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<?php // $Id: cache.inc,v 1.17 2008/01/29 11:36:06 goba Exp $
/** * Return data from the persistent cache. Data may be stored as either plain text or as serialized data. * cache_get will automatically return unserialized objects and arrays. * * @param $cid * The cache ID of the data to retrieve. * @param $table * The table $table to store the data in. Valid core values are 'cache_filter', * 'cache_menu', 'cache_page', or 'cache' for the default cache. */ function cache_get($cid, $table = 'cache') { global $user;
// Garbage collection necessary when enforcing a minimum cache lifetime $cache_flush = variable_get('cache_flush', 0); if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) { // Reset the variable immediately to prevent a meltdown in heavy load situations. variable_set('cache_flush', 0); // Time to flush old cache data db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush); }
$cache = db_fetch_object(db_query("SELECT data, created, headers, expire, serialized FROM {". $table ."} WHERE cid = '%s'", $cid)); if (isset($cache->data)) { // If the data is permanent or we're not enforcing a minimum cache lifetime // always return the cached data. if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) { $cache->data = db_decode_blob($cache->data); if ($cache->serialized) { $cache->data = unserialize($cache->data); } } // If enforcing a minimum cache lifetime, validate that the data is // currently valid for this user before we return it by making sure the // cache entry was created before the timestamp in the current session's // cache timer. The cache variable is loaded into the $user object by // sess_read() in session.inc. else { if ($user->cache > $cache->created) { // This cache data is too old and thus not valid for us, ignore it. return 0; } else { $cache->data = db_decode_blob($cache->data); if ($cache->serialized) { $cache->data = unserialize($cache->data); } } } return $cache; } return 0; }
/** * Store data in the persistent cache. * * The persistent cache is split up into four database * tables. Contributed modules can add additional tables. * * 'cache_page': This table stores generated pages for anonymous * users. This is the only table affected by the page cache setting on * the administrator panel. * * 'cache_menu': Stores the cachable part of the users' menus. * * 'cache_filter': Stores filtered pieces of content. This table is * periodically cleared of stale entries by cron. * * 'cache': Generic cache storage table. * * The reasons for having several tables are as follows: * * - smaller tables allow for faster selects and inserts * - we try to put fast changing cache items and rather static * ones into different tables. The effect is that only the fast * changing tables will need a lot of writes to disk. The more * static tables will also be better cachable with MySQL's query cache * * @param $cid * The cache ID of the data to store. * @param $data * The data to store in the cache. Complex data types will be automatically serialized before insertion. * Strings will be stored as plain text and not serialized. * @param $table * The table $table to store the data in. Valid core values are 'cache_filter', * 'cache_menu', 'cache_page', or 'cache'. * @param $expire * One of the following values: * - CACHE_PERMANENT: Indicates that the item should never be removed unless * explicitly told to using cache_clear_all() with a cache ID. * - CACHE_TEMPORARY: Indicates that the item should be removed at the next * general cache wipe. * - A Unix timestamp: Indicates that the item should be kept at least until * the given time, after which it behaves like CACHE_TEMPORARY. * @param $headers * A string containing HTTP header information for cached pages. */ function cache_set($cid, $data, $table = 'cache', $expire = CACHE_PERMANENT, $headers = NULL) { $serialized = 0; if (is_object($data) || is_array($data)) { $data = serialize($data); $serialized = 1; } $created = time(); db_query("UPDATE {". $table ."} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, $created, $expire, $headers, $serialized, $cid); if (!db_affected_rows()) { @db_query("INSERT INTO {". $table ."} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, $created, $expire, $headers, $serialized); } }
/** * * Expire data from the cache. If called without arguments, expirable * entries will be cleared from the cache_page and cache_block tables. * * @param $cid * If set, the cache ID to delete. Otherwise, all cache entries that can * expire are deleted. * * @param $table * If set, the table $table to delete from. Mandatory * argument if $cid is set. * * @param $wildcard * If set to TRUE, the $cid is treated as a substring * to match rather than a complete ID. The match is a right hand * match. If '*' is given as $cid, the table $table will be emptied. */ function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) { global $user;
if (!isset($cid) && !isset($table)) { // Clear the block cache first, so stale data will // not end up in the page cache. cache_clear_all(NULL, 'cache_block'); cache_clear_all(NULL, 'cache_page'); return; }
if (empty($cid)) { if (variable_get('cache_lifetime', 0)) { // We store the time in the current user's $user->cache variable which // will be saved into the sessions table by sess_write(). We then // simulate that the cache was flushed for this user by not returning // cached data that was cached before the timestamp. $user->cache = time();
$cache_flush = variable_get('cache_flush', 0); if ($cache_flush == 0) { // This is the first request to clear the cache, start a timer. variable_set('cache_flush', time()); } else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) { // Clear the cache for everyone, cache_flush_delay seconds have // passed since the first request to clear the cache. db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); variable_set('cache_flush', 0); } } else { // No minimum cache lifetime, flush all temporary cache entries now. db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); } } else { if ($wildcard) { if ($cid == '*') { db_query("DELETE FROM {". $table ."}"); } else { db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid); } } else { db_query("DELETE FROM {". $table ."} WHERE cid = '%s'", $cid); } } }
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