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<?php
/**
* CFileCache class file
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.yiiframework.com/
* @copyright 2008-2013 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* CFileCache provides a file-based caching mechanism.
*
* For each data value being cached, CFileCache will use store it in a separate file
* under {@link cachePath} which defaults to 'protected/runtime/cache'.
* CFileCache will perform garbage collection automatically to remove expired cache files.
*
* See {@link CCache} manual for common cache operations that are supported by CFileCache.
*
* @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.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @package system.caching
*/
class CFileCache extends CCache
{
/**
* @var string the directory to store cache files. Defaults to null, meaning
* using 'protected/runtime/cache' as the directory.
*/
public $cachePath;
/**
* @var integer the permission to be set for directory to store cache files
* This value will be used by PHP chmod function.
* Defaults to 0777, meaning the directory can be read, written and executed by all users.
* @since 1.1.16
*/
public $cachePathMode=0777;
/**
* @var string cache file suffix. Defaults to '.bin'.
*/
public $cacheFileSuffix='.bin';
/**
* @var integer the permission to be set for new cache files.
* This value will be used by PHP chmod function.
* Defaults to 0666, meaning the file is read-writable by all users.
* @since 1.1.16
*/
public $cacheFileMode=0666;
/**
* @var integer the level of sub-directories to store cache files. Defaults to 0,
* meaning no sub-directories. If the system has huge number of cache files (e.g. 10K+),
* you may want to set this value to be 1 or 2 so that the file system is not over burdened.
* The value of this property should not exceed 16 (less than 3 is recommended).
*/
public $directoryLevel=0;
/**
* @var boolean whether cache entry expiration time should be embedded into a physical file.
* Defaults to false meaning that the file modification time will be used to store expire value.
* True value means that first ten bytes of the file would be reserved and used to store expiration time.
* On some systems PHP is not allowed to change file modification time to be in future even with 777
* permissions, so this property could be useful in this case.
* @since 1.1.14
*/
public $embedExpiry=false;
private $_gcProbability=100;
private $_gced=false;
/**
* Initializes this application component.
* This method is required by the {@link IApplicationComponent} interface.
*/
public function init()
{
parent::init();
if($this->cachePath===null)
$this->cachePath=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'cache';
if(!is_dir($this->cachePath))
{
mkdir($this->cachePath,$this->cachePathMode,true);
chmod($this->cachePath,$this->cachePathMode);
}
}
/**
* @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;
}
/**
* 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->gc(false);
return true;
}
/**
* Retrieves a value from cache with a specified key.
* This is the implementation of the method declared in the parent class.
* @param string $key a unique key identifying the cached value
* @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
*/
protected function getValue($key)
{
$cacheFile=$this->getCacheFile($key);
if(($time=$this->filemtime($cacheFile))>time())
return @file_get_contents($cacheFile,false,null,$this->embedExpiry ? 10 : null);
elseif($time>0)
@unlink($cacheFile);
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 $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)
{
if(!$this->_gced && mt_rand(0,1000000)<$this->_gcProbability)
{
$this->gc();
$this->_gced=true;
}
if($expire<=0)
$expire=31536000; // 1 year
$expire+=time();
$cacheFile=$this->getCacheFile($key);
if($this->directoryLevel>0)
{
$cacheDir=dirname($cacheFile);
@mkdir($cacheDir,$this->cachePathMode,true);
@chmod($cacheDir,$this->cachePathMode);
}
if(@file_put_contents($cacheFile,$this->embedExpiry ? $expire.$value : $value,LOCK_EX)!==false)
{
@chmod($cacheFile,$this->cacheFileMode);
return $this->embedExpiry ? true : @touch($cacheFile,$expire);
}
else
return 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 $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)
{
$cacheFile=$this->getCacheFile($key);
if($this->filemtime($cacheFile)>time())
return false;
return $this->setValue($key,$value,$expire);
}
/**
* 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)
{
$cacheFile=$this->getCacheFile($key);
return @unlink($cacheFile);
}
/**
* Returns the cache file path given the cache key.
* @param string $key cache key
* @return string the cache file path
*/
protected function getCacheFile($key)
{
if($this->directoryLevel>0)
{
$base=$this->cachePath;
for($i=0;$i<$this->directoryLevel;++$i)
{
if(($prefix=substr($key,$i+$i,2))!==false)
$base.=DIRECTORY_SEPARATOR.$prefix;
}
return $base.DIRECTORY_SEPARATOR.$key.$this->cacheFileSuffix;
}
else
return $this->cachePath.DIRECTORY_SEPARATOR.$key.$this->cacheFileSuffix;
}
/**
* Removes expired cache files.
* @param boolean $expiredOnly whether only expired cache files should be removed.
* If false, all cache files under {@link cachePath} will be removed.
* @param string $path the path to clean with. If null, it will be {@link cachePath}.
*/
public function gc($expiredOnly=true,$path=null)
{
if($path===null)
$path=$this->cachePath;
if(($handle=opendir($path))===false)
return;
while(($file=readdir($handle))!==false)
{
if($file[0]==='.')
continue;
$fullPath=$path.DIRECTORY_SEPARATOR.$file;
if(is_dir($fullPath))
$this->gc($expiredOnly,$fullPath);
elseif($expiredOnly && $this->filemtime($fullPath)<time() || !$expiredOnly)
@unlink($fullPath);
}
closedir($handle);
}
/**
* Returns cache file modification time. {@link $embedExpiry} aware.
* @param string $path to the file, modification time to be retrieved from.
* @return integer file modification time.
*/
private function filemtime($path)
{
if($this->embedExpiry)
return (int)@file_get_contents($path,false,null,0,10);
else
return @filemtime($path);
}
}
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