=== modified file 'includes/cache.inc' --- includes/cache.inc 2009-05-21 10:17:37 +0000 +++ includes/cache.inc 2009-06-16 06:26:34 +0000 @@ -2,84 +2,98 @@ // $Id: cache.inc,v 1.33 2009/05/21 10:17:37 dries Exp $ /** + * Get the cache object for a cache bin. + * + * By default, this returns an instance of the DrupalDatabaseCache class. + * Contributed modules can register alternative implementations of the + * DrupalCacheInterface interface both for all and for specific cache bins, + * though. + * + * @see DrupalCacheInterface + * + * @param $bin + * The cache bin for which the cache object should be returned. + */ +function _cache_get_object($bin) { + // We do not use drupal_static() here because we do not want to change the + // storage of a cache bin mid-request. + static $cache_objects, $default_class; + if (!isset($cache_objects[$bin])) { + $class = variable_get($bin, FALSE); + if (empty($class)) { + $class = variable_get('cache_default_class', 'DrupalDatabaseCache'); + } + $cache_objects[$bin] = new $class($bin); + } + return $cache_objects[$bin]; +} + +/** * 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. + * @param $bin + * The cache bin to store the data in. Valid core values are 'cache_block', + * 'cache_field', 'cache_filter', 'cache_form', 'cache_menu', 'cache_page', + * 'cache_path', 'cache_registry', 'cache_update' or 'cache' for the default + * cache. * @return The cache or FALSE on failure. */ -function cache_get($cid, $table = 'cache') { - global $user; - - // Garbage collection necessary when enforcing a minimum cache lifetime - $cache_flush = variable_get('cache_flush_' . $table, 0); - if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= REQUEST_TIME)) { - // Reset the variable immediately to prevent a meltdown in heavy load situations. - variable_set('cache_flush_' . $table, 0); - // Time to flush old cache data - db_delete($table) - ->condition('expire', CACHE_PERMANENT, '<>') - ->condition('expire', $cache_flush, '<=') - ->execute(); - } - - $cache = db_query("SELECT data, created, headers, expire, serialized FROM {" . $table . "} WHERE cid = :cid", array(':cid' => $cid))->fetchObject(); - - if (!isset($cache->data)) { - return FALSE; - } - - // 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 $user object by _sess_read() - // in session.inc. If the data is permanent or we're not enforcing a minimum - // cache lifetime always return the cached data. - if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) && $user->cache > $cache->created) { - // This cache data is too old and thus not valid for us, ignore it. - return FALSE; - } - - if ($cache->serialized) { - $cache->data = unserialize($cache->data); - } - if (isset($cache->headers)) { - $cache->headers = unserialize($cache->headers); - } - - return $cache; +function cache_get($cid, $bin = 'cache') { + return _cache_get_object($bin)->get($cid); } /** * 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 cacheable 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 cacheable with MySQL's query cache + * The persistent cache is split up into several cache bins. In the default + * cache implementation, each cache bin corresponds to a database table by the + * same name. Other implementations might want to store several bins in data + * structures that get flushed together. While it is not a problem for most + * cache bins if the entries in them are flushed before their expire time, some + * might break functionality or are extremely expensive to recalculate. These + * will be marked with a (*). The other bins expired automatically by core. + * Contributed modules can add additional bins and get them expired + * automatically by implementing hook_flush_caches(). + * + * - cache: Generic cache storage bin (used for variables, theme registry, + * locale date, list of simpletest tests etc). + * + * - cache_block: Stores the content of various blocks. + * + * - cache field: Stores the field data belonging to a given object. + * + * - cache_filter: Stores filtered pieces of content. + * + * - cache_form(*): Stores multistep forms. Flushing this bin means that some + * forms displayed to users lose their state and the data already submitted + * to them. + * + * - cache_menu: Stores the structure of visible navigation menus per page. + * + * - cache_page: Stores generated pages for anonymous users. It is flushed + * very often, whenever a page changes, at least for every ode and comment + * submission. This is the only bin affected by the page cache setting on + * the administrator panel. + * + * - cache path: Stores the system paths that have an alias. + * + * - cache update(*): Stores available releases. The update server (for + * example, drupal.org) needs to produce the relevant XML for every project + * installed on the current site. As this is different for (almost) every + * site, it's very expensive to recalculate for the update server. + * + * The reasons for having several bins are as follows: + * + * - smaller bins mean smaller database tables and allow for faster selects and + * inserts + * - we try to put fast changing cache items and rather static ones into different + * bins. The effect is that only the fast changing bins will need a lot of + * writes to disk. The more static bins will also be better cacheable with + * MySQL's query cache. * * @param $cid * The cache ID of the data to store. @@ -87,8 +101,8 @@ function cache_get($cid, $table = 'cache * 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 + * @param $bin + * The bin to store the data in. Valid core values are * 'cache_filter', 'cache_menu', 'cache_page', or 'cache'. * @param $expire * One of the following values: @@ -101,50 +115,31 @@ function cache_get($cid, $table = 'cache * @param $headers * A string containing HTTP header information for cached pages. */ -function cache_set($cid, $data, $table = 'cache', $expire = CACHE_PERMANENT, array $headers = NULL) { - $fields = array( - 'serialized' => 0, - 'created' => REQUEST_TIME, - 'expire' => $expire, - 'headers' => isset($headers) ? serialize($headers) : NULL, - ); - if (!is_string($data)) { - $fields['data'] = serialize($data); - $fields['serialized'] = 1; - } - else { - $fields['data'] = $data; - $fields['serialized'] = 0; - } - - db_merge($table) - ->key(array('cid' => $cid)) - ->fields($fields) - ->execute(); +function cache_set($cid, $data, $bin = 'cache', $expire = CACHE_PERMANENT, array $headers = NULL) { + return _cache_get_object($bin)->set($cid, $data, $expire, $headers); } /** + * Expire data from the cache. * - * Expire data from the cache. If called without arguments, expirable - * entries will be cleared from the cache_page and cache_block tables. + * If called without arguments, expirable entries will be cleared from the + * cache_page and cache_block bins. * * @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 + * @param $bin + * If set, the bin $bin 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. + * match. If '*' is given as $cid, the bin $bin will be emptied. */ -function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) { - global $user; - - if (!isset($cid) && !isset($table)) { +function cache_clear_all($cid = NULL, $bin = NULL, $wildcard = FALSE) { + if (!isset($cid) && !isset($bin)) { // Clear the block cache first, so stale data will // not end up in the page cache. if (module_exists('block')) { @@ -153,53 +148,219 @@ function cache_clear_all($cid = NULL, $t cache_clear_all(NULL, 'cache_page'); return; } + return _cache_get_object($bin)->clear($cid, $wildcard); +} + +/** + * Interface for cache implementations. + * + * All cache implementations have to implement this interface. DrupalDatabaseCache + * provides the default implementation, which can be consulted as an example. + * + * To make Drupal use your implementation for a certain cache bin, you have to + * set a variable with the name of the cache bin as its key and the name of your + * class as its value. For example, if your implementation of DrupalCacheInterface + * was called MyCustomCache, the following line would make Drupal use it for the + * 'cache_page' bin: + * @code + * variable_set('cache_page', 'MyCustomCache'); + * @endcode + * + * Additionally, you can register your cache implementation to be used by default + * for all cache bins by setting the variable 'cache_default_class' to the name + * of your implementation of the DrupalCacheInterface, e.g. + * @code + * variable_set('cache_default_class', 'MyCustomCache'); + * @endcode + * + * @see _cache_get_object() + * @see DrupalDatabaseCache + */ +interface DrupalCacheInterface { + /** + * Constructor. + * + * @param $bin + * The cache bin for which the object is created. + */ + function __construct($bin); + + /** + * 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 $cid + * The cache ID of the data to retrieve. + * @return The cache or FALSE on failure. + */ + function get($cid); + + /** + * Store data in the persistent 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 $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 $headers + * A string containing HTTP header information for cached pages. + */ + function set($cid, $data, $expire = CACHE_PERMANENT, array $headers = NULL); + + + /** + * Expire data from the cache. If called without arguments, expirable + * entries will be cleared from the cache_page and cache_block bins. + * + * @param $cid + * If set, the cache ID to delete. Otherwise, all cache entries that can + * expire are deleted. + * @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 bin $bin will be emptied. + */ + function clear($cid = NULL, $wildcard = FALSE); +} + +/** + * Default cache implementation. + * + * This is Drupal's default cache implementation. It uses the database to store + * cached data. Each cache bin corresponds to a database table by the same name. + */ +class DrupalDatabaseCache implements DrupalCacheInterface { + protected $bin; + + function __construct($bin) { + $this->bin = $bin; + } + + function get($cid) { + global $user; + + // Garbage collection is necessary when enforcing a minimum cache lifetime. + $cache_flush = variable_get('cache_flush_' . $this->bin, 0); + if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= REQUEST_TIME)) { + // Reset the variable immediately to prevent a meltdown in heavy load situations. + variable_set('cache_flush_' . $this->bin, 0); + // Time to flush old cache data + db_delete($this->bin) + ->condition('expire', CACHE_PERMANENT, '<>') + ->condition('expire', $cache_flush, '<=') + ->execute(); + } - if (empty($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 = REQUEST_TIME; - - $cache_flush = variable_get('cache_flush_' . $table, 0); - if ($cache_flush == 0) { - // This is the first request to clear the cache, start a timer. - variable_set('cache_flush_' . $table, REQUEST_TIME); + $cache = db_query("SELECT data, created, headers, expire, serialized FROM {" . $this->bin . "} WHERE cid = :cid", array(':cid' => $cid))->fetchObject(); + + if (!isset($cache->data)) { + return FALSE; + } + + // 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 $user object by _sess_read() + // in session.inc. If the data is permanent or we're not enforcing a minimum + // cache lifetime always return the cached data. + if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) && $user->cache > $cache->created) { + // This cache data is too old and thus not valid for us, ignore it. + return FALSE; + } + + if ($cache->serialized) { + $cache->data = unserialize($cache->data); + } + if (isset($cache->headers)) { + $cache->headers = unserialize($cache->headers); + } + + return $cache; + } + + function set($cid, $data, $expire = CACHE_PERMANENT, array $headers = NULL) { + $fields = array( + 'serialized' => 0, + 'created' => REQUEST_TIME, + 'expire' => $expire, + 'headers' => isset($headers) ? serialize($headers) : NULL, + ); + if (!is_string($data)) { + $fields['data'] = serialize($data); + $fields['serialized'] = 1; + } + else { + $fields['data'] = $data; + $fields['serialized'] = 0; + } + + db_merge($this->bin) + ->key(array('cid' => $cid)) + ->fields($fields) + ->execute(); + } + + function clear($cid = NULL, $wildcard = FALSE) { + global $user; + + if (empty($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 bin 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 = REQUEST_TIME; + + $cache_flush = variable_get('cache_flush_' . $this->bin, 0); + if ($cache_flush == 0) { + // This is the first request to clear the cache, start a timer. + variable_set('cache_flush_' . $this->bin, REQUEST_TIME); + } + elseif (REQUEST_TIME > ($cache_flush + variable_get('cache_lifetime', 0))) { + // Clear the cache for everyone, cache_lifetime seconds have + // passed since the first request to clear the cache. + db_delete($this->bin) + ->condition('expire', CACHE_PERMANENT, '<>') + ->condition('expire', REQUEST_TIME, '<') + ->execute(); + variable_set('cache_flush_' . $this->bin, 0); + } } - elseif (REQUEST_TIME > ($cache_flush + variable_get('cache_lifetime', 0))) { - // Clear the cache for everyone, cache_lifetime seconds have - // passed since the first request to clear the cache. - db_delete($table) + else { + // No minimum cache lifetime, flush all temporary cache entries now. + db_delete($this->bin) ->condition('expire', CACHE_PERMANENT, '<>') ->condition('expire', REQUEST_TIME, '<') ->execute(); - variable_set('cache_flush_' . $table, 0); } } else { - // No minimum cache lifetime, flush all temporary cache entries now. - db_delete($table) - ->condition('expire', CACHE_PERMANENT, '<>') - ->condition('expire', REQUEST_TIME, '<') - ->execute(); - } - } - else { - if ($wildcard) { - if ($cid == '*') { - db_truncate($table)->execute(); + if ($wildcard) { + if ($cid == '*') { + db_truncate($this->bin)->execute(); + } + else { + db_delete($this->bin) + ->condition('cid', $cid . '%', 'LIKE') + ->execute(); + } } else { - db_delete($table) - ->condition('cid', $cid . '%', 'LIKE') + db_delete($this->bin) + ->condition('cid', $cid) ->execute(); } } - else { - db_delete($table) - ->condition('cid', $cid) - ->execute(); - } } -} +} \ No newline at end of file