<?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 $Id$ * @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 $Id$ * @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 $row['value']; else return false; } /** * Stores a value identified by a key in cache. * This is the implementation of the method declared in the parent class. * * @param string the key identifying the value to be cached * @param string the value to be cached * @param integer the number of seconds in which the cached value will expire. 0 means never expire. * @return boolean true if the value is successfully stored into cache, false otherwise */ protected function setValue($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; } } ?>