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Diffstat (limited to 'framework/caching/CDbCache.php')
| -rw-r--r-- | framework/caching/CDbCache.php | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/framework/caching/CDbCache.php b/framework/caching/CDbCache.php new file mode 100644 index 0000000..90e5009 --- /dev/null +++ b/framework/caching/CDbCache.php @@ -0,0 +1,314 @@ +<?php +/** + * CDbCache class file + * + * @author Qiang Xue <qiang.xue@gmail.com> + * @link http://www.yiiframework.com/ + * @copyright Copyright © 2008-2011 Yii Software LLC + * @license http://www.yiiframework.com/license/ + */ + +/** + * CDbCache implements a cache application component by storing cached data in a database. + * + * CDbCache stores cache data in a DB table named {@link cacheTableName}. + * If the table does not exist, it will be automatically created. + * By setting {@link autoCreateCacheTable} to false, you can also manually create the DB table. + * + * CDbCache relies on {@link http://www.php.net/manual/en/ref.pdo.php PDO} to access database. + * By default, it will use a SQLite3 database under the application runtime directory. + * You can also specify {@link connectionID} so that it makes use of + * a DB application component to access database. + * + * See {@link CCache} manual for common cache operations that are supported by CDbCache. + * + * @property integer $gCProbability The probability (parts per million) that garbage collection (GC) should be performed + * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. + * @property CDbConnection $dbConnection The DB connection instance. + * + * @author Qiang Xue <qiang.xue@gmail.com> + * @version $Id: CDbCache.php 3515 2011-12-28 12:29:24Z mdomba $ + * @package system.caching + * @since 1.0 + */ +class CDbCache extends CCache +{ + /** + * @var string the ID of the {@link CDbConnection} application component. If not set, + * a SQLite3 database will be automatically created and used. The SQLite database file + * is <code>protected/runtime/cache-YiiVersion.db</code>. + */ + public $connectionID; + /** + * @var string name of the DB table to store cache content. Defaults to 'YiiCache'. + * Note, if {@link 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: + * <pre> + * (id CHAR(128) PRIMARY KEY, expire INTEGER, value BLOB) + * </pre> + * Note, some DBMS might not support BLOB type. In this case, replace 'BLOB' with a suitable + * binary data type (e.g. LONGBLOB in MySQL, BYTEA in PostgreSQL.) + * @see autoCreateCacheTable + */ + public $cacheTableName='YiiCache'; + /** + * @var boolean whether the cache DB table should be created automatically if it does not exist. Defaults to true. + * If you already have the table created, it is recommended you set this property to be false to improve performance. + * @see cacheTableName + */ + public $autoCreateCacheTable=true; + /** + * @var CDbConnection the DB connection instance + */ + private $_db; + private $_gcProbability=100; + private $_gced=false; + + /** + * Initializes this application component. + * + * This method is required by the {@link IApplicationComponent} interface. + * It ensures the existence of the cache DB table. + * It also removes expired data items from the cache. + */ + public function init() + { + parent::init(); + + $db=$this->getDbConnection(); + $db->setActive(true); + if($this->autoCreateCacheTable) + { + $sql="DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time(); + try + { + $db->createCommand($sql)->execute(); + } + catch(Exception $e) + { + $this->createCacheTable($db,$this->cacheTableName); + } + } + } + + /** + * @return integer the probability (parts per million) that garbage collection (GC) should be performed + * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. + */ + public function getGCProbability() + { + return $this->_gcProbability; + } + + /** + * @param integer $value the probability (parts per million) that garbage collection (GC) should be performed + * when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. + * This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all. + */ + public function setGCProbability($value) + { + $value=(int)$value; + if($value<0) + $value=0; + if($value>1000000) + $value=1000000; + $this->_gcProbability=$value; + } + + /** + * Creates the cache DB table. + * @param CDbConnection $db the database connection + * @param string $tableName the name of the table to be created + */ + protected function createCacheTable($db,$tableName) + { + $driver=$db->getDriverName(); + if($driver==='mysql') + $blob='LONGBLOB'; + else if($driver==='pgsql') + $blob='BYTEA'; + else + $blob='BLOB'; + $sql=<<<EOD +CREATE TABLE $tableName +( + id CHAR(128) PRIMARY KEY, + expire INTEGER, + value $blob +) +EOD; + $db->createCommand($sql)->execute(); + } + + /** + * @return CDbConnection the DB connection instance + * @throws CException if {@link connectionID} does not point to a valid application component. + */ + public function getDbConnection() + { + if($this->_db!==null) + return $this->_db; + else if(($id=$this->connectionID)!==null) + { + if(($this->_db=Yii::app()->getComponent($id)) instanceof CDbConnection) + return $this->_db; + else + throw new CException(Yii::t('yii','CDbCache.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.', + array('{id}'=>$id))); + } + else + { + $dbFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'cache-'.Yii::getVersion().'.db'; + return $this->_db=new CDbConnection('sqlite:'.$dbFile); + } + } + + /** + * Sets the DB connection used by the cache component. + * @param CDbConnection $value the DB connection instance + * @since 1.1.5 + */ + public function setDbConnection($value) + { + $this->_db=$value; + } + + /** + * Retrieves a value from cache with a specified key. + * This is the implementation of the method declared in the parent class. + * @param string $key a unique key identifying the cached value + * @return string the value stored in cache, false if the value is not in the cache or expired. + */ + protected function getValue($key) + { + $time=time(); + $sql="SELECT value FROM {$this->cacheTableName} WHERE id='$key' AND (expire=0 OR expire>$time)"; + $db=$this->getDbConnection(); + if($db->queryCachingDuration>0) + { + $duration=$db->queryCachingDuration; + $db->queryCachingDuration=0; + $result=$db->createCommand($sql)->queryScalar(); + $db->queryCachingDuration=$duration; + return $result; + } + else + return $db->createCommand($sql)->queryScalar(); + } + + /** + * Retrieves multiple values from cache with the specified keys. + * @param array $keys a list of keys identifying the cached values + * @return array a list of cached values indexed by the keys + */ + protected function getValues($keys) + { + if(empty($keys)) + return array(); + + $ids=implode("','",$keys); + $time=time(); + $sql="SELECT id, value FROM {$this->cacheTableName} WHERE id IN ('$ids') AND (expire=0 OR expire>$time)"; + + $db=$this->getDbConnection(); + if($db->queryCachingDuration>0) + { + $duration=$db->queryCachingDuration; + $db->queryCachingDuration=0; + $rows=$db->createCommand($sql)->queryAll(); + $db->queryCachingDuration=$duration; + } + else + $rows=$db->createCommand($sql)->queryAll(); + + $results=array(); + foreach($keys as $key) + $results[$key]=false; + foreach($rows as $row) + $results[$row['id']]=$results[$row['value']]; + return $results; + } + + /** + * Stores a value identified by a key in cache. + * This is the implementation of the method declared in the parent class. + * + * @param string $key the key identifying the value to be cached + * @param string $value the value to be cached + * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire. + * @return boolean true if the value is successfully stored into cache, false otherwise + */ + protected function setValue($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 $key the key identifying the value to be cached + * @param string $value the value to be cached + * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire. + * @return boolean true if the value is successfully stored into cache, false otherwise + */ + protected function addValue($key,$value,$expire) + { + if(!$this->_gced && mt_rand(0,1000000)<$this->_gcProbability) + { + $this->gc(); + $this->_gced=true; + } + + if($expire>0) + $expire+=time(); + else + $expire=0; + $sql="INSERT INTO {$this->cacheTableName} (id,expire,value) VALUES ('$key',$expire,:value)"; + try + { + $command=$this->getDbConnection()->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 $key the key of the value to be deleted + * @return boolean if no error happens during deletion + */ + protected function deleteValue($key) + { + $sql="DELETE FROM {$this->cacheTableName} WHERE id='$key'"; + $this->getDbConnection()->createCommand($sql)->execute(); + return true; + } + + /** + * Removes the expired data values. + */ + protected function gc() + { + $this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName} WHERE expire>0 AND expire<".time())->execute(); + } + + /** + * Deletes all values from cache. + * This is the implementation of the method declared in the parent class. + * @return boolean whether the flush operation was successful. + * @since 1.1.5 + */ + protected function flushValues() + { + $this->getDbConnection()->createCommand("DELETE FROM {$this->cacheTableName}")->execute(); + return true; + } +} |