libavfilter/pthread.c

   1 /*
   2  *
   3  * This file is part of Libav.
   4  *
   5  * Libav 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  * Libav 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 Libav; 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_W32THREADS
  38 #include "compat/w32pthreads.h"
  39 #endif
  40
  41 typedef struct ThreadContext {
  42     AVFilterGraph *graph;
  43
  44     int nb_threads;
  45     pthread_t *workers;
  46     avfilter_action_func *func;
  47
  48     /* per-execute perameters */
  49     AVFilterContext *ctx;
  50     void *arg;
  51     int   *rets;
  52     int nb_rets;
  53     int nb_jobs;
  54
  55     pthread_cond_t last_job_cond;
  56     pthread_cond_t current_job_cond;
  57     pthread_mutex_t current_job_lock;
  58     int current_job;
  59     unsigned int current_execute;
  60     int done;
  61 } ThreadContext;
  62
  63 static void* attribute_align_arg worker(void *v)
  64 {
  65     ThreadContext *c = v;
  66     int our_job      = c->nb_jobs;
  67     int nb_threads   = c->nb_threads;
  68     unsigned int last_execute = 0;
  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             while (last_execute == c->current_execute && !c->done)
  79                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  80             last_execute = c->current_execute;
  81             our_job = self_id;
  82
  83             if (c->done) {
  84                 pthread_mutex_unlock(&c->current_job_lock);
  85                 return NULL;
  86             }
  87         }
  88         pthread_mutex_unlock(&c->current_job_lock);
  89
  90         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
  91
  92         pthread_mutex_lock(&c->current_job_lock);
  93         our_job = c->current_job++;
  94     }
  95 }
  96
  97 static void slice_thread_uninit(ThreadContext *c)
  98 {
  99     int i;
 100
 101     pthread_mutex_lock(&c->current_job_lock);
 102     c->done = 1;
 103     pthread_cond_broadcast(&c->current_job_cond);
 104     pthread_mutex_unlock(&c->current_job_lock);
 105
 106     for (i = 0; i < c->nb_threads; i++)
 107          pthread_join(c->workers[i], NULL);
 108
 109     pthread_mutex_destroy(&c->current_job_lock);
 110     pthread_cond_destroy(&c->current_job_cond);
 111     pthread_cond_destroy(&c->last_job_cond);
 112     av_freep(&c->workers);
 113 }
 114
 115 static void slice_thread_park_workers(ThreadContext *c)
 116 {
 117     while (c->current_job != c->nb_threads + c->nb_jobs)
 118         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 119     pthread_mutex_unlock(&c->current_job_lock);
 120 }
 121
 122 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
 123                           void *arg, int *ret, int nb_jobs)
 124 {
 125     ThreadContext *c = ctx->graph->internal->thread;
 126     int dummy_ret;
 127
 128     if (nb_jobs <= 0)
 129         return 0;
 130
 131     pthread_mutex_lock(&c->current_job_lock);
 132
 133     c->current_job = c->nb_threads;
 134     c->nb_jobs     = nb_jobs;
 135     c->ctx         = ctx;
 136     c->arg         = arg;
 137     c->func        = func;
 138     if (ret) {
 139         c->rets    = ret;
 140         c->nb_rets = nb_jobs;
 141     } else {
 142         c->rets    = &dummy_ret;
 143         c->nb_rets = 1;
 144     }
 145     c->current_execute++;
 146
 147     pthread_cond_broadcast(&c->current_job_cond);
 148
 149     slice_thread_park_workers(c);
 150
 151     return 0;
 152 }
 153
 154 static int thread_init_internal(ThreadContext *c, int nb_threads)
 155 {
 156     int i, ret;
 157
 158     if (!nb_threads) {
 159         int nb_cpus = av_cpu_count();
 160         av_log(c->graph, AV_LOG_DEBUG, "Detected %d logical cores.\n", nb_cpus);
 161         // use number of cores + 1 as thread count if there is more than one
 162         if (nb_cpus > 1)
 163             nb_threads = nb_cpus + 1;
 164         else
 165             nb_threads = 1;
 166     }
 167
 168     if (nb_threads <= 1)
 169         return 1;
 170
 171     c->nb_threads = nb_threads;
 172     c->workers = av_mallocz(sizeof(*c->workers) * nb_threads);
 173     if (!c->workers)
 174         return AVERROR(ENOMEM);
 175
 176     c->current_job = 0;
 177     c->nb_jobs     = 0;
 178     c->done        = 0;
 179
 180     pthread_cond_init(&c->current_job_cond, NULL);
 181     pthread_cond_init(&c->last_job_cond,    NULL);
 182
 183     pthread_mutex_init(&c->current_job_lock, NULL);
 184     pthread_mutex_lock(&c->current_job_lock);
 185     for (i = 0; i < nb_threads; i++) {
 186         ret = pthread_create(&c->workers[i], NULL, worker, c);
 187         if (ret) {
 188            pthread_mutex_unlock(&c->current_job_lock);
 189            c->nb_threads = i;
 190            slice_thread_uninit(c);
 191            return AVERROR(ret);
 192         }
 193     }
 194
 195     slice_thread_park_workers(c);
 196
 197     return c->nb_threads;
 198 }
 199
 200 int ff_graph_thread_init(AVFilterGraph *graph)
 201 {
 202     int ret;
 203
 204 #if HAVE_W32THREADS
 205     w32thread_init();
 206 #endif
 207
 208     if (graph->nb_threads == 1) {
 209         graph->thread_type = 0;
 210         return 0;
 211     }
 212
 213     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
 214     if (!graph->internal->thread)
 215         return AVERROR(ENOMEM);
 216
 217     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);
 218     if (ret <= 1) {
 219         av_freep(&graph->internal->thread);
 220         graph->thread_type = 0;
 221         graph->nb_threads  = 1;
 222         return (ret < 0) ? ret : 0;
 223     }
 224     graph->nb_threads = ret;
 225
 226     graph->internal->thread_execute = thread_execute;
 227
 228     return 0;
 229 }
 230
 231 void ff_graph_thread_free(AVFilterGraph *graph)
 232 {
 233     if (graph->internal->thread)
 234         slice_thread_uninit(graph->internal->thread);
 235     av_freep(&graph->internal->thread);
 236 }