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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 */ |
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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 | |
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32 | /** @brief The global cache */ |
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33 | static hash *h; |
34 | |
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35 | /** @brief One cache entry */ |
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36 | struct cache_entry { |
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37 | /** @brief What type of object this is */ |
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38 | const struct cache_type *type; |
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39 | |
40 | /** @brief Pointer to object value */ |
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41 | const void *value; |
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42 | |
43 | /** @brief Time that object was inserted into cache */ |
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44 | time_t birth; |
45 | }; |
46 | |
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47 | /** @brief Return true if object @p c has expired */ |
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48 | static int expired(const struct cache_entry *c, time_t now) { |
49 | return now - c->birth > c->type->lifetime; |
50 | } |
51 | |
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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 | */ |
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57 | void 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 | |
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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 | */ |
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75 | const 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 | |
87 | static int expiry_callback(const char *key, void *value, void *u) { |
88 | const struct cache_entry *c = value; |
89 | const time_t *now = u; |
90 | |
91 | if(expired(c, *now)) |
92 | hash_remove(h, key); |
93 | return 0; |
94 | } |
95 | |
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96 | /** @brief Expire the cache |
97 | * |
98 | * Called from time to time to expire cache entries. */ |
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99 | void cache_expire(void) { |
100 | time_t now; |
101 | |
102 | if(h) { |
103 | time(&now); |
104 | hash_foreach(h, expiry_callback, &now); |
105 | } |
106 | } |
107 | |
108 | static int clean_callback(const char *key, void *value, void *u) { |
109 | const struct cache_entry *c = value; |
110 | const struct cache_type *type = u; |
111 | |
112 | if(!type || c->type == type) |
113 | hash_remove(h, key); |
114 | return 0; |
115 | } |
116 | |
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117 | /** @brief Clean the cache |
118 | * @param type Pointer to type to clean |
119 | * |
120 | * Removes all entries of type @p type from the cache. |
121 | */ |
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122 | void cache_clean(const struct cache_type *type) { |
123 | if(h) |
124 | hash_foreach(h, clean_callback, (void *)type); |
125 | } |
126 | |
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127 | /** @brief Report cache size |
128 | * |
129 | * Returns the number of objects in the cache |
130 | */ |
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131 | size_t cache_count(void) { |
132 | return h ? hash_count(h) : 0; |
133 | } |
134 | |
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135 | /* |
136 | Local Variables: |
137 | c-basic-offset:2 |
138 | comment-column:40 |
139 | fill-column:79 |
140 | indent-tabs-mode:nil |
141 | End: |
142 | */ |