libavcodec/pthread_slice.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav 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  * Libav 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 Libav; 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  * Slice multithreading support functions
  22  * @see doc/multithreading.txt
  23  */
  24
  25 #include "config.h"
  26
  27 #if HAVE_PTHREADS
  28 #include <pthread.h>
  29 #elif HAVE_W32THREADS
  30 #include "compat/w32pthreads.h"
  31 #endif
  32
  33 #include "avcodec.h"
  34 #include "internal.h"
  35 #include "pthread_internal.h"
  36 #include "thread.h"
  37
  38 #include "libavutil/common.h"
  39 #include "libavutil/cpu.h"
  40 #include "libavutil/mem.h"
  41
  42 typedef int (action_func)(AVCodecContext *c, void *arg);
  43 typedef int (action_func2)(AVCodecContext *c, void *arg, int jobnr, int threadnr);
  44
  45 typedef struct SliceThreadContext {
  46     pthread_t *workers;
  47     action_func *func;
  48     action_func2 *func2;
  49     void *args;
  50     int *rets;
  51     int rets_count;
  52     int job_count;
  53     int job_size;
  54
  55     pthread_cond_t last_job_cond;
  56     pthread_cond_t current_job_cond;
  57     pthread_mutex_t current_job_lock;
  58     unsigned current_execute;
  59     int current_job;
  60     int done;
  61 } SliceThreadContext;
  62
  63 static void* attribute_align_arg worker(void *v)
  64 {
  65     AVCodecContext *avctx = v;
  66     SliceThreadContext *c = avctx->internal->thread_ctx;
  67     unsigned last_execute = 0;
  68     int our_job = c->job_count;
  69     int thread_count = avctx->thread_count;
  70     int self_id;
  71
  72     pthread_mutex_lock(&c->current_job_lock);
  73     self_id = c->current_job++;
  74     for (;;){
  75         while (our_job >= c->job_count) {
  76             if (c->current_job == thread_count + c->job_count)
  77                 pthread_cond_signal(&c->last_job_cond);
  78
  79             while (last_execute == c->current_execute && !c->done)
  80                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
  81             last_execute = c->current_execute;
  82             our_job = self_id;
  83
  84             if (c->done) {
  85                 pthread_mutex_unlock(&c->current_job_lock);
  86                 return NULL;
  87             }
  88         }
  89         pthread_mutex_unlock(&c->current_job_lock);
  90
  91         c->rets[our_job%c->rets_count] = c->func ? c->func(avctx, (char*)c->args + our_job*c->job_size):
  92                                                    c->func2(avctx, c->args, our_job, self_id);
  93
  94         pthread_mutex_lock(&c->current_job_lock);
  95         our_job = c->current_job++;
  96     }
  97 }
  98
  99 void ff_slice_thread_free(AVCodecContext *avctx)
 100 {
 101     SliceThreadContext *c = avctx->internal->thread_ctx;
 102     int i;
 103
 104     pthread_mutex_lock(&c->current_job_lock);
 105     c->done = 1;
 106     pthread_cond_broadcast(&c->current_job_cond);
 107     pthread_mutex_unlock(&c->current_job_lock);
 108
 109     for (i=0; i<avctx->thread_count; i++)
 110          pthread_join(c->workers[i], NULL);
 111
 112     pthread_mutex_destroy(&c->current_job_lock);
 113     pthread_cond_destroy(&c->current_job_cond);
 114     pthread_cond_destroy(&c->last_job_cond);
 115     av_free(c->workers);
 116     av_freep(&avctx->internal->thread_ctx);
 117 }
 118
 119 static av_always_inline void thread_park_workers(SliceThreadContext *c, int thread_count)
 120 {
 121     while (c->current_job != thread_count + c->job_count)
 122         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
 123     pthread_mutex_unlock(&c->current_job_lock);
 124 }
 125
 126 static int thread_execute(AVCodecContext *avctx, action_func* func, void *arg, int *ret, int job_count, int job_size)
 127 {
 128     SliceThreadContext *c = avctx->internal->thread_ctx;
 129     int dummy_ret;
 130
 131     if (!(avctx->active_thread_type&FF_THREAD_SLICE) || avctx->thread_count <= 1)
 132         return avcodec_default_execute(avctx, func, arg, ret, job_count, job_size);
 133
 134     if (job_count <= 0)
 135         return 0;
 136
 137     pthread_mutex_lock(&c->current_job_lock);
 138
 139     c->current_job = avctx->thread_count;
 140     c->job_count = job_count;
 141     c->job_size = job_size;
 142     c->args = arg;
 143     c->func = func;
 144     if (ret) {
 145         c->rets = ret;
 146         c->rets_count = job_count;
 147     } else {
 148         c->rets = &dummy_ret;
 149         c->rets_count = 1;
 150     }
 151     c->current_execute++;
 152     pthread_cond_broadcast(&c->current_job_cond);
 153
 154     thread_park_workers(c, avctx->thread_count);
 155
 156     return 0;
 157 }
 158
 159 static int thread_execute2(AVCodecContext *avctx, action_func2* func2, void *arg, int *ret, int job_count)
 160 {
 161     SliceThreadContext *c = avctx->internal->thread_ctx;
 162     c->func2 = func2;
 163     return thread_execute(avctx, NULL, arg, ret, job_count, 0);
 164 }
 165
 166 int ff_slice_thread_init(AVCodecContext *avctx)
 167 {
 168     int i;
 169     SliceThreadContext *c;
 170     int thread_count = avctx->thread_count;
 171
 172     if (!thread_count) {
 173         int nb_cpus = av_cpu_count();
 174         av_log(avctx, AV_LOG_DEBUG, "detected %d logical cores\n", nb_cpus);
 175         // use number of cores + 1 as thread count if there is more than one
 176         if (nb_cpus > 1)
 177             thread_count = avctx->thread_count = FFMIN(nb_cpus + 1, MAX_AUTO_THREADS);
 178         else
 179             thread_count = avctx->thread_count = 1;
 180     }
 181
 182     if (thread_count <= 1) {
 183         avctx->active_thread_type = 0;
 184         return 0;
 185     }
 186
 187     c = av_mallocz(sizeof(SliceThreadContext));
 188     if (!c)
 189         return -1;
 190
 191     c->workers = av_mallocz(sizeof(pthread_t)*thread_count);
 192     if (!c->workers) {
 193         av_free(c);
 194         return -1;
 195     }
 196
 197     avctx->internal->thread_ctx = c;
 198     c->current_job = 0;
 199     c->job_count = 0;
 200     c->job_size = 0;
 201     c->done = 0;
 202     pthread_cond_init(&c->current_job_cond, NULL);
 203     pthread_cond_init(&c->last_job_cond, NULL);
 204     pthread_mutex_init(&c->current_job_lock, NULL);
 205     pthread_mutex_lock(&c->current_job_lock);
 206     for (i=0; i<thread_count; i++) {
 207         if(pthread_create(&c->workers[i], NULL, worker, avctx)) {
 208            avctx->thread_count = i;
 209            pthread_mutex_unlock(&c->current_job_lock);
 210            ff_thread_free(avctx);
 211            return -1;
 212         }
 213     }
 214
 215     thread_park_workers(c, thread_count);
 216
 217     avctx->execute = thread_execute;
 218     avctx->execute2 = thread_execute2;
 219     return 0;
 220 }