diff -r 07239de796bb -r e756a8c72c3d cms/drupal/includes/cache.inc --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/cms/drupal/includes/cache.inc Fri Sep 08 12:04:06 2017 +0200 @@ -0,0 +1,590 @@ +get($cid); +} + +/** + * Returns data from the persistent cache when given an array of cache IDs. + * + * @param $cids + * An array of cache IDs for the data to retrieve. This is passed by + * reference, and will have the IDs successfully returned from cache removed. + * @param $bin + * The cache bin where the data is stored. + * + * @return + * An array of the items successfully returned from cache indexed by cid. + */ +function cache_get_multiple(array &$cids, $bin = 'cache') { + return _cache_get_object($bin)->getMultiple($cids); +} + +/** + * Stores data in the persistent 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. The + * other bins are expired automatically by core. Contributed modules can add + * additional bins and get them expired automatically by implementing + * hook_flush_caches(). + * + * 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. + * @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 are + * not serialized. Some storage engines only allow objects up to a maximum of + * 1MB in size to be stored by default. When caching large arrays or similar, + * take care to ensure $data does not exceed this size. + * @param $bin + * (optional) The cache bin to store the data in. Valid core values are: + * - cache: (default) Generic cache storage bin (used for theme registry, + * locale date, list of simpletest tests, etc.). + * - cache_block: Stores the content of various blocks. + * - cache_bootstrap: Stores the class registry, the system list of modules, + * the list of which modules implement which hooks, and the Drupal variable + * list. + * - 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. This bin should not be flushed before its expired time. + * - 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 node 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. + * @param $expire + * (optional) Controls the maximum lifetime of this cache entry. Note that + * caches might be subject to clearing at any time, so this setting does not + * guarantee a minimum lifetime. With this in mind, the cache should not be + * used for data that must be kept during a cache clear, like sessions. + * + * Use one of the following values: + * - CACHE_PERMANENT: Indicates that the item should never be removed unless + * explicitly told to using cache_clear_all() with a cache ID. + * - CACHE_TEMPORARY: Indicates that the item should be removed at the next + * general cache wipe. + * - A Unix timestamp: Indicates that the item should be kept at least until + * the given time, after which it behaves like CACHE_TEMPORARY. + * + * @see _update_cache_set() + * @see cache_get() + */ +function cache_set($cid, $data, $bin = 'cache', $expire = CACHE_PERMANENT) { + return _cache_get_object($bin)->set($cid, $data, $expire); +} + +/** + * Expires data from the cache. + * + * If called with the arguments $cid and $bin set to NULL or omitted, then + * expirable entries will be cleared from the cache_page and cache_block bins, + * and the $wildcard argument is ignored. + * + * @param $cid + * If set, the cache ID or an array of cache IDs. Otherwise, all cache entries + * that can expire are deleted. The $wildcard argument will be ignored if set + * to NULL. + * @param $bin + * If set, the cache bin to delete from. Mandatory argument if $cid is set. + * @param $wildcard + * If TRUE, the $cid argument must contain a string value and cache IDs + * starting with $cid are deleted in addition to the exact cache ID specified + * by $cid. If $wildcard is TRUE and $cid is '*', the entire cache is emptied. + */ +function cache_clear_all($cid = NULL, $bin = NULL, $wildcard = FALSE) { + if (!isset($cid) && !isset($bin)) { + // Clear the block cache first, so stale data will + // not end up in the page cache. + if (module_exists('block')) { + cache_clear_all(NULL, 'cache_block'); + } + cache_clear_all(NULL, 'cache_page'); + return; + } + return _cache_get_object($bin)->clear($cid, $wildcard); +} + +/** + * Checks if a cache bin is empty. + * + * A cache bin is considered empty if it does not contain any valid data for any + * cache ID. + * + * @param $bin + * The cache bin to check. + * + * @return + * TRUE if the cache bin specified is empty. + */ +function cache_is_empty($bin) { + return _cache_get_object($bin)->isEmpty(); +} + +/** + * Defines an interface for cache implementations. + * + * All cache implementations have to implement this interface. + * DrupalDatabaseCache provides the default implementation, which can be + * consulted as an example. + * + * To make Drupal use your implementation for a certain cache bin, you have to + * set a variable with the name of the cache bin as its key and the name of + * your class as its value. For example, if your implementation of + * DrupalCacheInterface was called MyCustomCache, the following line would make + * Drupal use it for the 'cache_page' bin: + * @code + * variable_set('cache_class_cache_page', 'MyCustomCache'); + * @endcode + * + * Additionally, you can register your cache implementation to be used by + * default for all cache bins by setting the variable 'cache_default_class' to + * the name of your implementation of the DrupalCacheInterface, e.g. + * @code + * variable_set('cache_default_class', 'MyCustomCache'); + * @endcode + * + * To implement a completely custom cache bin, use the same variable format: + * @code + * variable_set('cache_class_custom_bin', 'MyCustomCache'); + * @endcode + * To access your custom cache bin, specify the name of the bin when storing + * or retrieving cached data: + * @code + * cache_set($cid, $data, 'custom_bin', $expire); + * cache_get($cid, 'custom_bin'); + * @endcode + * + * @see _cache_get_object() + * @see DrupalDatabaseCache + */ +interface DrupalCacheInterface { + + /** + * Returns 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); + + /** + * Returns data from the persistent cache when given an array of cache IDs. + * + * @param $cids + * An array of cache IDs for the data to retrieve. This is passed by + * reference, and will have the IDs successfully returned from cache + * removed. + * + * @return + * An array of the items successfully returned from cache indexed by cid. + */ + function getMultiple(&$cids); + + /** + * Stores 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. Some storage engines only allow objects up to a maximum of + * 1MB in size to be stored by default. When caching large arrays or + * similar, take care to ensure $data does not exceed this size. + * @param $expire + * (optional) Controls the maximum lifetime of this cache entry. Note that + * caches might be subject to clearing at any time, so this setting does not + * guarantee a minimum lifetime. With this in mind, the cache should not be + * used for data that must be kept during a cache clear, like sessions. + * + * Use one of the following values: + * - CACHE_PERMANENT: Indicates that the item should never be removed unless + * explicitly told to using cache_clear_all() with a cache ID. + * - CACHE_TEMPORARY: Indicates that the item should be removed at the next + * general cache wipe. + * - A Unix timestamp: Indicates that the item should be kept at least until + * the given time, after which it behaves like CACHE_TEMPORARY. + */ + function set($cid, $data, $expire = CACHE_PERMANENT); + + + /** + * Expires 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 or an array of cache IDs. Otherwise, all cache + * entries that can expire are deleted. The $wildcard argument will be + * ignored if set to NULL. + * @param $wildcard + * If TRUE, the $cid argument must contain a string value and cache IDs + * starting with $cid are deleted in addition to the exact cache ID + * specified by $cid. If $wildcard is TRUE and $cid is '*', the entire + * cache is emptied. + */ + function clear($cid = NULL, $wildcard = FALSE); + + /** + * Checks if a cache bin is empty. + * + * A cache bin is considered empty if it does not contain any valid data for + * any cache ID. + * + * @return + * TRUE if the cache bin specified is empty. + */ + function isEmpty(); +} + +/** + * Defines a 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; + + /** + * Constructs a DrupalDatabaseCache object. + * + * @param $bin + * The cache bin for which the object is created. + */ + function __construct($bin) { + $this->bin = $bin; + } + + /** + * Implements DrupalCacheInterface::get(). + */ + function get($cid) { + $cids = array($cid); + $cache = $this->getMultiple($cids); + return reset($cache); + } + + /** + * Implements DrupalCacheInterface::getMultiple(). + */ + function getMultiple(&$cids) { + try { + // Garbage collection necessary when enforcing a minimum cache lifetime. + $this->garbageCollection($this->bin); + + // When serving cached pages, the overhead of using db_select() was found + // to add around 30% overhead to the request. Since $this->bin is a + // variable, this means the call to db_query() here uses a concatenated + // string. This is highly discouraged under any other circumstances, and + // is used here only due to the performance overhead we would incur + // otherwise. When serving an uncached page, the overhead of using + // db_select() is a much smaller proportion of the request. + $result = db_query('SELECT cid, data, created, expire, serialized FROM {' . db_escape_table($this->bin) . '} WHERE cid IN (:cids)', array(':cids' => $cids)); + $cache = array(); + foreach ($result as $item) { + $item = $this->prepareItem($item); + if ($item) { + $cache[$item->cid] = $item; + } + } + $cids = array_diff($cids, array_keys($cache)); + return $cache; + } + catch (Exception $e) { + // If the database is never going to be available, cache requests should + // return FALSE in order to allow exception handling to occur. + return array(); + } + } + + /** + * Garbage collection for get() and getMultiple(). + * + * @param $bin + * The bin being requested. + */ + protected function garbageCollection() { + $cache_lifetime = variable_get('cache_lifetime', 0); + + // Clean-up the per-user cache expiration session data, so that the session + // handler can properly clean-up the session data for anonymous users. + if (isset($_SESSION['cache_expiration'])) { + $expire = REQUEST_TIME - $cache_lifetime; + foreach ($_SESSION['cache_expiration'] as $bin => $timestamp) { + if ($timestamp < $expire) { + unset($_SESSION['cache_expiration'][$bin]); + } + } + if (!$_SESSION['cache_expiration']) { + unset($_SESSION['cache_expiration']); + } + } + + // Garbage collection of temporary items is only necessary when enforcing + // a minimum cache lifetime. + if (!$cache_lifetime) { + return; + } + // When cache lifetime is in force, avoid running garbage collection too + // often since this will remove temporary cache items indiscriminately. + $cache_flush = variable_get('cache_flush_' . $this->bin, 0); + if ($cache_flush && ($cache_flush + $cache_lifetime <= 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(); + } + } + + /** + * Prepares a cached item. + * + * Checks that items are either permanent or did not expire, and unserializes + * data as appropriate. + * + * @param $cache + * An item loaded from cache_get() or cache_get_multiple(). + * + * @return + * The item with data unserialized as appropriate or FALSE if there is no + * valid item to load. + */ + protected function prepareItem($cache) { + global $user; + + if (!isset($cache->data)) { + return FALSE; + } + // If the cached data is temporary and subject to a per-user minimum + // lifetime, compare the cache entry timestamp with the user session + // cache_expiration timestamp. If the cache entry is too old, ignore it. + if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) && isset($_SESSION['cache_expiration'][$this->bin]) && $_SESSION['cache_expiration'][$this->bin] > $cache->created) { + // Ignore cache data that is too old and thus not valid for this user. + return FALSE; + } + + // If the data is permanent or not subject to a minimum cache lifetime, + // unserialize and return the cached data. + if ($cache->serialized) { + $cache->data = unserialize($cache->data); + } + + return $cache; + } + + /** + * Implements DrupalCacheInterface::set(). + */ + function set($cid, $data, $expire = CACHE_PERMANENT) { + $fields = array( + 'serialized' => 0, + 'created' => REQUEST_TIME, + 'expire' => $expire, + ); + if (!is_string($data)) { + $fields['data'] = serialize($data); + $fields['serialized'] = 1; + } + else { + $fields['data'] = $data; + $fields['serialized'] = 0; + } + + try { + db_merge($this->bin) + ->key(array('cid' => $cid)) + ->fields($fields) + ->execute(); + } + catch (Exception $e) { + // The database may not be available, so we'll ignore cache_set requests. + } + } + + /** + * Implements DrupalCacheInterface::clear(). + */ + function clear($cid = NULL, $wildcard = FALSE) { + global $user; + + if (empty($cid)) { + if (variable_get('cache_lifetime', 0)) { + // We store the time in the current user's session. We then simulate + // that the cache was flushed for this user by not returning cached + // data that was cached before the timestamp. + $_SESSION['cache_expiration'][$this->bin] = 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_' . $this->bin, 0); + } + } + else { + // No minimum cache lifetime, flush all temporary cache entries now. + db_delete($this->bin) + ->condition('expire', CACHE_PERMANENT, '<>') + ->condition('expire', REQUEST_TIME, '<') + ->execute(); + } + } + else { + if ($wildcard) { + if ($cid == '*') { + // Check if $this->bin is a cache table before truncating. Other + // cache_clear_all() operations throw a PDO error in this situation, + // so we don't need to verify them first. This ensures that non-cache + // tables cannot be truncated accidentally. + if ($this->isValidBin()) { + db_truncate($this->bin)->execute(); + } + else { + throw new Exception(t('Invalid or missing cache bin specified: %bin', array('%bin' => $this->bin))); + } + } + else { + db_delete($this->bin) + ->condition('cid', db_like($cid) . '%', 'LIKE') + ->execute(); + } + } + elseif (is_array($cid)) { + // Delete in chunks when a large array is passed. + do { + db_delete($this->bin) + ->condition('cid', array_splice($cid, 0, 1000), 'IN') + ->execute(); + } + while (count($cid)); + } + else { + db_delete($this->bin) + ->condition('cid', $cid) + ->execute(); + } + } + } + + /** + * Implements DrupalCacheInterface::isEmpty(). + */ + function isEmpty() { + $this->garbageCollection(); + $query = db_select($this->bin); + $query->addExpression('1'); + $result = $query->range(0, 1) + ->execute() + ->fetchField(); + return empty($result); + } + + /** + * Checks if $this->bin represents a valid cache table. + * + * This check is required to ensure that non-cache tables are not truncated + * accidentally when calling cache_clear_all(). + * + * @return boolean + */ + function isValidBin() { + if ($this->bin == 'cache' || substr($this->bin, 0, 6) == 'cache_') { + // Skip schema check for bins with standard table names. + return TRUE; + } + // These fields are required for any cache table. + $fields = array('cid', 'data', 'expire', 'created', 'serialized'); + // Load the table schema. + $schema = drupal_get_schema($this->bin); + // Confirm that all fields are present. + return isset($schema['fields']) && !array_diff($fields, array_keys($schema['fields'])); + } +}