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Diffstat (limited to 'libavformat/cache.c')
-rw-r--r-- | libavformat/cache.c | 322 |
1 files changed, 322 insertions, 0 deletions
diff --git a/libavformat/cache.c b/libavformat/cache.c new file mode 100644 index 0000000..d3d12bb --- /dev/null +++ b/libavformat/cache.c @@ -0,0 +1,322 @@ +/* + * 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, +}; 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