/core/classes/framework/cache/engine/file.php

<?php

class Cache_Engine_File implements Cache_Interface {  
  
    private $_cacheDir = null;
    
    /**
     * 
     * Creates new FileBasedCache instance
     * 
     * @param string $directory
     * @throws Exception
     */
    function __construct($directory = "")  
    {  
        if (!$directory)
        {
            $directory = Loader::getCacheDirectoryPath();
        }
        else
        {
            $directory = Loader::getDirectPath($directory);
        }
        
        if (!is_dir($directory) || !is_writable($directory))  
        {  
            throw new Exception("Directory \"{$directory}\" is not writeable or does not exist!"); 
        }
        else
        {
            $this->_cacheDir = $directory;
        }
    }  
  
    private function _cacheFileName($key)  
    {  
        return $this->_cacheDir . Cfg_App::DS . md5($key);  
    }  
  
    public function get($key)  
    {  
        $cachePath = $this->_cacheFileName($key);  
  
        $cache = null;

        if (is_readable($cachePath))  
        {
            $fp = fopen($cachePath, 'rb');

            if ($fp)  
            {  
                flock($fp, LOCK_SH);  

                $cache = '';  

                if (filesize($cachePath) > 0)  
                {  
                    $cache = @unserialize(fread($fp, filesize($cachePath)));  
                }  
                else  
                {  
                    $cache = null;  
                }  

                flock($fp, LOCK_UN);  
                fclose($fp);
            }
            else 
            {
                trigger_error("Can not open \"{$cachePath}\" for reading!", E_USER_WARNING);
            }
        }
        else
        {
            trigger_error("\"{$cachePath}\" is not readable!", E_USER_WARNING);
        }

        return $cache;  
    }
  
    public function set($key, $data)  
    {  
        $cachePath = $this->_cacheFileName($key);  

        $fp = fopen($cachePath, 'wb');
        
        if ($fp)  
        {  
            if (flock($fp, LOCK_EX))  
            {  
                fwrite($fp, serialize($data));  
                flock($fp, LOCK_UN);  
            }  
            else  
            {
                trigger_error("Can not get lock for \"{$cachePath}\"!", E_USER_WARNING);
                
                return false;  
            }
            
            fclose($fp);
            
            chmod($cachePath, 0777); 
        }
        else
        {
            trigger_error("Can not open \"{$cachePath}\" for writing!", E_USER_WARNING);
            
            return false;
        }
      
        return true;  
    }  
  
    public function clear($key)  
    {  
        $cachePath = $this->_cacheFileName($key);  
  
        if (file_exists($cachePath))  
        {  
            if (unlink($cachePath))
            {
                return true;
            }
            else
            {
                trigger_error("Can not delete \"{$cachePath}\" cache file!", E_USER_NOTICE);
 
                return false;
            }
        }
        else
        {
            trigger_error("Can not locate \"{$cachePath}\" cache file!", E_USER_NOTICE);
        }
  
        return false;  
    }  
}