chiark / gitweb /
Switch to GPL v3
[disorder] / lib / cache.c
CommitLineData
460b9539 1/*
2 * This file is part of DisOrder
5aff007d 3 * Copyright (C) 2006-2008 Richard Kettlewell
460b9539 4 *
e7eb3a27 5 * This program is free software: you can redistribute it and/or modify
460b9539 6 * it under the terms of the GNU General Public License as published by
e7eb3a27 7 * the Free Software Foundation, either version 3 of the License, or
460b9539 8 * (at your option) any later version.
e7eb3a27
RK
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
460b9539 15 * You should have received a copy of the GNU General Public License
e7eb3a27 16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
460b9539 17 */
14ad73b9 18/** @file lib/cache.c @brief Object caching */
460b9539 19
05b75f8d 20#include "common.h"
460b9539 21
22#include <time.h>
23
24#include "hash.h"
25#include "mem.h"
26#include "log.h"
27#include "cache.h"
28
d7b6f0d1 29/** @brief The global cache */
460b9539 30static hash *h;
31
d7b6f0d1 32/** @brief One cache entry */
460b9539 33struct cache_entry {
d7b6f0d1 34 /** @brief What type of object this is */
460b9539 35 const struct cache_type *type;
d7b6f0d1 36
37 /** @brief Pointer to object value */
460b9539 38 const void *value;
d7b6f0d1 39
40 /** @brief Time that object was inserted into cache */
460b9539 41 time_t birth;
42};
43
d7b6f0d1 44/** @brief Return true if object @p c has expired */
460b9539 45static int expired(const struct cache_entry *c, time_t now) {
46 return now - c->birth > c->type->lifetime;
47}
48
d7b6f0d1 49/** @brief Insert an object into the cache
50 * @param type Pointer to object type
51 * @param key Unique key
52 * @param value Pointer to value
53 */
460b9539 54void cache_put(const struct cache_type *type,
55 const char *key, const void *value) {
56 struct cache_entry *c;
57
58 if(!h)
59 h = hash_new(sizeof (struct cache_entry));
60 c = xmalloc(sizeof *c);
61 c->type = type;
62 c->value = value;
63 time(&c->birth);
64 hash_add(h, key, c, HASH_INSERT_OR_REPLACE);
65}
66
d7b6f0d1 67/** @brief Look up an object in the cache
68 * @param type Pointer to object type
69 * @param key Unique key
70 * @return Pointer to object value or NULL if not found
71 */
460b9539 72const void *cache_get(const struct cache_type *type, const char *key) {
73 const struct cache_entry *c;
74
75 if(h
76 && (c = hash_find(h, key))
77 && c->type == type
78 && !expired(c, time(0)))
79 return c->value;
80 else
81 return 0;
82}
83
0e4472a0 84/** @brief Call used by from cache_expire() */
460b9539 85static int expiry_callback(const char *key, void *value, void *u) {
86 const struct cache_entry *c = value;
87 const time_t *now = u;
88
89 if(expired(c, *now))
90 hash_remove(h, key);
91 return 0;
92}
93
d7b6f0d1 94/** @brief Expire the cache
95 *
96 * Called from time to time to expire cache entries. */
460b9539 97void cache_expire(void) {
98 time_t now;
99
100 if(h) {
101 time(&now);
102 hash_foreach(h, expiry_callback, &now);
103 }
104}
105
0e4472a0 106/** @brief Callback used by cache_clean() */
460b9539 107static int clean_callback(const char *key, void *value, void *u) {
108 const struct cache_entry *c = value;
109 const struct cache_type *type = u;
110
111 if(!type || c->type == type)
112 hash_remove(h, key);
113 return 0;
114}
115
d7b6f0d1 116/** @brief Clean the cache
117 * @param type Pointer to type to clean
118 *
119 * Removes all entries of type @p type from the cache.
120 */
460b9539 121void cache_clean(const struct cache_type *type) {
122 if(h)
123 hash_foreach(h, clean_callback, (void *)type);
124}
125
d7b6f0d1 126/** @brief Report cache size
127 *
128 * Returns the number of objects in the cache
129 */
0b7c8909 130size_t cache_count(void) {
131 return h ? hash_count(h) : 0;
132}
133
460b9539 134/*
135Local Variables:
136c-basic-offset:2
137comment-column:40
138fill-column:79
139indent-tabs-mode:nil
140End:
141*/