ClassicInterwikiLookup.php

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<?php
namespace MediaWiki\Interwiki;

use \Cdb\Exception as CdbException;
use \Cdb\Reader as CdbReader;
use Database;
use Hooks;
use Interwiki;
use Language;
use MapCacheLRU;
use WANObjectCache;

class ClassicInterwikiLookup implements InterwikiLookup {

    private $localCache;

    private $contentLanguage;

    private $objectCache;

    private $objectCacheExpiry;

    private $cdbData;

    private $interwikiScopes;

    private $fallbackSite;

    private $cdbReader = null;

    private $thisSite = null;

    function __construct(
        Language $contentLanguage,
        WANObjectCache $objectCache,
        $objectCacheExpiry,
        $cdbData,
        $interwikiScopes,
        $fallbackSite
    ) {
        $this->localCache = new MapCacheLRU( 100 );

        $this->contentLanguage = $contentLanguage;
        $this->objectCache = $objectCache;
        $this->objectCacheExpiry = $objectCacheExpiry;
        $this->cdbData = $cdbData;
        $this->interwikiScopes = $interwikiScopes;
        $this->fallbackSite = $fallbackSite;
    }

    public function isValidInterwiki( $prefix ) {
        $result = $this->fetch( $prefix );

        return (bool)$result;
    }

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

        $prefix = $this->contentLanguage->lc( $prefix );
        if ( $this->localCache->has( $prefix ) ) {
            return $this->localCache->get( $prefix );
        }

        if ( $this->cdbData ) {
            $iw = $this->getInterwikiCached( $prefix );
        } else {
            $iw = $this->load( $prefix );
            if ( !$iw ) {
                $iw = false;
            }
        }
        $this->localCache->set( $prefix, $iw );

        return $iw;
    }

    public function resetLocalCache() {
        $this->localCache->clear();
    }

    public function invalidateCache( $prefix ) {
        $this->localCache->clear( $prefix );

        $key = $this->objectCache->makeKey( 'interwiki', $prefix );
        $this->objectCache->delete( $key );
    }

    private function getInterwikiCached( $prefix ) {
        $value = $this->getInterwikiCacheEntry( $prefix );

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

    private function getInterwikiCacheEntry( $prefix ) {
        wfDebug( __METHOD__ . "( $prefix )\n" );
        $value = false;
        try {
            // Resolve site name
            if ( $this->interwikiScopes >= 3 && !$this->thisSite ) {
                $this->thisSite = $this->getCacheValue( '__sites:' . wfWikiID() );
                if ( $this->thisSite == '' ) {
                    $this->thisSite = $this->fallbackSite;
                }
            }

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

        return $value;
    }

    private function getCacheValue( $key ) {
        if ( $this->cdbReader === null ) {
            if ( is_string( $this->cdbData ) ) {
                $this->cdbReader = \Cdb\Reader::open( $this->cdbData );
            } elseif ( is_array( $this->cdbData ) ) {
                $this->cdbReader = new \Cdb\Reader\Hash( $this->cdbData );
            } else {
                $this->cdbReader = false;
            }
        }

        if ( $this->cdbReader ) {
            return $this->cdbReader->get( $key );
        } else {
            return false;
        }
    }

    private function load( $prefix ) {
        $iwData = [];
        if ( !Hooks::run( 'InterwikiLoadPrefix', [ $prefix, &$iwData ] ) ) {
            return $this->loadFromArray( $iwData );
        }

        if ( is_array( $iwData ) ) {
            $iw = $this->loadFromArray( $iwData );
            if ( $iw ) {
                return $iw; // handled by hook
            }
        }

        $iwData = $this->objectCache->getWithSetCallback(
            $this->objectCache->makeKey( 'interwiki', $prefix ),
            $this->objectCacheExpiry,
            function ( $oldValue, &$ttl, array &$setOpts ) use ( $prefix ) {
                $dbr = wfGetDB( DB_REPLICA ); // TODO: inject LoadBalancer

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

                $row = $dbr->selectRow(
                    'interwiki',
                    ClassicInterwikiLookup::selectFields(),
                    [ 'iw_prefix' => $prefix ],
                    __METHOD__
                );

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

        if ( is_array( $iwData ) ) {
            return $this->loadFromArray( $iwData ) ?: false;
        }

        return false;
    }

    private function loadFromArray( $mc ) {
        if ( isset( $mc['iw_url'] ) ) {
            $url = $mc['iw_url'];
            $local = isset( $mc['iw_local'] ) ? $mc['iw_local'] : 0;
            $trans = isset( $mc['iw_trans'] ) ? $mc['iw_trans'] : 0;
            $api = isset( $mc['iw_api'] ) ? $mc['iw_api'] : '';
            $wikiId = isset( $mc['iw_wikiid'] ) ? $mc['iw_wikiid'] : '';

            return new Interwiki( null, $url, $api, $wikiId, $local, $trans );
        }

        return false;
    }

    private function getAllPrefixesCached( $local ) {
        wfDebug( __METHOD__ . "()\n" );
        $data = [];
        try {
            /* Resolve site name */
            if ( $this->interwikiScopes >= 3 && !$this->thisSite ) {
                $site = $this->getCacheValue( '__sites:' . wfWikiID() );

                if ( $site == '' ) {
                    $this->thisSite = $this->fallbackSite;
                } else {
                    $this->thisSite = $site;
                }
            }

            // List of interwiki sources
            $sources = [];
            // Global Level
            if ( $this->interwikiScopes >= 2 ) {
                $sources[] = '__global';
            }
            // Site level
            if ( $this->interwikiScopes >= 3 ) {
                $sources[] = '_' . $this->thisSite;
            }
            $sources[] = wfWikiID();

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

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

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

                    $data[$iw_prefix] = [
                        '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 );
    }

    private function getAllPrefixesDB( $local ) {
        $db = wfGetDB( DB_REPLICA ); // TODO: inject DB LoadBalancer

        $where = [];

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

        $res = $db->select( 'interwiki',
            $this->selectFields(),
            $where, __METHOD__, [ 'ORDER BY' => 'iw_prefix' ]
        );

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

        return $retval;
    }

    public function getAllPrefixes( $local = null ) {
        if ( $this->cdbData ) {
            return $this->getAllPrefixesCached( $local );
        }

        return $this->getAllPrefixesDB( $local );
    }

    private static function selectFields() {
        return [
            'iw_prefix',
            'iw_url',
            'iw_api',
            'iw_wikiid',
            'iw_local',
            'iw_trans'
        ];
    }

}