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<?php
// +----------------------------------------------------------------------+
// | PEAR :: Cache |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2003 The PHP Group |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2.0 of the PHP license, |
// | that is bundled with this package in the file LICENSE, and is |
// | available at through the world-wide-web at |
// | http://www.php.net/license/2_02.txt. |
// | If you did not receive a copy of the PHP license and are unable to |
// | obtain it through the world-wide-web, please send a note to |
// | license@php.net so we can mail you a copy immediately. |
// +----------------------------------------------------------------------+
// | Authors: Ulf Wendel <ulf.wendel@phpdoc.de> |
// | Sebastian Bergmann <sb@sebastian-bergmann.de> |
// | Christian Stocker <chregu@phant.ch> |
// +----------------------------------------------------------------------+
//
// $Id: Container.php,v 1.4 2003/01/04 11:54:45 mj Exp $
require_once 'Cache/Error.php';
/**
* Common base class of all cache storage container.
*
* To speed up things we do a preload you should know about, otherwise it might
* play you a trick. The Cache controller classes (Cache/Cache, Cache/Output, ...)
* usually do something like is (isCached($id) && !isExpired($id)) return $container->load($id).
* if you implement isCached(), isExpired() and load() straight ahead, each of this
* functions will result in a storage medium (db, file,...) access. This generates too much load.
* Now, a simple speculative preload should saves time in most cases. Whenever
* one of the mentioned methods is invoked we preload the cached dataset into class variables.
* That means that we have only one storage medium access for the sequence
* (isCached($id) && !isExpired($id)) return $container->load($id).
* The bad thing is that the preloaded data might be outdated meanwhile, which is
* unlikely but for you power users, be warned. If you do not want the preload
* you should switch it off by setting the class variable $preload to false. Anyway, this is
* not recommended!
*
* @author Ulf Wendel <ulf.wendel@phpdoc.de>
* @version $Id: Container.php,v 1.4 2003/01/04 11:54:45 mj Exp $
* @package Cache
* @access public
* @abstract
*/
class Cache_Container {
/**
* Flag indicating wheter to preload datasets.
*
* See the class description for more details.
*
* @var boolean
*/
var $preload = true;
/**
* ID of a preloaded dataset
*
* @var string
*/
var $id = '';
/**
* Cache group of a preloaded dataset
*
* @var string
*/
var $group = '';
/**
* Expiration timestamp of a preloaded dataset.
*
* @var integer 0 means never, endless
*/
var $expires = 0;
/**
* Value of a preloaded dataset.
*
* @var string
*/
var $cachedata = '';
/**
* Preloaded userdata field.
*
* @var string
*/
var $userdata = '';
/**
* Flag indicating that the dataset requested for preloading is unknown.
*
* @var boolean
*/
var $unknown = true;
/**
* Encoding mode for cache data: base64 or addslashes() (slash).
*
* @var string base64 or slash
*/
var $encoding_mode = 'base64';
/**
* Highwater mark - maximum space required by all cache entries.
*
* Whenever the garbage collection runs it checks the amount of space
* required by all cache entries. If it's more than n (highwater) bytes
* the garbage collection deletes as many entries as necessary to reach the
* lowwater mark.
*
* @var int
* @see lowwater
*/
var $highwater = 2048000;
/**
* Lowwater mark
*
* @var int
* @see highwater
*/
var $lowwater = 1536000;
/**
* Options that can be set in every derived class using it's constructor.
*
* @var array
*/
var $allowed_options = array('encoding_mode', 'highwater', 'lowwater');
/**
* Loads a dataset from the cache.
*
* @param string dataset ID
* @param string cache group
* @return mixed dataset value or NULL on failure
* @access public
*/
function load($id, $group) {
if ($this->preload) {
if ($this->id != $id || $this->group != $group)
$this->preload($id, $group);
return $this->cachedata;
} else {
list( , $data, ) = $this->fetch($id, $group);
return $data;
}
} // end func load
/**
* Returns the userdata field of a cached data set.
*
* @param string dataset ID
* @param string cache group
* @return string userdata
* @access public
*/
function getUserdata($id, $group) {
if ($this->preload) {
if ($this->id != $id || $this->group != $group)
$this->preload($id, $group);
return $this->userdata;
} else {
list( , , $userdata) = $this->fetch($id, $group);
return $userdata;
}
} // end func getUserdata
/**
* Checks if a dataset is expired.
*
* @param string dataset ID
* @param string cache group
* @param integer maximum age timestamp
* @return boolean
* @access public
*/
function isExpired($id, $group, $max_age) {
if ($this->preload) {
if ($this->id != $id || $this->group != $group)
$this->preload($id, $group);
if ($this->unknown)
return false;
} else {
// check if at all it is cached
if (!$this->isCached($id, $group))
return false;
// I'm lazy...
list($this->expires, , ) = $this->fetch($id, $group);
}
// endless
if (0 == $this->expires)
return false;
// you feel fine, Ulf?
if ($expired = ($this->expires <= time() || ($max_age && ($this->expires <= $max_age))) ) {
$this->remove($id, $group);
$this->flushPreload();
}
return $expired;
} // end func isExpired
/**
* Checks if a dataset is cached.
*
* @param string dataset ID
* @param string cache group
* @return boolean
*/
function isCached($id, $group) {
if ($this->preload) {
if ($this->id != $id || $this->group != $group)
$this->preload($id, $group);
return !($this->unknown);
} else {
return $this->idExists($id, $group);
}
} // end func isCached
//
// abstract methods
//
/**
* Fetches a dataset from the storage medium.
*
* @param string dataset ID
* @param string cache group
* @return array format: [expire date, cached data, user data]
* @throws Cache_Error
* @abstract
*/
function fetch($id, $group) {
return array(NULL, NULL, NULL);
} // end func fetch
/**
* Stores a dataset.
*
* @param string dataset ID
* @param mixed data to store
* @param mixed userdefined expire date
* @param string cache group
* @param string additional userdefined data
* @return boolean
* @throws Cache_Error
* @access public
* @abstract
*/
function save($id, $data, $expire, $group, $userdata) {
// QUESTION: Should we update the preload buffer instead?
// Don't think so as the sequence save()/load() is unlikely.
$this->flushPreload($id, $group);
return NULL;
} // end func save
/**
* Removes a dataset.
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
* @abstract
*/
function remove($id, $group) {
$this->flushPreload($id, $group);
return NULL;
} // end func remove
/**
* Flushes the cache - removes all caches datasets from the cache.
*
* @param string If a cache group is given only the group will be flushed
* @return integer Number of removed datasets, -1 on failure
* @access public
* @abstract
*/
function flush($group) {
$this->flushPreload();
return NULL;
} // end func flush
/**
* Checks if a dataset exists.
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
* @abstract
*/
function idExists($id, $group) {
return NULL;
} // end func idExists
/**
* Starts the garbage collection.
*
* @access public
* @abstract
*/
function garbageCollection() {
$this->flushPreload();
} // end func garbageCollection
/**
* Does a speculative preload of a dataset
*
* @param string dataset ID
* @param string cache group
* @return boolean
*/
function preload($id, $group) {
// whatever happens, remember the preloaded ID
$this->id = $id;
$this->group = $group;
list($this->expires, $this->cachedata, $this->userdata) = $this->fetch($id, $group);
if (NULL === $this->expires) {
// Uuups, unknown ID
$this->flushPreload();
return false;
}
$this->unknown = false;
return true;
} // end func preload
/**
* Flushes the internal preload buffer.
*
* save(), remove() and flush() must call this method
* to preevent differences between the preloaded values and
* the real cache contents.
*
* @param string dataset ID, if left out the preloaded values will be flushed.
* If given the preloaded values will only be flushed if they are
* equal to the given id and group
* @param string cache group
* @see preload()
*/
function flushPreload($id = '', $group = 'default') {
if (!$id || ($this->id == $id && $this->group == $group)) {
// clear the internal preload values
$this->id = '';
$this->group = '';
$this->cachedata = '';
$this->userdata = '';
$this->expires = -1;
$this->unknown = true;
}
} // end func flushPreload
/**
* Imports the requested datafields as object variables if allowed
*
* @param array List of fields to be imported as object variables
* @param array List of allowed datafields
*/
function setOptions($requested, $allowed) {
foreach ($allowed as $k => $field)
if (isset($requested[$field]))
$this->$field = $requested[$field];
} // end func setOptions
/**
* Encodes the data for the storage container.
*
* @var mixed data to encode
*/
function encode($data) {
if ('base64' == $this->encoding_mode)
return base64_encode(serialize($data));
else
return serialize($data);
} // end func encode
/**
* Decodes the data from the storage container.
*
* @var mixed
*/
function decode($data) {
if ('base64' == $this->encoding_mode)
return unserialize(base64_decode($data));
else
return unserialize($data);
} // end func decode
/**
* Translates human readable/relative times in unixtime
*
* @param mixed can be in the following formats:
* human readable : yyyymmddhhmm[ss]] eg: 20010308095100
* relative in seconds (1) : +xx eg: +10
* relative in seconds (2) : x < 946681200 eg: 10
* absolute unixtime : x < 2147483648 eg: 2147483648
* see comments in code for details
* @return integer unix timestamp
*/
function getExpiresAbsolute($expires)
{
if (!$expires)
return 0;
//for api-compatibility, one has not to provide a "+",
// if integer is < 946681200 (= Jan 01 2000 00:00:00)
if ('+' == $expires[0] || $expires < 946681200)
{
return(time() + $expires);
}
//if integer is < 100000000000 (= in 3140 years),
// it must be an absolut unixtime
// (since the "human readable" definition asks for a higher number)
elseif ($expires < 100000000000)
{
return $expires;
}
// else it's "human readable";
else
{
$year = substr($expires, 0, 4);
$month = substr($expires, 4, 2);
$day = substr($expires, 6, 2);
$hour = substr($expires, 8, 2);
$minute = substr($expires, 10, 2);
$second = substr($expires, 12, 2);
return mktime($hour, $minute, $second, $month, $day, $year);
}
} // end func getExpireAbsolute
} // end class Container
?>
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