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/*

 *

 * 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 

#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);

}