Move remaining LoadBalancer classes to Rdbms

[mediawiki.git] / includes / cache / HTMLFileCache.php

<?php
/**
 * Page view caching in the file system.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Cache
 */

use MediaWiki\MediaWikiServices;

/**
 * Page view caching in the file system.
 * The only cacheable actions are "view" and "history". Also special pages
 * will not be cached.
 *
 * @ingroup Cache
 */
class HTMLFileCache extends FileCacheBase {
        const MODE_NORMAL = 0; // normal cache mode
        const MODE_OUTAGE = 1; // fallback cache for DB outages
        const MODE_REBUILD = 2; // background cache rebuild mode

        /**
         * @param Title|string $title Title object or prefixed DB key string
         * @param string $action
         * @throws MWException
         */
        public function __construct( $title, $action ) {
                parent::__construct();

                $allowedTypes = self::cacheablePageActions();
                if ( !in_array( $action, $allowedTypes ) ) {
                        throw new MWException( 'Invalid file cache type given.' );
                }
                $this->mKey = ( $title instanceof Title )
                        ? $title->getPrefixedDBkey()
                        : (string)$title;
                $this->mType = (string)$action;
                $this->mExt = 'html';
        }

        /**
         * Cacheable actions
         * @return array
         */
        protected static function cacheablePageActions() {
                return [ 'view', 'history' ];
        }

        /**
         * Get the base file cache directory
         * @return string
         */
        protected function cacheDirectory() {
                return $this->baseCacheDirectory(); // no subdir for b/c with old cache files
        }

        /**
         * Get the cache type subdirectory (with the trailing slash) or the empty string
         * Alter the type -> directory mapping to put action=view cache at the root.
         *
         * @return string
         */
        protected function typeSubdirectory() {
                if ( $this->mType === 'view' ) {
                        return ''; //  b/c to not skip existing cache
                } else {
                        return $this->mType . '/';
                }
        }

        /**
         * Check if pages can be cached for this request/user
         * @param IContextSource $context
         * @param integer $mode One of the HTMLFileCache::MODE_* constants (since 1.28)
         * @return bool
         */
        public static function useFileCache( IContextSource $context, $mode = self::MODE_NORMAL ) {
                $config = MediaWikiServices::getInstance()->getMainConfig();

                if ( !$config->get( 'UseFileCache' ) && $mode !== self::MODE_REBUILD ) {
                        return false;
                } elseif ( $config->get( 'DebugToolbar' ) ) {
                        wfDebug( "HTML file cache skipped. \$wgDebugToolbar on\n" );

                        return false;
                }

                // Get all query values
                $queryVals = $context->getRequest()->getValues();
                foreach ( $queryVals as $query => $val ) {
                        if ( $query === 'title' || $query === 'curid' ) {
                                continue; // note: curid sets title
                        // Normal page view in query form can have action=view.
                        } elseif ( $query === 'action' && in_array( $val, self::cacheablePageActions() ) ) {
                                continue;
                        // Below are header setting params
                        } elseif ( $query === 'maxage' || $query === 'smaxage' ) {
                                continue;
                        }

                        return false;
                }

                $user = $context->getUser();
                // Check for non-standard user language; this covers uselang,
                // and extensions for auto-detecting user language.
                $ulang = $context->getLanguage();

                // Check that there are no other sources of variation
                if ( $user->getId() || $ulang->getCode() !== $config->get( 'LanguageCode' ) ) {
                        return false;
                }

                if ( $mode === self::MODE_NORMAL ) {
                        if ( $user->getNewtalk() ) {
                                return false;
                        }
                }

                // Allow extensions to disable caching
                return Hooks::run( 'HTMLFileCache::useFileCache', [ $context ] );
        }

        /**
         * Read from cache to context output
         * @param IContextSource $context
         * @param integer $mode One of the HTMLFileCache::MODE_* constants
         * @return void
         */
        public function loadFromFileCache( IContextSource $context, $mode = self::MODE_NORMAL ) {
                global $wgContLang;
                $config = MediaWikiServices::getInstance()->getMainConfig();

                wfDebug( __METHOD__ . "()\n" );
                $filename = $this->cachePath();

                if ( $mode === self::MODE_OUTAGE ) {
                        // Avoid DB errors for queries in sendCacheControl()
                        $context->getTitle()->resetArticleID( 0 );
                }

                $context->getOutput()->sendCacheControl();
                header( "Content-Type: {$config->get( 'MimeType' )}; charset=UTF-8" );
                header( "Content-Language: {$wgContLang->getHtmlCode()}" );
                if ( $this->useGzip() ) {
                        if ( wfClientAcceptsGzip() ) {
                                header( 'Content-Encoding: gzip' );
                                readfile( $filename );
                        } else {
                                /* Send uncompressed */
                                wfDebug( __METHOD__ . " uncompressing cache file and sending it\n" );
                                readgzfile( $filename );
                        }
                } else {
                        readfile( $filename );
                }

                $context->getOutput()->disable(); // tell $wgOut that output is taken care of
        }

        /**
         * Save this cache object with the given text.
         * Use this as an ob_start() handler.
         *
         * Normally this is only registed as a handler if $wgUseFileCache is on.
         * If can be explicitly called by rebuildFileCache.php when it takes over
         * handling file caching itself, disabling any automatic handling the the
         * process.
         *
         * @param string $text
         * @return string|bool The annotated $text or false on error
         */
        public function saveToFileCache( $text ) {
                if ( strlen( $text ) < 512 ) {
                        // Disabled or empty/broken output (OOM and PHP errors)
                        return $text;
                }

                wfDebug( __METHOD__ . "()\n", 'private' );

                $now = wfTimestampNow();
                if ( $this->useGzip() ) {
                        $text = str_replace(
                                '</html>', '<!-- Cached/compressed ' . $now . " -->\n</html>", $text );
                } else {
                        $text = str_replace(
                                '</html>', '<!-- Cached ' . $now . " -->\n</html>", $text );
                }

                // Store text to FS...
                $compressed = $this->saveText( $text );
                if ( $compressed === false ) {
                        return $text; // error
                }

                // gzip output to buffer as needed and set headers...
                if ( $this->useGzip() ) {
                        // @todo Ugly wfClientAcceptsGzip() function - use context!
                        if ( wfClientAcceptsGzip() ) {
                                header( 'Content-Encoding: gzip' );

                                return $compressed;
                        } else {
                                return $text;
                        }
                } else {
                        return $text;
                }
        }

        /**
         * Clear the file caches for a page for all actions
         * @param Title $title
         * @return bool Whether $wgUseFileCache is enabled
         */
        public static function clearFileCache( Title $title ) {
                $config = MediaWikiServices::getInstance()->getMainConfig();

                if ( !$config->get( 'UseFileCache' ) ) {
                        return false;
                }

                foreach ( self::cacheablePageActions() as $type ) {
                        $fc = new self( $title, $type );
                        $fc->clearCache();
                }

                return true;
        }
}