| 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 | */ |
| 20 | /** @file lib/cache.c @brief Object caching */ |
| 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 | |
| 32 | /** @brief The global cache */ |
| 33 | static hash *h; |
| 34 | |
| 35 | /** @brief One cache entry */ |
| 36 | struct cache_entry { |
| 37 | /** @brief What type of object this is */ |
| 38 | const struct cache_type *type; |
| 39 | |
| 40 | /** @brief Pointer to object value */ |
| 41 | const void *value; |
| 42 | |
| 43 | /** @brief Time that object was inserted into cache */ |
| 44 | time_t birth; |
| 45 | }; |
| 46 | |
| 47 | /** @brief Return true if object @p c has expired */ |
| 48 | static int expired(const struct cache_entry *c, time_t now) { |
| 49 | return now - c->birth > c->type->lifetime; |
| 50 | } |
| 51 | |
| 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 | */ |
| 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 | |
| 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 | */ |
| 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 | /** @brief Call used by from cache_expire() */ |
| 88 | static 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 | |
| 97 | /** @brief Expire the cache |
| 98 | * |
| 99 | * Called from time to time to expire cache entries. */ |
| 100 | void cache_expire(void) { |
| 101 | time_t now; |
| 102 | |
| 103 | if(h) { |
| 104 | time(&now); |
| 105 | hash_foreach(h, expiry_callback, &now); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | /** @brief Callback used by cache_clean() */ |
| 110 | static 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 | |
| 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 | */ |
| 124 | void cache_clean(const struct cache_type *type) { |
| 125 | if(h) |
| 126 | hash_foreach(h, clean_callback, (void *)type); |
| 127 | } |
| 128 | |
| 129 | /** @brief Report cache size |
| 130 | * |
| 131 | * Returns the number of objects in the cache |
| 132 | */ |
| 133 | size_t cache_count(void) { |
| 134 | return h ? hash_count(h) : 0; |
| 135 | } |
| 136 | |
| 137 | /* |
| 138 | Local Variables: |
| 139 | c-basic-offset:2 |
| 140 | comment-column:40 |
| 141 | fill-column:79 |
| 142 | indent-tabs-mode:nil |
| 143 | End: |
| 144 | */ |