Added TDbCache.

1 files changed, 323 insertions, 0 deletions

diff --git a/framework/Caching/TDbCache.php b/framework/Caching/TDbCache.php
new file mode 100644
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--- /dev/null
+++ b/framework/Caching/TDbCache.php
@@ -0,0 +1,323 @@
+<?php

+/**

+ * TDbCache class file

+ *

+ * @author Qiang Xue <qiang.xue@gmail.com>

+ * @link http://www.pradosoft.com/

+ * @copyright Copyright &copy; 2005-2007 PradoSoft

+ * @license http://www.pradosoft.com/license/

+ * @version $Id$

+ * @package System.Caching

+ */

+

+Prado::using('System.Data.TDbConnection');

+

+/**

+ * TDbCache class

+ *

+ * TDbCache implements a cache application module by storing cached data in a database.

+ *

+ * TDbCache relies on {@link http://www.php.net/manual/en/ref.pdo.php PDO} to retrieve

+ * data from databases. In order to use TDbCache, you need to enable the PDO extension

+ * as well as the corresponding PDO DB driver. For example, to use SQLite database

+ * to store cached data, you need both php_pdo and php_pdo_sqlite extensions.

+ *

+ * By default, TDbCache creates and uses an SQLite database under the application

+ * runtime directory. You may change this default setting by specifying the following

+ * properties:

+ * - {@link setConnectionString ConnectionString}

+ * - {@link setUsername Username}

+ * - {@link setPassword Pasword}

+ *

+ * The cached data is stored in a table in the specified database.

+ * By default, the name of the table is called 'pradocache'. If the table does not

+ * exist in the database, it will be automatically created with the following structure:

+ * (key CHAR(128) PRIMARY KEY, value BLOB, expire INT)

+ *

+ * If you want to change the cache table name, or if you want to create the table by yourself,

+ * you may set {@link setCacheTableName CacheTableName} and {@link setAutoCreateCacheTable AutoCreateCacheTableName} properties.

+ *

+ * 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 TDbCache.

+ * Also note, cache is shared by all user sessions of an application.

+ *

+ * To use this module, the sqlite PHP extension must be loaded. Note, Sqlite extension

+ * is no longer loaded by default since PHP 5.1.

+ *

+ * Some usage examples of TDbCache are as follows,

+ * <code>

+ * $cache=new TDbCache;  // TDbCache may also be loaded as a Prado application module

+ * $cache->init(null);

+ * $cache->add('object',$object);

+ * $object2=$cache->get('object');

+ * </code>

+ *

+ * If loaded, TDbCache will register itself with {@link TApplication} as the

+ * cache module. It can be accessed via {@link TApplication::getCache()}.

+ *

+ * TDbCache may be configured in application configuration file as follows

+ * <code>

+ * <module id="cache" class="System.Caching.TDbCache" />

+ * </code>

+ *

+ * @author Qiang Xue <qiang.xue@gmail.com>

+ * @version $Id$

+ * @package System.Caching

+ * @since 3.1.0

+ */

+class TDbCache extends TCache

+{

+	/**

+	 * @var TDbConnection the DB connection instance

+	 */

+	private $_db;

+	/**

+	 * @var string name of the DB cache table

+	 */

+	private $_cacheTable='pradocache';

+	/**

+	 * @var boolean whether the cache DB table should be created automatically

+	 */

+	private $_autoCreate=true;

+

+	/**

+	 * Destructor.

+	 * Disconnect the db connection.

+	 */

+	public function __destruct()

+	{

+		if($this->_db!==null)

+			$this->_db->setActive(false);

+	}

+

+	/**

+	 * 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)

+	{

+		$db=$this->getDbConnection();

+		if($db->getConnectionString()==='')

+		{

+			// default to SQLite3 database

+			$dbFile=$this->getApplication()->getRuntimePath().'/sqlite3.cache';

+			$db->setConnectionString('sqlite:'.$dbFile);

+		}

+

+		$db->setActive(true);

+

+		$sql='DELETE FROM '.$this->_cacheTable.' WHERE expire<>0 AND expire<'.time();

+		try

+		{

+			$db->createCommand($sql)->execute();

+		}

+		catch(Exception $e)

+		{

+			// DB table not exists

+			if($this->_autoCreate)

+			{

+				$sql='CREATE TABLE '.$this->_cacheTable.' (key CHAR(128) PRIMARY KEY, value BLOB, expire INT)';

+				$db->createCommand($sql)->execute();

+			}

+			else

+				throw TConfigurationException('pdocache_cachetable_inexistent',$this->_cacheTable);

+		}

+

+		parent::init($config);

+	}

+

+	/**

+	 * @return TDbConnection the DB connection instance

+	 */

+	public function getDbConnection()

+	{

+		if($this->_db===null)

+			$this->_db=new TDbConnection;

+		return $this->_db;

+	}

+

+	/**

+	 * @return string The Data Source Name, or DSN, contains the information required to connect to the database.

+	 */

+	public function getConnectionString()

+	{

+		return $this->getDbConnection()->getConnectionString();

+	}

+

+	/**

+	 * @param string The Data Source Name, or DSN, contains the information required to connect to the database.

+	 * @see http://www.php.net/manual/en/function.pdo-construct.php

+	 */

+	public function setConnectionString($value)

+	{

+		$this->getDbConnection()->getConnectionString($value);

+	}

+

+	/**

+	 * @return string the username for establishing DB connection. Defaults to empty string.

+	 */

+	public function getUsername()

+	{

+		return $this->getDbConnection()->getUsername();

+	}

+

+	/**

+	 * @param string the username for establishing DB connection

+	 */

+	public function setUsername($value)

+	{

+		$this->getDbConnection()->setUsername($value);

+	}

+

+	/**

+	 * @return string the password for establishing DB connection. Defaults to empty string.

+	 */

+	public function getPassword()

+	{

+		return $this->getDbConnection()->getPassword();

+	}

+

+	/**

+	 * @param string the password for establishing DB connection

+	 */

+	public function setPassword($value)

+	{

+		$this->getDbConnection()->setPassword($value);

+	}

+

+	/**

+	 * @return string the name of the DB table to store cache content. Defaults to 'pradocache'.

+	 * @see setAutoCreateCacheTable

+	 */

+	public function getCacheTableName()

+	{

+		return $this->_cacheTable;

+	}

+

+	/**

+	 * Sets the name of the DB table to store cache content.

+	 * Note, if {@link setAutoCreateCacheTable AutoCreateCacheTable} is false

+	 * and you want to create the DB table manually by yourself,

+	 * you need to make sure the DB table is of the following structure:

+	 * (key CHAR(128) PRIMARY KEY, value BLOB, expire INT)

+	 * @param string the name of the DB table to store cache content

+	 * @see setAutoCreateCacheTable

+	 */

+	public function setCacheTableName($value)

+	{

+		$this->_cacheTable=$value;

+	}

+

+	/**

+	 * @return boolean whether the cache DB table should be automatically created if not exists. Defaults to true.

+	 * @see setAutoCreateCacheTable

+	 */

+	public function getAutoCreateCacheTable()

+	{

+		return $this->_autoCreate;

+	}

+

+	/**

+	 * @param boolean whether the cache DB table should be automatically created if not exists.

+	 * @see setCacheTableName

+	 */

+	public function setAutoCreateCacheTable($value)

+	{

+		$this->_autoCreate=TPropertyValue::ensureBoolean($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)

+	{

+		$sql='SELECT value FROM '.$this->_cacheTable.' WHERE key=\''.$key.'\' AND (expire=0 OR expire>'.time().')';

+		return $this->_db->createCommand($sql)->queryScalar();

+	}

+

+	/**

+	 * 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)

+	{

+		$this->deleteValue($key);

+		return $this->addValue($key,$value,$expire);

+	}

+

+	/**

+	 * 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)

+	{

+		$sql="INSERT INTO {$this->_cacheTable} (key,value,expire) VALUES('$key',:value,$expire)";

+		try

+		{

+			$command=$this->_db->createCommand($sql);

+			$command->bindValue(':value',$value,PDO::PARAM_LOB);

+			$command->execute();

+			return true;

+		}

+		catch(Exception $e)

+		{

+			return 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)

+	{

+		$this->_db->createCommand("DELETE FROM {$this->_cacheTable} WHERE key='$key'")->execute();

+		return true;

+	}

+

+	/**

+	 * Deletes all values from cache.

+	 * Be careful of performing this operation if the cache is shared by multiple applications.

+	 */

+	public function flush()

+	{

+		$this->_db->createCommand("DELETE FROM {$this->_cacheTable}")->execute();

+		return true;

+	}

+}

+

+?>
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