--- /dev/null
+<?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> |
+// +----------------------------------------------------------------------+
+//
+// $Id$
+
+/**
+* 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 $container;
+
+ //
+ // public methods
+ //
+
+ /**
+ *
+ * @param string Name of storage container class
+ * @param array Array with storage class dependend config options
+ * @see setOptions()
+ */
+ function Cache($storage_driver, $storage_options = "")
+ {
+ $storage_driver = strtolower($storage_driver);
+ $storage_class = 'Cache_Container_' . $storage_driver;
+ $storage_classfile = 'Cache/Container/' . $storage_driver . '.php';
+
+ if (@include_once $storage_classfile) {
+ $this->container = new $storage_class($storage_options);
+ $this->garbageCollection();
+ } else {
+ return null;
+ }
+ }
+
+ /**
+ * Returns the requested dataset it if exists and is not expired
+ *
+ * @param string dataset ID
+ * @return mixed cached data or NULL on failure
+ * @access public
+ */
+ function get($id) {
+ if ($this->no_cache)
+ return "";
+
+ if ($this->isCached($id) && !$this->isExpired($id))
+ return $this->load($id);
+
+ 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
+ * @return boolean
+ * @access public
+ */
+ function save($id, $data, $expires = 0) {
+ if ($this->no_cache)
+ return true;
+
+ return $this->container->save($id, $data, $expires);
+ } // end func save
+
+ /**
+ * Loads the given ID from the cache.
+ *
+ * @param string dataset ID
+ * @return mixed cached data or NULL on failure
+ * @access public
+ */
+ function load($id) {
+ if ($this->no_cache)
+ return "";
+
+ return $this->container->load($id);
+ } // end func load
+
+ /**
+ * Removes the specified dataset from the cache.
+ *
+ * @param string dataset ID
+ * @return boolean
+ * @access public
+ */
+ function delete($id) {
+ if ($this->no_cache)
+ return true;
+
+ return $this->container->delete($id);
+ } // end func delete
+
+ /**
+ * Flushes the cache - removes all data from it
+ *
+ * @return integer number of removed datasets
+ */
+ function flush() {
+ if ($this->no_cache)
+ return true;
+
+ return $this->container->flush();
+ } // end func flush
+
+ /**
+ * Checks if a dataset exists.
+ *
+ * Note: this does not say that the cached data is not expired!
+ *
+ * @param string dataset ID
+ * @return boolean
+ * @access public
+ */
+ function isCached($id) {
+ if ($this->no_cache)
+ return false;
+
+ return $this->container->isCached($id);
+ } // end func isCached
+
+ /**
+ * Checks if a dataset is expired
+ *
+ * @param string dataset ID
+ * @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, $max_age = 0) {
+ if ($this->no_cache)
+ return true;
+
+ return $this->container->isExpired($id, $max_age);
+ } // end func isExpired
+
+ /**
+ * Generates a "unique" ID for the given value
+ *
+ * This is a quick but dirty hack to get a "unique" ID for a any kind of variable.
+ * ID clashes might occur from time to time although they are extreme unlikely!
+ *
+ * @param mixed variable to generate a ID for
+ * @return string "unique" ID
+ * @access public
+ */
+ function generateID($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, $gc_time, setOptions()
+ */
+ function garbageCollection($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
+?>
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