/*
 * cache.h : deal with indexed LRU caches
 *
 * Copyright (c) 2008-2009 Jean-Pierre Andre
 *
 * This program/include file 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.
 *
 * This program/include file 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 this program (in the main directory of the NTFS-3G
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _NTFS_CACHE_H_
#define _NTFS_CACHE_H_

#include "volume.h"

struct CACHED_GENERIC
{
        struct CACHED_GENERIC *next;
        struct CACHED_GENERIC *previous;
        void *variable;
        size_t varsize;
        union
        {
                /* force alignment for pointers and u64 */
                u64 u64align;
                void *ptralign;
        } fixed[0];
};

struct CACHED_INODE
{
        struct CACHED_INODE *next;
        struct CACHED_INODE *previous;
        const char *pathname;
        size_t varsize;
        /* above fields must match "struct CACHED_GENERIC" */
        u64 inum;
};

struct CACHED_NIDATA
{
        struct CACHED_NIDATA *next;
        struct CACHED_NIDATA *previous;
        const char *pathname; /* not used */
        size_t varsize; /* not used */
        /* above fields must match "struct CACHED_GENERIC" */
        u64 inum;
        ntfs_inode *ni;
};

struct CACHED_LOOKUP
{
        struct CACHED_LOOKUP *next;
        struct CACHED_LOOKUP *previous;
        const char *name;
        size_t namesize;
        /* above fields must match "struct CACHED_GENERIC" */
        u64 parent;
        u64 inum;
};

enum
{
    CACHE_FREE = 1, CACHE_NOHASH = 2
};

typedef int (*cache_compare)(const struct CACHED_GENERIC *cached, const struct CACHED_GENERIC *item);
typedef void (*cache_free)(const struct CACHED_GENERIC *cached);
typedef int (*cache_hash)(const struct CACHED_GENERIC *cached);

struct HASH_ENTRY
{
        struct HASH_ENTRY *next;
        struct CACHED_GENERIC *entry;
};

struct CACHE_HEADER
{
        const char *name;
        struct CACHED_GENERIC *most_recent_entry;
        struct CACHED_GENERIC *oldest_entry;
        struct CACHED_GENERIC *free_entry;
        struct HASH_ENTRY *free_hash;
        struct HASH_ENTRY **first_hash;
        cache_free dofree;
        cache_hash dohash;
        unsigned long reads;
        unsigned long writes;
        unsigned long hits;
        int fixed_size;
        int max_hash;
        struct CACHED_GENERIC entry[0];
};

/* cast to generic, avoiding gcc warnings */
#define GENERIC(pstr) ((const struct CACHED_GENERIC*)(const void*)(pstr))

struct CACHED_GENERIC *ntfs_fetch_cache(struct CACHE_HEADER *cache, const struct CACHED_GENERIC *wanted,
        cache_compare compare);
struct CACHED_GENERIC *ntfs_enter_cache(struct CACHE_HEADER *cache, const struct CACHED_GENERIC *item,
        cache_compare compare);
int ntfs_invalidate_cache(struct CACHE_HEADER *cache, const struct CACHED_GENERIC *item, cache_compare compare,
        int flags);
int ntfs_remove_cache(struct CACHE_HEADER *cache, struct CACHED_GENERIC *item, int flags);

void ntfs_create_lru_caches(ntfs_volume *vol);
void ntfs_free_lru_caches(ntfs_volume *vol);

#endif /* _NTFS_CACHE_H_ */