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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 #include "libavutil/thread.h"
  31
  32 #include "avfilter.h"
  33 #include "internal.h"
  34 #include "thread.h"
  35
  36 typedef struct ThreadContext {
  37     AVFilterGraph *graph;
  38
  39     int nb_threads;
  40     pthread_t *workers;
  41     avfilter_action_func *func;
  42
  43     /* per-execute parameters */
  44     AVFilterContext *ctx;
  45     void *arg;
  46     int   *rets;
  47     int nb_rets;
  48     int nb_jobs;
  49
  50     pthread_cond_t last_job_cond;
  51     pthread_cond_t current_job_cond;
  52     pthread_mutex_t current_job_lock;
  53     int current_job;
  54     unsigned int current_execute;
  55     int done;
  56 } ThreadContext;
  57
  58 static void* attribute_align_arg worker(void *v)
  59 {
  60     ThreadContext *c = v;
  61     int our_job      = c->nb_jobs;
  62     int nb_threads   = c->nb_threads;
  63     unsigned int last_execute = 0;
  64     int self_id;
  65
  66     pthread_mutex_lock(&c->current_job_lock);
  67     self_id = c->current_job++;
  68     for (;;) {
  69         while (our_job >= c->nb_jobs) {
  70             if (c->current_job == nb_threads + c->nb_jobs)
  71                 pthread_cond_signal(&c->last_job_cond);
  72
  73             while (last_execute == c->current_execute && !c->done)
  74                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  75             last_execute = c->current_execute;
  76             our_job = self_id;
  77
  78             if (c->done) {
  79                 pthread_mutex_unlock(&c->current_job_lock);
  80                 return NULL;
  81             }
  82         }
  83         pthread_mutex_unlock(&c->current_job_lock);
  84
  85         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  86
  87         pthread_mutex_lock(&c->current_job_lock);
  88         our_job = c->current_job++;
  89     }
  90 }
  91
  92 static void slice_thread_uninit(ThreadContext *c)
  93 {
  94     int i;
  95
  96     pthread_mutex_lock(&c->current_job_lock);
  97     c->done = 1;
  98     pthread_cond_broadcast(&c->current_job_cond);
  99     pthread_mutex_unlock(&c->current_job_lock);
 100
 101     for (i = 0; i < c->nb_threads; i++)
 102          pthread_join(c->workers[i], NULL);
 103
 104     pthread_mutex_destroy(&c->current_job_lock);
 105     pthread_cond_destroy(&c->current_job_cond);
 106     pthread_cond_destroy(&c->last_job_cond);
 107     av_freep(&c->workers);
 108 }
 109
 110 static void slice_thread_park_workers(ThreadContext *c)
 111 {
 112     while (c->current_job != c->nb_threads + c->nb_jobs)
 113         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 114     pthread_mutex_unlock(&c->current_job_lock);
 115 }
 116
 117 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 118                           void *arg, int *ret, int nb_jobs)
 119 {
 120     ThreadContext *c = ctx->graph->internal->thread;
 121     int dummy_ret;
 122
 123     if (nb_jobs <= 0)
 124         return 0;
 125
 126     pthread_mutex_lock(&c->current_job_lock);
 127
 128     c->current_job = c->nb_threads;
 129     c->nb_jobs     = nb_jobs;
 130     c->ctx         = ctx;
 131     c->arg         = arg;
 132     c->func        = func;
 133     if (ret) {
 134         c->rets    = ret;
 135         c->nb_rets = nb_jobs;
 136     } else {
 137         c->rets    = &dummy_ret;
 138         c->nb_rets = 1;
 139     }
 140     c->current_execute++;
 141
 142     pthread_cond_broadcast(&c->current_job_cond);
 143
 144     slice_thread_park_workers(c);
 145
 146     return 0;
 147 }
 148
 149 static int thread_init_internal(ThreadContext *c, int nb_threads)
 150 {
 151     int i, ret;
 152
 153     if (!nb_threads) {
 154         int nb_cpus = av_cpu_count();
 155         // use number of cores + 1 as thread count if there is more than one
 156         if (nb_cpus > 1)
 157             nb_threads = nb_cpus + 1;
 158         else
 159             nb_threads = 1;
 160     }
 161
 162     if (nb_threads <= 1)
 163         return 1;
 164
 165     c->nb_threads = nb_threads;
 166     c->workers = av_mallocz_array(sizeof(*c->workers), nb_threads);
 167     if (!c->workers)
 168         return AVERROR(ENOMEM);
 169
 170     c->current_job = 0;
 171     c->nb_jobs     = 0;
 172     c->done        = 0;
 173
 174     pthread_cond_init(&c->current_job_cond, NULL);
 175     pthread_cond_init(&c->last_job_cond,    NULL);
 176
 177     pthread_mutex_init(&c->current_job_lock, NULL);
 178     pthread_mutex_lock(&c->current_job_lock);
 179     for (i = 0; i < nb_threads; i++) {
 180         ret = pthread_create(&c->workers[i], NULL, worker, c);
 181         if (ret) {
 182            pthread_mutex_unlock(&c->current_job_lock);
 183            c->nb_threads = i;
 184            slice_thread_uninit(c);
 185            return AVERROR(ret);
 186         }
 187     }
 188
 189     slice_thread_park_workers(c);
 190
 191     return c->nb_threads;
 192 }
 193
 194 int ff_graph_thread_init(AVFilterGraph *graph)
 195 {
 196     int ret;
 197
 198 #if HAVE_W32THREADS
 199     w32thread_init();
 200 #endif
 201
 202     if (graph->nb_threads == 1) {
 203         graph->thread_type = 0;
 204         return 0;
 205     }
 206
 207     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 208     if (!graph->internal->thread)
 209         return AVERROR(ENOMEM);
 210
 211     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 212     if (ret <= 1) {
 213         av_freep(&graph->internal->thread);
 214         graph->thread_type = 0;
 215         graph->nb_threads  = 1;
 216         return (ret < 0) ? ret : 0;
 217     }
 218     graph->nb_threads = ret;
 219
 220     graph->internal->thread_execute = thread_execute;
 221
 222     return 0;
 223 }
 224
 225 void ff_graph_thread_free(AVFilterGraph *graph)
 226 {
 227     if (graph->internal->thread)
 228         slice_thread_uninit(graph->internal->thread);
 229     av_freep(&graph->internal->thread);
 230 }