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libavcodec/pthread.c

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00001 /*
00002  * Copyright (c) 2004 Roman Shaposhnik
00003  *
00004  * Many thanks to Steven M. Schultz for providing clever ideas and
00005  * to Michael Niedermayer <michaelni@gmx.at> for writing initial
00006  * implementation.
00007  *
00008  * This file is part of FFmpeg.
00009  *
00010  * FFmpeg is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * FFmpeg is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with FFmpeg; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 #include <pthread.h>
00025 
00026 #include "avcodec.h"
00027 
00028 typedef int (action_func)(AVCodecContext *c, void *arg);
00029 typedef int (action_func2)(AVCodecContext *c, void *arg, int jobnr, int threadnr);
00030 
00031 typedef struct ThreadContext {
00032     pthread_t *workers;
00033     action_func *func;
00034     action_func2 *func2;
00035     void *args;
00036     int *rets;
00037     int rets_count;
00038     int job_count;
00039     int job_size;
00040 
00041     pthread_cond_t last_job_cond;
00042     pthread_cond_t current_job_cond;
00043     pthread_mutex_t current_job_lock;
00044     int current_job;
00045     int done;
00046 } ThreadContext;
00047 
00048 static void* attribute_align_arg worker(void *v)
00049 {
00050     AVCodecContext *avctx = v;
00051     ThreadContext *c = avctx->thread_opaque;
00052     int our_job = c->job_count;
00053     int thread_count = avctx->thread_count;
00054     int self_id;
00055 
00056     pthread_mutex_lock(&c->current_job_lock);
00057     self_id = c->current_job++;
00058     for (;;){
00059         while (our_job >= c->job_count) {
00060             if (c->current_job == thread_count + c->job_count)
00061                 pthread_cond_signal(&c->last_job_cond);
00062 
00063             pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
00064             our_job = self_id;
00065 
00066             if (c->done) {
00067                 pthread_mutex_unlock(&c->current_job_lock);
00068                 return NULL;
00069             }
00070         }
00071         pthread_mutex_unlock(&c->current_job_lock);
00072 
00073         c->rets[our_job%c->rets_count] = c->func ? c->func(avctx, (char*)c->args + our_job*c->job_size):
00074                                                    c->func2(avctx, c->args, our_job, self_id);
00075 
00076         pthread_mutex_lock(&c->current_job_lock);
00077         our_job = c->current_job++;
00078     }
00079 }
00080 
00081 static av_always_inline void avcodec_thread_park_workers(ThreadContext *c, int thread_count)
00082 {
00083     pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
00084     pthread_mutex_unlock(&c->current_job_lock);
00085 }
00086 
00087 void avcodec_thread_free(AVCodecContext *avctx)
00088 {
00089     ThreadContext *c = avctx->thread_opaque;
00090     int i;
00091 
00092     pthread_mutex_lock(&c->current_job_lock);
00093     c->done = 1;
00094     pthread_cond_broadcast(&c->current_job_cond);
00095     pthread_mutex_unlock(&c->current_job_lock);
00096 
00097     for (i=0; i<avctx->thread_count; i++)
00098          pthread_join(c->workers[i], NULL);
00099 
00100     pthread_mutex_destroy(&c->current_job_lock);
00101     pthread_cond_destroy(&c->current_job_cond);
00102     pthread_cond_destroy(&c->last_job_cond);
00103     av_free(c->workers);
00104     av_freep(&avctx->thread_opaque);
00105 }
00106 
00107 static int avcodec_thread_execute(AVCodecContext *avctx, action_func* func, void *arg, int *ret, int job_count, int job_size)
00108 {
00109     ThreadContext *c= avctx->thread_opaque;
00110     int dummy_ret;
00111 
00112     if (job_count <= 0)
00113         return 0;
00114 
00115     pthread_mutex_lock(&c->current_job_lock);
00116 
00117     c->current_job = avctx->thread_count;
00118     c->job_count = job_count;
00119     c->job_size = job_size;
00120     c->args = arg;
00121     c->func = func;
00122     if (ret) {
00123         c->rets = ret;
00124         c->rets_count = job_count;
00125     } else {
00126         c->rets = &dummy_ret;
00127         c->rets_count = 1;
00128     }
00129     pthread_cond_broadcast(&c->current_job_cond);
00130 
00131     avcodec_thread_park_workers(c, avctx->thread_count);
00132 
00133     return 0;
00134 }
00135 
00136 static int avcodec_thread_execute2(AVCodecContext *avctx, action_func2* func2, void *arg, int *ret, int job_count)
00137 {
00138     ThreadContext *c= avctx->thread_opaque;
00139     c->func2 = func2;
00140     return avcodec_thread_execute(avctx, NULL, arg, ret, job_count, 0);
00141 }
00142 
00143 int avcodec_thread_init(AVCodecContext *avctx, int thread_count)
00144 {
00145     int i;
00146     ThreadContext *c;
00147 
00148     avctx->thread_count = thread_count;
00149 
00150     if (thread_count <= 1)
00151         return 0;
00152 
00153     c = av_mallocz(sizeof(ThreadContext));
00154     if (!c)
00155         return -1;
00156 
00157     c->workers = av_mallocz(sizeof(pthread_t)*thread_count);
00158     if (!c->workers) {
00159         av_free(c);
00160         return -1;
00161     }
00162 
00163     avctx->thread_opaque = c;
00164     c->current_job = 0;
00165     c->job_count = 0;
00166     c->job_size = 0;
00167     c->done = 0;
00168     pthread_cond_init(&c->current_job_cond, NULL);
00169     pthread_cond_init(&c->last_job_cond, NULL);
00170     pthread_mutex_init(&c->current_job_lock, NULL);
00171     pthread_mutex_lock(&c->current_job_lock);
00172     for (i=0; i<thread_count; i++) {
00173         if(pthread_create(&c->workers[i], NULL, worker, avctx)) {
00174            avctx->thread_count = i;
00175            pthread_mutex_unlock(&c->current_job_lock);
00176            avcodec_thread_free(avctx);
00177            return -1;
00178         }
00179     }
00180 
00181     avcodec_thread_park_workers(c, thread_count);
00182 
00183     avctx->execute = avcodec_thread_execute;
00184     avctx->execute2 = avcodec_thread_execute2;
00185     return 0;
00186 }

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