/*
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * Libavfilter multithreading support
  */
 
 #include "config.h"
 
 #include "libavutil/common.h"
 #include "libavutil/cpu.h"
 #include "libavutil/mem.h"
 
 #include "avfilter.h"
 #include "internal.h"
 #include "thread.h"
 
 #if HAVE_PTHREADS
 #include <pthread.h>

 #elif HAVE_OS2THREADS
 #include "compat/os2threads.h"

 #elif HAVE_W32THREADS
 #include "compat/w32pthreads.h"
 #endif
 
 typedef struct ThreadContext {
     AVFilterGraph *graph;
 
     int nb_threads;
     pthread_t *workers;

     avfilter_action_func *func;

 
     /* per-execute perameters */
     AVFilterContext *ctx;
     void *arg;
     int   *rets;
     int nb_rets;
     int nb_jobs;
 
     pthread_cond_t last_job_cond;
     pthread_cond_t current_job_cond;
     pthread_mutex_t current_job_lock;
     int current_job;

     unsigned int current_execute;

     int done;
 } ThreadContext;
 
 static void* attribute_align_arg worker(void *v)
 {
     ThreadContext *c = v;
     int our_job      = c->nb_jobs;
     int nb_threads   = c->nb_threads;

     unsigned int last_execute = 0;

     int self_id;
 
     pthread_mutex_lock(&c->current_job_lock);
     self_id = c->current_job++;
     for (;;) {
         while (our_job >= c->nb_jobs) {
             if (c->current_job == nb_threads + c->nb_jobs)
                 pthread_cond_signal(&c->last_job_cond);
 

             while (last_execute == c->current_execute && !c->done)

                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);

             last_execute = c->current_execute;

             our_job = self_id;
 
             if (c->done) {
                 pthread_mutex_unlock(&c->current_job_lock);
                 return NULL;
             }
         }
         pthread_mutex_unlock(&c->current_job_lock);
 
         c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
 
         pthread_mutex_lock(&c->current_job_lock);
         our_job = c->current_job++;
     }
 }
 
 static void slice_thread_uninit(ThreadContext *c)
 {
     int i;
 
     pthread_mutex_lock(&c->current_job_lock);
     c->done = 1;
     pthread_cond_broadcast(&c->current_job_cond);
     pthread_mutex_unlock(&c->current_job_lock);
 
     for (i = 0; i < c->nb_threads; i++)
          pthread_join(c->workers[i], NULL);
 
     pthread_mutex_destroy(&c->current_job_lock);
     pthread_cond_destroy(&c->current_job_cond);
     pthread_cond_destroy(&c->last_job_cond);
     av_freep(&c->workers);
 }
 
 static void slice_thread_park_workers(ThreadContext *c)
 {

     while (c->current_job != c->nb_threads + c->nb_jobs)
         pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);

     pthread_mutex_unlock(&c->current_job_lock);
 }
 

 static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,

                           void *arg, int *ret, int nb_jobs)
 {
     ThreadContext *c = ctx->graph->internal->thread;
     int dummy_ret;
 
     if (nb_jobs <= 0)
         return 0;
 
     pthread_mutex_lock(&c->current_job_lock);
 
     c->current_job = c->nb_threads;
     c->nb_jobs     = nb_jobs;
     c->ctx         = ctx;
     c->arg         = arg;
     c->func        = func;
     if (ret) {
         c->rets    = ret;
         c->nb_rets = nb_jobs;
     } else {
         c->rets    = &dummy_ret;
         c->nb_rets = 1;
     }

     c->current_execute++;
 

     pthread_cond_broadcast(&c->current_job_cond);
 
     slice_thread_park_workers(c);
 
     return 0;
 }
 

 static int thread_init_internal(ThreadContext *c, int nb_threads)

 {
     int i, ret;
 
     if (!nb_threads) {
         int nb_cpus = av_cpu_count();
         // use number of cores + 1 as thread count if there is more than one
         if (nb_cpus > 1)
             nb_threads = nb_cpus + 1;
         else
             nb_threads = 1;
     }
 
     if (nb_threads <= 1)
         return 1;
 
     c->nb_threads = nb_threads;
     c->workers = av_mallocz(sizeof(*c->workers) * nb_threads);
     if (!c->workers)
         return AVERROR(ENOMEM);
 
     c->current_job = 0;
     c->nb_jobs     = 0;
     c->done        = 0;
 
     pthread_cond_init(&c->current_job_cond, NULL);
     pthread_cond_init(&c->last_job_cond,    NULL);
 
     pthread_mutex_init(&c->current_job_lock, NULL);
     pthread_mutex_lock(&c->current_job_lock);
     for (i = 0; i < nb_threads; i++) {
         ret = pthread_create(&c->workers[i], NULL, worker, c);
         if (ret) {
            pthread_mutex_unlock(&c->current_job_lock);
            c->nb_threads = i;
            slice_thread_uninit(c);
            return AVERROR(ret);
         }
     }
 
     slice_thread_park_workers(c);
 
     return c->nb_threads;
 }
 
 int ff_graph_thread_init(AVFilterGraph *graph)
 {
     int ret;
 
 #if HAVE_W32THREADS
     w32thread_init();
 #endif
 
     if (graph->nb_threads == 1) {
         graph->thread_type = 0;
         return 0;
     }
 
     graph->internal->thread = av_mallocz(sizeof(ThreadContext));
     if (!graph->internal->thread)
         return AVERROR(ENOMEM);
 

     ret = thread_init_internal(graph->internal->thread, graph->nb_threads);

     if (ret <= 1) {
         av_freep(&graph->internal->thread);
         graph->thread_type = 0;
         graph->nb_threads  = 1;
         return (ret < 0) ? ret : 0;
     }
     graph->nb_threads = ret;
 
     graph->internal->thread_execute = thread_execute;
 
     return 0;
 }
 
 void ff_graph_thread_free(AVFilterGraph *graph)
 {
     if (graph->internal->thread)
         slice_thread_uninit(graph->internal->thread);
     av_freep(&graph->internal->thread);
 }