PHPSessionHandler: Implement SessionHandlerInterface

[mediawiki.git] / includes / interwiki / Interwiki.php

<?php
/**
 * Interwiki table entry.
 *
 * 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
 */
use \Cdb\Exception as CdbException;
use \Cdb\Reader as CdbReader;

/**
 * The interwiki class
 * All information is loaded on creation when called by Interwiki::fetch( $prefix ).
 * All work is done on slave, because this should *never* change (except during
 * schema updates etc, which aren't wiki-related)
 */
class Interwiki {
        // Cache - removes oldest entry when it hits limit
        protected static $smCache = array();
        const CACHE_LIMIT = 100; // 0 means unlimited, any other value is max number of entries.

        /** @var string The interwiki prefix, (e.g. "Meatball", or the language prefix "de") */
        protected $mPrefix;

        /** @var string The URL of the wiki, with "$1" as a placeholder for an article name. */
        protected $mURL;

        /** @var string The URL of the file api.php  */
        protected $mAPI;

        /** @var string The name of the database (for a connection to be established
         *    with wfGetLB( 'wikiid' ))
         */
        protected $mWikiID;

        /** @var bool Whether the wiki is in this project */
        protected $mLocal;

        /** @var bool Whether interwiki transclusions are allowed */
        protected $mTrans;

        public function __construct( $prefix = null, $url = '', $api = '', $wikiId = '', $local = 0,
                $trans = 0
        ) {
                $this->mPrefix = $prefix;
                $this->mURL = $url;
                $this->mAPI = $api;
                $this->mWikiID = $wikiId;
                $this->mLocal = $local;
                $this->mTrans = $trans;
        }

        /**
         * Check whether an interwiki prefix exists
         *
         * @param string $prefix Interwiki prefix to use
         * @return bool Whether it exists
         */
        public static function isValidInterwiki( $prefix ) {
                $result = self::fetch( $prefix );

                return (bool)$result;
        }

        /**
         * Fetch an Interwiki object
         *
         * @param string $prefix Interwiki prefix to use
         * @return Interwiki|null|bool
         */
        public static function fetch( $prefix ) {
                global $wgContLang;

                if ( $prefix == '' ) {
                        return null;
                }

                $prefix = $wgContLang->lc( $prefix );
                if ( isset( self::$smCache[$prefix] ) ) {
                        return self::$smCache[$prefix];
                }

                global $wgInterwikiCache;
                if ( $wgInterwikiCache ) {
                        $iw = Interwiki::getInterwikiCached( $prefix );
                } else {
                        $iw = Interwiki::load( $prefix );
                        if ( !$iw ) {
                                $iw = false;
                        }
                }

                if ( self::CACHE_LIMIT && count( self::$smCache ) >= self::CACHE_LIMIT ) {
                        reset( self::$smCache );
                        unset( self::$smCache[key( self::$smCache )] );
                }

                self::$smCache[$prefix] = $iw;

                return $iw;
        }

        /**
         * Purge the cache for an interwiki prefix
         * @param string $prefix
         * @since 1.26
         */
        public static function invalidateCache( $prefix ) {
                $cache = ObjectCache::getMainWANInstance();
                $key = wfMemcKey( 'interwiki', $prefix );
                $cache->delete( $key );
        }

        /**
         * Fetch interwiki prefix data from local cache in constant database.
         *
         * @note More logic is explained in DefaultSettings.
         *
         * @param string $prefix Interwiki prefix
         * @return Interwiki
         */
        protected static function getInterwikiCached( $prefix ) {
                $value = self::getInterwikiCacheEntry( $prefix );

                $s = new Interwiki( $prefix );
                if ( $value ) {
                        // Split values
                        list( $local, $url ) = explode( ' ', $value, 2 );
                        $s->mURL = $url;
                        $s->mLocal = (int)$local;
                } else {
                        $s = false;
                }

                return $s;
        }

        /**
         * Get entry from interwiki cache
         *
         * @note More logic is explained in DefaultSettings.
         *
         * @param string $prefix Database key
         * @return bool|string The interwiki entry or false if not found
         */
        protected static function getInterwikiCacheEntry( $prefix ) {
                global $wgInterwikiScopes, $wgInterwikiFallbackSite;
                static $site;

                wfDebug( __METHOD__ . "( $prefix )\n" );
                $value = false;
                try {
                        // Resolve site name
                        if ( $wgInterwikiScopes >= 3 && !$site ) {
                                $site = self::getCacheValue( '__sites:' . wfWikiID() );
                                if ( $site == '' ) {
                                        $site = $wgInterwikiFallbackSite;
                                }
                        }

                        $value = self::getCacheValue( wfMemcKey( $prefix ) );
                        // Site level
                        if ( $value == '' && $wgInterwikiScopes >= 3 ) {
                                $value = self::getCacheValue( "_{$site}:{$prefix}" );
                        }
                        // Global Level
                        if ( $value == '' && $wgInterwikiScopes >= 2 ) {
                                $value = self::getCacheValue( "__global:{$prefix}" );
                        }
                        if ( $value == 'undef' ) {
                                $value = '';
                        }
                } catch ( CdbException $e ) {
                        wfDebug( __METHOD__ . ": CdbException caught, error message was "
                                . $e->getMessage() );
                }

                return $value;
        }

        private static function getCacheValue( $key ) {
                global $wgInterwikiCache;
                static $reader;
                if ( $reader === null ) {
                        $reader = is_array( $wgInterwikiCache ) ? false : CdbReader::open( $wgInterwikiCache );
                }
                if ( $reader ) {
                        return $reader->get( $key );
                } else {
                        return isset( $wgInterwikiCache[$key] ) ? $wgInterwikiCache[$key] : false;
                }
        }

        /**
         * Load the interwiki, trying first memcached then the DB
         *
         * @param string $prefix The interwiki prefix
         * @return Interwiki|bool Interwiki if $prefix is valid, otherwise false
         */
        protected static function load( $prefix ) {
                global $wgInterwikiExpiry;

                $iwData = array();
                if ( !Hooks::run( 'InterwikiLoadPrefix', array( $prefix, &$iwData ) ) ) {
                        return Interwiki::loadFromArray( $iwData );
                }

                if ( is_array( $iwData ) ) {
                        $iw = Interwiki::loadFromArray( $iwData );
                        if ( $iw ) {
                                return $iw; // handled by hook
                        }
                }

                $iwData = ObjectCache::getMainWANInstance()->getWithSetCallback(
                        wfMemcKey( 'interwiki', $prefix ),
                        $wgInterwikiExpiry,
                        function ( $oldValue, &$ttl, array &$setOpts ) use ( $prefix ) {
                                $dbr = wfGetDB( DB_SLAVE );

                                $setOpts += Database::getCacheSetOptions( $dbr );

                                $row = $dbr->selectRow(
                                        'interwiki',
                                        Interwiki::selectFields(),
                                        array( 'iw_prefix' => $prefix ),
                                        __METHOD__
                                );

                                return $row ? (array)$row : '!NONEXISTENT';
                        }
                );

                if ( is_array( $iwData ) ) {
                        return Interwiki::loadFromArray( $iwData ) ?: false;
                }

                return false;
        }

        /**
         * Fill in member variables from an array (e.g. memcached result, Database::fetchRow, etc)
         *
         * @param array $mc Associative array: row from the interwiki table
         * @return Interwiki|bool Interwiki object or false if $mc['iw_url'] is not set
         */
        protected static function loadFromArray( $mc ) {
                if ( isset( $mc['iw_url'] ) ) {
                        $iw = new Interwiki();
                        $iw->mURL = $mc['iw_url'];
                        $iw->mLocal = isset( $mc['iw_local'] ) ? $mc['iw_local'] : 0;
                        $iw->mTrans = isset( $mc['iw_trans'] ) ? $mc['iw_trans'] : 0;
                        $iw->mAPI = isset( $mc['iw_api'] ) ? $mc['iw_api'] : '';
                        $iw->mWikiID = isset( $mc['iw_wikiid'] ) ? $mc['iw_wikiid'] : '';

                        return $iw;
                }

                return false;
        }

        /**
         * Fetch all interwiki prefixes from interwiki cache
         *
         * @param null|string $local If not null, limits output to local/non-local interwikis
         * @return array List of prefixes
         * @since 1.19
         */
        protected static function getAllPrefixesCached( $local ) {
                global $wgInterwikiScopes, $wgInterwikiFallbackSite;
                static $site;

                wfDebug( __METHOD__ . "()\n" );
                $data = array();
                try {
                        /* Resolve site name */
                        if ( $wgInterwikiScopes >= 3 && !$site ) {
                                $site = self::getCacheValue( '__sites:' . wfWikiID() );

                                if ( $site == '' ) {
                                        $site = $wgInterwikiFallbackSite;
                                }
                        }

                        // List of interwiki sources
                        $sources = array();
                        // Global Level
                        if ( $wgInterwikiScopes >= 2 ) {
                                $sources[] = '__global';
                        }
                        // Site level
                        if ( $wgInterwikiScopes >= 3 ) {
                                $sources[] = '_' . $site;
                        }
                        $sources[] = wfWikiID();

                        foreach ( $sources as $source ) {
                                $list = self::getCacheValue( '__list:' . $source );
                                foreach ( explode( ' ', $list ) as $iw_prefix ) {
                                        $row = self::getCacheValue( "{$source}:{$iw_prefix}" );
                                        if ( !$row ) {
                                                continue;
                                        }

                                        list( $iw_local, $iw_url ) = explode( ' ', $row );

                                        if ( $local !== null && $local != $iw_local ) {
                                                continue;
                                        }

                                        $data[$iw_prefix] = array(
                                                'iw_prefix' => $iw_prefix,
                                                'iw_url' => $iw_url,
                                                'iw_local' => $iw_local,
                                        );
                                }
                        }
                } catch ( CdbException $e ) {
                        wfDebug( __METHOD__ . ": CdbException caught, error message was "
                                . $e->getMessage() );
                }

                ksort( $data );

                return array_values( $data );
        }

        /**
         * Fetch all interwiki prefixes from DB
         *
         * @param string|null $local If not null, limits output to local/non-local interwikis
         * @return array List of prefixes
         * @since 1.19
         */
        protected static function getAllPrefixesDB( $local ) {
                $db = wfGetDB( DB_SLAVE );

                $where = array();

                if ( $local !== null ) {
                        if ( $local == 1 ) {
                                $where['iw_local'] = 1;
                        } elseif ( $local == 0 ) {
                                $where['iw_local'] = 0;
                        }
                }

                $res = $db->select( 'interwiki',
                        self::selectFields(),
                        $where, __METHOD__, array( 'ORDER BY' => 'iw_prefix' )
                );

                $retval = array();
                foreach ( $res as $row ) {
                        $retval[] = (array)$row;
                }

                return $retval;
        }

        /**
         * Returns all interwiki prefixes
         *
         * @param string|null $local If set, limits output to local/non-local interwikis
         * @return array List of prefixes
         * @since 1.19
         */
        public static function getAllPrefixes( $local = null ) {
                global $wgInterwikiCache;

                if ( $wgInterwikiCache ) {
                        return self::getAllPrefixesCached( $local );
                }

                return self::getAllPrefixesDB( $local );
        }

        /**
         * Get the URL for a particular title (or with $1 if no title given)
         *
         * @param string $title What text to put for the article name
         * @return string The URL
         * @note Prior to 1.19 The getURL with an argument was broken.
         *       If you if you use this arg in an extension that supports MW earlier
         *       than 1.19 please wfUrlencode and substitute $1 on your own.
         */
        public function getURL( $title = null ) {
                $url = $this->mURL;
                if ( $title !== null ) {
                        $url = str_replace( "$1", wfUrlencode( $title ), $url );
                }

                return $url;
        }

        /**
         * Get the API URL for this wiki
         *
         * @return string The URL
         */
        public function getAPI() {
                return $this->mAPI;
        }

        /**
         * Get the DB name for this wiki
         *
         * @return string The DB name
         */
        public function getWikiID() {
                return $this->mWikiID;
        }

        /**
         * Is this a local link from a sister project, or is
         * it something outside, like Google
         *
         * @return bool
         */
        public function isLocal() {
                return $this->mLocal;
        }

        /**
         * Can pages from this wiki be transcluded?
         * Still requires $wgEnableScaryTransclusion
         *
         * @return bool
         */
        public function isTranscludable() {
                return $this->mTrans;
        }

        /**
         * Get the name for the interwiki site
         *
         * @return string
         */
        public function getName() {
                $msg = wfMessage( 'interwiki-name-' . $this->mPrefix )->inContentLanguage();

                return !$msg->exists() ? '' : $msg;
        }

        /**
         * Get a description for this interwiki
         *
         * @return string
         */
        public function getDescription() {
                $msg = wfMessage( 'interwiki-desc-' . $this->mPrefix )->inContentLanguage();

                return !$msg->exists() ? '' : $msg;
        }

        /**
         * Return the list of interwiki fields that should be selected to create
         * a new Interwiki object.
         * @return string[]
         */
        public static function selectFields() {
                return array(
                        'iw_prefix',
                        'iw_url',
                        'iw_api',
                        'iw_wikiid',
                        'iw_local',
                        'iw_trans'
                );
        }
}