wikimedia/mediawiki-core

<?php
/**
 * 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
 */

/**
 * LocalisationCache optimised for loading many languages at once.
 *
 * Used by maintenance/rebuildLocalisationCache.php.
 *
 * @ingroup Language
 */
class LocalisationCacheBulkLoad extends LocalisationCache {

    /**
     * A cache for the contents of the data files.
     * Core files are serialized to avoid using ~1GB of RAM during a re-cache.
     * @var string[][]
     */
    private $fileCache = [];

    /**
     * Most recently used languages. Uses the linked-list aspect of PHP hashtables
     * to keep the most recently used language codes at the end of the array, and
     * the language codes that are ready to be deleted at the beginning.
     * @var array<string,true>
     */
    private $mruLangs = [];

    /**
     * Maximum number of languages that may be loaded into $this->data
     * @var int
     */
    private $maxLoadedLangs = 10;

    /**
     * @param string $fileName
     * @param string $fileType
     * @return array|mixed
     */
    protected function readPHPFile( $fileName, $fileType ) {
        $serialize = $fileType === 'core';
        if ( !isset( $this->fileCache[$fileName][$fileType] ) ) {
            $data = parent::readPHPFile( $fileName, $fileType );

            if ( $serialize ) {
                $encData = serialize( $data );
            } else {
                $encData = $data;
            }

            $this->fileCache[$fileName][$fileType] = $encData;

            return $data;
        } elseif ( $serialize ) {
            return unserialize( $this->fileCache[$fileName][$fileType] );
        } else {
            return $this->fileCache[$fileName][$fileType];
        }
    }

    /**
     * @param string $code
     * @param string $key
     * @return mixed
     */
    public function getItem( $code, $key ) {
        unset( $this->mruLangs[$code] );
        $this->mruLangs[$code] = true;

        return parent::getItem( $code, $key );
    }

    /**
     * @param string $code
     * @param string $key
     * @param string $subkey
     * @return mixed
     */
    public function getSubitem( $code, $key, $subkey ) {
        unset( $this->mruLangs[$code] );
        $this->mruLangs[$code] = true;

        return parent::getSubitem( $code, $key, $subkey );
    }

    /**
     * @param string $code
     */
    public function recache( $code ) {
        parent::recache( $code );
        unset( $this->mruLangs[$code] );
        $this->mruLangs[$code] = true;
        $this->trimCache();
    }

    /**
     * @param string $code
     */
    public function unload( $code ) {
        unset( $this->mruLangs[$code] );
        parent::unload( $code );
    }

    /**
     * Unload cached languages until there are less than $this->maxLoadedLangs
     */
    protected function trimCache() {
        while ( count( $this->data ) > $this->maxLoadedLangs && count( $this->mruLangs ) ) {
            $code = array_key_first( $this->mruLangs );
            wfDebug( __METHOD__ . ": unloading $code" );
            $this->unload( $code );
        }
    }

}