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   1 /*
   2  *
   3  * This file is part of FFmpeg.
   4  *
   5  * FFmpeg is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * FFmpeg is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with FFmpeg; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /**
  21  * @file
  22  * Libavfilter multithreading support
  23  */
  24
  25 #include "config.h"
  26
  27 #include "libavutil/common.h"
  28 #include "libavutil/cpu.h"
  29 #include "libavutil/mem.h"
  30
  31 #include "avfilter.h"
  32 #include "internal.h"
  33 #include "thread.h"
  34
  35 #if HAVE_PTHREADS
  36 #include <pthread.h>
  37 #elif HAVE_OS2THREADS
  38 #include "compat/os2threads.h"
  39 #elif HAVE_W32THREADS
  40 #include "compat/w32pthreads.h"
  41 #endif
  42
  43 typedef struct ThreadContext {
  44     AVFilterGraph *graph;
  45
  46     int nb_threads;
  47     pthread_t *workers;
  48     avfilter_action_func *func;
  49
  50     /* per-execute perameters */
  51     AVFilterContext *ctx;
  52     void *arg;
  53     int   *rets;
  54     int nb_rets;
  55     int nb_jobs;
  56
  57     pthread_cond_t last_job_cond;
  58     pthread_cond_t current_job_cond;
  59     pthread_mutex_t current_job_lock;
  60     int current_job;
  61     unsigned int current_execute;
  62     int done;
  63 } ThreadContext;
  64
  65 static void* attribute_align_arg worker(void *v)
  66 {
  67     ThreadContext *c = v;
  68     int our_job      = c->nb_jobs;
  69     int nb_threads   = c->nb_threads;
  70     unsigned int last_execute = 0;
  71     int self_id;
  72
  73     pthread_mutex_lock(&c->current_job_lock);
  74     self_id = c->current_job++;
  75     for (;;) {
  76         while (our_job >= c->nb_jobs) {
  77             if (c->current_job == nb_threads + c->nb_jobs)
  78                 pthread_cond_signal(&c->last_job_cond);
  79
  80             while (last_execute == c->current_execute && !c->done)
  81                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  82             last_execute = c->current_execute;
  83             our_job = self_id;
  84
  85             if (c->done) {
  86                 pthread_mutex_unlock(&c->current_job_lock);
  87                 return NULL;
  88             }
  89         }
  90         pthread_mutex_unlock(&c->current_job_lock);
  91
  92         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  93
  94         pthread_mutex_lock(&c->current_job_lock);
  95         our_job = c->current_job++;
  96     }
  97 }
  98
  99 static void slice_thread_uninit(ThreadContext *c)
 100 {
 101     int i;
 102
 103     pthread_mutex_lock(&c->current_job_lock);
 104     c->done = 1;
 105     pthread_cond_broadcast(&c->current_job_cond);
 106     pthread_mutex_unlock(&c->current_job_lock);
 107
 108     for (i = 0; i < c->nb_threads; i++)
 109          pthread_join(c->workers[i], NULL);
 110
 111     pthread_mutex_destroy(&c->current_job_lock);
 112     pthread_cond_destroy(&c->current_job_cond);
 113     pthread_cond_destroy(&c->last_job_cond);
 114     av_freep(&c->workers);
 115 }
 116
 117 static void slice_thread_park_workers(ThreadContext *c)
 118 {
 119     while (c->current_job != c->nb_threads + c->nb_jobs)
 120         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 121     pthread_mutex_unlock(&c->current_job_lock);
 122 }
 123
 124 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 125                           void *arg, int *ret, int nb_jobs)
 126 {
 127     ThreadContext *c = ctx->graph->internal->thread;
 128     int dummy_ret;
 129
 130     if (nb_jobs <= 0)
 131         return 0;
 132
 133     pthread_mutex_lock(&c->current_job_lock);
 134
 135     c->current_job = c->nb_threads;
 136     c->nb_jobs     = nb_jobs;
 137     c->ctx         = ctx;
 138     c->arg         = arg;
 139     c->func        = func;
 140     if (ret) {
 141         c->rets    = ret;
 142         c->nb_rets = nb_jobs;
 143     } else {
 144         c->rets    = &dummy_ret;
 145         c->nb_rets = 1;
 146     }
 147     c->current_execute++;
 148
 149     pthread_cond_broadcast(&c->current_job_cond);
 150
 151     slice_thread_park_workers(c);
 152
 153     return 0;
 154 }
 155
 156 static int thread_init_internal(ThreadContext *c, int nb_threads)
 157 {
 158     int i, ret;
 159
 160     if (!nb_threads) {
 161         int nb_cpus = av_cpu_count();
 162         // use number of cores + 1 as thread count if there is more than one
 163         if (nb_cpus > 1)
 164             nb_threads = nb_cpus + 1;
 165         else
 166             nb_threads = 1;
 167     }
 168
 169     if (nb_threads <= 1)
 170         return 1;
 171
 172     c->nb_threads = nb_threads;
 173     c->workers = av_mallocz_array(sizeof(*c->workers), nb_threads);
 174     if (!c->workers)
 175         return AVERROR(ENOMEM);
 176
 177     c->current_job = 0;
 178     c->nb_jobs     = 0;
 179     c->done        = 0;
 180
 181     pthread_cond_init(&c->current_job_cond, NULL);
 182     pthread_cond_init(&c->last_job_cond,    NULL);
 183
 184     pthread_mutex_init(&c->current_job_lock, NULL);
 185     pthread_mutex_lock(&c->current_job_lock);
 186     for (i = 0; i < nb_threads; i++) {
 187         ret = pthread_create(&c->workers[i], NULL, worker, c);
 188         if (ret) {
 189            pthread_mutex_unlock(&c->current_job_lock);
 190            c->nb_threads = i;
 191            slice_thread_uninit(c);
 192            return AVERROR(ret);
 193         }
 194     }
 195
 196     slice_thread_park_workers(c);
 197
 198     return c->nb_threads;
 199 }
 200
 201 int ff_graph_thread_init(AVFilterGraph *graph)
 202 {
 203     int ret;
 204
 205 #if HAVE_W32THREADS
 206     w32thread_init();
 207 #endif
 208
 209     if (graph->nb_threads == 1) {
 210         graph->thread_type = 0;
 211         return 0;
 212     }
 213
 214     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 215     if (!graph->internal->thread)
 216         return AVERROR(ENOMEM);
 217
 218     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 219     if (ret <= 1) {
 220         av_freep(&graph->internal->thread);
 221         graph->thread_type = 0;
 222         graph->nb_threads  = 1;
 223         return (ret < 0) ? ret : 0;
 224     }
 225     graph->nb_threads = ret;
 226
 227     graph->internal->thread_execute = thread_execute;
 228
 229     return 0;
 230 }
 231
 232 void ff_graph_thread_free(AVFilterGraph *graph)
 233 {
 234     if (graph->internal->thread)
 235         slice_thread_uninit(graph->internal->thread);
 236     av_freep(&graph->internal->thread);
 237 }