1/*-
2 * Copyright (c) 2005 Michael Bushkov <bushman@rsu.ru>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#ifndef __NSCD_CACHEPLCS_H__
28#define __NSCD_CACHEPLCS_H__
29
30#include <sys/queue.h>
31
32/* common policy definitions */
33#define CACHELIB_MAX_FREQUENCY 100
34
35/*
36 * cache_policy_item_ represents some abstract cache element in the policy
37 * queue. connected_item pointers to the corresponding cache_policy_item_ in
38 * another policy queue.
39 */
40struct cache_policy_item_ {
41	char	*key;
42    	size_t	key_size;
43
44	size_t	request_count;
45	struct timeval last_request_time;
46	struct timeval creation_time;
47
48	struct cache_policy_item_ *connected_item;
49};
50
51/*
52 * cache_policy_ represents an abstract policy queue. It can be customized by
53 * setting appropriate function pointers
54 */
55struct cache_policy_ {
56	struct cache_policy_item_* (*create_item_func)(void);
57	void (*destroy_item_func)(struct cache_policy_item_ *);
58
59	void (*add_item_func)(struct cache_policy_ *,
60		struct cache_policy_item_ *);
61	void (*remove_item_func)(struct cache_policy_ *,
62		struct cache_policy_item_ *);
63	void (*update_item_func)(struct cache_policy_ *,
64		struct cache_policy_item_ *);
65
66	struct cache_policy_item_ *(*get_first_item_func)(
67		struct cache_policy_ *);
68	struct cache_policy_item_ *(*get_last_item_func)(
69		struct cache_policy_ *);
70	struct cache_policy_item_ *(*get_next_item_func)(
71		struct cache_policy_ *, struct cache_policy_item_ *);
72	struct cache_policy_item_ *(*get_prev_item_func)(
73		struct cache_policy_ *, struct cache_policy_item_ *);
74};
75
76/*
77 * LFU cache policy item "inherited" from cache_policy_item_ structure
78 */
79struct cache_lfu_policy_item_ {
80	struct cache_policy_item_ parent_data;
81	int	frequency;
82
83	TAILQ_ENTRY(cache_lfu_policy_item_) entries;
84};
85
86TAILQ_HEAD(cache_lfu_policy_group_, cache_lfu_policy_item_);
87
88/*
89 * LFU policy queue "inherited" from cache_policy_.
90 */
91struct cache_lfu_policy_ {
92	struct cache_policy_ parent_data;
93	struct cache_lfu_policy_group_ groups[CACHELIB_MAX_FREQUENCY];
94};
95
96/*
97 * LRU and FIFO policies item "inherited" from cache_policy_item_
98 */
99struct cache_queue_policy_item_ {
100	struct cache_policy_item_ parent_data;
101	TAILQ_ENTRY(cache_queue_policy_item_) entries;
102};
103
104/*
105 * LRU and FIFO policies "inherited" from cache_policy_
106 */
107struct cache_queue_policy_ {
108	struct cache_policy_ parent_data;
109	TAILQ_HEAD(cache_queue_policy_head_, cache_queue_policy_item_) head;
110};
111
112typedef struct cache_queue_policy_ cache_fifo_policy_;
113typedef struct cache_queue_policy_ cache_lru_policy_;
114
115/* fifo policy routines */
116struct cache_policy_ *init_cache_fifo_policy(void);
117void destroy_cache_fifo_policy(struct cache_policy_ *);
118
119/* lru policy routines */
120struct cache_policy_ *init_cache_lru_policy(void);
121void destroy_cache_lru_policy(struct cache_policy_ *);
122
123/* lfu policy routines */
124struct cache_policy_ *init_cache_lfu_policy(void);
125void destroy_cache_lfu_policy(struct cache_policy_ *);
126
127#endif
128