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comparison includes/cache.inc @ 1:c1f4ac30525a 6.0

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Drupal 6.0
author Franck Deroche <webmaster@defr.org>
date Tue, 23 Dec 2008 14:28:28 +0100
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0:5a113a1c4740 1:c1f4ac30525a
1 <?php
2 // $Id: cache.inc,v 1.17 2008/01/29 11:36:06 goba Exp $
3
4 /**
5 * Return data from the persistent cache. Data may be stored as either plain text or as serialized data.
6 * cache_get will automatically return unserialized objects and arrays.
7 *
8 * @param $cid
9 * The cache ID of the data to retrieve.
10 * @param $table
11 * The table $table to store the data in. Valid core values are 'cache_filter',
12 * 'cache_menu', 'cache_page', or 'cache' for the default cache.
13 */
14 function cache_get($cid, $table = 'cache') {
15 global $user;
16
17 // Garbage collection necessary when enforcing a minimum cache lifetime
18 $cache_flush = variable_get('cache_flush', 0);
19 if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) {
20 // Reset the variable immediately to prevent a meltdown in heavy load situations.
21 variable_set('cache_flush', 0);
22 // Time to flush old cache data
23 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush);
24 }
25
26 $cache = db_fetch_object(db_query("SELECT data, created, headers, expire, serialized FROM {". $table ."} WHERE cid = '%s'", $cid));
27 if (isset($cache->data)) {
28 // If the data is permanent or we're not enforcing a minimum cache lifetime
29 // always return the cached data.
30 if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) {
31 $cache->data = db_decode_blob($cache->data);
32 if ($cache->serialized) {
33 $cache->data = unserialize($cache->data);
34 }
35 }
36 // If enforcing a minimum cache lifetime, validate that the data is
37 // currently valid for this user before we return it by making sure the
38 // cache entry was created before the timestamp in the current session's
39 // cache timer. The cache variable is loaded into the $user object by
40 // sess_read() in session.inc.
41 else {
42 if ($user->cache > $cache->created) {
43 // This cache data is too old and thus not valid for us, ignore it.
44 return 0;
45 }
46 else {
47 $cache->data = db_decode_blob($cache->data);
48 if ($cache->serialized) {
49 $cache->data = unserialize($cache->data);
50 }
51 }
52 }
53 return $cache;
54 }
55 return 0;
56 }
57
58 /**
59 * Store data in the persistent cache.
60 *
61 * The persistent cache is split up into four database
62 * tables. Contributed modules can add additional tables.
63 *
64 * 'cache_page': This table stores generated pages for anonymous
65 * users. This is the only table affected by the page cache setting on
66 * the administrator panel.
67 *
68 * 'cache_menu': Stores the cachable part of the users' menus.
69 *
70 * 'cache_filter': Stores filtered pieces of content. This table is
71 * periodically cleared of stale entries by cron.
72 *
73 * 'cache': Generic cache storage table.
74 *
75 * The reasons for having several tables are as follows:
76 *
77 * - smaller tables allow for faster selects and inserts
78 * - we try to put fast changing cache items and rather static
79 * ones into different tables. The effect is that only the fast
80 * changing tables will need a lot of writes to disk. The more
81 * static tables will also be better cachable with MySQL's query cache
82 *
83 * @param $cid
84 * The cache ID of the data to store.
85 * @param $data
86 * The data to store in the cache. Complex data types will be automatically serialized before insertion.
87 * Strings will be stored as plain text and not serialized.
88 * @param $table
89 * The table $table to store the data in. Valid core values are 'cache_filter',
90 * 'cache_menu', 'cache_page', or 'cache'.
91 * @param $expire
92 * One of the following values:
93 * - CACHE_PERMANENT: Indicates that the item should never be removed unless
94 * explicitly told to using cache_clear_all() with a cache ID.
95 * - CACHE_TEMPORARY: Indicates that the item should be removed at the next
96 * general cache wipe.
97 * - A Unix timestamp: Indicates that the item should be kept at least until
98 * the given time, after which it behaves like CACHE_TEMPORARY.
99 * @param $headers
100 * A string containing HTTP header information for cached pages.
101 */
102 function cache_set($cid, $data, $table = 'cache', $expire = CACHE_PERMANENT, $headers = NULL) {
103 $serialized = 0;
104 if (is_object($data) || is_array($data)) {
105 $data = serialize($data);
106 $serialized = 1;
107 }
108 $created = time();
109 db_query("UPDATE {". $table ."} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, $created, $expire, $headers, $serialized, $cid);
110 if (!db_affected_rows()) {
111 @db_query("INSERT INTO {". $table ."} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, $created, $expire, $headers, $serialized);
112 }
113 }
114
115 /**
116 *
117 * Expire data from the cache. If called without arguments, expirable
118 * entries will be cleared from the cache_page and cache_block tables.
119 *
120 * @param $cid
121 * If set, the cache ID to delete. Otherwise, all cache entries that can
122 * expire are deleted.
123 *
124 * @param $table
125 * If set, the table $table to delete from. Mandatory
126 * argument if $cid is set.
127 *
128 * @param $wildcard
129 * If set to TRUE, the $cid is treated as a substring
130 * to match rather than a complete ID. The match is a right hand
131 * match. If '*' is given as $cid, the table $table will be emptied.
132 */
133 function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) {
134 global $user;
135
136 if (!isset($cid) && !isset($table)) {
137 // Clear the block cache first, so stale data will
138 // not end up in the page cache.
139 cache_clear_all(NULL, 'cache_block');
140 cache_clear_all(NULL, 'cache_page');
141 return;
142 }
143
144 if (empty($cid)) {
145 if (variable_get('cache_lifetime', 0)) {
146 // We store the time in the current user's $user->cache variable which
147 // will be saved into the sessions table by sess_write(). We then
148 // simulate that the cache was flushed for this user by not returning
149 // cached data that was cached before the timestamp.
150 $user->cache = time();
151
152 $cache_flush = variable_get('cache_flush', 0);
153 if ($cache_flush == 0) {
154 // This is the first request to clear the cache, start a timer.
155 variable_set('cache_flush', time());
156 }
157 else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
158 // Clear the cache for everyone, cache_flush_delay seconds have
159 // passed since the first request to clear the cache.
160 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
161 variable_set('cache_flush', 0);
162 }
163 }
164 else {
165 // No minimum cache lifetime, flush all temporary cache entries now.
166 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
167 }
168 }
169 else {
170 if ($wildcard) {
171 if ($cid == '*') {
172 db_query("DELETE FROM {". $table ."}");
173 }
174 else {
175 db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid);
176 }
177 }
178 else {
179 db_query("DELETE FROM {". $table ."} WHERE cid = '%s'", $cid);
180 }
181 }
182 }
183