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Diffstat (limited to 'framework/Data/TSqliteCache.php')
| -rw-r--r-- | framework/Data/TSqliteCache.php | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/framework/Data/TSqliteCache.php b/framework/Data/TSqliteCache.php new file mode 100644 index 00000000..8d59b035 --- /dev/null +++ b/framework/Data/TSqliteCache.php @@ -0,0 +1,277 @@ +<?php
+/**
+ * TSqliteCache class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link http://www.pradosoft.com/
+ * @copyright Copyright © 2005 PradoSoft
+ * @license http://www.pradosoft.com/license/
+ * @version $Revision: $ $Date: $
+ * @package System.Data
+ */
+
+/**
+ * TSqliteCache class
+ *
+ * TSqliteCache implements a cache application module based on SQLite database.
+ *
+ * The database file is specified by the DbFile property. This property must
+ * be set before {@link init} is invoked. If the specified database file does not
+ * exist, it will be created automatically. Make sure the database file is writable.
+ *
+ * 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 replace} : store the value only if cache has 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 can
+ * be specified by the number of seconds (maximum 60*60*24*30)
+ * or a UNIX timestamp. 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.
+ *
+ * To use this module, the sqlite PHP extension must be loaded. Sqlite extension
+ * is no longer loaded by default since PHP 5.1.
+ *
+ * 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>
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @version $Revision: $ $Date: $
+ * @package System.Data
+ * @since 3.0
+ */
+class TSqliteCache extends TComponent implements IModule, ICache
+{
+ /**
+ * name of the table storing cache data
+ */
+ const CACHE_TABLE='cache';
+ /**
+ * extension of the db file name
+ */
+ const DB_FILE_EXT='.db';
+ /**
+ * maximum number of seconds specified as expire
+ */
+ const EXPIRE_LIMIT=2592000; // 30 days
+
+ /**
+ * @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;
+ /**
+ * @var string id of this module
+ */
+ private $_id='';
+
+ /**
+ * Destructor.
+ * Disconnect the db connection.
+ */
+ public function __destruct()
+ {
+ $this->_db=null;
+ parent::__destruct();
+ }
+
+ /**
+ * Initializes this module.
+ * This method is required by the IModule interface. It checks if the DbFile
+ * property is set, and creates a SQLiteDatabase instance for it.
+ * The database or the cache table does not exist, they will be created.
+ * Expired values are also deleted.
+ * @param IApplication Prado application, can be null
+ * @param TXmlElement configuration for this module, can be null
+ * @throws TConfigurationException if sqlite extension is not installed,
+ * DbFile is set invalid, or any error happens during creating database or cache table.
+ */
+ public function init($application,$config)
+ {
+ if(!function_exists('sqlite_open'))
+ throw new TConfigurationException('sqlitecache_extension_required');
+ if($this->_file===null)
+ throw new TConfigurationException('sqlitecache_filename_required');
+ $error='';
+ if(($fname=Prado::getPathOfNamespace($this->_file,self::DB_FILE_EXT))===null)
+ throw new TConfigurationException('sqlitecache_dbfile_invalid',$this->_file);
+ if(($this->_db=new SQLiteDatabase($fname,0666,$error))===false)
+ throw new TConfigurationException('sqlitecache_connection_failed',$error);
+ if(($res=$this->_db->query('SELECT * FROM sqlite_master WHERE tbl_name=\''.self::CACHE_TABLE.'\' AND type=\'table\''))!=false)
+ {
+ if($res->numRows()===0)
+ {
+ if($this->_db->query('CREATE TABLE '.self::CACHE_TABLE.' (key CHAR(128) PRIMARY KEY, value BLOB, serialized INT, expire INT)')===false)
+ throw new TConfigurationException('sqlitecache_table_creation_failed',sqlite_error_string(sqlite_last_error()));
+ }
+ }
+ else
+ throw new TConfigurationException('sqlitecache_table_creation_failed',sqlite_error_string(sqlite_last_error()));
+ $this->_initialized=true;
+ $this->_db->query('DELETE FROM '.self::CACHE_TABLE.' WHERE expire<>0 AND expire<'.time());
+ }
+
+ /**
+ * @return string id of this module
+ */
+ public function getID()
+ {
+ return $this->_id;
+ }
+
+ /**
+ * @param string id of this module
+ */
+ public function setID($value)
+ {
+ $this->_id=$value;
+ }
+
+ /**
+ * @return string database file path (in namespace form)
+ */
+ public function getDbFile()
+ {
+ return $this->_file;
+ }
+
+ /**
+ * @param string database file path (in namespace form)
+ * @throws TInvalidOperationException if the module is already initialized
+ */
+ public function setDbFile($value)
+ {
+ if($this->_initialized)
+ throw new TInvalidOperationException('sqlitecache_dbfile_unchangeable');
+ else
+ $this->_file=$value;
+ }
+
+ /**
+ * Retrieves a value from cache with a specified key.
+ * @return mixed the value stored in cache, false if the value is not in the cache or expired.
+ */
+ public function get($key)
+ {
+ $sql='SELECT serialized,value FROM '.self::CACHE_TABLE.' WHERE key=\''.md5($key).'\' AND (expire=0 OR expire>'.time().')';
+ if(($ret=$this->_db->query($sql))!=false && ($row=$ret->fetch(SQLITE_ASSOC))!==false)
+ return $row['serialized']?Prado::unserialize($row['value']):$row['value'];
+ else
+ return false;
+ }
+
+ /**
+ * Stores a value identified by a key into cache.
+ * If the cache already contains such a key, the existing value and
+ * expiration time will be replaced with the new ones.
+ *
+ * Note, avoid using this method whenever possible. Database insertion is
+ * very expensive. Try using {@link add} instead, which will not store the value
+ * if the key is already in cache.
+ *
+ * @param string the key identifying the value to be cached
+ * @param mixed the value to be cached
+ * @param integer the expiration time of the value,
+ * 0 means never expire,
+ * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid.
+ * a number greater than 60 means a UNIX timestamp after which the value will expire.
+ * @return boolean true if the value is successfully stored into cache, false otherwise
+ */
+ public function set($key,$value,$expire=0)
+ {
+ $serialized=is_string($value)?0:1;
+ $value1=sqlite_escape_string($serialized?Prado::serialize($value):$value);
+ if($expire && $expire<=self::EXPIRE_LIMIT)
+ $expire=time()+$expire;
+ $sql='REPLACE INTO '.self::CACHE_TABLE.' VALUES(\''.md5($key).'\',\''.$value1.'\','.$serialized.','.$expire.')';
+ return $this->_db->query($sql)!==false;
+ }
+
+ /**
+ * Stores a value identified by a key into cache if the cache does not contain this key.
+ * Nothing will be done if the cache already contains the key.
+ * @param string the key identifying the value to be cached
+ * @param mixed the value to be cached
+ * @param integer the expiration time of the value,
+ * 0 means never expire,
+ * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid.
+ * a number greater than 60 means a UNIX timestamp after which the value will expire.
+ * @return boolean true if the value is successfully stored into cache, false otherwise
+ */
+ public function add($key,$value,$expire=0)
+ {
+ $serialized=is_string($value)?0:1;
+ $value1=sqlite_escape_string($serialized?Prado::serialize($value):$value);
+ if($expire && $expire<=self::EXPIRE_LIMIT)
+ $expire=time()+$expire;
+ $sql='INSERT INTO '.self::CACHE_TABLE.' VALUES(\''.md5($key).'\',\''.$value1.'\','.$serialized.','.$expire.')';
+ return @$this->_db->query($sql)!==false;
+ }
+
+ /**
+ * Stores a value identified by a key into cache only if the cache contains this key.
+ * The existing value and expiration time will be overwritten with the new ones.
+ * @param string the key identifying the value to be cached
+ * @param mixed the value to be cached
+ * @param integer the expiration time of the value,
+ * 0 means never expire,
+ * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid.
+ * a number greater than 60 means a UNIX timestamp after which the value will expire.
+ * @return boolean true if the value is successfully stored into cache, false otherwise
+ */
+ public function replace($key,$value,$expire=0)
+ {
+ $serialized=is_string($value)?0:1;
+ $value1=sqlite_escape_string($serialized?Prado::serialize($value):$value);
+ if($expire && $expire<=self::EXPIRE_LIMIT)
+ $expire=time()+$expire;
+ $sql='UPDATE '.self::CACHE_TABLE.' SET value=\''.$value1.'\', serialized='.$serialized.',expire='.$expire.' WHERE key=\''.md5($key).'\'';
+ $this->_db->query($sql);
+ $ret=$this->_db->query('SELECT serialized FROM '.self::CACHE_TABLE.' WHERE key=\''.md5($key).'\'');
+ return ($ret!=false && $ret->numRows()>0);
+ }
+
+ /**
+ * Deletes a value with the specified key from cache
+ * @param string the key of the value to be deleted
+ * @return boolean if no error happens during deletion
+ */
+ public function delete($key)
+ {
+ $sql='DELETE FROM '.self::CACHE_TABLE.' WHERE key=\''.md5($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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