Custom Cache Implementation {#caching.custom} =========================== As an alternative to using the default file-based caching mechanism, you can specify a custom cache implementation that will be used to read, write and clear cached files. > **Note** > > In Smarty2 this used to be a callback function called > `$cache_handler_func`. Smarty3 replaced this callback by the > `Smarty_CacheResource` module. With a custom cache implementation you\'re likely trying to achieve at least one of the following goals: replace the slow filesystem by a faster storage engine, centralize the cache to be accessible to multiple servers. Smarty allows CacheResource implementations to use one of the APIs `\Smarty\Cacheresource\Custom` or `\Smarty\Cacheresource\KeyValueStore`. `\Smarty\Cacheresource\Custom` is a simple API directing all read, write, clear calls to your implementation. This API allows you to store wherever and however you deem fit. The `\Smarty\Cacheresource\KeyValueStore` API allows you to turn any \"dumb\" KeyValue-Store (like APC, Memcache, ...) into a full-featured CacheResource implementation. That is, everything around deep cache-groups like \"a\|b\|c\" is being handled for you in way that allows clearing the cache-group \"a\" and all nested groups are cleared as well - even though KeyValue-Stores don\'t allow this kind of hierarchy by nature. Custom CacheResources may be put in a file `cacheresource.foobarxyz.php` within your [`$plugins_dir`](#variable.plugins.dir), or registered on runtime with [`registerCacheResource()`](#api.register.cacheresource). In either case you need to set [`$caching_type`](#variable.caching.type) to invoke your custom CacheResource implementation. caching_type = 'mysql'; /** * MySQL CacheResource * * CacheResource Implementation based on the Custom API to use * MySQL as the storage resource for Smarty's output caching. * * Table definition: * 
CREATE TABLE IF NOT EXISTS `output_cache` (
     *   `id` CHAR(40) NOT NULL COMMENT 'sha1 hash',
     *   `name` VARCHAR(250) NOT NULL,
     *   `cache_id` VARCHAR(250) NULL DEFAULT NULL,
     *   `compile_id` VARCHAR(250) NULL DEFAULT NULL,
     *   `modified` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
     *   `content` LONGTEXT NOT NULL,
     *   PRIMARY KEY (`id`),
     *   INDEX(`name`),
     *   INDEX(`cache_id`),
     *   INDEX(`compile_id`),
     *   INDEX(`modified`)
     * ) ENGINE = InnoDB;
* * @author Rodney Rehm */ class My_CacheResource_Mysql extends \Smarty\Cacheresource\Custom { // PDO instance protected $db; protected $fetch; protected $fetchTimestamp; protected $save; public function __construct() { try { $this->db = new PDO("mysql:dbname=test;host=127.0.0.1", "smarty", "smarty"); } catch (PDOException $e) { throw new \Smarty\Exception('Mysql Resource failed: ' . $e->getMessage()); } $this->fetch = $this->db->prepare('SELECT modified, content FROM output_cache WHERE id = :id'); $this->fetchTimestamp = $this->db->prepare('SELECT modified FROM output_cache WHERE id = :id'); $this->save = $this->db->prepare('REPLACE INTO output_cache (id, name, cache_id, compile_id, content) VALUES (:id, :name, :cache_id, :compile_id, :content)'); } /** * fetch cached content and its modification time from data source * * @param string $id unique cache content identifier * @param string $name template name * @param string $cache_id cache id * @param string $compile_id compile id * @param string $content cached content * @param integer $mtime cache modification timestamp (epoch) * @return void */ protected function fetch($id, $name, $cache_id, $compile_id, &$content, &$mtime) { $this->fetch->execute(array('id' => $id)); $row = $this->fetch->fetch(); $this->fetch->closeCursor(); if ($row) { $content = $row['content']; $mtime = strtotime($row['modified']); } else { $content = null; $mtime = null; } } /** * Fetch cached content's modification timestamp from data source * * @note implementing this method is optional. Only implement it if modification times can be accessed faster than loading the complete cached content. * @param string $id unique cache content identifier * @param string $name template name * @param string $cache_id cache id * @param string $compile_id compile id * @return integer|boolean timestamp (epoch) the template was modified, or false if not found */ protected function fetchTimestamp($id, $name, $cache_id, $compile_id) { $this->fetchTimestamp->execute(array('id' => $id)); $mtime = strtotime($this->fetchTimestamp->fetchColumn()); $this->fetchTimestamp->closeCursor(); return $mtime; } /** * Save content to cache * * @param string $id unique cache content identifier * @param string $name template name * @param string $cache_id cache id * @param string $compile_id compile id * @param integer|null $exp_time seconds till expiration time in seconds or null * @param string $content content to cache * @return boolean success */ protected function save($id, $name, $cache_id, $compile_id, $exp_time, $content) { $this->save->execute(array( 'id' => $id, 'name' => $name, 'cache_id' => $cache_id, 'compile_id' => $compile_id, 'content' => $content, )); return !!$this->save->rowCount(); } /** * Delete content from cache * * @param string $name template name * @param string $cache_id cache id * @param string $compile_id compile id * @param integer|null $exp_time seconds till expiration or null * @return integer number of deleted caches */ protected function delete($name, $cache_id, $compile_id, $exp_time) { // delete the whole cache if ($name === null && $cache_id === null && $compile_id === null && $exp_time === null) { // returning the number of deleted caches would require a second query to count them $query = $this->db->query('TRUNCATE TABLE output_cache'); return -1; } // build the filter $where = array(); // equal test name if ($name !== null) { $where[] = 'name = ' . $this->db->quote($name); } // equal test compile_id if ($compile_id !== null) { $where[] = 'compile_id = ' . $this->db->quote($compile_id); } // range test expiration time if ($exp_time !== null) { $where[] = 'modified < DATE_SUB(NOW(), INTERVAL ' . intval($exp_time) . ' SECOND)'; } // equal test cache_id and match sub-groups if ($cache_id !== null) { $where[] = '(cache_id = '. $this->db->quote($cache_id) . ' OR cache_id LIKE '. $this->db->quote($cache_id .'|%') .')'; } // run delete query $query = $this->db->query('DELETE FROM output_cache WHERE ' . join(' AND ', $where)); return $query->rowCount(); } } caching_type = 'memcache'; /** * Memcache CacheResource * * CacheResource Implementation based on the KeyValueStore API to use * memcache as the storage resource for Smarty's output caching. * * Note that memcache has a limitation of 256 characters per cache-key. * To avoid complications all cache-keys are translated to a sha1 hash. * * @author Rodney Rehm */ class My_CacheResource_Memcache extends \Smarty\Cacheresource\KeyValueStore { /** * memcache instance * @var Memcache */ protected $memcache = null; public function __construct() { $this->memcache = new Memcache(); $this->memcache->addServer( '127.0.0.1', 11211 ); } /** * Read values for a set of keys from cache * * @param array $keys list of keys to fetch * @return array list of values with the given keys used as indexes * @return boolean true on success, false on failure */ protected function read(array $keys) { $_keys = $lookup = array(); foreach ($keys as $k) { $_k = sha1($k); $_keys[] = $_k; $lookup[$_k] = $k; } $_res = array(); $res = $this->memcache->get($_keys); foreach ($res as $k => $v) { $_res[$lookup[$k]] = $v; } return $_res; } /** * Save values for a set of keys to cache * * @param array $keys list of values to save * @param int $expire expiration time * @return boolean true on success, false on failure */ protected function write(array $keys, $expire=null) { foreach ($keys as $k => $v) { $k = sha1($k); $this->memcache->set($k, $v, 0, $expire); } return true; } /** * Remove values from cache * * @param array $keys list of keys to delete * @return boolean true on success, false on failure */ protected function delete(array $keys) { foreach ($keys as $k) { $k = sha1($k); $this->memcache->delete($k); } return true; } /** * Remove *all* values from cache * * @return boolean true on success, false on failure */ protected function purge() { return $this->memcache->flush(); } }