libavfilter/pthread.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav 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  * Libav 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 GNU
  12  * 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 Libav; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 /**
  20  * @file
  21  * Libavfilter multithreading support
  22  */
  23
  24 #include "config.h"
  25
  26 #include "libavutil/common.h"
  27 #include "libavutil/cpu.h"
  28 #include "libavutil/mem.h"
  29
  30 #include "avfilter.h"
  31 #include "internal.h"
  32 #include "thread.h"
  33
  34 #if HAVE_PTHREADS
  35 #include <pthread.h>
  36 #elif HAVE_W32THREADS
  37 #include "compat/w32pthreads.h"
  38 #endif
  39
  40 typedef struct ThreadContext {
  41     AVFilterGraph *graph;
  42
  43     int nb_threads;
  44     pthread_t *workers;
  45     avfilter_action_func *func;
  46
  47     /* per-execute parameters */
  48     AVFilterContext *ctx;
  49     void *arg;
  50     int   *rets;
  51     int nb_rets;
  52     int nb_jobs;
  53
  54     pthread_cond_t last_job_cond;
  55     pthread_cond_t current_job_cond;
  56     pthread_mutex_t current_job_lock;
  57     int current_job;
  58     unsigned int current_execute;
  59     int done;
  60 } ThreadContext;
  61
  62 static void* attribute_align_arg worker(void *v)
  63 {
  64     ThreadContext *c = v;
  65     int our_job      = c->nb_jobs;
  66     int nb_threads   = c->nb_threads;
  67     unsigned int last_execute = 0;
  68     int self_id;
  69
  70     pthread_mutex_lock(&c->current_job_lock);
  71     self_id = c->current_job++;
  72     for (;;) {
  73         while (our_job >= c->nb_jobs) {
  74             if (c->current_job == nb_threads + c->nb_jobs)
  75                 pthread_cond_signal(&c->last_job_cond);
  76
  77             while (last_execute == c->current_execute && !c->done)
  78                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  79             last_execute = c->current_execute;
  80             our_job = self_id;
  81
  82             if (c->done) {
  83                 pthread_mutex_unlock(&c->current_job_lock);
  84                 return NULL;
  85             }
  86         }
  87         pthread_mutex_unlock(&c->current_job_lock);
  88
  89         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  90
  91         pthread_mutex_lock(&c->current_job_lock);
  92         our_job = c->current_job++;
  93     }
  94 }
  95
  96 static void slice_thread_uninit(ThreadContext *c)
  97 {
  98     int i;
  99
 100     pthread_mutex_lock(&c->current_job_lock);
 101     c->done = 1;
 102     pthread_cond_broadcast(&c->current_job_cond);
 103     pthread_mutex_unlock(&c->current_job_lock);
 104
 105     for (i = 0; i < c->nb_threads; i++)
 106          pthread_join(c->workers[i], NULL);
 107
 108     pthread_mutex_destroy(&c->current_job_lock);
 109     pthread_cond_destroy(&c->current_job_cond);
 110     pthread_cond_destroy(&c->last_job_cond);
 111     av_freep(&c->workers);
 112 }
 113
 114 static void slice_thread_park_workers(ThreadContext *c)
 115 {
 116     while (c->current_job != c->nb_threads + c->nb_jobs)
 117         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 118     pthread_mutex_unlock(&c->current_job_lock);
 119 }
 120
 121 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 122                           void *arg, int *ret, int nb_jobs)
 123 {
 124     ThreadContext *c = ctx->graph->internal->thread;
 125     int dummy_ret;
 126
 127     if (nb_jobs <= 0)
 128         return 0;
 129
 130     pthread_mutex_lock(&c->current_job_lock);
 131
 132     c->current_job = c->nb_threads;
 133     c->nb_jobs     = nb_jobs;
 134     c->ctx         = ctx;
 135     c->arg         = arg;
 136     c->func        = func;
 137     if (ret) {
 138         c->rets    = ret;
 139         c->nb_rets = nb_jobs;
 140     } else {
 141         c->rets    = &dummy_ret;
 142         c->nb_rets = 1;
 143     }
 144     c->current_execute++;
 145
 146     pthread_cond_broadcast(&c->current_job_cond);
 147
 148     slice_thread_park_workers(c);
 149
 150     return 0;
 151 }
 152
 153 static int thread_init_internal(ThreadContext *c, int nb_threads)
 154 {
 155     int i, ret;
 156
 157     if (!nb_threads) {
 158         int nb_cpus = av_cpu_count();
 159         av_log(c->graph, AV_LOG_DEBUG, "Detected %d logical cores.\n", nb_cpus);
 160         // use number of cores + 1 as thread count if there is more than one
 161         if (nb_cpus > 1)
 162             nb_threads = nb_cpus + 1;
 163         else
 164             nb_threads = 1;
 165     }
 166
 167     if (nb_threads <= 1)
 168         return 1;
 169
 170     c->nb_threads = nb_threads;
 171     c->workers = av_mallocz(sizeof(*c->workers) * nb_threads);
 172     if (!c->workers)
 173         return AVERROR(ENOMEM);
 174
 175     c->current_job = 0;
 176     c->nb_jobs     = 0;
 177     c->done        = 0;
 178
 179     pthread_cond_init(&c->current_job_cond, NULL);
 180     pthread_cond_init(&c->last_job_cond,    NULL);
 181
 182     pthread_mutex_init(&c->current_job_lock, NULL);
 183     pthread_mutex_lock(&c->current_job_lock);
 184     for (i = 0; i < nb_threads; i++) {
 185         ret = pthread_create(&c->workers[i], NULL, worker, c);
 186         if (ret) {
 187            pthread_mutex_unlock(&c->current_job_lock);
 188            c->nb_threads = i;
 189            slice_thread_uninit(c);
 190            return AVERROR(ret);
 191         }
 192     }
 193
 194     slice_thread_park_workers(c);
 195
 196     return c->nb_threads;
 197 }
 198
 199 int ff_graph_thread_init(AVFilterGraph *graph)
 200 {
 201     int ret;
 202
 203     if (graph->nb_threads == 1) {
 204         graph->thread_type = 0;
 205         return 0;
 206     }
 207
 208     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 209     if (!graph->internal->thread)
 210         return AVERROR(ENOMEM);
 211
 212     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 213     if (ret <= 1) {
 214         av_freep(&graph->internal->thread);
 215         graph->thread_type = 0;
 216         graph->nb_threads  = 1;
 217         return (ret < 0) ? ret : 0;
 218     }
 219     graph->nb_threads = ret;
 220
 221     graph->internal->thread_execute = thread_execute;
 222
 223     return 0;
 224 }
 225
 226 void ff_graph_thread_free(AVFilterGraph *graph)
 227 {
 228     if (graph->internal->thread)
 229         slice_thread_uninit(graph->internal->thread);
 230     av_freep(&graph->internal->thread);
 231 }