lite.php

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<?php

/**
* Fast, light and safe Cache Class
*
* Cache_Lite is a fast, light and safe cache system. It's optimized
* for file containers. It is fast and safe (because it uses file
* locking and/or anti-corruption tests).
*
* There are some examples in the 'docs/examples' file
* Technical choices are described in the 'docs/technical' file
*
* Memory Caching is from an original idea of
* Mike BENOIT <[e-mail]>
*
* Nota : A chinese documentation (thanks to RainX <[e-mail]>) is
* available at :
* http://rainx.phpmore.com/manual/cache_lite.html
*
* @package Cache_Lite
* @category Caching
* @version $Id: Lite.php,v 1.30 2005/06/13 20:50:48 fab Exp $
* @author Fabien MARTY <[e-mail]>
*/

define('CACHE_LITE_ERROR_RETURN', 1);
define('CACHE_LITE_ERROR_DIE', 8);

class Cache_Lite
{

    // --- Private properties ---

    /**
    * Directory where to put the cache files
    * (make sure to add a trailing slash)
    *
    * @var string $_cacheDir
    */
    var $_cacheDir = '/tmp/';

    /**
    * Enable / disable caching
    *
    * (can be very usefull for the debug of cached scripts)
    *
    * @var boolean $_caching
    */
    var $_caching = true;

    /**
    * Cache lifetime (in seconds)
    *
    * @var int $_lifeTime
    */
    var $_lifeTime = 3600;

    /**
    * Enable / disable fileLocking
    *
    * (can avoid cache corruption under bad circumstances)
    *
    * @var boolean $_fileLocking
    */
    var $_fileLocking = true;

    /**
    * Timestamp of the last valid cache
    *
    * @var int $_refreshTime
    */
    var $_refreshTime;

    /**
    * File name (with path)
    *
    * @var string $_file
    */
    var $_file;
    
    /**
    * File name (without path)
    *
    * @var string $_fileName
    */
    var $_fileName;

    /**
    * Enable / disable write control (the cache is read just after writing to detect corrupt entries)
    *
    * Enable write control will lightly slow the cache writing but not the cache reading
    * Write control can detect some corrupt cache files but maybe it's not a perfect control
    *
    * @var boolean $_writeControl
    */
    var $_writeControl = true;

    /**
    * Enable / disable read control
    *
    * If enabled, a control key is embeded in cache file and this key is compared with the one
    * calculated after the reading.
    *
    * @var boolean $_writeControl
    */
    var $_readControl = true;

    /**
    * Type of read control (only if read control is enabled)
    *
    * Available values are :
    * 'md5' for a md5 hash control (best but slowest)
    * 'crc32' for a crc32 hash control (lightly less safe but faster, better choice)
    * 'strlen' for a length only test (fastest)
    *
    * @var boolean $_readControlType
    */
    var $_readControlType = 'crc32';

    /**
    * Pear error mode (when raiseError is called)
    *
    * (see PEAR doc)
    *
    * @see setToDebug()
    * @var int $_pearErrorMode
    */
    var $_pearErrorMode = CACHE_LITE_ERROR_RETURN;
    
    /**
    * Current cache id
    *
    * @var string $_id
    */
    var $_id;

    /**
    * Current cache group
    *
    * @var string $_group
    */
    var $_group;

    /**
    * Enable / Disable "Memory Caching"
    *
    * NB : There is no lifetime for memory caching ! 
    *
    * @var boolean $_memoryCaching
    */
    var $_memoryCaching = false;

    /**
    * Enable / Disable "Only Memory Caching"
    * (be carefull, memory caching is "beta quality")
    *
    * @var boolean $_onlyMemoryCaching
    */
    var $_onlyMemoryCaching = false;

    /**
    * Memory caching array
    *
    * @var array $_memoryCachingArray
    */
    var $_memoryCachingArray = array();

    /**
    * Memory caching counter
    *
    * @var int $memoryCachingCounter
    */
    var $_memoryCachingCounter = 0;

    /**
    * Memory caching limit
    *
    * @var int $memoryCachingLimit
    */
    var $_memoryCachingLimit = 1000;
    
    /**
    * File Name protection
    *
    * if set to true, you can use any cache id or group name
    * if set to false, it can be faster but cache ids and group names
    * will be used directly in cache file names so be carefull with
    * special characters...
    *
    * @var boolean $fileNameProtection
    */
    var $_fileNameProtection = true;
    
    /**
    * Enable / disable automatic serialization
    *
    * it can be used to save directly datas which aren't strings
    * (but it's slower)    
    *
    * @var boolean $_serialize
    */
    var $_automaticSerialization = false;
    
    /**
    * Disable / Tune the automatic cleaning process
    *
    * The automatic cleaning process destroy too old (for the given life time)
    * cache files when a new cache file is written.
    * 0               => no automatic cache cleaning
    * 1               => systematic cache cleaning
    * x (integer) > 1 => automatic cleaning randomly 1 times on x cache write
    *
    * @var int $_automaticCleaning
    */
    var $_automaticCleaningFactor = 0;
    
    /**
    * Nested directory level
    *
    * Set the hashed directory structure level. 0 means "no hashed directory 
    * structure", 1 means "one level of directory", 2 means "two levels"... 
    * This option can speed up Cache_Lite only when you have many thousands of 
    * cache file. Only specific benchs can help you to choose the perfect value 
    * for you. Maybe, 1 or 2 is a good start.
    *
    * @var int $_hashedDirectoryLevel
    */
    var $_hashedDirectoryLevel = 0;
    
    /**
    * Umask for hashed directory structure
    *
    * @var int $_hashedDirectoryUmask
    */
    var $_hashedDirectoryUmask = 0700;
    
    // --- Public methods ---

    /**
    * Constructor
    *
    * $options is an assoc. Available options are :
    * $options = array(
    *     'cacheDir' => directory where to put the cache files (string),
    *     'caching' => enable / disable caching (boolean),
    *     'lifeTime' => cache lifetime in seconds (int),
    *     'fileLocking' => enable / disable fileLocking (boolean),
    *     'writeControl' => enable / disable write control (boolean),
    *     'readControl' => enable / disable read control (boolean),
    *     'readControlType' => type of read control 'crc32', 'md5', 'strlen' (string),
    *     'pearErrorMode' => pear error mode (when raiseError is called) (cf PEAR doc) (int),
    *     'memoryCaching' => enable / disable memory caching (boolean),
    *     'onlyMemoryCaching' => enable / disable only memory caching (boolean),
    *     'memoryCachingLimit' => max nbr of records to store into memory caching (int),
    *     'fileNameProtection' => enable / disable automatic file name protection (boolean),
    *     'automaticSerialization' => enable / disable automatic serialization (boolean)
    *     'automaticCleaningFactor' => distable / tune automatic cleaning process (int)
    *     'hashedDirectoryLevel' => level of the hashed directory system (int)
    *     'hashedDirectoryUmask' => umask for hashed directory structure (int)
    * );
    *
    * @param array $options options
    * @access public
    */
    function Cache_Lite($options = array(NULL))
    {
        $availableOptions = array('hashedDirectoryUmask', 'hashedDirectoryLevel', 'automaticCleaningFactor', 'automaticSerialization', 'fileNameProtection', 'memoryCaching', 'onlyMemoryCaching', 'memoryCachingLimit', 'cacheDir', 'caching', 'lifeTime', 'fileLocking', 'writeControl', 'readControl', 'readControlType', 'pearErrorMode');
        foreach($options as $key => $value) {
            if(in_array($key, $availableOptions)) {
                $property = '_'.$key;
                $this->$property = $value;
            }
        }
        $this->_refreshTime = time() - $this->_lifeTime;
    }
    
    /**
    * Test if a cache is available and (if yes) return it
    *
    * @param string $id cache id
    * @param string $group name of the cache group
    * @param boolean $doNotTestCacheValidity if set to true, the cache validity won't be tested
    * @return string data of the cache (or false if no cache available)
    * @access public
    */
    function get($id, $group = 'default', $doNotTestCacheValidity = false)
    {
        $this->_id = $id;
        $this->_group = $group;
        $data = false;
        if ($this->_caching) {
            $this->_setFileName($id, $group);
            if ($this->_memoryCaching) {
                if (isset($this->_memoryCachingArray[$this->_file])) {
                    if ($this->_automaticSerialization) {
                        return unserialize($this->_memoryCachingArray[$this->_file]);
                    } else {
                        return $this->_memoryCachingArray[$this->_file];
                    }
                } else {
                    if ($this->_onlyMemoryCaching) {
                        return false;
                    }
                }
            }
            if ($doNotTestCacheValidity) {
                if (file_exists($this->_file)) {
                    $data = $this->_read();
                }
            } else {
                if ((file_exists($this->_file)) && (@filemtime($this->_file) > $this->_refreshTime)) {
                    $data = $this->_read();
                }
            }
            if (($data) and ($this->_memoryCaching)) {
                $this->_memoryCacheAdd($this->_file, $data);
            }
            if (($this->_automaticSerialization) and (is_string($data))) {
                $data = unserialize($data);
            }
            return $data;
        }
        return false;
    }
    
    /**
    * Save some data in a cache file
    *
    * @param string $data data to put in cache (can be another type than strings if automaticSerialization is on)
    * @param string $id cache id
    * @param string $group name of the cache group
    * @return boolean true if no problem
    * @access public
    */
    function save($data, $id = NULL, $group = 'default')
    {
        if ($this->_caching) {
            if ($this->_automaticSerialization) {
                $data = serialize($data);
            }
            if (isset($id)) {
                $this->_setFileName($id, $group);
            }
            if ($this->_memoryCaching) {
                $this->_memoryCacheAdd($this->_file, $data);
                if ($this->_onlyMemoryCaching) {
                    return true;
                }
            }
	    if ($this->_automaticCleaningFactor>0) {
                $rand = rand(1, $this->_automaticCleaningFactor);
	        if ($rand==1) {
	            $this->clean(false, 'old');
		}
            }
            if ($this->_writeControl) {
                if (!$this->_writeAndControl($data)) {
                    @touch($this->_file, time() - 2*abs($this->_lifeTime));
                    return false;
                } else {
                    return true;
                }
            } else {
	        return $this->_write($data);
	    }
        }
        return false;
    }

    /**
    * Remove a cache file
    *
    * @param string $id cache id
    * @param string $group name of the cache group
    * @return boolean true if no problem
    * @access public
    */
    function remove($id, $group = 'default')