php-src/pear/Cache.php
2001-03-08 20:41:39 +00:00

287 lines
8.6 KiB
PHP

<?php
// +----------------------------------------------------------------------+
// | PHP version 4.0 |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997, 1998, 1999, 2000, 2001 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> |
// +----------------------------------------------------------------------+
//
// $Id$
require_once "Cache/Error.php";
/**
* Cache is a base class for cache implementations.
*
* TODO: Simple usage example goes here.
*
* @author Ulf Wendel <ulf.wendel@phpdoc.de>
* @version $Id$
* @package Cache
* @access public
*/
class Cache {
/**
* Disables the caching.
*
* TODO: Add explanation what this is good for.
*
* @var boolean
* @access public
*/
var $no_cache = false;
/**
* Garbage collection: probability in seconds
*
* If set to a value above 0 a garbage collection will
* flush all cache entries older than the specified number
* of seconds.
*
* @var integer
* @see $gc_probability
* @access public
*/
var $gc_time = 1;
/**
* Garbage collection: probability in percent
*
* TODO: Add an explanation.
*
* @var integer 0 => never
* @see $gc_time
* @access public
*/
var $gc_probability = 1;
/**
* Storage container object.
*
* @var object Cache_Container
*/
var $container;
//
// public methods
//
/**
*
* @param string Name of storage container class
* @param array Array with storage class dependend config options
*/
function Cache($storage_driver, $storage_options = "")
{
$storage_driver = strtolower($storage_driver);
$storage_class = 'Cache_Container_' . $storage_driver;
$storage_classfile = 'Cache/Container/' . $storage_driver . '.php';
include_once $storage_classfile;
$this->container = new $storage_class($storage_options);
$this->garbageCollection();
}
/**
* Returns the requested dataset it if exists and is not expired
*
* @param string dataset ID
* @param string cache group
* @return mixed cached data or NULL on failure
* @access public
*/
function get($id, $group = "default") {
if ($this->no_cache)
return "";
if ($this->isCached($id, $group) && !$this->isExpired($id, $group))
return $this->load($id, $group);
return NULL;
} // end func get
/**
* Stores the given data in the cache.
*
* @param string dataset ID used as cache identifier
* @param mixed data to cache
* @param integer lifetime of the cached data in seconds - 0 for endless
* @param string cache group
* @return boolean
* @access public
*/
function save($id, $data, $expires = 0, $group = "default") {
if ($this->no_cache)
return true;
return $this->container->save($id, $data, $expires, $group, "");
} // end func save
/**
* Stores a dataset without additional userdefined data.
*
* @param string dataset ID
* @param mixed data to store
* @param string additional userdefined data
* @param mixed userdefined expire date
* @param string cache group
* @return boolean
* @throws Cache_Error
* @access public
* @see getUserdata()
*/
function extSave($id, $cachedata, $userdata, $expires = 0, $group = "default") {
if ($this->no_cache)
return true;
return $this->container->save($id, $cachedata, $expires, $group, $userdata);
} // end func extSave
/**
* Loads the given ID from the cache.
*
* @param string dataset ID
* @param string cache group
* @return mixed cached data or NULL on failure
* @access public
*/
function load($id, $group = "default") {
if ($this->no_cache)
return "";
return $this->container->load($id, $group);
} // end func load
/**
* Returns the userdata field of a cached data set.
*
* @param string dataset ID
* @param string cache group
* @return string userdata
* @access public
* @see extSave()
*/
function getUserdata($id, $group = "default") {
if ($this->no_cache)
return "";
return $this->container->getUserdata($id, $group);
} // end func getUserdata
/**
* Removes the specified dataset from the cache.
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
*/
function delete($id, $group = "default") {
if ($this->no_cache)
return true;
return $this->container->delete($id, $group);
} // end func delete
/**
* Flushes the cache - removes all data from it
*
* @param string cache group, if empty all groups will be flashed
* @return integer number of removed datasets
*/
function flush($group = "") {
if ($this->no_cache)
return true;
return $this->container->flush($group);
} // end func flush
/**
* Checks if a dataset exists.
*
* Note: this does not say that the cached data is not expired!
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
*/
function isCached($id, $group = "default") {
if ($this->no_cache)
return false;
return $this->container->isCached($id, $group);
} // end func isCached
/**
* Checks if a dataset is expired
*
* @param string dataset ID
* @param string cache group
* @param integer maximum age for the cached data in seconds - 0 for endless
* If the cached data is older but the given lifetime it will
* be removed from the cache. You don't have to provide this
* argument if you call isExpired(). Every dataset knows
* it's expire date and will be removed automatically. Use
* this only if you know what you're doing...
* @return boolean
* @access public
*/
function isExpired($id, $group = "default", $max_age = 0) {
if ($this->no_cache)
return true;
return $this->container->isExpired($id, $group, $max_age);
} // end func isExpired
/**
* Generates a "unique" ID for the given value
*
* This is a quick but dirty hack to get a "unique" ID for a any kind of variable.
* ID clashes might occur from time to time although they are extreme unlikely!
*
* @param mixed variable to generate a ID for
* @return string "unique" ID
* @access public
*/
function generateID($variable) {
// WARNING: ID clashes are possible although unlikely
return md5(serialize($variable));
}
/**
* Calls the garbage collector of the storage object with a certain probability
*
* @param boolean Force a garbage collection run?
* @see $gc_probability, $gc_time
*/
function garbageCollection($force = false) {
static $last_run = 0;
if ($this->no_cache)
return;
srand((double) microtime() * 1000000);
// time and probability based
if (($force) || ($last_run && $last_run < time() + $this->gc_time) || (rand(1, 100) < $this->gc_probability)) {
$this->container->garbageCollection();
$last_run = time();
}
} // end func garbageCollection
} // end class cache
?>