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<?php
/**
* This factory retrieves the instance of StudipCache configured for use in
* this Stud.IP installation.
*
* @package studip
* @subpackage lib
*
* @author Marco Diedrich (mdiedric@uos)
* @author Marcus Lunzenauer (mlunzena@uos.de)
* @copyright 2007 (c) Authors
* @since 1.6
* @license GPL2 or any later version
*/
class StudipCacheFactory
{
/**
* the default cache class
*
* @var string
*/
const DEFAULT_CACHE_CLASS = StudipDbCache::class;
/**
* singleton instance
*
* @var StudipCache
*/
private static $cache;
/**
* config instance
*
* @var Config
*/
private static $config = null;
/**
* Returns the currently used config instance
*
* @return Config an instance of class Config used by this factory to
* determine the class of the actual implementation of
* the StudipCache interface; if no config was set, it
* returns the instance returned by Config#getInstance
* @see Config
*/
public static function getConfig()
{
return is_null(self::$config) ? Config::getInstance() : self::$config;
}
/**
* @param Config an instance of class Config which will be used to
* determine the class of the implementation of interface
* StudipCache
*
* @return void
*/
public static function setConfig($config)
{
self::$config = $config;
self::$cache = NULL;
}
/**
* Configure the file, class and arguments used for instantiation of the
* StudipCache instance. After sending this method, the previously used cache
* instance is voided and a new instance will be created on demand.
*
* @param string the absolute path to the implementing class
* @param string the name of the class
* @param array an array of custom arguments
*
* @return void
*/
public static function configure($file, $class, $arguments)
{
# TODO encoding for strings... but probably the caller should care..
$arguments = json_encode($arguments);
// strip leading STUDIP_BASE_PATH from file path
$file = studip_relative_path($file);
self::unconfigure();
$cfg = self::getConfig();
$cfg->create('cache_class', [
'comment' => 'Pfad der Datei, die die StudipCache-Klasse enthält',
'value' => $class]
);
$cfg->create('cache_class_file', [
'comment' => 'Klassenname des zu verwendenden StudipCaches',
'value' => $file]
);
$cfg->create('cache_init_args', [
'comment' => 'JSON-kodiertes Array von Argumenten für die Instanziierung der StudipCache-Klasse',
'value' => $arguments]
);
$cfg->store('cache_class', $class);
$cfg->store('cache_class_file', $file);
$cfg->store('cache_init_args', $arguments);
}
/**
* Resets the configuration and voids the cache instance.
*
* @return void
*/
public static function unconfigure()
{
self::$cache = NULL;
}
/**
* Returns a cache instance.
*
* @param bool $apply_proxied_operations Whether or not to apply any
* proxied (disable this in tests!)
* @return StudipCache the cache instance
*/
public static function getCache($apply_proxied_operations = true)
{
if (is_null(self::$cache)) {
$proxied = false;
if (!$GLOBALS['CACHING_ENABLE']) {
self::$cache = new StudipMemoryCache();
// Proxy cache operations if CACHING_ENABLE is different from the globally set
// caching value. This should only be the case in cli mode.
if (isset($GLOBALS['GLOBAL_CACHING_ENABLE']) && $GLOBALS['GLOBAL_CACHING_ENABLE']) {
$proxied = true;
}
} else {
try {
$class = self::loadCacheClass();
$args = self::retrieveConstructorArguments();
self::$cache = self::instantiateCache($class, $args);
} catch (Exception $e) {
error_log(__METHOD__ . ': ' . $e->getMessage());
PageLayout::addBodyElements(MessageBox::error(__METHOD__ . ': ' . $e->getMessage()));
$class = self::DEFAULT_CACHE_CLASS;
self::$cache = new $class();
}
}
// If proxy should be used, inject it. Otherwise apply pending
// operations, if any.
if ($proxied) {
self::$cache = new StudipCacheProxy(self::$cache);
} elseif ($GLOBALS['CACHING_ENABLE'] && $apply_proxied_operations) {
// Even if the above condition will try to eliminate most
// failures, the following operation still needs to be wrapped
// in a try/catch block. Otherwise there are no means to
// execute migration 166 which creates the neccessary tables
// for said operation.
try {
StudipCacheOperation::apply(self::$cache);
} catch (Exception $e) {
}
}
}
return self::$cache;
}
/**
* Load configured cache class and return its name.
*
* @return string the name of the configured cache class
*/
public static function loadCacheClass()
{
$cacheConfig = self::getConfig()->SYSTEMCACHE;
$cache_class = $cacheConfig['type'] ?: null;
# default class
if (is_null($cache_class)) {
$version = new DBSchemaVersion();
if (!$version->contains(224)) {
// db cache is not yet available, use StudipMemoryCache
return 'StudipMemoryCache';
}
return self::DEFAULT_CACHE_CLASS;
}
# already loaded
if (class_exists($cache_class)) {
return $cache_class;
}
$loaded = false;
if (file_exists($cache_class_file) || file_exists($GLOBALS['STUDIP_BASE_PATH'] . '/' . $cache_class_file)) {
$loaded = include $cache_class_file;
}
if ($loaded === FALSE || !class_exists($cache_class)) {
# TODO (mlunzena) a more specific exception would be welcome here
throw new Exception("Could not find class: '$cache_class'");
}
return $cache_class;
}
/**
* Return an array of arguments required for instantiation of the cache
* class.
*
* @return array the array of arguments
*/
public static function retrieveConstructorArguments()
{
$cacheConfig = self::getConfig()->SYSTEMCACHE;
return $cacheConfig ?: [];
}
/**
* Return an instance of a given class using some arguments
*
* @param string the name of the class
* @param array an array of arguments to be used by the constructor
*
* @return StudipCache an instance of the specified class
*/
public static function instantiateCache($class, $arguments)
{
$reflection_class = new ReflectionClass($class);
return (is_array($arguments['config']) && count($arguments['config']) > 0)
? $reflection_class->newInstanceArgs($arguments['config'])
: $reflection_class->newInstance();
}
}
|
