chiark / gitweb /
time/space limits for client output buffering
[disorder] / lib / cache.c
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460b9539 1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2006 Richard Kettlewell
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
14ad73b9 20/** @file lib/cache.c @brief Object caching */
460b9539 21
22#include <config.h>
23#include "types.h"
24
25#include <time.h>
26
27#include "hash.h"
28#include "mem.h"
29#include "log.h"
30#include "cache.h"
31
d7b6f0d1 32/** @brief The global cache */
460b9539 33static hash *h;
34
d7b6f0d1 35/** @brief One cache entry */
460b9539 36struct cache_entry {
d7b6f0d1 37 /** @brief What type of object this is */
460b9539 38 const struct cache_type *type;
d7b6f0d1 39
40 /** @brief Pointer to object value */
460b9539 41 const void *value;
d7b6f0d1 42
43 /** @brief Time that object was inserted into cache */
460b9539 44 time_t birth;
45};
46
d7b6f0d1 47/** @brief Return true if object @p c has expired */
460b9539 48static int expired(const struct cache_entry *c, time_t now) {
49 return now - c->birth > c->type->lifetime;
50}
51
d7b6f0d1 52/** @brief Insert an object into the cache
53 * @param type Pointer to object type
54 * @param key Unique key
55 * @param value Pointer to value
56 */
460b9539 57void cache_put(const struct cache_type *type,
58 const char *key, const void *value) {
59 struct cache_entry *c;
60
61 if(!h)
62 h = hash_new(sizeof (struct cache_entry));
63 c = xmalloc(sizeof *c);
64 c->type = type;
65 c->value = value;
66 time(&c->birth);
67 hash_add(h, key, c, HASH_INSERT_OR_REPLACE);
68}
69
d7b6f0d1 70/** @brief Look up an object in the cache
71 * @param type Pointer to object type
72 * @param key Unique key
73 * @return Pointer to object value or NULL if not found
74 */
460b9539 75const void *cache_get(const struct cache_type *type, const char *key) {
76 const struct cache_entry *c;
77
78 if(h
79 && (c = hash_find(h, key))
80 && c->type == type
81 && !expired(c, time(0)))
82 return c->value;
83 else
84 return 0;
85}
86
0e4472a0 87/** @brief Call used by from cache_expire() */
460b9539 88static int expiry_callback(const char *key, void *value, void *u) {
89 const struct cache_entry *c = value;
90 const time_t *now = u;
91
92 if(expired(c, *now))
93 hash_remove(h, key);
94 return 0;
95}
96
d7b6f0d1 97/** @brief Expire the cache
98 *
99 * Called from time to time to expire cache entries. */
460b9539 100void cache_expire(void) {
101 time_t now;
102
103 if(h) {
104 time(&now);
105 hash_foreach(h, expiry_callback, &now);
106 }
107}
108
0e4472a0 109/** @brief Callback used by cache_clean() */
460b9539 110static int clean_callback(const char *key, void *value, void *u) {
111 const struct cache_entry *c = value;
112 const struct cache_type *type = u;
113
114 if(!type || c->type == type)
115 hash_remove(h, key);
116 return 0;
117}
118
d7b6f0d1 119/** @brief Clean the cache
120 * @param type Pointer to type to clean
121 *
122 * Removes all entries of type @p type from the cache.
123 */
460b9539 124void cache_clean(const struct cache_type *type) {
125 if(h)
126 hash_foreach(h, clean_callback, (void *)type);
127}
128
d7b6f0d1 129/** @brief Report cache size
130 *
131 * Returns the number of objects in the cache
132 */
0b7c8909 133size_t cache_count(void) {
134 return h ? hash_count(h) : 0;
135}
136
460b9539 137/*
138Local Variables:
139c-basic-offset:2
140comment-column:40
141fill-column:79
142indent-tabs-mode:nil
143End:
144*/