tpi_worksource_steal_job(TPContext *ctx, unsigned int worker_idx) +{ + int ret = -1; + + atomic_store(&ctx->workers[worker_idx].queue_empty, 1); + atomic_fetch_add(&ctx->nb_workers_queue_empty, 1); + + while (atomic_load(&ctx->nb_workers_queue_empty) < ctx->nb_workers) { + unsigned int w_victim_idx = rand_r(&ctx->workers[worker_idx].rand_seed) % ctx->nb_workers; + + if (w_victim_idx == worker_idx || atomic_load(&ctx->workers[w_victim_idx].queue_empty)) + continue; + + ret = tpi_worker_steal_job(ctx->workers[w_victim_idx].w); + if (ret >= 0) + break; + } + + return ret; +} + +int tp_execute(TPContext *ctx, unsigned int nb_jobs, + TPExecuteCallback func, void *func_arg) +{ + unsigned int max_batch_size = (nb_jobs + ctx->nb_workers - 1) / ctx->nb_workers; + + pthread_mutex_lock(&ctx->execute_lock); + + atomic_store(&ctx->nb_workers_finished, 0); + atomic_store(&ctx->nb_workers_queue_empty, 0); + + for (unsigned int i = 0; i < ctx->nb_workers; i++) { + WorkBatch *wb = &ctx->workers[i].wb; + + pthread_mutex_lock(&ctx->workers[i].work_lock); + + wb->job_func = func; + wb->func_arg = func_arg; + wb->job_idx_start = i * max_batch_size; + wb->job_idx_end = MIN((i + 1) * max_batch_size, nb_jobs); + ctx->workers[i].have_work = 1; + atomic_store(&ctx->workers[i].work_completed, 0); + atomic_store(&ctx->workers[i].queue_empty, 0); + + pthread_cond_signal(&ctx->workers[i].work_cond); + + pthread_mutex_unlock(&ctx->workers[i].work_lock); + } + + pthread_mutex_lock(&ctx->progress_lock); + while (atomic_load(&ctx->nb_workers_finished) < ctx->nb_workers) + pthread_cond_wait(&ctx->progress_cond, &ctx->progress_lock); + pthread_mutex_unlock(&ctx->progress_lock); + + pthread_mutex_unlock(&ctx->execute_lock); + + return 0; +} |