59 lines
2 KiB
PHP
59 lines
2 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Cache
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*/
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namespace MediaWiki\Cache;
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use LogicException;
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use MediaWiki\Linker\LinkTarget;
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use MediaWiki\Page\PageReference;
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/**
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* Helper class for mapping value objects representing basic entities to cache keys.
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*
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* Rationale:
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* The logic for deriving the cache key should not be in the value object themselves for two reasons:
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* Firstly, the value object should not contain knowledge about caching or keys in general.
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* Secondly, all implementations of a given interface must have the exact same logic for deriving
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* the cache key. Otherwise, caches will break when different implementations are used when
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* interacting with a cache.
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*
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* Furthermore, the logic for deriving cache keys should not be in a service instance: there can
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* only ever be one implementation, it must not depend on configuration, and it should never change.
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*
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* @ingroup Cache
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*/
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abstract class CacheKeyHelper {
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/** Private constructor to defy instantiation. */
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private function __construct() {
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// we should never even get here...
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throw new LogicException( 'Should not instantiate ' . __CLASS__ );
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}
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/**
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* @param LinkTarget|PageReference $page
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*
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* @return string
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*/
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public static function getKeyForPage( $page ): string {
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return 'ns' . $page->getNamespace() . ':' . $page->getDBkey();
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}
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}
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