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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     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     int done;
  62 } ThreadContext;
  63
  64 static void* attribute_align_arg worker(void *v)
  65 {
  66     ThreadContext *c = v;
  67     int our_job      = c->nb_jobs;
  68     int nb_threads   = c->nb_threads;
  69     int self_id;
  70
  71     pthread_mutex_lock(&c->current_job_lock);
  72     self_id = c->current_job++;
  73     for (;;) {
  74         while (our_job >= c->nb_jobs) {
  75             if (c->current_job == nb_threads + c->nb_jobs)
  76                 pthread_cond_signal(&c->last_job_cond);
  77
  78             pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  79             our_job = self_id;
  80
  81             if (c->done) {
  82                 pthread_mutex_unlock(&c->current_job_lock);
  83                 return NULL;
  84             }
  85         }
  86         pthread_mutex_unlock(&c->current_job_lock);
  87
  88         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  89
  90         pthread_mutex_lock(&c->current_job_lock);
  91         our_job = c->current_job++;
  92     }
  93 }
  94
  95 static void slice_thread_uninit(ThreadContext *c)
  96 {
  97     int i;
  98
  99     pthread_mutex_lock(&c->current_job_lock);
 100     c->done = 1;
 101     pthread_cond_broadcast(&c->current_job_cond);
 102     pthread_mutex_unlock(&c->current_job_lock);
 103
 104     for (i = 0; i < c->nb_threads; i++)
 105          pthread_join(c->workers[i], NULL);
 106
 107     pthread_mutex_destroy(&c->current_job_lock);
 108     pthread_cond_destroy(&c->current_job_cond);
 109     pthread_cond_destroy(&c->last_job_cond);
 110     av_freep(&c->workers);
 111 }
 112
 113 static void slice_thread_park_workers(ThreadContext *c)
 114 {
 115     pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 116     pthread_mutex_unlock(&c->current_job_lock);
 117 }
 118
 119 static int thread_execute(AVFilterContext *ctx, action_func *func,
 120                           void *arg, int *ret, int nb_jobs)
 121 {
 122     ThreadContext *c = ctx->graph->internal->thread;
 123     int dummy_ret;
 124
 125     if (nb_jobs <= 0)
 126         return 0;
 127
 128     pthread_mutex_lock(&c->current_job_lock);
 129
 130     c->current_job = c->nb_threads;
 131     c->nb_jobs     = nb_jobs;
 132     c->ctx         = ctx;
 133     c->arg         = arg;
 134     c->func        = func;
 135     if (ret) {
 136         c->rets    = ret;
 137         c->nb_rets = nb_jobs;
 138     } else {
 139         c->rets    = &dummy_ret;
 140         c->nb_rets = 1;
 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(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 }