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read_cache.c    353 lines (300 with data), 11.4 kB

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/*
* Copyright (C) 2000 Rich Wareham <richwareham@users.sourceforge.net>
* 2001-2004 the dvdnav project
*
* This file is part of libdvdnav, a DVD navigation library.
*
* libdvdnav is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* libdvdnav 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with libdvdnav; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* There was a multithreaded read ahead cache in here for some time, but
* it had only been used for a short time. If you want to have a look at it,
* search the CVS attic.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <inttypes.h>
#include <stdlib.h>
#include <limits.h>
#include <sys/time.h>
#include <time.h>
#include "dvdnav/dvdnav.h"
#include <dvdread/nav_types.h>
#include <dvdread/ifo_types.h>
#include "remap.h"
#include "vm/decoder.h"
#include "vm/vm.h"
#include "dvdnav_internal.h"
#include "read_cache.h"
#define READ_CACHE_CHUNKS 10
/* all cache chunks must be memory aligned to allow use of raw devices */
#define ALIGNMENT 2048
#define READ_AHEAD_SIZE_MIN 4
#define READ_AHEAD_SIZE_MAX 512
typedef struct read_cache_chunk_s {
uint8_t *cache_buffer;
uint8_t *cache_buffer_base; /* used in malloc and free for alignment */
int32_t cache_start_sector; /* -1 means cache invalid */
int32_t cache_read_count; /* this many sectors are already read */
size_t cache_block_count; /* this many sectors will go in this chunk */
size_t cache_malloc_size;
int cache_valid;
int usage_count; /* counts how many buffers where issued from this chunk */
} read_cache_chunk_t;
struct read_cache_s {
read_cache_chunk_t chunk[READ_CACHE_CHUNKS];
int current;
int freeing; /* is set to one when we are about to dispose the cache */
uint32_t read_ahead_size;
int read_ahead_incr;
int last_sector;
pthread_mutex_t lock;
/* Bit of strange cross-linking going on here :) -- Gotta love C :) */
dvdnav_t *dvd_self;
};
/*
#define READ_CACHE_TRACE 0
*/
#ifdef __GNUC__
# if READ_CACHE_TRACE
# define dprintf(fmt, args...) fprintf(MSG_OUT, "libdvdnav: %s: "fmt, __func__ , ## args)
# else
# define dprintf(fmt, args...) /* Nowt */
# endif
#else
# if READ_CACHE_TRACE
# define dprintf(fmt, ...) fprintf(MSG_OUT, "libdvdnav: %s: "fmt, __func__ , __VA_ARGS__)
# else
#ifdef _MSC_VER
# define dprintf(fmt, str) /* Nowt */
#else
# define dprintf(fmt, ...) /* Nowt */
#endif /* _MSC_VER */
# endif
#endif
read_cache_t *dvdnav_read_cache_new(dvdnav_t* dvd_self) {
read_cache_t *self;
int i;
self = (read_cache_t *)malloc(sizeof(read_cache_t));
if(self) {
self->current = 0;
self->freeing = 0;
self->dvd_self = dvd_self;
self->last_sector = 0;
self->read_ahead_size = READ_AHEAD_SIZE_MIN;
self->read_ahead_incr = 0;
pthread_mutex_init(&self->lock, NULL);
dvdnav_read_cache_clear(self);
for (i = 0; i < READ_CACHE_CHUNKS; i++) {
self->chunk[i].cache_buffer = NULL;
self->chunk[i].usage_count = 0;
}
}
return self;
}
void dvdnav_read_cache_free(read_cache_t* self) {
dvdnav_t *tmp;
int i;
pthread_mutex_lock(&self->lock);
self->freeing = 1;
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (self->chunk[i].cache_buffer && self->chunk[i].usage_count == 0) {
free(self->chunk[i].cache_buffer_base);
self->chunk[i].cache_buffer = NULL;
}
pthread_mutex_unlock(&self->lock);
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (self->chunk[i].cache_buffer) return;
/* all buffers returned, free everything */
tmp = self->dvd_self;
pthread_mutex_destroy(&self->lock);
free(self);
free(tmp);
}
/* This function MUST be called whenever self->file changes. */
void dvdnav_read_cache_clear(read_cache_t *self) {
int i;
if(!self)
return;
pthread_mutex_lock(&self->lock);
for (i = 0; i < READ_CACHE_CHUNKS; i++)
self->chunk[i].cache_valid = 0;
pthread_mutex_unlock(&self->lock);
}
/* This function is called just after reading the NAV packet. */
void dvdnav_pre_cache_blocks(read_cache_t *self, int sector, size_t block_count) {
int i, use;
if(!self)
return;
if(!self->dvd_self->use_read_ahead)
return;
pthread_mutex_lock(&self->lock);
/* find a free cache chunk that best fits the required size */
use = -1;
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (self->chunk[i].usage_count == 0 && self->chunk[i].cache_buffer &&
self->chunk[i].cache_malloc_size >= block_count &&
(use == -1 || self->chunk[use].cache_malloc_size > self->chunk[i].cache_malloc_size))
use = i;
if (use == -1) {
/* we haven't found a cache chunk, so we try to reallocate an existing one */
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (self->chunk[i].usage_count == 0 && self->chunk[i].cache_buffer &&
(use == -1 || self->chunk[use].cache_malloc_size < self->chunk[i].cache_malloc_size))
use = i;
if (use >= 0) {
self->chunk[use].cache_buffer_base = realloc(self->chunk[use].cache_buffer_base,
block_count * DVD_VIDEO_LB_LEN + ALIGNMENT);
self->chunk[use].cache_buffer =
(uint8_t *)(((uintptr_t)self->chunk[use].cache_buffer_base & ~((uintptr_t)(ALIGNMENT - 1))) + ALIGNMENT);
dprintf("pre_cache DVD read realloc happened\n");
self->chunk[use].cache_malloc_size = block_count;
} else {
/* we still haven't found a cache chunk, let's allocate a new one */
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (!self->chunk[i].cache_buffer) {
use = i;
break;
}
if (use >= 0) {
/* We start with a sensible figure for the first malloc of 500 blocks.
* Some DVDs I have seen venture to 450 blocks.
* This is so that fewer realloc's happen if at all.
*/
self->chunk[i].cache_buffer_base =
malloc((block_count > 500 ? block_count : 500) * DVD_VIDEO_LB_LEN + ALIGNMENT);
self->chunk[i].cache_buffer =
(uint8_t *)(((uintptr_t)self->chunk[i].cache_buffer_base & ~((uintptr_t)(ALIGNMENT - 1))) + ALIGNMENT);
self->chunk[i].cache_malloc_size = block_count > 500 ? block_count : 500;
dprintf("pre_cache DVD read malloc %d blocks\n",
(block_count > 500 ? block_count : 500 ));
}
}
}
if (use >= 0) {
self->chunk[use].cache_start_sector = sector;
self->chunk[use].cache_block_count = block_count;
self->chunk[use].cache_read_count = 0;
self->chunk[use].cache_valid = 1;
self->current = use;
} else {
dprintf("pre_caching was impossible, no cache chunk available\n");
}
pthread_mutex_unlock(&self->lock);
}
int dvdnav_read_cache_block(read_cache_t *self, int sector, size_t block_count, uint8_t **buf) {
int i, use;
int start;
int size;
int incr;
uint8_t *read_ahead_buf;
int32_t res;
if(!self)
return 0;
use = -1;
if(self->dvd_self->use_read_ahead) {
/* first check, if sector is in current chunk */
read_cache_chunk_t cur = self->chunk[self->current];
if (cur.cache_valid && sector >= cur.cache_start_sector &&
sector <= (cur.cache_start_sector + cur.cache_read_count) &&
sector + block_count <= cur.cache_start_sector + cur.cache_block_count)
use = self->current;
else
for (i = 0; i < READ_CACHE_CHUNKS; i++)
if (self->chunk[i].cache_valid &&
sector >= self->chunk[i].cache_start_sector &&
sector <= (self->chunk[i].cache_start_sector + self->chunk[i].cache_read_count) &&
sector + block_count <= self->chunk[i].cache_start_sector + self->chunk[i].cache_block_count)
use = i;
}
if (use >= 0) {
read_cache_chunk_t *chunk;
/* Increment read-ahead size if sector follows the last sector */
if (sector == (self->last_sector + 1)) {
if (self->read_ahead_incr < READ_AHEAD_SIZE_MAX)
self->read_ahead_incr++;
} else {
self->read_ahead_size = READ_AHEAD_SIZE_MIN;
self->read_ahead_incr = 0;
}
self->last_sector = sector;
/* The following resources need to be protected by a mutex :
* self->chunk[*].cache_buffer
* self->chunk[*].cache_malloc_size
* self->chunk[*].usage_count
*/
pthread_mutex_lock(&self->lock);
chunk = &self->chunk[use];
read_ahead_buf = chunk->cache_buffer + chunk->cache_read_count * DVD_VIDEO_LB_LEN;
*buf = chunk->cache_buffer + (sector - chunk->cache_start_sector) * DVD_VIDEO_LB_LEN;
chunk->usage_count++;
pthread_mutex_unlock(&self->lock);
dprintf("libdvdnav: sector=%d, start_sector=%d, last_sector=%d\n", sector, chunk->cache_start_sector, chunk->cache_start_sector + chunk->cache_block_count);
/* read_ahead_size */
incr = self->read_ahead_incr >> 1;
if ((self->read_ahead_size + incr) > READ_AHEAD_SIZE_MAX) {
self->read_ahead_size = READ_AHEAD_SIZE_MAX;
} else {
self->read_ahead_size += incr;
}
/* real read size */
start = chunk->cache_start_sector + chunk->cache_read_count;
if (chunk->cache_read_count + self->read_ahead_size > chunk->cache_block_count) {
size = chunk->cache_block_count - chunk->cache_read_count;
} else {
size = self->read_ahead_size;
/* ensure that the sector we want will be read */
if (sector >= chunk->cache_start_sector + chunk->cache_read_count + size)
size = sector - chunk->cache_start_sector - chunk->cache_read_count;
}
dprintf("libdvdnav: read_ahead_size=%d, size=%d\n", self->read_ahead_size, size);
if (size)
chunk->cache_read_count += DVDReadBlocks(self->dvd_self->file,
start,
size,
read_ahead_buf);
res = DVD_VIDEO_LB_LEN * block_count;
} else {
if (self->dvd_self->use_read_ahead)
dprintf("cache miss on sector %d\n", sector);
res = DVDReadBlocks(self->dvd_self->file,
sector,
block_count,
*buf) * DVD_VIDEO_LB_LEN;
}
return res;
}
dvdnav_status_t dvdnav_free_cache_block(dvdnav_t *self, unsigned char *buf) {
read_cache_t *cache;
int i;
if (!self)
return DVDNAV_STATUS_ERR;
cache = self->cache;
if (!cache)
return DVDNAV_STATUS_ERR;
pthread_mutex_lock(&cache->lock);
for (i = 0; i < READ_CACHE_CHUNKS; i++) {
if (cache->chunk[i].cache_buffer && buf >= cache->chunk[i].cache_buffer &&
buf < cache->chunk[i].cache_buffer + cache->chunk[i].cache_malloc_size * DVD_VIDEO_LB_LEN) {
cache->chunk[i].usage_count--;
}
}
pthread_mutex_unlock(&cache->lock);
if (cache->freeing)
/* when we want to dispose the cache, try freeing it now */
dvdnav_read_cache_free(cache);
return DVDNAV_STATUS_OK;
}