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   1 /*
   2  * This file is part of FFmpeg.
   3  *
   4  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 #include "libavutil/thread.h"
  30
  31 #include "avfilter.h"
  32 #include "internal.h"
  33 #include "thread.h"
  34
  35 typedef struct ThreadContext {
  36     AVFilterGraph *graph;
  37
  38     int nb_threads;
  39     pthread_t *workers;
  40     avfilter_action_func *func;
  41
  42     /* per-execute parameters */
  43     AVFilterContext *ctx;
  44     void *arg;
  45     int   *rets;
  46     int nb_rets;
  47     int nb_jobs;
  48
  49     pthread_cond_t last_job_cond;
  50     pthread_cond_t current_job_cond;
  51     pthread_mutex_t current_job_lock;
  52     int current_job;
  53     unsigned int current_execute;
  54     int done;
  55 } ThreadContext;
  56
  57 static void* attribute_align_arg worker(void *v)
  58 {
  59     ThreadContext *c = v;
  60     int our_job      = c->nb_jobs;
  61     int nb_threads   = c->nb_threads;
  62     unsigned int last_execute = 0;
  63     int self_id;
  64
  65     pthread_mutex_lock(&c->current_job_lock);
  66     self_id = c->current_job++;
  67     for (;;) {
  68         while (our_job >= c->nb_jobs) {
  69             if (c->current_job == nb_threads + c->nb_jobs)
  70                 pthread_cond_signal(&c->last_job_cond);
  71
  72             while (last_execute == c->current_execute && !c->done)
  73                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  74             last_execute = c->current_execute;
  75             our_job = self_id;
  76
  77             if (c->done) {
  78                 pthread_mutex_unlock(&c->current_job_lock);
  79                 return NULL;
  80             }
  81         }
  82         pthread_mutex_unlock(&c->current_job_lock);
  83
  84         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  85
  86         pthread_mutex_lock(&c->current_job_lock);
  87         our_job = c->current_job++;
  88     }
  89 }
  90
  91 static void slice_thread_uninit(ThreadContext *c)
  92 {
  93     int i;
  94
  95     pthread_mutex_lock(&c->current_job_lock);
  96     c->done = 1;
  97     pthread_cond_broadcast(&c->current_job_cond);
  98     pthread_mutex_unlock(&c->current_job_lock);
  99
 100     for (i = 0; i < c->nb_threads; i++)
 101          pthread_join(c->workers[i], NULL);
 102
 103     pthread_mutex_destroy(&c->current_job_lock);
 104     pthread_cond_destroy(&c->current_job_cond);
 105     pthread_cond_destroy(&c->last_job_cond);
 106     av_freep(&c->workers);
 107 }
 108
 109 static void slice_thread_park_workers(ThreadContext *c)
 110 {
 111     while (c->current_job != c->nb_threads + c->nb_jobs)
 112         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 113     pthread_mutex_unlock(&c->current_job_lock);
 114 }
 115
 116 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 117                           void *arg, int *ret, int nb_jobs)
 118 {
 119     ThreadContext *c = ctx->graph->internal->thread;
 120     int dummy_ret;
 121
 122     if (nb_jobs <= 0)
 123         return 0;
 124
 125     pthread_mutex_lock(&c->current_job_lock);
 126
 127     c->current_job = c->nb_threads;
 128     c->nb_jobs     = nb_jobs;
 129     c->ctx         = ctx;
 130     c->arg         = arg;
 131     c->func        = func;
 132     if (ret) {
 133         c->rets    = ret;
 134         c->nb_rets = nb_jobs;
 135     } else {
 136         c->rets    = &dummy_ret;
 137         c->nb_rets = 1;
 138     }
 139     c->current_execute++;
 140
 141     pthread_cond_broadcast(&c->current_job_cond);
 142
 143     slice_thread_park_workers(c);
 144
 145     return 0;
 146 }
 147
 148 static int thread_init_internal(ThreadContext *c, int nb_threads)
 149 {
 150     int i, ret;
 151
 152     if (!nb_threads) {
 153         int nb_cpus = av_cpu_count();
 154         // use number of cores + 1 as thread count if there is more than one
 155         if (nb_cpus > 1)
 156             nb_threads = nb_cpus + 1;
 157         else
 158             nb_threads = 1;
 159     }
 160
 161     if (nb_threads <= 1)
 162         return 1;
 163
 164     c->nb_threads = nb_threads;
 165     c->workers = av_mallocz_array(sizeof(*c->workers), nb_threads);
 166     if (!c->workers)
 167         return AVERROR(ENOMEM);
 168
 169     c->current_job = 0;
 170     c->nb_jobs     = 0;
 171     c->done        = 0;
 172
 173     pthread_cond_init(&c->current_job_cond, NULL);
 174     pthread_cond_init(&c->last_job_cond,    NULL);
 175
 176     pthread_mutex_init(&c->current_job_lock, NULL);
 177     pthread_mutex_lock(&c->current_job_lock);
 178     for (i = 0; i < nb_threads; i++) {
 179         ret = pthread_create(&c->workers[i], NULL, worker, c);
 180         if (ret) {
 181            pthread_mutex_unlock(&c->current_job_lock);
 182            c->nb_threads = i;
 183            slice_thread_uninit(c);
 184            return AVERROR(ret);
 185         }
 186     }
 187
 188     slice_thread_park_workers(c);
 189
 190     return c->nb_threads;
 191 }
 192
 193 int ff_graph_thread_init(AVFilterGraph *graph)
 194 {
 195     int ret;
 196
 197 #if HAVE_W32THREADS
 198     w32thread_init();
 199 #endif
 200
 201     if (graph->nb_threads == 1) {
 202         graph->thread_type = 0;
 203         return 0;
 204     }
 205
 206     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 207     if (!graph->internal->thread)
 208         return AVERROR(ENOMEM);
 209
 210     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 211     if (ret <= 1) {
 212         av_freep(&graph->internal->thread);
 213         graph->thread_type = 0;
 214         graph->nb_threads  = 1;
 215         return (ret < 0) ? ret : 0;
 216     }
 217     graph->nb_threads = ret;
 218
 219     graph->internal->thread_execute = thread_execute;
 220
 221     return 0;
 222 }
 223
 224 void ff_graph_thread_free(AVFilterGraph *graph)
 225 {
 226     if (graph->internal->thread)
 227         slice_thread_uninit(graph->internal->thread);
 228     av_freep(&graph->internal->thread);
 229 }