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ffmpeg / libavcodec / pthread.c @ 399cec2f

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/*
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 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2 of the License, or (at your option) any later version.
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 *
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 * This library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 */
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#include <semaphore.h>
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#include <pthread.h>
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//#define DEBUG
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#include "avcodec.h"
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#include "common.h"
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typedef struct JobContext{
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    sem_t available_sem;
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    int assigned;
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    int (*func)(AVCodecContext *c, void *arg);
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    void *arg;
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    int ret;
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}JobContext;
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typedef struct WorkerContext{
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    AVCodecContext *avctx;
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    pthread_t thread;
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    int start_index;
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    sem_t work_sem;
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    sem_t done_sem;
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}WorkerContext;
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typedef struct ThreadContext{
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    WorkerContext *worker;
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    JobContext *job;
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    int job_count;
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    int allocated_job_count;
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}ThreadContext;
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static void * thread_func(void *v){
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    WorkerContext *w= v;
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    ThreadContext *c= w->avctx->thread_opaque;
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    int i;
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    for(;;){
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X enter wait\n", (int)v);
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        sem_wait(&w->work_sem);
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X after wait\n", (int)v);
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        if(c->job_count == 0)
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           break;
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        for(i=0; i<c->job_count; i++){
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            int index= (i + w->start_index) % c->job_count;
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            JobContext *j= &c->job[index];
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X first check of %d\n", (int)v, index);
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            if(j->assigned) continue; //unsynced check, if != 0 it is already given to another worker, it never becomes available before the next execute() call so this should be safe
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X second check of %d\n", (int)v, index);
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            if(sem_trywait(&j->available_sem) == 0){
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                j->assigned=1;
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                j->ret= j->func(w->avctx, j->arg);
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X done %d\n", (int)v, index);
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            }
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        }
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//av_log(w->avctx, AV_LOG_DEBUG, "thread_func %X complete\n", (int)v);
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        sem_post(&w->done_sem);
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    }
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    return NULL;
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}
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/**
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 * free what has been allocated by avcodec_thread_init().
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 * must be called after decoding has finished, especially dont call while avcodec_thread_execute() is running
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 */
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void avcodec_thread_free(AVCodecContext *s){
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    ThreadContext *c= s->thread_opaque;
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    int i, val;
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    for(i=0; i<c->allocated_job_count; i++){
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        sem_getvalue(&c->job[i].available_sem, &val); assert(val == 0);
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        sem_destroy(&c->job[i].available_sem);
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    }
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    c->job_count= 0;
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    for(i=0; i<s->thread_count; i++){
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        sem_getvalue(&c->worker[i].work_sem, &val); assert(val == 0);
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        sem_getvalue(&c->worker[i].done_sem, &val); assert(val == 0);
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        sem_post(&c->worker[i].work_sem);
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        pthread_join(c->worker[i].thread, NULL);
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        sem_destroy(&c->worker[i].work_sem);
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        sem_destroy(&c->worker[i].done_sem);
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    }
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    av_freep(&c->job);
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    av_freep(&c->worker);
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    av_freep(&s->thread_opaque);
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}
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int avcodec_thread_execute(AVCodecContext *s, int (*func)(AVCodecContext *c2, void *arg2),void **arg, int *ret, int job_count){
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    ThreadContext *c= s->thread_opaque;
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    int i, val;
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    assert(s == c->avctx);
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    if(job_count > c->allocated_job_count){
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        c->job= av_realloc(c->job, job_count*sizeof(JobContext));
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        for(i=c->allocated_job_count; i<job_count; i++){
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            memset(&c->job[i], 0, sizeof(JobContext));
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            c->allocated_job_count++;
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            if(sem_init(&c->job[i].available_sem, 0, 0))
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                return -1;
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        }
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    }
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    c->job_count= job_count;
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    /* note, we can be certain that this is not called with the same AVCodecContext by different threads at the same time */
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    for(i=0; i<job_count; i++){
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        sem_getvalue(&c->job[i].available_sem, &val); assert(val == 0);
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        c->job[i].arg= arg[i];
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        c->job[i].func= func;
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        c->job[i].ret= 12345;
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        c->job[i].assigned= 0;
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        sem_post(&c->job[i].available_sem);
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    }
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    for(i=0; i<s->thread_count && i<job_count; i++){
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        sem_getvalue(&c->worker[i].work_sem, &val); assert(val == 0);
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        sem_getvalue(&c->worker[i].done_sem, &val); assert(val == 0);
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        c->worker[i].start_index= (i + job_count/2)/job_count;
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//av_log(s, AV_LOG_DEBUG, "start worker %d\n", i);
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        sem_post(&c->worker[i].work_sem);
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    }
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    for(i=0; i<s->thread_count && i<job_count; i++){
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//av_log(s, AV_LOG_DEBUG, "wait for worker %d\n", i);
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        sem_wait(&c->worker[i].done_sem);
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        sem_getvalue(&c->worker[i].work_sem, &val); assert(val == 0);
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        sem_getvalue(&c->worker[i].done_sem, &val); assert(val == 0);
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    }
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    for(i=0; i<job_count; i++){
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        sem_getvalue(&c->job[i].available_sem, &val); assert(val == 0);
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        c->job[i].func= NULL;
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        if(ret) ret[i]= c->job[i].ret;
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    }
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    return 0;
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}
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int avcodec_thread_init(AVCodecContext *s, int thread_count){
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    int i;
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    ThreadContext *c;
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    WorkerContext *worker;
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    s->thread_count= thread_count;
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    assert(!s->thread_opaque);
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    c= av_mallocz(sizeof(ThreadContext));
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    worker= av_mallocz(sizeof(WorkerContext)*thread_count);
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    s->thread_opaque= c;
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    c->worker= worker;
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    for(i=0; i<thread_count; i++){
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//printf("init semaphors %d\n", i); fflush(stdout);
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        worker[i].avctx= s;
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        if(sem_init(&worker[i].work_sem, 0, 0))
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            goto fail;
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        if(sem_init(&worker[i].done_sem, 0, 0))
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            goto fail;
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//printf("create thread %d\n", i); fflush(stdout);
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        if(pthread_create(&worker[i].thread, NULL, thread_func, &worker[i]))
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            goto fail;
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    }
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//printf("init done\n"); fflush(stdout);
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    s->execute= avcodec_thread_execute;
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    return 0;
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fail:
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    avcodec_thread_free(s);
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    return -1;
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}