[thirdparty/xfsprogs-dev.git] / include / cache.h

/*
 * Copyright (c) 2006 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program 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.
 *
 * This program is distributed in the hope that it would 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; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __CACHE_H__
#define __CACHE_H__

/*
 * initialisation flags
 */
/*
 * xfs_db always writes changes immediately, and so we need to purge buffers
 * when we get a buffer lookup mismatch due to reading the same block with a
 * different buffer configuration.
 */
#define CACHE_MISCOMPARE_PURGE	(1 << 0)

/*
 * cache object campare return values
 */
enum {
	CACHE_HIT,
	CACHE_MISS,
	CACHE_PURGE,
};

#define	HASH_CACHE_RATIO	8

/*
 * Cache priorities range from BASE to MAX.
 *
 * For prefetch support, the top half of the range starts at
 * CACHE_PREFETCH_PRIORITY and everytime the buffer is fetched and is at or
 * above this priority level, it is reduced to below this level (refer to
 * libxfs_getbuf).
 *
 * If we have dirty nodes, we can't recycle them until they've been cleaned. To
 * keep these out of the reclaimable lists (as there can be lots of them) give
 * them their own priority that the shaker doesn't attempt to walk.
 */

#define CACHE_BASE_PRIORITY	0
#define CACHE_PREFETCH_PRIORITY	8
#define CACHE_MAX_PRIORITY	15
#define CACHE_DIRTY_PRIORITY	(CACHE_MAX_PRIORITY + 1)
#define CACHE_NR_PRIORITIES	CACHE_DIRTY_PRIORITY

/*
 * Simple, generic implementation of a cache (arbitrary data).
 * Provides a hash table with a capped number of cache entries.
 */

struct cache;
struct cache_node;

typedef void *cache_key_t;

typedef void (*cache_walk_t)(struct cache_node *);
typedef struct cache_node * (*cache_node_alloc_t)(cache_key_t);
typedef int (*cache_node_flush_t)(struct cache_node *);
typedef void (*cache_node_relse_t)(struct cache_node *);
typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int,
					  unsigned int);
typedef int (*cache_node_compare_t)(struct cache_node *, cache_key_t);
typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);

struct cache_operations {
	cache_node_hash_t	hash;
	cache_node_alloc_t	alloc;
	cache_node_flush_t	flush;
	cache_node_relse_t	relse;
	cache_node_compare_t	compare;
	cache_bulk_relse_t	bulkrelse;	/* optional */
};

struct cache_hash {
	struct list_head	ch_list;	/* hash chain head */
	unsigned int		ch_count;	/* hash chain length */
	pthread_mutex_t		ch_mutex;	/* hash chain mutex */
};

struct cache_mru {
	struct list_head	cm_list;	/* MRU head */
	unsigned int		cm_count;	/* MRU length */
	pthread_mutex_t		cm_mutex;	/* MRU lock */
};

struct cache_node {
	struct list_head	cn_hash;	/* hash chain */
	struct list_head	cn_mru;		/* MRU chain */
	unsigned int		cn_count;	/* reference count */
	unsigned int		cn_hashidx;	/* hash chain index */
	int			cn_priority;	/* priority, -1 = free list */
	int			cn_old_priority;/* saved pre-dirty prio */
	pthread_mutex_t		cn_mutex;	/* node mutex */
};

struct cache {
	int			c_flags;	/* behavioural flags */
	unsigned int		c_maxcount;	/* max cache nodes */
	unsigned int		c_count;	/* count of nodes */
	pthread_mutex_t		c_mutex;	/* node count mutex */
	cache_node_hash_t	hash;		/* node hash function */
	cache_node_alloc_t	alloc;		/* allocation function */
	cache_node_flush_t	flush;		/* flush dirty data function */
	cache_node_relse_t	relse;		/* memory free function */
	cache_node_compare_t	compare;	/* comparison routine */
	cache_bulk_relse_t	bulkrelse;	/* bulk release routine */
	unsigned int		c_hashsize;	/* hash bucket count */
	unsigned int		c_hashshift;	/* hash key shift */
	struct cache_hash	*c_hash;	/* hash table buckets */
	struct cache_mru	c_mrus[CACHE_DIRTY_PRIORITY + 1];
	unsigned long long	c_misses;	/* cache misses */
	unsigned long long	c_hits;		/* cache hits */
	unsigned int 		c_max;		/* max nodes ever used */
};

struct cache *cache_init(int, unsigned int, struct cache_operations *);
void cache_destroy(struct cache *);
void cache_walk(struct cache *, cache_walk_t);
void cache_purge(struct cache *);
void cache_flush(struct cache *);

int cache_node_get(struct cache *, cache_key_t, struct cache_node **);
void cache_node_put(struct cache *, struct cache_node *);
void cache_node_set_priority(struct cache *, struct cache_node *, int);
int cache_node_get_priority(struct cache_node *);
int cache_node_purge(struct cache *, cache_key_t, struct cache_node *);
void cache_report(FILE *fp, const char *, struct cache *);
int cache_overflowed(struct cache *);

#endif	/* __CACHE_H__ */
Commit	Line	Data
e80aa729 NS	1	/*
	2	* Copyright (c) 2006 Silicon Graphics, Inc.
	3	* All Rights Reserved.
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License as
	7	* published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope that it would be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write the Free Software Foundation,
	16	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	17	*/
	18	#ifndef __CACHE_H__
	19	#define __CACHE_H__
	20
ba9ecd40 DC	21	/*
	22	* initialisation flags
	23	*/
	24	/*
	25	* xfs_db always writes changes immediately, and so we need to purge buffers
	26	* when we get a buffer lookup mismatch due to reading the same block with a
	27	* different buffer configuration.
	28	*/
	29	#define CACHE_MISCOMPARE_PURGE (1 << 0)
	30
	31	/*
	32	* cache object campare return values
	33	*/
	34	enum {
	35	CACHE_HIT,
	36	CACHE_MISS,
	37	CACHE_PURGE,
	38	};
	39
2556c98b BN	40	#define HASH_CACHE_RATIO 8
2556c98b BN	41
a040d7c9 BN	42	/*
	43	* Cache priorities range from BASE to MAX.
	44	*
	45	* For prefetch support, the top half of the range starts at
aef29e17 DC	46	* CACHE_PREFETCH_PRIORITY and everytime the buffer is fetched and is at or
	47	* above this priority level, it is reduced to below this level (refer to
	48	* libxfs_getbuf).
	49	*
	50	* If we have dirty nodes, we can't recycle them until they've been cleaned. To
	51	* keep these out of the reclaimable lists (as there can be lots of them) give
	52	* them their own priority that the shaker doesn't attempt to walk.
a040d7c9 BN	53	*/
	54
	55	#define CACHE_BASE_PRIORITY 0
	56	#define CACHE_PREFETCH_PRIORITY 8
69ec88b5	57	#define CACHE_MAX_PRIORITY 15
aef29e17 DC	58	#define CACHE_DIRTY_PRIORITY (CACHE_MAX_PRIORITY + 1)
aef29e17 DC	59	#define CACHE_NR_PRIORITIES CACHE_DIRTY_PRIORITY
69ec88b5	60
e80aa729 NS	61	/*
	62	* Simple, generic implementation of a cache (arbitrary data).
	63	* Provides a hash table with a capped number of cache entries.
	64	*/
	65
	66	struct cache;
e80aa729 NS	67	struct cache_node;
	68
	69	typedef void *cache_key_t;
2556c98b	70
e80aa729	71	typedef void (cache_walk_t)(struct cache_node );
2556c98b	72	typedef struct cache_node * (*cache_node_alloc_t)(cache_key_t);
0a7942b3	73	typedef int (cache_node_flush_t)(struct cache_node );
e80aa729	74	typedef void (cache_node_relse_t)(struct cache_node );
602dcc0e DC	75	typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int,
602dcc0e DC	76	unsigned int);
e80aa729	77	typedef int (cache_node_compare_t)(struct cache_node , cache_key_t);
1c4110bd	78	typedef unsigned int (cache_bulk_relse_t)(struct cache , struct list_head *);
e80aa729 NS	79
	80	struct cache_operations {
	81	cache_node_hash_t hash;
	82	cache_node_alloc_t alloc;
33165ec3	83	cache_node_flush_t flush;
e80aa729 NS	84	cache_node_relse_t relse;
e80aa729 NS	85	cache_node_compare_t compare;
1c4110bd	86	cache_bulk_relse_t bulkrelse; /* optional */
e80aa729 NS	87	};
e80aa729 NS	88
69ec88b5 BN	89	struct cache_hash {
	90	struct list_head ch_list; /* hash chain head */
	91	unsigned int ch_count; /* hash chain length */
	92	pthread_mutex_t ch_mutex; /* hash chain mutex */
	93	};
	94
	95	struct cache_mru {
	96	struct list_head cm_list; /* MRU head */
	97	unsigned int cm_count; /* MRU length */
	98	pthread_mutex_t cm_mutex; /* MRU lock */
	99	};
	100
	101	struct cache_node {
	102	struct list_head cn_hash; /* hash chain */
	103	struct list_head cn_mru; /* MRU chain */
	104	unsigned int cn_count; /* reference count */
	105	unsigned int cn_hashidx; /* hash chain index */
	106	int cn_priority; /* priority, -1 = free list */
1b9fecf7	107	int cn_old_priority;/* saved pre-dirty prio */
69ec88b5 BN	108	pthread_mutex_t cn_mutex; /* node mutex */
	109	};
	110
e80aa729	111	struct cache {
ba9ecd40	112	int c_flags; /* behavioural flags */
e80aa729 NS	113	unsigned int c_maxcount; /* max cache nodes */
	114	unsigned int c_count; /* count of nodes */
	115	pthread_mutex_t c_mutex; /* node count mutex */
	116	cache_node_hash_t hash; /* node hash function */
	117	cache_node_alloc_t alloc; /* allocation function */
33165ec3	118	cache_node_flush_t flush; /* flush dirty data function */
e80aa729 NS	119	cache_node_relse_t relse; /* memory free function */
e80aa729 NS	120	cache_node_compare_t compare; /* comparison routine */
1c4110bd	121	cache_bulk_relse_t bulkrelse; /* bulk release routine */
e80aa729	122	unsigned int c_hashsize; /* hash bucket count */
602dcc0e	123	unsigned int c_hashshift; /* hash key shift */
e80aa729	124	struct cache_hash c_hash; / hash table buckets */
aef29e17	125	struct cache_mru c_mrus[CACHE_DIRTY_PRIORITY + 1];
9f38f08d MV	126	unsigned long long c_misses; /* cache misses */
	127	unsigned long long c_hits; /* cache hits */
	128	unsigned int c_max; /* max nodes ever used */
e80aa729 NS	129	};
e80aa729 NS	130
ba9ecd40	131	struct cache cache_init(int, unsigned int, struct cache_operations );
e80aa729 NS	132	void cache_destroy(struct cache *);
	133	void cache_walk(struct cache *, cache_walk_t);
	134	void cache_purge(struct cache *);
33165ec3	135	void cache_flush(struct cache *);
e80aa729 NS	136
e80aa729 NS	137	int cache_node_get(struct cache , cache_key_t, struct cache_node *);
a040d7c9	138	void cache_node_put(struct cache , struct cache_node );
69ec88b5 BN	139	void cache_node_set_priority(struct cache , struct cache_node , int);
69ec88b5 BN	140	int cache_node_get_priority(struct cache_node *);
e80aa729	141	int cache_node_purge(struct cache , cache_key_t, struct cache_node );
b6281496	142	void cache_report(FILE fp, const char , struct cache *);
2556c98b	143	int cache_overflowed(struct cache *);
e80aa729 NS	144
e80aa729 NS	145	#endif /* __CACHE_H__ */