/*

 * Copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at>

 *

 * 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

 */

#include <stdatomic.h>

#include "frame_thread_encoder.h"

#include "libavutil/avassert.h"

#include "libavutil/cpu.h"

#include "libavutil/mem.h"

#include "libavutil/opt.h"

#include "libavutil/thread.h"

#include "avcodec.h"

#include "avcodec_internal.h"

#include "codec_par.h"

#include "encode.h"

#include "internal.h"

#include "pthread_internal.h"

#define MAX_THREADS 64

/* There can be as many as MAX_THREADS + 1 outstanding tasks.

 * An additional + 1 is needed so that one can distinguish

 * the case of zero and MAX_THREADS + 1 outstanding tasks modulo

 * the number of buffers. */

#define BUFFER_SIZE (MAX_THREADS + 2)

typedef struct{

    AVFrame  *indata;

    AVPacket *outdata;

    int       return_code;

    int       finished;

    int       got_packet;

} Task;

typedef struct{

    AVCodecContext *parent_avctx;

    pthread_mutex_t task_fifo_mutex; /* Used to guard (next_)task_index */

    pthread_cond_t task_fifo_cond;

    unsigned pthread_init_cnt;

    unsigned max_tasks;

    Task tasks[BUFFER_SIZE];

    pthread_mutex_t finished_task_mutex; /* Guards tasks[i].finished */

    pthread_cond_t finished_task_cond;

    unsigned next_task_index;

    unsigned task_index;

    unsigned finished_task_index;

    pthread_t worker[MAX_THREADS];

    atomic_int exit;

} ThreadContext;

#define OFF(member) offsetof(ThreadContext, member)

DEFINE_OFFSET_ARRAY(ThreadContext, thread_ctx, pthread_init_cnt,

                    (OFF(task_fifo_mutex), OFF(finished_task_mutex)),

                    (OFF(task_fifo_cond),  OFF(finished_task_cond)));

#undef OFF

static void * attribute_align_arg worker(void *v){

    AVCodecContext *avctx = v;

    ThreadContext *c = avctx->internal->frame_thread_encoder;

    while (!atomic_load(&c->exit)) {

        int ret;

        AVPacket *pkt;

        AVFrame *frame;

        Task *task;

        unsigned task_index;

        pthread_mutex_lock(&c->task_fifo_mutex);

        while (c->next_task_index == c->task_index || atomic_load(&c->exit)) {

            if (atomic_load(&c->exit)) {

                pthread_mutex_unlock(&c->task_fifo_mutex);

                goto end;

            }

            pthread_cond_wait(&c->task_fifo_cond, &c->task_fifo_mutex);

        }

        task_index         = c->next_task_index;

        c->next_task_index = (c->next_task_index + 1) % c->max_tasks;

        pthread_mutex_unlock(&c->task_fifo_mutex);

        /* The main thread ensures that any two outstanding tasks have

         * different indices, ergo each worker thread owns its element

         * of c->tasks with the exception of finished, which is shared

         * with the main thread and guarded by finished_task_mutex. */

        task  = &c->tasks[task_index];

        frame = task->indata;

        pkt   = task->outdata;

        ret = ff_encode_encode_cb(avctx, pkt, frame, &task->got_packet);

        pthread_mutex_lock(&c->finished_task_mutex);

        task->return_code = ret;

        task->finished    = 1;

        pthread_cond_signal(&c->finished_task_cond);

        pthread_mutex_unlock(&c->finished_task_mutex);

    }

end:

    avcodec_free_context(&avctx);

    return NULL;

}

av_cold int ff_frame_thread_encoder_init(AVCodecContext *avctx)

{

    int i=0;

    ThreadContext *c;

    AVCodecContext *thread_avctx = NULL;

    AVCodecParameters *par = NULL;

    int ret;

    if(   !(avctx->thread_type & FF_THREAD_FRAME)

       || !(avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS))

        return 0;

    if(   !avctx->thread_count

       && avctx->codec_id == AV_CODEC_ID_MJPEG

       && !(avctx->flags & AV_CODEC_FLAG_QSCALE)) {

        av_log(avctx, AV_LOG_DEBUG,

               "Forcing thread count to 1 for MJPEG encoding, use -thread_type slice "

               "or a constant quantizer if you want to use multiple cpu cores\n");

        avctx->thread_count = 1;

    }

    if(   avctx->thread_count > 1

       && avctx->codec_id == AV_CODEC_ID_MJPEG

       && !(avctx->flags & AV_CODEC_FLAG_QSCALE))

        av_log(avctx, AV_LOG_WARNING,

               "MJPEG CBR encoding works badly with frame multi-threading, consider "

               "using -threads 1, -thread_type slice or a constant quantizer.\n");

    if (avctx->codec_id == AV_CODEC_ID_HUFFYUV ||

        avctx->codec_id == AV_CODEC_ID_FFVHUFF) {

        int warn = 0;

        int64_t tmp;

        if (avctx->flags & AV_CODEC_FLAG_PASS1)

            warn = 1;

        else if (av_opt_get_int(avctx->priv_data, "context", 0, &tmp) >= 0 &&

                 tmp > 0) {

            warn = av_opt_get_int(avctx->priv_data, "non_deterministic", 0, &tmp) < 0

                   || !tmp;

        }

        // huffyuv does not support these with multiple frame threads currently

        if (warn) {

            av_log(avctx, AV_LOG_WARNING,

               "Forcing thread count to 1 for huffyuv encoding with first pass or context 1\n");

            avctx->thread_count = 1;

        }

    }

    if(!avctx->thread_count) {

        avctx->thread_count = av_cpu_count();

        avctx->thread_count = FFMIN(avctx->thread_count, MAX_THREADS);

    }

    if(avctx->thread_count <= 1)

        return 0;

    if(avctx->thread_count > MAX_THREADS)

        return AVERROR(EINVAL);

    av_assert0(!avctx->internal->frame_thread_encoder);

    c = avctx->internal->frame_thread_encoder = av_mallocz(sizeof(ThreadContext));

    if(!c)

        return AVERROR(ENOMEM);

    c->parent_avctx = avctx;

    ret = ff_pthread_init(c, thread_ctx_offsets);

    if (ret < 0)

        goto fail;

    atomic_init(&c->exit, 0);

    c->max_tasks = avctx->thread_count + 2;

    for (unsigned j = 0; j < c->max_tasks; j++) {

        if (!(c->tasks[j].indata  = av_frame_alloc()) ||

            !(c->tasks[j].outdata = av_packet_alloc())) {

            ret = AVERROR(ENOMEM);

            goto fail;

        }

    }

    par = avcodec_parameters_alloc();

    if (!par) {

        ret = AVERROR(ENOMEM);

        goto fail;

    }

    ret = avcodec_parameters_from_context(par, avctx);

    if (ret < 0)

        goto fail;

    for(i=0; i<avctx->thread_count ; i++){

        thread_avctx = avcodec_alloc_context3(avctx->codec);

        if (!thread_avctx) {

            ret = AVERROR(ENOMEM);

            goto fail;

        }

        ret = avcodec_parameters_to_context(thread_avctx, par);

        if (ret < 0)

            goto fail;

        ret = av_opt_copy(thread_avctx, avctx);

        if (ret < 0)

            goto fail;

        if (avctx->codec->priv_class) {

            ret = av_opt_copy(thread_avctx->priv_data, avctx->priv_data);

            if (ret < 0)

                goto fail;

        }

        thread_avctx->thread_count = 1;

        thread_avctx->active_thread_type &= ~FF_THREAD_FRAME;

#define DUP_MATRIX(m)                                                       \

        if (avctx->m) {                                                     \

            thread_avctx->m = av_memdup(avctx->m, 64 * sizeof(*avctx->m));  \

            if (!thread_avctx->m) {                                         \

                ret = AVERROR(ENOMEM);                                      \

                goto fail;                                                  \

            }                                                               \

        }

        DUP_MATRIX(intra_matrix);

        DUP_MATRIX(chroma_intra_matrix);

        DUP_MATRIX(inter_matrix);

#undef DUP_MATRIX

        thread_avctx->opaque            = avctx->opaque;

        thread_avctx->get_encode_buffer = avctx->get_encode_buffer;

        thread_avctx->execute           = avctx->execute;

        thread_avctx->execute2          = avctx->execute2;

        thread_avctx->stats_in          = avctx->stats_in;

        if ((ret = avcodec_open2(thread_avctx, avctx->codec, NULL)) < 0)

            goto fail;

        av_assert0(!thread_avctx->internal->frame_thread_encoder);

        thread_avctx->internal->frame_thread_encoder = c;

        if ((ret = pthread_create(&c->worker[i], NULL, worker, thread_avctx))) {

            ret = AVERROR(ret);

            goto fail;

        }

    }

    avcodec_parameters_free(&par);

    avctx->active_thread_type = FF_THREAD_FRAME;

    return 0;

fail:

    avcodec_parameters_free(&par);

    avcodec_free_context(&thread_avctx);

    avctx->thread_count = i;

    av_log(avctx, AV_LOG_ERROR, "ff_frame_thread_encoder_init failed\n");

    ff_frame_thread_encoder_free(avctx);

    return ret;

}

av_cold void ff_frame_thread_encoder_free(AVCodecContext *avctx)

{

    ThreadContext *c= avctx->internal->frame_thread_encoder;

    /* In case initializing the mutexes/condition variables failed,

     * they must not be used. In this case the thread_count is zero

     * as no thread has been initialized yet. */

    if (avctx->thread_count > 0) {

        pthread_mutex_lock(&c->task_fifo_mutex);

        atomic_store(&c->exit, 1);

        pthread_cond_broadcast(&c->task_fifo_cond);

        pthread_mutex_unlock(&c->task_fifo_mutex);

        for (int i = 0; i < avctx->thread_count; i++)

            pthread_join(c->worker[i], NULL);

    }

    for (unsigned i = 0; i < c->max_tasks; i++) {

        av_frame_free(&c->tasks[i].indata);

        av_packet_free(&c->tasks[i].outdata);

    }

    ff_pthread_free(c, thread_ctx_offsets);

    av_freep(&avctx->internal->frame_thread_encoder);

}

int ff_thread_video_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

                                 AVFrame *frame, int *got_packet_ptr)

{

    ThreadContext *c = avctx->internal->frame_thread_encoder;

    Task *outtask;

    av_assert1(!*got_packet_ptr);

    if(frame){

        av_frame_move_ref(c->tasks[c->task_index].indata, frame);

        pthread_mutex_lock(&c->task_fifo_mutex);

        c->task_index = (c->task_index + 1) % c->max_tasks;

        pthread_cond_signal(&c->task_fifo_cond);

        pthread_mutex_unlock(&c->task_fifo_mutex);

    }

    outtask = &c->tasks[c->finished_task_index];

    pthread_mutex_lock(&c->finished_task_mutex);

    /* The access to task_index in the following code is ok,

     * because it is only ever changed by the main thread. */

    if (c->task_index == c->finished_task_index ||

        (frame && !outtask->finished &&

         (c->task_index - c->finished_task_index + c->max_tasks) % c->max_tasks <= avctx->thread_count)) {

            pthread_mutex_unlock(&c->finished_task_mutex);

            return 0;

        }

    while (!outtask->finished) {

        pthread_cond_wait(&c->finished_task_cond, &c->finished_task_mutex);

    }

    pthread_mutex_unlock(&c->finished_task_mutex);

    /* We now own outtask completely: No worker thread touches it any more,

     * because there is no outstanding task with this index. */

    outtask->finished = 0;

    av_packet_move_ref(pkt, outtask->outdata);

    *got_packet_ptr = outtask->got_packet;

    c->finished_task_index = (c->finished_task_index + 1) % c->max_tasks;

    return outtask->return_code;

}