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<?php/*** TSqliteCache class file** @author Qiang Xue <qiang.xue@gmail.com>* @link http://www.pradosoft.com/* @copyright Copyright © 2005-2008 PradoSoft* @license http://www.pradosoft.com/license/* @version $Id: TSqliteCache.php 2541 2008-10-21 15:05:13Z qiang.xue $* @package System.Caching*//*** TSqliteCache class** TSqliteCache implements a cache application module based on SQLite database.** To use this module, the sqlite PHP extension must be loaded. Note, Sqlite extension* is no longer loaded by default since PHP 5.1.** Sine PRADO v3.1.0, a new DB-based cache module called {@link TDbCache}* is provided. If you have PDO extension installed, you may consider using* the new cache module instead as it allows you to use different database* to store the cached data.** The database file is specified by the {@link setDbFile DbFile} property.* If not set, the database file will be created under the system state path.* If the specified database file does not exist, it will be created automatically.* Make sure the directory containing the specified DB file and the file itself is* writable by the Web server process.** The following basic cache operations are implemented:* - {@link get} : retrieve the value with a key (if any) from cache* - {@link set} : store the value with a key into cache* - {@link add} : store the value only if cache does not have this key* - {@link delete} : delete the value with the specified key from cache* - {@link flush} : delete all values from cache** Each value is associated with an expiration time. The {@link get} operation* ensures that any expired value will not be returned. The expiration time by* the number of seconds. A expiration time 0 represents never expire.** By definition, cache does not ensure the existence of a value* even if it never expires. Cache is not meant to be an persistent storage.** Do not use the same database file for multiple applications using TSqliteCache.* Also note, cache is shared by all user sessions of an application.** Some usage examples of TSqliteCache are as follows,* <code>* $cache=new TSqliteCache; // TSqliteCache may also be loaded as a Prado application module* $cache->setDbFile($dbFilePath);* $cache->init(null);* $cache->add('object',$object);* $object2=$cache->get('object');* </code>** If loaded, TSqliteCache will register itself with {@link TApplication} as the* cache module. It can be accessed via {@link TApplication::getCache()}.** TSqliteCache may be configured in application configuration file as follows* <code>* <module id="cache" class="System.Caching.TSqliteCache" DbFile="Application.Data.site" />* </code>* where {@link getDbFile DbFile} is a property specifying the location of the* SQLite DB file (in the namespace format).** @author Qiang Xue <qiang.xue@gmail.com>* @version $Id: TSqliteCache.php 2541 2008-10-21 15:05:13Z qiang.xue $* @package System.Caching* @since 3.0*/class TSqliteCache extends TCache{/*** name of the table storing cache data*/const CACHE_TABLE='cache';/*** extension of the db file name*/const DB_FILE_EXT='.db';/*** @var boolean if the module has been initialized*/private $_initialized=false;/*** @var SQLiteDatabase the sqlite database instance*/private $_db=null;/*** @var string the database file name*/private $_file=null;/*** Destructor.* Disconnect the db connection.*/public function __destruct(){$this->_db=null;}/*** Initializes this module.* This method is required by the IModule interface. It checks if the DbFile* property is set, and creates a SQLiteDatabase instance for it.* The database or the cache table does not exist, they will be created.* Expired values are also deleted.* @param TXmlElement configuration for this module, can be null* @throws TConfigurationException if sqlite extension is not installed,* DbFile is set invalid, or any error happens during creating database or cache table.*/public function init($config){if(!function_exists('sqlite_open'))throw new TConfigurationException('sqlitecache_extension_required');if($this->_file===null)$this->_file=$this->getApplication()->getRuntimePath().'/sqlite.cache';$error='';if(($this->_db=new SQLiteDatabase($this->_file,0666,$error))===false)throw new TConfigurationException('sqlitecache_connection_failed',$error);if(@$this->_db->query('DELETE FROM '.self::CACHE_TABLE.' WHERE expire<>0 AND expire<'.time())===false){if($this->_db->query('CREATE TABLE '.self::CACHE_TABLE.' (key CHAR(128) PRIMARY KEY, value BLOB, expire INT)')===false)throw new TConfigurationException('sqlitecache_table_creation_failed',sqlite_error_string(sqlite_last_error()));}$this->_initialized=true;parent::init($config);}/*** @return string database file path (in namespace form)*/public function getDbFile(){return $this->_file;}/*** @param string database file path (in namespace form)* @throws TInvalidOperationException if the module is already initialized* @throws TConfigurationException if the file is not in proper namespace format*/public function setDbFile($value){if($this->_initialized)throw new TInvalidOperationException('sqlitecache_dbfile_unchangeable');else if(($this->_file=Prado::getPathOfNamespace($value,self::DB_FILE_EXT))===null)throw new TConfigurationException('sqlitecache_dbfile_invalid',$value);}/*** Retrieves a value from cache with a specified key.* This is the implementation of the method declared in the parent class.* @param string a unique key identifying the cached value* @return string the value stored in cache, false if the value is not in the cache or expired.*/protected function getValue($key){$sql='SELECT value FROM '.self::CACHE_TABLE.' WHERE key=\''.$key.'\' AND (expire=0 OR expire>'.time().') LIMIT 1';if(($ret=$this->_db->query($sql))!=false && ($row=$ret->fetch(SQLITE_ASSOC))!==false)return $row['value'];elsereturn false;}/*** Stores a value identified by a key in cache.* This is the implementation of the method declared in the parent class.** @param string the key identifying the value to be cached* @param string the value to be cached* @param integer the number of seconds in which the cached value will expire. 0 means never expire.* @return boolean true if the value is successfully stored into cache, false otherwise*/protected function setValue($key,$value,$expire){$expire=($expire<=0)?0:time()+$expire;$sql='REPLACE INTO '.self::CACHE_TABLE.' VALUES(\''.$key.'\',\''.sqlite_escape_string($value).'\','.$expire.')';return $this->_db->query($sql)!==false;}/*** Stores a value identified by a key into cache if the cache does not contain this key.* This is the implementation of the method declared in the parent class.** @param string the key identifying the value to be cached* @param string the value to be cached* @param integer the number of seconds in which the cached value will expire. 0 means never expire.* @return boolean true if the value is successfully stored into cache, false otherwise*/protected function addValue($key,$value,$expire){$expire=($expire<=0)?0:time()+$expire;$sql='INSERT INTO '.self::CACHE_TABLE.' VALUES(\''.$key.'\',\''.sqlite_escape_string($value).'\','.$expire.')';return @$this->_db->query($sql)!==false;}/*** Deletes a value with the specified key from cache* This is the implementation of the method declared in the parent class.* @param string the key of the value to be deleted* @return boolean if no error happens during deletion*/protected function deleteValue($key){$sql='DELETE FROM '.self::CACHE_TABLE.' WHERE key=\''.$key.'\'';return $this->_db->query($sql)!==false;}/*** Deletes all values from cache.* Be careful of performing this operation if the cache is shared by multiple applications.*/public function flush(){return $this->_db->query('DELETE FROM '.self::CACHE_TABLE)!==false;}}