/*
 * 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_ */