libavfilter/pthread.c

   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_jobs;
  47
  48     pthread_cond_t last_job_cond;
  49     pthread_cond_t current_job_cond;
  50     pthread_mutex_t current_job_lock;
  51     int current_job;
  52     unsigned int current_execute;
  53     int done;
  54 } ThreadContext;
  55
  56 static void* attribute_align_arg worker(void *v)
  57 {
  58     ThreadContext *c = v;
  59     int our_job      = c->nb_jobs;
  60     int nb_threads   = c->nb_threads;
  61     unsigned int last_execute = 0;
  62     int ret, self_id;
  63
  64     pthread_mutex_lock(&c->current_job_lock);
  65     self_id = c->current_job++;
  66
  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         ret = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  85         if (c->rets)
  86             c->rets[our_job % c->nb_jobs] = ret;
  87
  88         pthread_mutex_lock(&c->current_job_lock);
  89         our_job = c->current_job++;
  90     }
  91 }
  92
  93 static void slice_thread_uninit(ThreadContext *c)
  94 {
  95     int i;
  96
  97     pthread_mutex_lock(&c->current_job_lock);
  98     c->done = 1;
  99     pthread_cond_broadcast(&c->current_job_cond);
 100     pthread_mutex_unlock(&c->current_job_lock);
 101
 102     for (i = 0; i < c->nb_threads; i++)
 103          pthread_join(c->workers[i], NULL);
 104
 105     pthread_mutex_destroy(&c->current_job_lock);
 106     pthread_cond_destroy(&c->current_job_cond);
 107     pthread_cond_destroy(&c->last_job_cond);
 108     av_freep(&c->workers);
 109 }
 110
 111 static void slice_thread_park_workers(ThreadContext *c)
 112 {
 113     while (c->current_job != c->nb_threads + c->nb_jobs)
 114         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 115     pthread_mutex_unlock(&c->current_job_lock);
 116 }
 117
 118 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 119                           void *arg, int *ret, int nb_jobs)
 120 {
 121     ThreadContext *c = ctx->graph->internal->thread;
 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     c->rets        = ret;
 134     c->current_execute++;
 135
 136     pthread_cond_broadcast(&c->current_job_cond);
 137
 138     slice_thread_park_workers(c);
 139
 140     return 0;
 141 }
 142
 143 static int thread_init_internal(ThreadContext *c, int nb_threads)
 144 {
 145     int i, ret;
 146
 147     if (!nb_threads) {
 148         int nb_cpus = av_cpu_count();
 149         // use number of cores + 1 as thread count if there is more than one
 150         if (nb_cpus > 1)
 151             nb_threads = nb_cpus + 1;
 152         else
 153             nb_threads = 1;
 154     }
 155
 156     if (nb_threads <= 1)
 157         return 1;
 158
 159     c->nb_threads = nb_threads;
 160     c->workers = av_mallocz_array(sizeof(*c->workers), nb_threads);
 161     if (!c->workers)
 162         return AVERROR(ENOMEM);
 163
 164     c->current_job = 0;
 165     c->nb_jobs     = 0;
 166     c->done        = 0;
 167
 168     pthread_cond_init(&c->current_job_cond, NULL);
 169     pthread_cond_init(&c->last_job_cond,    NULL);
 170
 171     pthread_mutex_init(&c->current_job_lock, NULL);
 172     pthread_mutex_lock(&c->current_job_lock);
 173     for (i = 0; i < nb_threads; i++) {
 174         ret = pthread_create(&c->workers[i], NULL, worker, c);
 175         if (ret) {
 176            pthread_mutex_unlock(&c->current_job_lock);
 177            c->nb_threads = i;
 178            slice_thread_uninit(c);
 179            return AVERROR(ret);
 180         }
 181     }
 182
 183     slice_thread_park_workers(c);
 184
 185     return c->nb_threads;
 186 }
 187
 188 int ff_graph_thread_init(AVFilterGraph *graph)
 189 {
 190     int ret;
 191
 192 #if HAVE_W32THREADS
 193     w32thread_init();
 194 #endif
 195
 196     if (graph->nb_threads == 1) {
 197         graph->thread_type = 0;
 198         return 0;
 199     }
 200
 201     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 202     if (!graph->internal->thread)
 203         return AVERROR(ENOMEM);
 204
 205     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 206     if (ret <= 1) {
 207         av_freep(&graph->internal->thread);
 208         graph->thread_type = 0;
 209         graph->nb_threads  = 1;
 210         return (ret < 0) ? ret : 0;
 211     }
 212     graph->nb_threads = ret;
 213
 214     graph->internal->thread_execute = thread_execute;
 215
 216     return 0;
 217 }
 218
 219 void ff_graph_thread_free(AVFilterGraph *graph)
 220 {
 221     if (graph->internal->thread)
 222         slice_thread_uninit(graph->internal->thread);
 223     av_freep(&graph->internal->thread);
 224 }