mirror of
https://github.com/FFmpeg/FFmpeg.git
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ca2e3e47fc
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
323 lines
8.6 KiB
C
323 lines
8.6 KiB
C
/*
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* Input cache protocol.
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* Copyright (c) 2011,2014 Michael Niedermayer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg 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 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Based on file.c by Fabrice Bellard
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*/
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/**
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* @TODO
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* support keeping files
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* support filling with a background thread
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*/
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#include "libavutil/avassert.h"
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#include "libavutil/avstring.h"
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#include "libavutil/file.h"
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#include "libavutil/opt.h"
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#include "libavutil/tree.h"
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#include "avformat.h"
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#include <fcntl.h>
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#if HAVE_IO_H
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#include <io.h>
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#endif
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <sys/stat.h>
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#include <stdlib.h>
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#include "os_support.h"
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#include "url.h"
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typedef struct CacheEntry {
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int64_t logical_pos;
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int64_t physical_pos;
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int size;
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} CacheEntry;
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typedef struct Context {
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AVClass *class;
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int fd;
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struct AVTreeNode *root;
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int64_t logical_pos;
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int64_t cache_pos;
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int64_t inner_pos;
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int64_t end;
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int is_true_eof;
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URLContext *inner;
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int64_t cache_hit, cache_miss;
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int read_ahead_limit;
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} Context;
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static int cmp(void *key, const void *node)
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{
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return (*(int64_t *) key) - ((const CacheEntry *) node)->logical_pos;
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}
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static int cache_open(URLContext *h, const char *arg, int flags, AVDictionary **options)
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{
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char *buffername;
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Context *c= h->priv_data;
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av_strstart(arg, "cache:", &arg);
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c->fd = av_tempfile("ffcache", &buffername, 0, h);
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if (c->fd < 0){
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av_log(h, AV_LOG_ERROR, "Failed to create tempfile\n");
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return c->fd;
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}
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unlink(buffername);
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av_freep(&buffername);
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return ffurl_open(&c->inner, arg, flags, &h->interrupt_callback, options);
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}
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static int add_entry(URLContext *h, const unsigned char *buf, int size)
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{
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Context *c= h->priv_data;
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int64_t pos = -1;
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int ret;
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CacheEntry *entry = NULL, *next[2] = {NULL, NULL};
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CacheEntry *entry_ret;
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struct AVTreeNode *node = NULL;
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//FIXME avoid lseek
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pos = lseek(c->fd, 0, SEEK_END);
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if (pos < 0) {
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ret = AVERROR(errno);
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av_log(h, AV_LOG_ERROR, "seek in cache failed\n");
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goto fail;
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}
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c->cache_pos = pos;
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ret = write(c->fd, buf, size);
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if (ret < 0) {
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ret = AVERROR(errno);
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av_log(h, AV_LOG_ERROR, "write in cache failed\n");
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goto fail;
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}
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c->cache_pos += ret;
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entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);
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if (!entry)
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entry = next[0];
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if (!entry ||
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entry->logical_pos + entry->size != c->logical_pos ||
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entry->physical_pos + entry->size != pos
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) {
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entry = av_malloc(sizeof(*entry));
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node = av_tree_node_alloc();
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if (!entry || !node) {
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ret = AVERROR(ENOMEM);
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goto fail;
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}
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entry->logical_pos = c->logical_pos;
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entry->physical_pos = pos;
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entry->size = ret;
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entry_ret = av_tree_insert(&c->root, entry, cmp, &node);
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if (entry_ret && entry_ret != entry) {
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ret = -1;
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av_log(h, AV_LOG_ERROR, "av_tree_insert failed\n");
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goto fail;
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}
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} else
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entry->size += ret;
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return 0;
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fail:
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//we could truncate the file to pos here if pos >=0 but ftruncate isnt available in VS so
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//for simplicty we just leave the file a bit larger
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av_free(entry);
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av_free(node);
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return ret;
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}
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static int cache_read(URLContext *h, unsigned char *buf, int size)
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{
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Context *c= h->priv_data;
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CacheEntry *entry, *next[2] = {NULL, NULL};
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int r;
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entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);
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if (!entry)
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entry = next[0];
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if (entry) {
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int64_t in_block_pos = c->logical_pos - entry->logical_pos;
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av_assert0(entry->logical_pos <= c->logical_pos);
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if (in_block_pos < entry->size) {
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int64_t physical_target = entry->physical_pos + in_block_pos;
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if (c->cache_pos != physical_target) {
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r = lseek(c->fd, physical_target, SEEK_SET);
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} else
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r = c->cache_pos;
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if (r >= 0) {
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c->cache_pos = r;
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r = read(c->fd, buf, FFMIN(size, entry->size - in_block_pos));
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}
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if (r > 0) {
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c->cache_pos += r;
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c->logical_pos += r;
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c->cache_hit ++;
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return r;
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}
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}
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}
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// Cache miss or some kind of fault with the cache
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if (c->logical_pos != c->inner_pos) {
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r = ffurl_seek(c->inner, c->logical_pos, SEEK_SET);
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if (r<0) {
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av_log(h, AV_LOG_ERROR, "Failed to perform internal seek\n");
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return r;
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}
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c->inner_pos = r;
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}
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r = ffurl_read(c->inner, buf, size);
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if (r == 0 && size>0) {
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c->is_true_eof = 1;
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av_assert0(c->end >= c->logical_pos);
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}
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if (r<=0)
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return r;
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c->inner_pos += r;
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c->cache_miss ++;
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add_entry(h, buf, r);
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c->logical_pos += r;
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c->end = FFMAX(c->end, c->logical_pos);
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return r;
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}
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static int64_t cache_seek(URLContext *h, int64_t pos, int whence)
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{
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Context *c= h->priv_data;
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int64_t ret;
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if (whence == AVSEEK_SIZE) {
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pos= ffurl_seek(c->inner, pos, whence);
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if(pos <= 0){
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pos= ffurl_seek(c->inner, -1, SEEK_END);
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if (ffurl_seek(c->inner, c->inner_pos, SEEK_SET) < 0)
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av_log(h, AV_LOG_ERROR, "Inner protocol failed to seekback end : %"PRId64"\n", pos);
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}
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if (pos > 0)
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c->is_true_eof = 1;
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c->end = FFMAX(c->end, pos);
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return pos;
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}
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if (whence == SEEK_CUR) {
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whence = SEEK_SET;
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pos += c->logical_pos;
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} else if (whence == SEEK_END && c->is_true_eof) {
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resolve_eof:
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whence = SEEK_SET;
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pos += c->end;
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}
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if (whence == SEEK_SET && pos >= 0 && pos < c->end) {
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//Seems within filesize, assume it will not fail.
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c->logical_pos = pos;
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return pos;
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}
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//cache miss
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ret= ffurl_seek(c->inner, pos, whence);
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if ((whence == SEEK_SET && pos >= c->logical_pos ||
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whence == SEEK_END && pos <= 0) && ret < 0) {
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if ( (whence == SEEK_SET && c->read_ahead_limit >= pos - c->logical_pos)
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|| c->read_ahead_limit < 0) {
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uint8_t tmp[32768];
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while (c->logical_pos < pos || whence == SEEK_END) {
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int size = sizeof(tmp);
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if (whence == SEEK_SET)
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size = FFMIN(sizeof(tmp), pos - c->logical_pos);
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ret = cache_read(h, tmp, size);
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if (ret == 0 && whence == SEEK_END) {
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av_assert0(c->is_true_eof);
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goto resolve_eof;
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}
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if (ret < 0) {
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return ret;
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}
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}
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return c->logical_pos;
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}
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}
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if (ret >= 0) {
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c->logical_pos = ret;
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c->end = FFMAX(c->end, ret);
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}
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return ret;
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}
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static int cache_close(URLContext *h)
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{
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Context *c= h->priv_data;
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av_log(h, AV_LOG_INFO, "Statistics, cache hits:%"PRId64" cache misses:%"PRId64"\n",
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c->cache_hit, c->cache_miss);
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close(c->fd);
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ffurl_close(c->inner);
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av_tree_destroy(c->root);
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return 0;
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}
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#define OFFSET(x) offsetof(Context, x)
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#define D AV_OPT_FLAG_DECODING_PARAM
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static const AVOption options[] = {
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{ "read_ahead_limit", "Amount in bytes that may be read ahead when seeking isnt supported, -1 for unlimited", OFFSET(read_ahead_limit), AV_OPT_TYPE_INT, { .i64 = 65536 }, -1, INT_MAX, D },
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{NULL},
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};
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static const AVClass cache_context_class = {
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.class_name = "Cache",
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.item_name = av_default_item_name,
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.option = options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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URLProtocol ff_cache_protocol = {
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.name = "cache",
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.url_open2 = cache_open,
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.url_read = cache_read,
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.url_seek = cache_seek,
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.url_close = cache_close,
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.priv_data_size = sizeof(Context),
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.priv_data_class = &cache_context_class,
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};
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