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