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<?php
/**
* TSqliteCache class file
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.pradosoft.com/
* @copyright Copyright © 2005-2015 PradoSoft
* @license http://www.pradosoft.com/license/
* @package System.Caching
*/
/**
* TSqliteCache class
*
* TSqliteCache implements a cache application module based on SQLite database.
*
* THIS CLASS IS DEPRECATED since it relies on the sqlite PHP extension, that is
* no longer loaded by default since PHP 5.1. You are discouraged from using it:
* use {@link TDbCache} instead.
*
* Since 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>
* @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=$ret->fetch(SQLITE_ASSOC))!==false)
return unserialize($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(serialize($value)).'\','.$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(serialize($value)).'\','.$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;
}
}
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